Twin reverb has a 56pf cap from pins 6 to 8 on reverb driver...

[Gareth81]

This silverface twin reverb has a 56pf cap from pins 6 to 8 on the reverb driver. I don't see this on any schematics or layout diagrams... should I remove it?

[HotBluePlates]

If you want. If the reverb is working well and sounds like you want, leave it.

Most additions like this in silverface versions were used to cure oscillations that happened because board layout and wire routing was changed from the blackface style. In essence, they are production expedients to ensure all amps produced worked properly; with marginal layout/lead dress, you might have 1 or 2 out of 10 give problems. Rather than fix individual amps, all amps would get the "cure".

[PRR]

It's far above the audio band. I see no need to remove it.

[sluckey]

The cap in your pic is a 560pF, not 56pF. Look on page 2 of this pdf...

http://www.el34world.com/charts/Schematics/files/fender/twin_reverb_sf_100_schem.pdf

[Geezer]

Yep, there it is!

Looks like a LNFB "smoothing cap" to take some edge off the verb(?)..... if so, it's the first time I remember seeing that used in a commercial amp, aside from Dumble-esk boutique stuff.

G

[tubeswell]

Its a plate bypass cap to 'cure' HF oscillation - like HBP said.

[PRR]

> a 560pF, not 56pF

60 KHz. Still no audio effect. Leave it be.

[Willabe]

I've seen guys say it's to take the "ring" out of the verb OT.       

I've also seen it wired from the plate to cathode on the verb driver tube.


                 Brad     

[sluckey]

I've also seen it wired from the plate to cathode on the verb driver tube.

Uh, that's how this one is connected.

[Willabe]

Sorry, I looked at page 1 and not page 2 like you said.


              Brad