Designer:
Shannon Ley

Project Category:
Bookshelf Speakers

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
$500 – $1,000

Project Description:
These satellite speakers were designed for use on my desk where space is at a premium and listening volumes are low.

At present I am running them with a Logitech subwoofer, but eventually I will build a matching sub with USB DAC (to run off my computer), DSP and amp.

Design Goals:
The design goals were:
– Very small footprint
– Look awesome
– Great mid to high frequency sound

The design goals were NOT:
– High volume
– Deep bass (the sub will do that from under my desk)

Driver Selection:
They use AuraSound NS2-326-8AT drivers with the mounting tabs sanded off and glued in place.

Enclosure Design:
Closed box design

Enclosure Assembly:
They are made from stacked layers of CNC-routed MDF and covered in walnut veneer. The mounting brackets are polished aluminium.

Connection is via flush mounted banana plug sockets with laser etched positive terminal indication.

Tips & Tricks:
My top tip: receive and measure the drivers before getting the CNC cutting done (rather than going by the spec sheet)! I had to make some slight modifications to accommodate the wiring and the holes in the brackets for the drivers are slightly too large.

Conclusion:
Overall they sound great over the mid to high frequency range and have great imaging. With a sub, they make a great, small footprint desktop system.

About the Designer:
Former automotive engineer and tinkerer, now entrepreneur and tinkerer.

Parts Used:
AuraSound NS2-326-8AT, Part # 296-252
Custom machined and bent aluminium brackets
Custom CNC routed 12mm thick MDF pannels
Walnut veneer
Banana plug sockets

Designer:
Nick

Project Category:
Portable Speakers

Project Level:
Beginner

Project Time:
8-20 Hours

Project Cost:
$100 – $500

Project Description:
Ported portable speaker system with two 3 inch full range speakers, one 8 inch woofer and a Kenwood headunit

Design Goals:
Wanted a portable speaker system for at work that has the sound I like and didn’t have to put a lot of money into it because of it being a shop system. Don’t wanna ruin expensive things. Also wanted to re-purpose a Kenwood headunit to control everything.

Driver Selection:
FaitalPro 3FE25 3″ Professional Full-Range Woofer 4ohm. Part # 294-1103

AT-8030 8″ Treated Paper Cone Woofer with Rubber Surround 4ohm Part # 299-2150

Enclosure Design:
Ported enclosure roughly .5 cubic foot. Enough space to let the PartsExpress buyout 8″ woofer cause avalanches from deep low bass

Enclosure Assembly:
Made from wood used to build Noah’s Arc

Crossover Design:
No external crossover was used. High pass and low pass filters were done on the kenwood headunit as well as subwoofer control (the 8″ woofer) and 3 band parametric eq

Products Used:
AT-8030 8″ Treated Paper Cone Woofer with Rubber Surround 4ohm
Part # 299-2150

FaitalPro 3FE25 3″ Professional Full-Range Woofer 4ohm.
Part # 294-1103

Sure Electronics 2x100w Class D Audio Amplifire Board (T-amp Technology)

Tips & Tricks:
I originally had 3.5″ speakers in there and went down to 3″ speakers so I just put hot glue to fill the space around the full ranges. Doesn’t look the cleanest with the glue showing but it does allow some of the blue LED light from inside the box to show around them aswell as the ports

Conclusion:
The buyout speaker has an impressive preformance for it only costing under $20. The full ranges sound very detailed, although harsh with the “sss” sound at times still sounds very nice and clear. The Kenwood headunit is by far the coolest feature in this build. Has Bluetooth, usb and aux connectivity. Will charge device If connected to usb. Variable color led display and plenty more features. A voltage stepdown was needed because the Kenwood runs off 14v and the power supply is 24v I believe.

About the Designer:
Probably the most awesome person you’ll ever meet. Unless you meet me.

Designer:
Electrowiz

Project Category:
Portable Speakers

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
$100 – $500

Project Description:
A combined two input stereo amplifier with tone controls and stereo speakers in a custom enclosure. Used as a synthesizer practice amp and for general music enjoyment.

Design Goals:
Three key design goals: 1) Stereo amp with good room filling volume, and tone control. 2) Portable size, easy to sit on table, shelf, or floor. 3) A custom design style retro candy apple red with a feel of the hot rods/Fenders guitars from the 60’s.

Driver Selection:
Part # 297-428 – HiVi B3N 3″ Aluminum Driver Round Frame

Enclosure Design:
Custom design, sealed enclosure, stereo. 1.5 Cu/Ft per speaker.

Enclosure Assembly:
Used PVC sheets, from hardware store. Bonded with two part epoxy. Inside lined with rubberized coating. Speaker boxes filled with poly-fiber.

Crossover Design:
Direct, no cross-over.

Products Used:
Spkr Part # 297-428 – HiVi B3N 3″ Aluminum Driver Round Frame

Amp Part # 310-300 – Lepai Tripath-LP2020A+ mini audio amp
Modified per website:http://techtalk.parts-express.com/forum/tech-talk-forum/45432-modding-the-lepai-t2020a

Silver flake spray, Candy apple red transparent spray. Final acrylic clear coat.

Tips & Tricks:
The PVC sheets are nice in that they are easy to machine, inexpensive and don’t have grain to worry about and tend not to have un-wanted resonances like wood. Need to be prepped well for painting.

Conclusion:
The amp sounds great, used in large lab with a two synthesizer input, plenty of volume Bass, Midrange, and high end solid.
Sounds bigger than it looks

About the Designer:
Worked in Aerospace, and Bio-med electronics design work. Hobbies are electronic music synthesizer building and music composing and recording.

Designer:
Thepensname

Project Category:
Car Audio

Project Level:
Beginner

Project Time:
20+ Hours

Project Cost:
Over $1,000

Project Description:
Love my car, despised my stock stereo.

The stock 6×8 speakers in my 2010 Ford Edge were quite possibly the worst sounding speakers I’d ever had in a vehicle. I was already missing my 3″ FaitalPro dash speakers & Pioneer tweets I’d previously purchased for my 1992 Olds Cutlas Ciera wagon from . This wasn’t an exclusively Parts Express build, but I felt PE played a big enough role to cover just a tad more than the subwoofer’s contribution to my project.

Design Goals:
To feel the sounds we can’t hear, or at least play lower than 98% of the aftermarket systems out there, with clarity throughout the 20-80hz range. To compete in Springfest (MECA Sanctioned Stereo Competition) in SQ division.

Driver Selection:
Part # 295-518 Dayton Audio UM18-22 18″ Ultimax
Part # 264-1034 Tymphany NE25VTS-04 1″ Silk Dome Tweeter
Part # 091-340 Gold Binding Post Banana Jack Pair Extra Long Shaft with Solder Tabs
Part # 260-779 Cast Frame #8-32 Speaker Mounting Kit

Enclosure Design:
PE Recommended Sealed (Home Theater):
4 cubic ft. (net internal, not including driver) for an f3 of 31 Hz, f10 of 18 Hz with a Qtc of 0.72
Being sealed, I opted for traditional fiberglass fill over poly, walls covered.

Enclosure Assembly:
3/4″ MDF – Glued & Screwed
Skim Coat of Bondo

Crossover Design:
I run a completely active set up on a Pioneer DEH80-PRS, sub is crossed at 80 HZ 18db/octave. Head unit compenates for phase/time/level, full DSP on board.

Conclusion:
This is the first 18″ I’ve owned, I didn’t expect the level of accuracy in the upper bass tones. I’d expected something that sounded like a massive 18″ in my trunk, but once the system was tuned in the transition was seamless from 6.5″ Silver Flutes to UM18-22. I also own two Rockford T1D412’s, they can get loud, but they miss everything below 28hz (at least in my head). The UM on test tracks will easily play below what I can hear, it gives me that urge to explore audio tracks on my daily drives that may have notes I hadn’t heard before. Deadmau5 track “Right this second” for example, makes for a great lower back massage. The only downfall here is that I feel compelled to remove the spare tire and build a 7-8 cu ft box to hold an additional UM18, luckily they are on backorder or I’d be back at again. There is absolutely no need for a second one, but lets face it, we don’t buy 18″ subwoofers for cars b/c we need them.

