Tascam VL-A4 monitor fix

[tedmich]

I picked up two pairs of Tascan VL-A4 monitors for very cheap because they had a busted tweeter and a bad vol pot (on the different pairs). I made one functional pair and gave them to my Mom and Dad along with an ART Clean Box II (design still available from MCM MCM Custom Audio Balanced / Unbalanced Line Level Converter | 555-8485 (5558485) | MCM Custom Audio for $40) for them to use to crank their opera up in the TV room (away from their nice Sonus Fabers downstairs!).

I finally got a replacement tweeter from Teac for $30 and now have a set of my own. Unfortunately these monitors had substandard pots in them, 20k Audio/log taper I believe. Reworked ones from Tascam have a piece of tape under knob on shaft, but even the functional pots are crappy and introduce bad high frequency distortion. I got a couple of BI Tech part# P092N-QC15AR20K, $3 at Mouser, which are dual CP pots (I only need one section) and the speakers now sound AMAZING. Quite flat to ~90Hz so I am now putting together a small sealed sub for them, quite possible a Linkwitz transform on a closeout Klipsch THX driver from their KW-120 monster.

One take home message, a "bad volume pot" which introduces noise when actuated often is NOT solved by setting and not adjusting, the distortion remains and a clean high quality pot can sound infinitely better.

[Steve Conner]

I agree, I once had a volume pot on my bass with a loose contact that picked up the body vibrations and caused distortion. Replacing it made the bass sound much better. Probably a similar issue here since the woofer will vibrate the whole cabinet.

[tedmich]

thanks Steve! I value your opinion in these matters.

the pot is smaller than the large plastic shafted one it replaces and in order to get everything lined up I decided to use jumper wires rather than mount directly on the pcb

I really cinched them down in the overly big hole for the old pots using a star washer.

Now by the same logic I really need to swap out those scratchy pots on my QSC RMX 800 amp...