Tone control pec integrated circuit upgrade.

[Carbsandcaps]

Has anyone tried these yet? A guy makes them and sells them on eBay. They take the place of the tone control integrated board and use film caps and close tolerance resistors built on a single board. They’re made for the 400 preamp but I checked the part numbers and they are the same in the x-202-b. It’s close quarter in the compared to the 400 preamp but I’ll keep you updated along the way.

 

[Carbsandcaps]

First one is in. Not much room in there at all. A few wires came in from the front and a few from the rear. Luckily he made it so you can solder from the front or rear.

 

[gadget73]

Thats a nice tidy solution. Drifted values in PEC units isn't too uncommon, and having a small PCB that fits in the space of the original unit is a nice option. I've built my own before but being limited to through-hole parts you can only really get it so small, and the parts themselves add significant extra height to it even if you do get the LxW dimensions the same.

 

[Carbsandcaps]

Thats a nice tidy solution. Drifted values in PEC units isn't too uncommon, and having a small PCB that fits in the space of the original unit is a nice option. I've built my own before but being limited to through-hole parts you can only really get it so small, and the parts themselves add significant extra height to it even if you do get the LxW dimensions the same.

Ya I jumped on them as soon as I saw them I was wondering what the options for replacing the whole thing would be aside from assembling the whole thing

 

[Carbsandcaps]

I also decided while I was there to replace the high pass filter pec which was much easier with 3 560pf capacitors and 2 47k resistors. All in my journey to replace all of the signal capacitors with film. Don’t mind the AA battery sized 1uf pio capacitor

 

[jvstratman]

I installed these (Today) in my x-202 and I'm happy with the initial results. Very good bass & Treble control and smoothed out the discrepancies of the OEM pecs.

I'd made my own pec on a single perf board but it eventually fell out of favor and I stuck another closer matched set of pecs back in and wasn't thrilled with those either.

The tolerances on these blue ones are spot on. Pins 1 & 2 = 100k. Pins 6 & 7 = 100k. Pins 3 & 5 = 121k. The OEMs were all over the place.

BTW - The grounding scheme works quite well. I ran a short wire from each board and it dramatically reduced the signal bleed with the volume turned down.

 

[Carbsandcaps]

I installed these (Today) in my x-202 and I'm happy with the initial results. Very good bass & Treble control and smoothed out the discrepancies of the OEM pecs.

I'd made my own pec on a single perf board but it eventually fell out of favor and I stuck another closer matched set of pecs back in and wasn't thrilled with those either.

The tolerances on these blue ones are spot on. Pins 1 & 2 = 100k. Pins 6 & 7 = 100k. Pins 3 & 5 = 121k. The OEMs were all over the place.

BTW - The grounding scheme works quite well. I ran a short wire from each board and it dramatically reduced the signal bleed with the volume turned down.

Ya I noticed a definite difference in tone. It’s a lot clearer and has quite a bit more treble. Found myself turning the treble down actually

 

[Masonavenut]

Veeeery eeenteresting. In my best Arte Johnson voice.

 

[gadget73]

just for yucks, did you ohm check the bass and treble pots to see how they compare to each other, and to the schematic value? If those are off it will affect the response too.

 

[jvstratman]

just for yucks, did you ohm check the bass and treble pots to see how they compare to each other, and to the schematic value? If those are off it will affect the response too.

Not sure if your asking me or the OP but in my case, I had another treble potentiometer and built one from two. Keeping in mind these are stacked, Channels A & B are now 568 k ohm each so, mine (along with new PEC'S) sound equal.

Question: With 500k being spec., If it's higher (600k) will you achieve more treble and if lower (400k) have less treble at full CW?

 

[gadget73]

not sure it will affect it all that much at full boost or cut, but it will likely shift the "flat" point off center. It will also tweak the turnover frequency a bit but I'd be lying if I could tell you precisely how much or in what direction.

the bigger concern is having both the same, even if its not perfectly on value.