After tuning and/or gutting every aspect of this preamp and deleting some really dumb stuff.. I have decided the most effective way to release a fix, is to completely rebuild the preamp board so that it can easily be plugged in without any soldering. This would eliminate customer service troubleshooting emails and potentially boinking the stock pre. And it can be returned to stock very easily.
I have most of the schematic drawn up and a rough layout. I was pretty happy to see that I already have almost all of the passives (resistors, caps, and nice pots) here in the shop.
I am socketing the ICs so they can easily be swapped for Burr Browns or your favorite PDip sized opamps. I added a clip light that will probably light up a clear volume knob (no drilling for the LED). And I am working on using an optocoupler for audio delay and soft amp turn on instead of the current ancient 80's transistor gimmick in the stock pre.
The differential inputs, 2nd gain stage, 4 eq filters, are all tuned up and ready. I still need to lay out the
tuned Xover, amp turn on, and the TDA2050 pwr amp for the horn.. and figure out final cabling and sockets.
Here is the current drawing of the work in progress.
View attachment 131164