1st Place in “Street/Modified” Sound Qualtiy @ Springfest

About the Designer:
Jack of All Trades and Master of Interior Design, Dad, attended Vanderbilt for EE, worked in virtually every field known to Homer Simpson for those that keep track (minus nuclear), car audio fanatic raised on Chopin & Bach with guilty pleasures for really bad bass cd’s from the 90’s and everything in between.

Parts Used:

Project Parts List

Designer:
Derek Minor

Project Category:
Home Electronics

Project Level:
Advanced

Project Time:
20+ Hours

Project Cost:
Over $1,000

Project Description:
I’ve always been a fan of the games of my youth. In the past I built an arcade cabinet that had just MAME emulated games (arcade games) and was very utilitarian. So after I sold it I decided to build the arcade that I had always wanted.

The cabinet has over 30,000 games and will play M.A.M.E, NES, SNES, n64, Atari, Dreamcast, Genesis, and pretty much anything else you would ever want to play. It also doubles as a karoke machine and a jukebox.

I spent over 6 months on this designing and building, I tried to incorporate all the ideas and tricks I could to make it a system that would last and be easily maintainable for many many years to come.

Design Goals:
The goal was to build a system, that looked good, sounded good, reliable, and was easily maintained and/or updated.

Driver Selection:
299-208

Enclosure Design:
I designed this to have a small footprint, while still having a large control and display area.

Enclosure Assembly:
The box is made entirely of 3/4″ mdf. The sides are 2 sheets of 3/4″ screwed together to give the cabinet more rigidity during intense gaming sessions. The rear access panels are all attached using easily removable bolts for quick access to the electronics. I made sure to add in a number of fans to keep the heat down in such a small area.

Tips & Tricks:
Plan and plan some more, due to the constrictive space I had to layout all of the electronics, bracing and access panels ahead of time to make sure I didn’t get into a bind with fitment.

Conclusion:
This was an extremely challenging build, but well worth the results. I love it, and everyone that has seen the design assumes it was ‘store-bought’. The sound as well as video is loud and punchy which fits perfectly into the arcade vision.

About the Designer:
I like building things: speakers, arcades, furniture, anything I see on the internet or just come up with myself. Gaming and audio have always been a passion of mine.

Products Used:

The sound starts with 8 of the HiWave BMR12’s. These little guys play relatively loud and decently down to 150hz, this allowed me to use one 10″ subwoofer in a rear firing vented enclosure to fill in the low end. Remember space is at a premium in the design.

Along with the HiWave’s and the sub, I used a Nakamichi active crossover and 2 old Coustic car amps. Because the system is really just a fancy computer, I wired in 2 separate ATX power supplies. One controls the computer and temperature sensing fans, and the other controls the audio and led lighting.

I used a HP zr30w 16:10 monitor for the display, and off the shelf led strip lighting to light up the marquee and under the cabinet.

Designer:
Tim

Project Category:
Portable Speakers

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
Under $100

Project Description:
Boombox

Design Goals:
Good highs and banging bass

Driver Selection:
2 – 6 1/5 kicker 2way

Enclosure Design:
Ported

Conclusion:
Does what I wanted to plus more.

Designer:
Twain

Project Category:
Bookshelf Speakers

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
$100 – $500

Project Description:
A versatile, easy to duplicate and very nice looking casing concept for the legendary Paul Carmody’s Speedsters.

Design Goals:
Layering of CNC machined casing parts (made from any kind of wood) with seamlessly integrated BR pipe. No sealing or glueing required for assembling. Just screws.

Driver Selection:
Speedster Reference Design:
– TangBand W4_1720 Mid-Woofer
– Fountek Neo 1.0

Enclosure Design:
Bassreflex with front port.

Enclosure Assembly:
Trapezoidal. Layered wood CNC machined. No glue or sealing required.

Crossover Design:
Speedster Reference Design. Potentially to be fine-tuned.

Conclusion:
A good project for my new DIY milling machine. Looking forward to the first soundcheck.

About the Designer:
R&D Engineer – Professional Audio Video Broadcast Business (RCR/Thompson Multimedia/Alcatel).

Designer:
John H

Project Category:
Bookshelf Speakers

Project Level:
Beginner

Project Time:
8-20 Hours

Project Cost:
$100 – $500

Project Description:
This project remakes the B452 speaker. They look nice for being so inexpensive. The front baffle looks to be 3/8 inch thick with black vinyl that was thermal formed into the cut outs. The rest of the cabinet is black vinyl.

At my first listening session I was impressed with the highs. With more detailed listening you could hear some flaws. Of note, the bass needed some help when stand mounted. The stock speaker would best against the wall or in a corner.

Design Goals:
The first phase of the project was to see what could be done with a crossover addition to the stock B452 speakers.

The second phase is a complete speaker (driver) transplant into the B452 cabinets. After modeling the new CF120 woofer it seemed like a perfect fit for the B452 cabinet. The ultimate goal was to create a surround and HT speaker that could reach to 80 Hz where a subwoofer would pick up.

Driver Selection:
The project started in reverse as I had a pair of the CF120 drivers and started looking for a cabinet that would fit the CF120 woofer. The B452 cabinets looked about the right size and the CF120 frame seemed to be close in size to the stock woofer.

After some modeling and testing the stock B452 tweeter did not match well with the CF120. The ND28F-6 was chosen for its small flange size and the ability to provide a lowish x-o point to help with CF120 break up.

Enclosure Design:
The B452 cabinet was estimate to be 3 liters. After subtracting the driver and port the volume for the CF120 woofer should be 2.5 liters. This is enough volume for a low response F3 of 67 Hz with the CF120.

Enclosure Assembly:
Disassembly of the B452 starts with removing the woofer. Clip the wires close to the woofer so they can be reused. Clip the tweeter wires next to the terminal cup, they cannot be reused, with a pliers pry out the resistor and capacitor.

There’s not much assembly but the CF120 woofer is not a drop in. The woofer hole needs to be enlarged so the driver can be recessed to fit the grill.

My technique for recessing the woofer is to mount the woofer on the surface though the existing screw holes. You will need longer screws for this. With the driver mounted score/ cut around the outside of the woofer with a sharp utility knife. Cut enough to go through the black plastic. Take your time and make sure you know where the knife is going if you slip.

Remove the CF120 driver. Remove the vinyl. Use a utility knife to cut horizontally at the bottom of the existing recess in the MDF. Using a sharp chisel, with one corner at the bottom of the recess tilt the chisel and bite off a piece of the MDF. Walk the chisel around the cut out. Finish the cut edge with sandpaper. Use a black marker to hide imperfections.

There’s not much MDF thickness for the driver mounting screws so glue blocks of wood under the driver mounting holes. The screw holes should be predrilled and the screws run in to make sure the blocks don’t get pushed out.

Use gasket tape on the CF120 driver to ensure an airtight seal.

For the tweeter, the through hole is too large to mount the ND28. There are several ways to fill the hole. I chose to cut a disc with a hole saw and glue it in the hole then drill it out the next day with a smaller hole saw. Note that the tweeter through hole is not centered in the recessed hole.

The tweeter recessed hole is larger than the flange of the ND28, It’s optional but I filled the gap with some peal and stick craft felt.

After a couple of experiments, it looks like the best location for the port is in the bottom of the cabinet. The center is 4.4 cm, 1.75 inches from the back and 4.8 cm, 1.875 inches from the side. The port length was designed for the proximity of the port to the surface. The port length is 16.5 cm, 6.5 inches from end to end. New .53 inch high feet were installed.

Although the picture shows a notch in the port flange it’s not required to accommodate the feet.

The crossover is mounted on a board and attached to the side of the cabinet. The terminal strip shown in the pictures hit the back of the CF120 woofer so the crossover had to be mounted higher up the side of the cabinet. The crossover in a picture is the test x-o but the final x-o is very close.

The cabinet has about 4 oz. of poly stuffing around the port tube. A piece of batting is glued to the port tube to hold the stuffing in place. There is no stuffing above the opening of the port.

Crossover Design:
Two (2) crossovers were designed. One for the stock drivers with a sealed cabinet and one with all new drivers ported.

All the measurements were done with the grills in place.

The stock B452 speakers run the woofer full range then add the tweeter to fill in the top range. The tweeter has an electrolytic cap and resistor.

The modified x-o has the stock woofer notched to smooth the baffle step then the tweeter rolls in to support the highs similar to the original. The big change was to drop the mid response for better alignment. This will not be very noticeable. Unless you like tinkering and want the perception of more bass, put the money toward upgrading the drivers.

