Fisher XP7 upgrade

Designer:
Mort

Project Category:
Loudspeakers/Cabinets

Project Level:
Advanced

Project Time:
20+ Hours

Project Cost:
Over $1,000

Project Description:
Take a pair of 1965 Fisher XP7s and modernize them but keep their vintage look.

Design Goals:
Create a good three way design that will fit the vintage speaker box.

Driver Selection:
I decided to go with all Dayton audio drivers. I like the look of the drivers and was able to make them work in my existing cabinets with some modification to the front baffle.
DSA315-8 Woofer PN # 295-534
RST28A-4 Tweeter PN # 275-131
RS52AN-8 Midrange PN # 285-020

Enclosure Design:
The original Fisher XP7 is a sealed enclosure with sub enclosures behind the midrange drivers. I decided to keep them sealed, and removed the original sub enclosures, the new midranges are a sealed back design, and I wanted to take advantage of as much cabinet volume as possible.

Enclosure Assembly:
I had to carefully remove the original grills as they were nailed on. I Plugged the original holes in the baffle that I was not going to use with with new MDF and wood glue. I modified the original tweeter hole the same way and cut the new hole using a palm router and some custom templates. I had to plug, and re cut the Terminal cup hole on the back of the enclosure as well. I made the original Grills removable with the small 3/8 neodymium magnet kit that Parts express sells. I then refinished the exterior and used Exohyde coating for the baffle and back of the cabinet. The cabinet is stuffed with poly-fill.

Crossover Design:
I used Xover pro to design the crossover. I went with a 750 Hz and 2500 Hz crossover points. I used second order filters on the low pass and high pass filters and a first order solen split on the band pass filter. I went ahead and incorporated the impedance EQs on all the filters. I wired the speakers so they can be bi-wired with separate amps between the woofers and the high frequency drivers. I built a separate filter board for each driver.

Conclusion:
This is the first time I have done this and I couldn’t be happier with the results. The speakers sound very clear and articulate. The bass needs a little boost with the tone controls but sounds great. I have played them for friends and family, and everyone was very surprised at how well they turned out.

About the Designer:
I have been an Aircraft structures mechanic for 25 years and an audiophile all my life.

Project Parts List: