Fender Studio Bass Club!

[Patrice B]

Not sure if that is quite right. Here's my circuit analysis...but keep in mind my electronics knowledge is pretty basic, so I may be wrong. Let me know what you think.

See schematic of circuit below.

AFAIK, the tube section (V3A) has two operating points. The cathode circuit is fed -30V when distortion is off and -11V when distortion is on. AFAIK none of the pots have an impact on the tube operating point.

Looks like the signal is taken off a pot connected between the cathode and control grid of V3A. I assume this pot allows you to blend the clean signal present at the control grid with the distorted signal at the cathode.

The signal from the distortion (blend) pot is fed through a capacitor to another pot that sets the level.
View attachment 7447067

Hypothetically, what does the suggested mod, replacing the 2.2K with 1 megOhm?

 

[Wasnex]

Hypothetically, what does the suggested mod, replacing the 2.2K with 1 megOhm?

The commentor said the resistor was originally 3.3k and Fender changed it to 2.2k. The commentor said he changed it to 1Meg and the circuit sounded better. So he went in the opposite direction of Fender.


I don't know for sure how this would change the operation of the circuit. Since a negative voltage is supplied from the bottom of the coil, I would assume the diode would be forward biased...so the value of the resistor would not matter very much, unless the diode switches on and off with the AC waveform. A bigger resistor should cause larger voltage swings.