WHAT'S THE RIGHT POT?

[sergio]

There are many schematics of #124 , but what is the right value of the drive/level OD POT?

[dogears]

OD Stage 2 is the correct pic. The 250K is on OD1.

[sergio]

But 250K is linear?

[Bob-I]

But 250K is linear?

That's one of the great debates. I prefer Audio but Dumble always used Linear. It's a matter of sensitivity at the lower end of travel. Linear pots are very sensitive from off to the first few degrees of turn, that's the reason for audio, to remove this sensitivity.

Bottom line, 250k for the proper loading on the stage, Audio or Linear is a personal choice.

[ayan]

But 250K is linear?

My two cents is that the 250K pot is actually audio taper and that Dumble probably recycled the one he took out of the old bass position, and he recycled the old treble pot 250KA to the middle position -- or vice versa. Theere is no telling for sure what is in 124 since there was solder over the part of the pot's case in which it would have said "A" or not. The pot is a CTS and its code is identical to that on the middle pot, which we can see is labeled as audio.

Now, if you will be cloning 124 you may want to try (out of V1A) .005uF + 100K resistor + 250K "level" pot and listen. Personally, I did and prefer the sound using a .01uF cap and a 100KL pot instead. The sound is more focused with the smaller pot, IMHO. For what it's worth, I recently was chatting with Gary about this and he said the same thing about using a 250K "drive" pot.

For what it's worth, I believe the reason Dumble used 100KL pots is that they were readily available in the early days, since Fender used them in their reverb amps. The 100KL works great in the "ratio" position, but may be too much for the "level" position. Unfortunately, a 100KA (10 or 15% taper) in the "Level" position is too little. You can use Weber's 30% taper pots, they should be just fine. The only drawback, if I recall correctly, is that they have a different size bushing.

Gil