The ND28 and CF120 crossover is Linkwitz Riley 4th order at 2,000 hz. The CF120 has some breakup that needs to be pushed down with a tank filter.

The part list calls for a 12.5 ohm resistor on the tweeter which is not a noticeable difference from the 12 ohm shown.

Tips & Tricks:
Inside the cabinet the MDF blocks and glue can be pried up with pliers, screwdriver or a chisel to make smoother mounting surfaces.

Conclusion:
The Dayton CF120 and ND28 sound good for such a small speaker.

Small cabinets are nice until you have to start modifying them. That said with a chisel and a few hole saws this project should not be too difficult to accomplish.

About the Designer:
John is a member of the Speaker Design Team

Project Parts List:

Designer:
Fred van Sand

Project Category:
Portable Speakers

Project Level:
Advanced

Project Time:
20+ Hours

Project Cost:
$100 – $500

Project Description:
This is a handtruck with a light duty powered speaker built in for monitoring and setup. It will transport my synthesizer.

Design Goals:
Light, mobile, as near flat and as loud as can be accomplished for as little money as possible.

Driver Selection:
1 ea; Dayton Audio Bass Shaker; 300-386:
2 ea; Tectonics Exciters; 297-224

Enclosure Design:
panels delimited by hand truck dimensions…ratio 1:1.6 overall;
woofer panel long sides; 1:1.4, tweeter panel long sides 0.67:1

Enclosure Assembly:
48″h x 16″w x 3 1/2 thick except add 3 1/2 for blade

Crossover Design:
xkitz 2 way 24 dB active crossover set at 200 Hz

Tips & Tricks:
the overlapping panels on the back reduce drumming without increasing the weight.

Conclusion:
goals have been reached

About the Designer:
Fred van Sand is a professional musician who travels extensively. For ten years, he earned a living as a bench technician with a large audio repair service. Although he has retired from the repair end of the business, he maintains his music interest and hobbies at electronics. He builds everything wooden in his assemblage of instruments and has done so throughout his career.

Products Used:
Sure Power Amp board 2 x 50 320-310
Mean Well Power Supply 24 V 320-314
Xkitz 2 way Active Crossover
3ea: neutrik male xlr connector 092-034
3ea: female combo connector 092-043
1 ea: 2 pole slide switch (Radio Shack)
ac power connector 090-442
21 linear feet 1 x 4 poplar Home Depot
2 x 4 sheet 1/4″ plywood
24″ x 32″ 1/8″ luan plywood
box of kreg pocket screws 1 1/4″
16″ 1 1/8″ dowel
2 ea: salvaged 2″ casters
2 1/2″ x 1/4″ bolts (axles)
Heavy felt
batting
GE silicone caulk
Elmer’s wood glue

Designer:
dynamo

Project Category:
Tower Speakers

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
$500 – $1,000

Project Description:
A compact three-way floor-standing speaker featuring a ribbon tweeter, 4″ mid, and 8″ woofer in a vented enclosure.

Design Goals:
The goal was to design a compact and lightweight floor standing speaker with high resolution of detail and to be able to stand on it’s own for music reproduction without absolute need a sub for two channel listening.

Driver Selection:
The tweeter is a Fountek neocd1.0 (296-701) and is very nicely priced for a true ribbon driver. It has an attractive aluminum face and is full of that ribbon goodness. The mid is a Scan Speak 10F/4424G and was chosen as one of extremely few drivers this small that can do what it does. The woofer is a Dayton Reference RS225-8 (295-356) and is truly a nice driver, priced at probably half of what it could be for what it delivers in quality.

Enclosure Design:
The enclosure is roughly 35L gross, with a faceted birch ply baffle and curved body. The body does not need to be curved so long as baffle dimensions are maintained. The mid is in it’s own separate pvc enclosure. The crossover schematic provides further details.

Enclosure Assembly:
The enclosure consists of a highly cross-braced frame wrapped in hardboard (1/8″ Masonite) I used only two layers for weight, however more may be used for additional rigidity. The baffle was wrapped in gloss black VVivid vinyl. Photos and additional info on the build can be found in the Tech Talk project gallery here: http://techtalk.parts-express.com/forum/speaker-project-gallery/1285035-transcend

Crossover Design:
The crossover employs third order electrical filters throughout. The crossover points are 400 and 5khz. The filter orders were not sought out, but were what worked out for phase alignment and system impedance. The higher order filters do help heep the aluminum woofer resonance low, and help keep the mid and ribbon clean. The pic of the crossovers were prior to some minor changes, but everything is the same aside from a few resistors.

Tips & Tricks:
The downside to a revealing speaker is tht they are not kind to bad recordings. For this reason I voiced them a little warm which takes away a little ribbon goodness, but allows for better listenability on streaming audio and downloaded music. If you listened to high quality tracks more often, simply increase the resistance of the resistor in parallel with the tweeter a little.

Conclusion:
I am happy with them, they are a revealing speaker, which is good, and exactly what I wanted.

About the Designer:
Been tinkering with speakers most of my life, learning more every day. I learned a ton on the Tech Talk forum where there is a wealth of knowledge and resources and am very thankful for the help I have gotten from the members there.

Project Parts List

Scan Speak 10F/4424G
All crossover component values available at PE

Designer:
xander

Project Category:
Bookshelf Speakers

Project Level:
Intermediate

Project Time:
8-20 Hours

Project Cost:
$100 – $500

Project Description:
This is a compact speaker with relatively flat response and decent bass extension. My daughter is moving off to college and wanted a pair of speakers to take with her. She asked for something that would not take up much space, but would sound good when playing her music.

The selected color is a bit brighter that might normally be considered for bookshelf speakers.

Design Goals:
The goal was a relatively flat response as far below 100 Hz as possible with a small enclosure.

Driver Selection:
Given the tradeoff of size and ability to move air, I looked for a 6 1/2″ woofer with a good XMax. It ended up a choice between the Dayton DCS165 and the TangBand W6-1139SIF. The DCS has a higher sensitivity and power handling where the TangBand has a bigger Xmax. In the end I went with the Dayton as it was easier to match with the other drivers.

I’ve used the Tymphany BC25SC06-04 before and like the way it sounds. It has a bit of a on-axis bump from 10K-20K and is more sensitive than the other drivers, so it needs a little damping down.

While a 2-way would have been easier, the DCS165 needs to be crossed pretty low to get rid of its tendency to beam in the middle frequencies. The Tymphany can’t go too low, so it was time to dig around for a small midrange to fill in the gap. The Eminence Alpha 4-4 turned out to be just about right for both sensitivity and power handling.

Final selection:

Dayton Audio DCS165-4 6-1/2″ Classic Subwoofer, 295-198
Eminence Alpha 4-4 4″ Full-Range Pair, 290-4010
Tymphany BC25SC06-04 1″ Textile Dome Tweeter, 264-1028

Enclosure Design:
The entire box measures 8 1/2″ W x 12 3/4″ H x 8″ D. Edges are all routed with a 3/4″ round over bit to produce a box with not points or sharp edges to scrape against.

I used a 1 1/2″ diameter chrome tailpiece (any hardware store) cut to length for the vent. While venting at the back limits placement a little bit, it looks better than a deep hole in the front.

A bag of Poly-Fill split evenly between the two speakers worked well.

Enclosure Assembly:
Double Rabbet joints were used for all sides. Wood glue and strap clamps were all that was necessary to assemble the boxes.

Crossover Design:
I modelled a wide variety of crossovers in WinPCD, ranging from 1st through third order. During testing, I found the best balance of complexity versus quality was a very simple mix of: 2nd order on the Woofer to reduce the DCS165’s spike at 2K, 1st order on the midrange and tweeter. There is a resistor inline on the tweeter to bring its response to the same level as the others.

Conclusion:
The speakers are performing well. They were drive hard during the course of a graduation party, with a broad range of music. These seem well suited to both Jazz and Rock.

About the Designer:
Built a few different speakers from bookshelf to medium floorstanding. Enjoy the entire process of cabinet construction, driver selection, crossover design, and final measurements and tuning.

Project Parts List:

1.0 MH Inductor, Bourns 5258-RC
0.5 MH Inductor, Bourns 5256-RC
100 uF 50G BiPolar Capacitor, Nichicon UES1H101MHM1TO
10 uF 50V BiPolar Capacitor, Nichicon UES1H100MPM1TD

Designer:
18hands

Project Category:
Loudspeakers/Cabinets

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
Over $1,000

Project Description:
Based on the popular QSC K series. This is our take on probability, construction, style, and staying true to the DMT (Directivity Matched Transition) concept. While providing a community built sound system that can work in outdoor settings for the PEX summer festival in the Sound Camp.

Design Goals:
Many festivals around the country are big into building stages and camps that have a theme. It’s a challenge to bring the community of festival goers together to pitch into funding special art projects and sound systems. Typically, what happens is that sound is either rented or store bought. In this case, we wanted to build it ourselves and try to inspire other camps to do likewise. Currently, the standard sound systems at festivals are Funktion One (very pricy) and the good old QSC K series (somewhat affordable). We wanted to build on the familiar set up of the QSC system since we knew we can get them to sound comparable to Funktion One with the right drivers and design. Most folks know the amount of power they need when someone is bringing a QSC K setup. This is a critical consideration since these types of festivals is BYOP (bring your own power). Also, the amps in the K series are easy to connect and can easily replace the QSC system that is being rented or borrowed. Unlike store bought QSC KW153 series, we wanted the towers to be modular for portability and easy storage. Then we wanted to add a subwoofer to each tower. However, we wanted the woofers to match the waveguide of the towers. This means that this was different than a KSub since it has two 12 inch woofers. We wanted to use 15 inch woofers to match the towers. They had to be rugged and be able to handle chaotic festival environments.

Driver Selection:
Quantity 4 Celestion TF1530 (Bass/Mid Bass)
Quantity 2 Celestion TF0615MR (Midrange)
Quantity 2 Celestion Celestion CDX1-1730 (Highs)

Enclosure Design:
The towers are High, Midrange, Midbass, and Bass.

We separated this into 3 different enclosures.
Hand built and cut cherry wood for the High/Mid.
For the Midas and bass we used Denovo Audio Knock-Down MDF 3.0 cu. ft. Subwoofer Cabinet for Dayton Audio 15″ Ultimax Subwoofer.

We would integrate 1 QSC K amp into each enclosure plus 1 QSC Ksub amp for the 2 dedicated bass units.

Wave guides for the high and midrange were set to 75 degrees of coverage. This coverage matches the 15inch woofer coverage of the mid bass and bass.

Enclosure Assembly:
Getting the Denovo Audio Knock-Down MDF 3.0 for 15″ subwoofer enclosure was easy to glue together and paint with Duartex. We added some custom color to the duratex from the art store. It’s a deep dark purple with sparkles.

We then added some rubber feet. Penn-Elcom F1686 Rubber Cabinet Foot 1.57″ Dia. x 0.61″ H. To the subwoofer boxes.

We used a jigsaw to cut out the hole for the QSC K amps to fit in the back of the subwoofer enclosures. These amps have a custom harness so it was barely reaching the 15 inch sub. But we got it to connect. We then drilled holes for the speakon female connectors so we can send power to the mid/high. We drilled the crossover into the inside of the subwoofer enclosure and connected that to the speakon connectors. We went with NL2 for each driver instead of NL4. Just to keep things separate in case of troubleshooting at the festival.

We then had to drill holes for the 15 inch metal grill. It had one of those mounting bolts with the teeth. This is something that needs to be done with the metal fasteners to give you leverage or the teeth won’t sink in and the screw will go into the soft wood. We then just screwed in rubber feet for protection.

For the high and mids we bought some hard cherry wood from the local hardware store. This proved to be more difficult to sand and than the MDF subwoofer enclosure. We then designed a box with an angle. That way we could also use them as floor monitors if needed. Cutting them with a jigsaw was difficult but we cut out holes for the 2 waveguides which were square and so we didn’t need to cut in a circle. We then mounted the compression driver and mirage to the wave guides. Finally, we stained the high/mid cabinet red and painted the edges with dark purple duratex to seal the enclosure. We also painted the very top and bottom with duratex to protect from typical spills. Rubber feet were added.

Crossover Design:
The crossover was OEM from QSC.
It was input 129 hz to 20 khz and then split into midrange and highs. Cut off was around 350 hz.

The QSC AMP also had a built-in cross over for the mid/bass as long as the settings are set to ext. sub. If not then it also becomes bass. Engage the ext. sub setting to get the 100 Hz high-pass filter.

The final KSub amp also has cross over for dual subwoofer drivers. So we connected the two dedicated subwoofers for this amp.

Tips & Tricks:
Build your own speakon speaker cables. This is waterproof and beefy. It locks so kids can’t pull them out. Even big kids.

I feel like every speaker system should have this instead of banana plugs.

Get L shaped driver connectors for the drivers. This means there is less of a chance of the interior speaker wire to disconnect.

Set up separate connectors for each driver. This helps to make sure there is a good connection and provides possible set up for additional amps.

Use dremel to cut the holes for the handles. The jig saw was difficult to control with hard wood.

Conclusion:
Being able to match the subs to the mid-bass driver made a big difference as far as clarity and overall clean bass. Having a separate enclosure for the 15 inch drivers really helped sound imaging and separation. Carrying this set up in sections really helps when moving them across camping ground where a truck isn’t allowed or can reach. Overall, it was fun and we were able to get more out of the QSC amps with the upgraded drivers. I feel that this set up sounds just as good as any Funktion One medium sized set up for a fraction of the cost.

About the Designer:
Software engineer and product manager for TV broadcast software industry. Former pro DJ and current audiophile.
First time to build speakers was this project. Home set up is Mirage Omnipolar towers. 3 year burning man veteran. Love going camping. My advice is, build a sound system you can take camping.

Project Parts List

Designer:
Dan Poinsett

Project Category:
Tower Speakers

Project Level:
Intermediate

Project Time:
8-20 Hours

Project Cost:
$100 – $500

Project Description:
Coneccentric is a small, floorstanding, 3-way loudspeaker featuring a midrange section that consists of four Aura NS2-326-8AT (Whisper) 2″ drivers surrounding a Dayton ND20FB-4 3/4″ tweeter. The bottom end is supplied by a Dayton DS175-8 and two matching passive radiators operating in just over 0.4 cu ft. The overall dimensions are 32″ H x 7.5″ W x 7.5″ deep.

Design Goals:
The major design goal was to experiment with the idea of mounting a tweeter concentrically to a group of small midrange units to see if there is any sonic benefit. There are currently several different types of coaxial 2-ways that all have their own set of compromises. I had not seen this arrangement before and was curious about the results. In order to keep the drivers in a tight grouping to minimize comb filtering, I settled on using very small drivers for the midrange and treble and then supplement the bottom end with a woofer. Going through various layouts, I settled on the woofer + 2 PRs format mostly for aesthetic purposes.

Driver Selection:
I knew there would be some drawbacks to using multiple midrange drivers in this layout, so I wanted to keep them as close as possible. This led me to the square-frame mini-drivers, of which the Aura Whisper seemed the most capable and amongst the smallest. Since I was going 3-way, this driver’s lack of bass capability was a non-issue.

The tweeter was easily chosen as the ND20FB-4 is a proven performer and happens to mount the same way as the Whisper, and has a similar square frame that can squeeze right in the square void left by the four Whispers.

Once I had chosen my format, I needed a woofer that had matching PRs available. Since the mid/tweeter combo would fit in the space of a 6.5″ woofer, the Dayton DS175-8 seemed a natural choice.

Enclosure Design:
The enclosure is a simple rectangular prism 32″ x 7.5″ x 7.5″ that is divided into two sections: a 0.12 cu ft sealed midrange enclosure in the top 1/4 of the tower and a 0.4 cu ft bass reflex enclosure for the woofer and PRs in the bottom 3/4 of the tower. There are window braces every ~8″ in the woofer section to minimize panel resonances.

The passive radiators were tuned low for an EBS type alignment that was then augmented by lowering the upper frequencies in the woofer passband in the crossover, effectively trading efficiency for low frequency extension flat to about 40Hz. This was achieved by adding 35g to each passive radiator.

I initially tried to put the active woofer in the bottom position to gain the benefit of the boundary reinforcement, but I could not get rid of a very annoying midbass hump in that position. I subsequently moved the woofer to the top position, just below the midrange section. This cleared up the boominess and provided much better woofer-to-midrange integration.

The midranges and tweeter were mounted on a 1/2″ thick MDF “plate” that I cut to be the same diameter as the DS175-8 woofers.

Enclosure Assembly:
I used solid poplar for this project because 1) the panels are narrow enough that the soft wood should not resonate too much, 2) I love the color variances of poplar sealed with a natural finish, 3) it is inexpensive for solid wood. As can be seen in the photos, each speaker consists of four identical poplar panels for the front, rear and sides. Each panel is dadoed or rabbeted to accept either the top/bottom panel, the window braces, or the mid/woofer divider. The edges of the poplar panels were mitered, then the four panels were glued and “rolled up” with the internal braces/divider in place, then clamped with strap clamps. Once glued, I ran a cove bit down the 32″ corners to help conceal the imperfect glue joint. This left just barely enough room for the nearly 7″ woofer diameter.

The top panel is solid walnut, which protrudes just slightly from the surrounding poplar edges. The bottom panel is MDF (painted black) that is inset just slightly to partially conceal the floor spikes that are mounted in the bottom panel.

I cut all the holes on the front panels after the box was glued up. This is very scary, but I wasn’t sure the front panel could withstand the force of the strap clamps with holes cut so close to their edges. Thankfully, it turned out fine.

The midrange opening was made by first cutting a recess 9mm deep where the plate would sit and then cutting the hole the rest of the way through only in the necessary areas (with a jigsaw), which leaves a mounting lip all the way around the inside of the hole (see pics). I then rabbeted the midrange plate to leave a 3.5mm lip on the front to match the thickness of the DS175 flange. This allows firm mounting engagement between the midrange plate and the lip in the midrange mounting hole. I used 8 screws as I was screwing directly into a soft wood. Mounting the mids and tweets was relatively straightforward, although I did have to use an adjustable hole cutter for the tweeter to get the hole size just right. The Whispers were a perfect press fit into the hole left by a 1-7/8″ hole saw. All drivers were mounted from the rear with 1/2″ screws.

Crossover Design:
Things got a little dicey here! As mentioned before, the woofer did not want to cooperate when mounted low to the ground, but as soon as I moved it to the top position, it played nicely. Using the LCR circuit to tame the impedance peaks, I was able to tilt the top end of the woofer’s passband down to be in line with the “extended” portion of the EBS alignment, effectively extending what should have been a 55Hz F3 down to below 40Hz – of course, at the expense of efficiency. A standard 2nd order electrical circuit crosses the woofer over nicely at about 350Hz.

Now the on-axis tweeter response was horrible due to the equally located disturbances from the Aura cones as well as the 3.5mm lip that the tweeter is concentric with. As this is a short tower, however, and even seated listeners will be 10-15 degrees off axis in the vertical, I used this as my design axis and the tweeter response here was smooth as silk.

The midrange response was the complete opposite – very smooth on the tweeter axis as all four drivers were equidistant from the mic, but pretty rocky off axis as the comb filtering started to materialize. Luckily, on the design axis of 10-15 degrees up, the first cancellation happens above the 4300Hz crossover frequency, so within the normal range of standing and sitting, near and far, the midrange group and the tweeter remained in a range of flat FR and good integration.

A 3rd order electrical highpass on the mid and tweeter and a 2nd order lowpass on the mid created good 4th order acoustical roll-offs with decent phase tracking as can be seen in the reverse null witness lines on the FR graph.

Conclusion:
This was cool and I learned a few things from this project. I already knew the ND20FB-4 was a solid performer in a really compact package, but now I can put the Aura Whisper in that category too. It has a very unique and open architecture that pack just about as much speaker as possible in a box that size. The open back leads to a very open and natural sound. I’m looking forward to using this driver again.

The DS175-8 was a pleasant surprise too, because I thought it would be the same build level as the matching SD series DVC woofers, but I think they are actually a step up. The large magnet controls the cone very well and in this small enclosure with the PRs, this woofer just wouldn’t give up. I was getting after it pretty good with a 300 watt amp and it didn’t mind at all. This is a good woofer at this price point.

As for the system – it’s a great sounding system that can put out a lot more sound than you’d think based on its size. Also, I really like the aesthetic, just because it’s different. But… I can’t say my experiment was a success. I don’t think I am hearing any sonic benefit from the concentric mounting format. There may be a higher level of coherence in the midrange/tweeter transition, but it’s not strong enough for me to sure. These drivers were well suited enough to the format that it worked out well, but I’m not sure the format itself adds much benefit.

About the Designer:
I have been building speakers for over 20 years and am a member of the Parts Express Design Team.

Project Parts List

Designer:
John H

Project Category:
Freestyle Speakers

Project Level:
Intermediate

Project Time:
1-8 Hours

Project Cost:
$100 – $500

Project Description:
This project uses the Buyout Titan 15-inch woofer in an open baffle configuration.

Design Goals:
The goal was to make something that would sound great with the Titan 15-inch woofer and be colorful. The design needed to be relatively easy and inexpensive to make.

Driver Selection:
The project started with the Titan 15-inch woofer. As these were going to be used open baffle, the dipole roll off meant at least 2 woofers are needed to reach reasonable volume levels. More woofers would have been better but this complicated the baffle design.

To keep the project simple a passive 2-way crossover design would be used. A small 2-inch full range driver would keep the directivity wide, but would have low sensitivity. This required the use of multiple mid-tweeters to match up with the Titan pair.

The Tang Band W2-1803S 2″ Neodymium Poly Full Range Driver, fit these requirements and had the benefit of an open frame due to the neo magnet. The TB W2-1803S also has a bit of a high frequency rise that would help with the off axis response.

Four of the Tang Band W2 were used to match the Titan pair sensitivity. The Tang Band W2 has an FS of 155 Hz.

Enclosure Design:
The open baffle is a single piece of ¾ inch plywood. The flat baffle eliminates cabinet resonances associated with other open baffle designs and makes for a simple passive crossover design.

The lower woofer is placed close to the floor to pick up some room gain. The narrow mid-tweeter baffle is used to keep constant directivity at higher frequencies.

The rounded baffle shape was chosen and as it’s more interesting than a rectangular slab of plywood. The shape can be changed but is critical near the mid-tweeters. An optional squared off shape is shown in the drawings.

All the edges have a ¼ inch round over. The baffle is tilted back at 4.5 degrees.

Enclosure Assembly:
To cut the baffle shape, two of the baffle blanks are screwed together then the shape is cut out with a router and spiral up-cut bit. The woofers are surface mounted. Check the woofer frame opening and cut out the woofer holes.

The mid-tweeters are recess mounted. The first step is to measure mid-tweeters and cut the through holes with a hole saw. The back side of the holes are then chamfered. A large rectangular recess is then cut on the front of the baffle with a template and a router with a bushing.

The stand tilts the baffle back at 4.5 degrees. The baffle is attached to the stand with bolts and cross dowels available from Rockler Woodworking. The stand could also be permanently attached.

Crossover Design:
The Titan woofers and Tang Band mid-tweeters have reasonable distortion in the 400 to 1,000 Hz range. The woofer’s first dipole null is near 1,000 Hz.

After listening, an x-o at 600 Hz with Linkwitz Riley second order slopes works well. This keeps most of the vocals away from the Titan drivers without stressing the Tang Band mid-tweeters too much.

The measured sensitivity is about 85 dB at 2.83 volts, 1 meter, 50 Hz. The estimated max power at x-max of the system 15 to 20 watts, about 98 db assuming some floor gain. The impedance stays above 8 ohms so they should be OK for the tube amp guys.

The Titan woofers are wired in series; the Tang Band mid-tweeters are two series groups wired in parallel.

While not shown on the schematic the 22-ohm resistance is made by wiring 12-ohm and 10-ohm resistors in series.

Tips & Tricks:
These speakers will sound best when they are spaced away from walls and other boundaries by 3 feet.

Despite having two 15-inch woofers these are not going to get very loud before the woofer bottoms out. Consider using a high pass filter of a single 500 uF capacitor ahead of the woofer’s inductor if this becomes a problem.

Conclusion:
The sound quality per dollar is quite high. With a few more parts the response could have been flatter but the added cost did not fit with the budget goal of this design.

