Speaker Related Projects

   2-Way Ribbon Tweeter Speakers
(Vifa and Pioneer. May-2020)

   Transmission Line Speakers
(Aborted attempt at a TL. September-2012)

   Acoustic Research AR-4x Rehab
(Rehab of a garage sale find. January-2016)

   Infinity RS-4000 Rehab
(Rehab of a garage sale find. June-2015)

   Polaris
(A tall, thin, upwards firing omnidirectional speaker. May-2010)

   Shiva_PR15
(A powered subwoofer using a 12" driver and 15" passive radiator. Jan-2010)

   Can-Less
(A computer speaker; redux. December-2005)

   Can-Can
(A computer speaker in a light canister. Jan-2005)

   Sonosub
(10" vented subwoofer in a cardboard tube, powered by a Parapix amp. May-1999)

   MTM Center Channel Speaker
(A Madisound design. Nov-1997)

   2-way Surround Speakers
(5" woofer and 1" tweeter. July 1997)

   3-piece mini system
(6" DVC bass module mated to 4" car speaker. June 1997)

   3-way Vented Floorstanding Speaker
(vented 10" woofer, 5" mid and 1" tweeter in a 4 ft tower. Summer 1995)

   NHT1259 Subwoofer
(A 12" woofer in a sealed architectural pedestal. Winter 1994-95)

   Inexpensive Speaker Stands
(Particle board, sand and spray paint. Fall 1994)

   2-way satellite
(6.5" woofer and 1" tweeter. Summer/Fall 1994)

Audio Electronics Related Projects

  900 MHz Audio Receiver
(Better use for bad headphones. Jan-2008)

  Buster - A Simple Guitar Amp
(Perfect for the beginner. Jan-2010)

  A PC-based Audio Console
(Use a PC to play tunes. Jan-2010)

  LM-12 Amp
(Bridged LM-12 opamps. Aug-2003)

   CeeDeePee
(A CD player and FM tuner from spare computer parts. Oct-2002)

   Quad 2000 4-Channel Amp
(Premade modules by Marantz. May-1998)

   Zen Amp and Bride of Zen Preamp
(by Nelson Pass. Apr-1997)

Articles

  Using Wood in Speakers FAQ
(Work in progress)

   MDF FAQ for speaker builders

   Woodworking Tools for the DYIer
(HomeTheaterHiFi.com Oct-1998)

  Some Thoughts on Cabinet Finished for DIY Speakers

   Large Grills Made Easy

   Some Parts Suppliers
(Outdated)

Other Useful Stuff

   DIY Audio Related URLs

  Veneering Primer
(by Keith Lahteine)

   How to get a Black Piano Finish
(by DYI Loudspeaker List members)

   Sonotube FAQ
(by Gordon McGill)

   Excerpts from the Bass List
(Oldies but Goodies)

DIY Loudspeaker List

  DIY Loudspeaker List Archives

Acoustic Research AR-4x Rehab

This rehab project was another garage sale find. The AR-4x are not sought-after like their AR-3a sibling so I had no qualms with making changes to the speaker both inside and out. The cabinet was structurally sound but the finish was very poor. This model originally came in oiled walnut, pine, and birch and the one I got was walnut. Deep scratches were all over the exterior and some surfaces were water stained. The bulk of the restoration involved carefully sanding the veneer and applying new stain and oil for a rich looking finish. Here are both speakers sitting over a Fisher MC-3010 receiver (with 8-track tape!).

Here's what the business end of the two speakers looked like intially. The baffle doesn't look very different before and after. I don't have "before" pictures of the cabinet exterior.

The tweeters were both bad. Modern replacement tweeters can easily be found online but I found used original tweeters online (~$30) for a more faithful restoration. The woofers were fine - the fabric surround meant no foam to rot. The gasket on both tweeter and woofer were replaced (left). The original stuffing was put back along with the fabric that separated the stuffing from the woofer's back (right).

The original potentiometer in the crossover (left) was also bad and rather than replace it, I added a fixed resistor (right) electrically in its place for better reliability. The potentiometer is now unused but still physically there.

The grill was discolored and had numerous holes so I replaced it entirely with modern black acoustic fabric stretched over the old frame. One of the original AR badges on the grill was missing so I opted not to put the remaining one back to keep the two speakers the same.

Here's what the finished front, side and rear look like.

12-April-2020


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