This designed used the “purple glitter cone” Titan woofers, but it appears that any of the Titan 15 inch 4 ohm woofers would work in this application. I’d choose the woofers with a QTS of over 1.3 first. Other drivers from Eminence or GRS will require a different crossover.

About the Designer:
John is a member of the Speaker Design Team

Project Parts List

TBD Binding posts, Banana Jacks, or terminal cup 2

Project Category:
Tower Speakers

Project Level:
Intermediate

Project Time:
8-20 Hours

Project Cost:
$100 – $500

Project Description:
These are my first try at speaker building. I’ve had this shape stuck in my head for 20 years and it needed to be freed. These are front channel and are to be paired with a sub. I used Baltic birch ply and sycamore for the materials. The inside is a crazy array of baffles ….. Because it was fun and I was trying to keep the drivers from cancelling each other out. The box is separated into two ; where each has a pair or mids.

Design Goals:
I was looking to build something that would fill the room with sound and not have any particular focal points. I guess I wanted to create sound that would fill a room like fog.

Driver Selection:
Pyramid W64 6.5″ mid bass woofers. PE #295-025
Tymphany 1″ textile dome
264-1028

Conclusion:
These came out sounding crisp but I need to work out a few weak points still.

About the Designer:
Im a exhibit builder and have a BFA in sculpture.

Designer:
Chris N

Project Category:
Freestyle Speakers

Project Level:
Beginner

Project Time:
1-8 Hours

Project Cost:
Under $100

Project Description:
The Zivojinovich Birdhouse Speakers are a compact speaker, designed to be used outdoors, but would work just as well on a bookshelf or desk.

Design Goals:
The primary design goal is weather resistance. A secondary goal is low cost, being used outdoors, they are less protected and may succumb to damage easier than if they were indoors. Being inexpensive drivers eases the pain should they need to be replaced. A small size is desired for a variety of locations, such as wall mounting. The birdhouse design fits in with the outdoor location, so they don’t stand out.

Driver Selection:
I searched my inventory of drivers and chose the Aura NS35-255-4A woofers. The tweeters are an un-named 1″ plastic cone tweeter designed for car use. I bought these from PE years ago, I think they may be Onkyo’s. Both drivers have poly cones, a material that should hold up to moisture better than untreated paper, and more dent resistant than a metal cone.

Enclosure Design:
The enclosure is made to emulate a traditional birdhouse. They are 8″ in height, about 7″ at their widest point, and 5.25″ deep. The lower, red, part of the cabinet is 4.5″ wide and 4.5″ deep. The cabinet is sealed.

Enclosure Assembly:
Enclosure assembly is basic, using butt joints, held with glue and brad nails. The top is removable, held in place by screws. The tweeter is an odd shape, so I traced its shape onto the back of the baffle. The bulk of material was removed with a 1″ Forstner bit. The rest of the shape was chiseled out by hand. The front of the tweeter through hole was routed over with a 45 degree chamfer bit, which looks nicer than a 90 degree opening, and also boosts the tweeters low end. The same bit was used to chamfer the rear of the woofers opening on the baffle, giving it much needed breathing room in the narrow cabinet. The cabinet is lightly stuffed with poly fill.

The Rustic finish starts with Kilz primer, 2-3 coats. I’ve found it to be durable, and the white color shows through the distressed edges nicely. The red and blue color are standard spray paint, another 2-3 coats. The top coat is wipe on polyurethane, satin finish. I applied the first coat with a rag, before the paint was completely dry. This allowed me to remove some of the paint as I applied the poly, giving the cabinets a weathered appearance. After the first coat dried, I used #0000 steel wool to both smooth and distress the finish. The second coat was then applied and smoothed with more steel wool before the third and final coat.

Crossover Design:
The frequency response and impedance of both drivers was measured in cabinet. I used Passive Crossover Designer (PCD) to simulate the crossover. The woofer was relatively flat, aside from a peak in the low end, and gets reinforcement when wall mounted, and its top end rolled off well enough that I left it unfiltered. The tweeter had slight low end rise, presumably from the mild waveguide. A 4.7uf cap rolls it off. The tweeters level matched the woofer closely, no padding deemed necessary. The tweeter is connected with normal polarity, the woofer’s polarity is reversed. The responseis best when listened to at or below the woofer.

Conclusion:
This was a fun project. They sound decent, although they are light on bass. They were easy to assemble, and the crossover, which performs well, is as simple as it gets.

About the Designer:
I’ve building and modifying speakers almost as long as I’ve been listening to them.

Products Used:
Aura NS35-255-4A

Buyout Plastic tweeter

4.7 uf capacitor:

Press fit terminal cup: 

8 x 3/4″ Screws: 

Designer:
Chris N

Project Category:
Bookshelf Speakers

Project Level:
Beginner

Project Time:
1-8 Hours

Project Cost:
100 – $500

Project Description:
A simple, straightforward , 2 way speaker suitable for a bookshelf or on stands.

Design Goals:
Good performance that can be placed in different locations, without a large price tag.

Driver Selection:
Dayton DA175 295-335
Peerless/Vifa DX25 264-1020

I chose the DA175 because I’ve used them before, I like the way they sound and perform, and they have held up very well. I hadn’t used the Vifa DX25 previously, and wanted to see how well it got along with the Dayton woofer.

Enclosure Design:
The cabinet is .75″ MDF, 8.5″ wide, 13.5″ tall, and 10.75″ deep. The enclosure is sealed, and roughly .42 cubic feet. The baffle is double thickness, two layers of .75″ MDF laminated together. The drivers are flush mounted, and the rear of the woofer cutout has a 45 degree bevel for breathing room. The sides of the cabinet are tied together with a brace, also made from MDF.

Enclosure Assembly:
The cabinet was assembled using Titebond wood glue and many clamps. The edges were trimmed with a flush cutting router bit. The same router bit has a slight, V shaped protrusion that cuts a groove, which I used to cut along the joint where the MDF joined. Usually those areas will, over time, expand and contract differently, leaving a slight mismatch. Since the plan was to paint these a glossy color, I did not want to have the seams show through. I painted the cabinets with orange Rustoleum, and while the small grooves I cut are black, an homage to a brand of musical instrument amplifiers and cabinets.

Crossover Design:
The crossover is an asymmetrical Linkwitz/Riley 4th order at about 1700hz, with an L-pad on the tweeter. The drivers are connected with the same polarity. I aimed for a fairly flat response in the room I listen to them in, but the tweeter level can be adjusted by increasing or decreasing the value of either resistor to taste, or to accommodate difference in rooms.

Tips & Tricks:
Use black paint or a Sharpie to black out the driver recess. The same marker works well for highlighting the groove cut on the outside of the cabinets.

Conclusion:
enjoy the sound these speakers produce. The DA175 has good bass from a relatively small, sealed, enclosure. The DX25 doesn’t draw attention to itself, it blends nicely with the woofer.

About the Designer:
My name is Chris and I’m addicted to building and listening to speakers.

Parts Used:

Designer:
JavadS

Project Category:
Bookshelf Speakers

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
$100 – $500

Project Description:
This project was conceived after I decided to make the trip out to MWAF 2016 from my home in California. After looking over the competition categories, I decided to enter in the $200 or less category and everything went from there!

What I came up with was a 2-way “bookshelf” speaker with full range sound and ample bass, which drivers cost less than $200 to purchase and some really cool tech entered to make it sound like a much more expensive speaker.

Design Goals:
I had several design goals that I needed to meet:

1 – Make the best sounding speaker possible including flat frequency response, good clarity and excellent imaging. Part of that would be locating the tweeter and woofer w/in 1/2 wavelength of the crossover frequency to each other, as well as minimizing enclosure resonances and vibrations.

2 – Speakers that were portable, I decided to ship my speakers to Ohio and needed to be sure they weren’t too big or unruly.

3 – I wanted to do something special, something that used a lot of the new skills and concepts I’ve learned about this year, something that had a lot more tech that appears on the surface.

Driver Selection:
Since I was on a tight budget, I had limited choices, but often limiting constraints often spark the most innovation and creativity (See F1 racing for example!).

I was able to pick up the Vifa BC25SC06-04 1″ Textile Dome Tweeter #264-1028 for under $15 each, well rated tweeter with good smooth frequency response, most importantly it had a very small frame and looked like it would cross over well at around 2000hz.

For the woofer I was looking for a 6.5″ woofer that had smooth response past 2000rpm but was also able to produce great bass in a smallish enclosure, thanks for a Parts Express sale I was able to pick up the Tang Band W6-1721 6-1/2″ Underhung Midbass Driver #264-874 for $75 each, boom I was in business! I was truly enamored with the massive motor assembly and couldn’t wait to get my hands on this beast!

Enclosure Design:
I wanted to achieve several things with the enclosure:

1 – Lightweight – so I could travel with them, considering a driver that weighed in over 5lbs alone, this would be important. I decided to use 3/4″ Arouco Plywood, this is a dense and high quality plywood with minimal voids, it is very flat and strong and really nice to work with. The pine veneer is very thin which demands care if you’re not going to paint or veneer your enclosure, which I did not. I did not use any bracing as to keep the weight down.

2 – Low Resonance – to allow the cleanest and uncolored sound from the drivers, and since I wasn’t going to be using bracing, I needed to get creative. Along came CLD or Constrained Layer Dampening, you can google it to read more. Basically this is an anti-vibration technique that adds dampening to a stiff layer such as a sheet of plywood by sandwiching a soft layer of rubber between two stiff pieces. After doing some experimentation, I found a nice technique that worked well and attached the baffle to the enclosure in an isolated fashion.

3 – Good Bass – The TangBand woofer modeled well in a 1.3 cubic foot enclosure, I wanted to make it smaller but the modeling looked really good and should rival the average 8 or 10″ subwoofer. I included a amply sized 3″ port with generous 1.5″ radii on the inside and out. I ended up tuning the port to 43hz for the best performance, length around 5″ or so.

Enclosure Assembly:
Assembly of the basic enclosure was quite straight forward, I built a box from 3/4″ plywood, there isn’t any metal in the assembly of these, all seams are glued with Titebond II Premium wood glue.

Where things got complicated was the front baffle! Once the basic enclosure was made, I cut two intersecting holes in the base front baffle, these would be the breathing/clearance holes for the woofer and tweeter.

Once that was finished, I smeared on a 1/16″ layer of 50 durometer polyurethane adhesive, once dry this remains quite pliable or elastic and works well to create the CLD effect needed to dampen vibrations. On this layer of polyurethane adhesive I bonded a layer of 1/4″ birch plywood, then onto that another layer of adhesive and the final front baffle. What I ended up with was a 1/4″ layer sandwiched by two layers of viscoelastic polyurethane adhesive. This created a very acoustically dead front baffle, a rap on it with a metal wrench results is a dead thud vs. the resonant musical note you’d normally get from a piece of wood.

To continue the CLD treatment, I treated the inside of the enclosure with a foil CLD sound deadening material, this adds CLD to the inside plywood walls and greatly dampens the panel vibrations. I also glued a layer of 1.5″ open cell egg crate foam to all inner surfaces as well as added some poly fill (tuned by ear) to create a smooth and mellow bass sound w/o any boominess or resonance.

The last trick I used was to bring the already small framed tweeter even closer to the woofer center by routing the woofer frame into the plastic tweeter frame by about 3/8″, this brought the driver centers to about 1/2 wavelength of the approx 1700hz crossover frequency, which helps minimize diffraction and lobing.

I personally love the look of plywood so I always show off the seams with pride and finish them off nicely. In this case I sourced a 1.5″ radius router bit and modified my router to allow it to be run, this guy is a handful but it makes very nice big radii! The front baffle was treated with this large radius to reduce the effects of diffraction on the front baffle. The port also got a 1.5″ radius to eliminate turbulence, the rest of the enclosure got a 3/4″ radius.

The back of the enclosure was stained with Minwax Espresso stain, then the 1/4″ layer on the front baffle was stained red to highlight it, and the front of the baffle was left unstained. The whole enclosure was sprayed with Minwax semigloss polyurethane to finish.

Crossover Design:
I modeled the passive crossover several different ways, this was the most effort I’ve ever put into a passive crossover and I am really pleased with the results! Initial modeling showed a 12db Bessel on the woofer of about 1800 and the tweeter of about 2000 would give flat response, so that’s where I started.

Initial frequency response measurements showed the tweeter about 6db hot of the woofer and with a very rising response to 10kHz. Adding a zobel smoothed out tweeter response noticeably, I padded the tweeter about 5db down and after playing with component values, was able to get a very smooth response of about +-2dB from 40-20kHz.

I lost track of the exact components, but leave a comment below if you’d like help replicating one, I need to pop one out of the box and write down the final values.

Tips & Tricks:
Many are outlined above, but here are a few more:

1 – I highly recommend using the red corner clamps pictured in the box construction, they make assembling the box a breeze and save a lot of time.

2 – Test everything on scrap so when you do it on your final piece, it’s not an experiment. Once I prove it works on some scrap material, then I’m confident to do it right the first time on my final piece.

3 – Get a good mic measuring system like Omnimic or similar, ears are only so good for tuning a speaker but they’ll know it once it’s tuned correctly using measuring equipment!

Conclusion:

I am very pleased with these and they scored a respectable 7.2/10 at MWAF, considered “above average”. But most importantly, these sound very good in my listening room, they don’t need a subwoofer and can play loud bass in room to 30hz, as much as many 10″ subwoofers I’ve heard. Imaging and clarity are excellent, these speakers belie their size and can really fill a room with virtually realistic sound.

About the Designer:
Javad Shadzi manufactures high performance auto products during the day and speakers during every other waking minute he can steal away when he’s not spending time with his incredible wife and 4 children.

Project Parts List

Designer:
Shawn Kipka

Project Category:
Under $200

Project Inspiration:
DCT = Dispersion Control Technology

The inspiration for this design came from the realistic 3D sound I enjoy listening to when I have two small drivers facing upwards on a desk during driver evaluation. I also had a desire to build a system that didn’t have a crossover point where the human ear is most sensitive (2-4 kHz).

Project Description:
The design is a 2-way floor standing system with semi omnidirectional dispersion. The wide dispersion is accomplished by firing the high frequency driver in a mostly upwards direction. An acoustic lens and reflector focus the sound semi Omni directionally.

Design Goals:
Design a system that provides realistic sound that most people could enjoy listening to with the total driver cost being less than $200.

Driver Selection:
The full range driver has its own sealed chamber at the top of the enclosure with a cone shaped section behind the driver to reduce the back wave reflection affects. The woofer is a Peerless 6-1/2 inch HDS Aluminum cone. Due to the systems low 1 kHz crossover frequency, I could take advantage of the reduced mid-bass distortion that and aluminum cone offers without the need for an electrical notch filter to suppress the cone break-up resonance.

The Woofer is a Peerless 6-1/2″ Aluminum Cone #264-1086
The Driver that is pointed upward is a Dayton Audio PS95-8 3-1/2″ Full range #295-349

Enclosure Design:
The shape of the enclosure is very much a form follows function type of design. The enclosure is made narrower at the rear so that the surface area on the top baffle farthest from the full range driver is reduced. The wall are non parallel to hinder the creation of standing waves. The geometry of the folded MLTL was designed so that the exit ports crossed the line path to provide the rear exit. The extra side panel detail allowed the main panels to have cut outs to increase the MLTL cross section area where the ports cross and make the panel stiffer and heavier. The front vertical baffle round overs help smooth baffle refraction and make the front baffle narrower increasing stiffness. The alignment for the woofer is a folded Mass loaded Transmission line with two 1-5/8″ ID ports on the rear panel. The transmission line also has a separate chamber at the bottom tuned to suppress unwanted line resonances. The full range driver is housed in its own sealed compartment that has a cone shaped section behind the driver to help reduce standing waves.

Enclosure Assembly:

The exterior panels are 18mm baltic birch plywood except for the top baffle that is solid Qtr. sawn white oak and the black painted side panels are 1/2″ MDF. The internal partitions are 1/2″ baltic birch plywood and the cone section of the full range enclosure is two cardboard cones from a craft store glued together to increase strength. The enclosure panels are put together wood glued miter or butt joints. After I built the prototype enclosure and had issues with aligning the panels I built fixtures to help align the panels for the final version. The vertical round overs are made by cutting a section out of a 3″ ABS drain pipe that was epoxied to the chamfer panel behind it.

Crossover Design:
Designing the crossover was done rather unconventionally. I started using the PCD spreadsheet and had to set a large offset from the baffle for the tweeter (full range in my case). I started with 1st order electrical slopes and found that I could combine the woofer baffle step compensation with the low pass filter by using a larger 5mH inductor. A ERSE Super Q inductor was chosen for lower DCR to not overly affect enclosure tuning. The simulated crossover was about 600Hz and a flat on axis response was possible with a single capacitor on the full range driver and inverting the phase like is usually done with linkwitz-riley circuits. After tweaking the crossover frequency is closer to 1kHz.

Parts Used:

Designer:
Paul Kittinger

Project Desctiption:
The BALMORA is a high-performance, 3-way, floor-standing speaker with its woofer in a mass-loaded transmission line (ML-TL) that can be built for a moderate cost.

Design Goals:
This speaker was designed specifically to compete in the under-$200 category at the 2016 MWAF without its operating range and overall performance being unduly limited by this cost constraint.  In other words, what was desired was a speaker with high performance but moderate cost.

Driver Selection:
The first driver I chose was Tectonic’s TEBM46C20N-4B Balanced Mode Radiator for the midrange.  A couple of commercial speaker manufacturers use this driver in their products, one of which is Dennis Murphy (Philharmonic Audio) who speaks highly of it.  It performs quite well over a wide frequency range, is very small and is happy working in a really small, sealed box.  Having picked this midrange driver with its extended range, I was able to use a reasonably priced, small-dome tweeter because it wouldn’t need to be crossed below 3 kHz (and the midrange driver could allow crossing even higher).  Too, a small-diameter tweeter usually has better dispersion than is typical of 1-inch dome tweeters. So, I chose the SB Acoustics SB19ST-C000-4 because it has a reputation for very good performance.  With the standard list prices of the midrange and tweeter totaling to just over $78 for both speakers, there was a maximum of ~$121 available for a pair of woofers to keep the total driver costs under $200.  I had decided upfront to use a 6-1/2 or 7-inch woofer.  I wanted to use a Dayton Audio RS180-4, a driver that I’ve used in a couple of previous designs, because it performs really well in a transmission line, has a bit higher sensitivity due to its 4-ohm impedance and a compatible price.  Seeking advice, I was told that since the Tectonic driver has a 4-ohm impedance, it might be tough to come up with a crossover having an impedance characteristic that wouldn’t be difficult to drive and/or wouldn’t be rather complex.  So, I started looking for another woofer with a higher impedance.  The only one I found that I knew would work well in a transmission line, and had a list price in the ballpark, was the SB Acoustics SB17NRX35-8.  The first vendor I looked at had a list price of a bit more than $62, which would make the total driver cost about $4 too high.  I was disappointed, but then I looked at a second vendor and found their standard list price was just under $58.  Yea, that got total driver costs down to just over $194!

Enclosure Design:
As already stated, the cabinet design is an ML-TL.  More specifically it’s a single-fold line that’s 5-feet long, with the first foot of the line comprising ~1/3 of the line’s total volume and an area just over twice the area in the remaining 4 feet of the line.  This is a variation on a so-called coupling chamber but with the woofer’s center located at the transition from the larger area to the smaller area instead of being located entirely within the coupling chamber.  On the cabinet’s back panel is the mass-loading port; together it and the 1/4-wave resonant frequency created by the line’s length tunes the system to just under 30 Hz, resulting in a predicted anechoic f3 of 37 Hz, an f6 of 30 Hz, and an f10 of ~25 Hz (see the modeled bass response graph).  For the midrange driver there’s a sealed box (3.5 inches square and 1.25 inches deep internally), creating a volume of ~15 cubic inches.  The tweeter’s center is 37 inches above the floor, a generally good height.

Enclosure Assembly:
I used 18-mm Baltic Birch Plywood for the cabinet, except for one piece of 1/2-inch MDF for the divider that creates the folded line (see the cabinet drawing).  Internal cabinet dimensions are 7.5 inches wide, 9.5 inches deep and 38.5 inches high. There’s a solid, horizontal divider (Brace D) near the bottom of the cabinet that creates a compartment for housing the crossover assembly.  The top 12 inches of the cabinet form the coupling chamber and the first 12 inches of the line’s length, with Brace A creating the transition to the line’s remaining 4 feet and smaller area.  Polyester fiber is located from the top of the cabinet down the front to Brace C, 6 ounces in the coupling chamber and another 4 ounces below it.  Installing the fiber uniformly by weight creates a stuffing density of 0.75 lbs/ft3.   There’s a side-to-side brace in the middle of the coupling chamber made from a 1-inch diameter dowel.  All of the braces and the MDF line divider are 8 inches wide and installed in 1/4-inch-deep dadoes in the cabinet’s sides.  Dimensions for the mass-loading port are 2-inch ID and 3-inch length.  The relative locations of the port and woofer in the line optimize the shape of system’s overall response.  The small enclosure for the midrange is filled with denim insulation (more on this in the crossover design discussion).  I made a bezel from solid, 1/2-inch thick walnut, glued to the main baffle where the drivers are mounted, thus providing both esthetic and structural benefits. The back sides of the woofer and midrange through-holes are chamfered at 45 degrees.  I also made decorative feet from solid walnut.  The cabinet is covered with maple veneer and it, the bezel and feet were finished with 5 coats of satin polyurethane (first two coats brushed on and the last 3 wiped on).  On its feet the cabinet stands 40 inches tall, has a width of 9 inches and a depth of 11 inches deep.  Connections for the driving amplifier are a pair of binding posts on the back panel near the bottom.

Crossover Design:
Dan Neubecker designed the crossover and it uses 13 components (see the crossover schematic).  The woofer crosses to the midrange at ~480 Hz with asymmetrical slopes, 4th-order on woofer and 2nd-order transitioning to 4th-order on midrange.  The midrange crosses symmetrically to the tweeter at ~3800 Hz with LR2 slopes (see the simulated responses with crossover in place).  Dan optimized this design based on the 30-degree, off-axis measurements because that best matched the overall power response when compared to the sum of 0-15-30-45 and 60º measurements.  Overall, the impedance magnitude varies between 4 and 8 ohms from 60 Hz to 20 kHz, barely dropping below 4 ohms between 100 and 200 Hz.  Impedance phase is also quite good overall, staying between -20 and +20 degrees from just over 100 Hz to 10 kHz; there’s an impedance magnitude of 8 ohms to counter a -60 degree phase angle just below 60 Hz.  Note that the tweeter is wired in reverse polarity from both midrange and woofer.  I built my pair of crossovers with the components shown on the schematic at a total cost of just over $199, essentially identical to the total driver costs.  Substituting components from PE with lower costs, but still using polypropylene capacitors where called out, total component costs for a pair should not exceed $165.  Regarding the midrange’s sealed box, I originally lined it with 1/2-inch thick foam rubber.  Dan’s initial driver measurements showed several glitches in both impedance magnitude and phase from the midrange, with a prominent glitch at ~2 kHz.  So he experimented with other materials in this chamber, ending up with a 3-1/2-inch cube of denim insulation to replace the foam rubber because it resulted in a much smoother midrange response.

Conclusion:
A pair of BALMORA speakers can be built for $500 or less, depending on how you finish them and any changes you might make to crossover components choices.  You could dispense with the solid walnut bezel if desired.  The 2.83v/1m sensitivity ended up at 85-86 dB, and even though the impedance is generally 4 ohms from 60 Hz to 1 kHz, it doesn’t present a difficult load for the driving amplifier.  How do they perform and sound?  For my initial listening session I gathered up 5-6 demo CDs I had taken to a several DIY events, giving me 25-30 short tracks containing a good variety of music.  My first comment to my wife was, “these are REALLY good”!  She was also listening and commented, without any prompting from me, that the high frequencies (like from piccolos, violins in their upper ranges and percussive instruments) were reproduced prominently (where appropriate) and accurately without any harshness or stridency.  After more extensive listening I was really pleased with the sound, finding no need to tweak the crossover.  The sound is very well balanced across the frequency spectrum.  With only 6-1/2 inch woofers, these aren’t likely to rattle windows, but a pair of them will safely generate 99-100 dB SPL (at 1 meter) from ~40 Hz on up.  The overall sound is spacious (if it is in the source), sweet (without being rolled off) and quite articulate (without being “ruthlessly revealing”).  Some of this is due to the Tectonic midrange driver, which performs way above its pay grade IMO, but more important, to Dan’s excellent crossover design.