Unused triode

[tubeswell]

What Chuck said - A CF driving the tone stack will make the tone controls come alive more

[Ptron]

What Chuck said - A CF driving the tone stack will make the tone controls come alive more

Not to be contrary but I thought I'd throw this out there. I have a little SE hombrew with a CF driving the tone stack and the controls hardly do squat. Maybe it's not true but I swear I've been told or read somewhere that a CF reduces the losses in the tonestack but also reduces the effect of the controls.

[Chuck H]

I have a little SE hombrew with a CF driving the tone stack and the controls hardly do squat.

I'm taking a tip that your amp is SE and guessing you run it dimed alot of the time. If the power amp is in OD it will compress any changes in the preamp to a large degree making the tone controls much less effective. If the tone controls don't do squat when playing clean I would guess that something may be wrong with it.

Maybe it's not true but I swear I've been told or read somewhere that a CF reduces the losses in the tonestack but also reduces the effect of the controls.

A CF can give an extra 2 or 3db with a normal Fender/Marshall type tonestack. But I have noticed limited range on the bass pot when changing to a CF too. Acording to Duncan TSC, using a CF you lose about 1/2db of swing on the high range for the bass control and gain about 1db on the treble.

Chuck

[Ptron]

If the tone controls don't do squat when playing clean I would guess that something may be wrong with it.

Could be. I'm actually about to start digging into it to make some changes and I will definitely re-visit this but I know I tried to figure this out when I first built it and didn't find any mistakes or wrong value components. It's a bedroom amp so I don't really dime it.

A CF can give an extra 2 or 3db with a normal Fender/Marshall type tonestack. But I have noticed limited range on the bass pot when changing to a CF too. Acording to Duncan TSC, using a CF you lose about 1/2db of swing on the high range for the bass control and gain about 1db on the treble.

Chuck

Hmm. That points something being wrong wrong with mine because the treble is the least effective control.

[octal]

Not to be contrary but I thought I'd throw this out there. I have a little SE hombrew with a CF driving the tone stack and the controls hardly do squat. Maybe it's not true but I swear I've been told or read somewhere that a CF reduces the losses in the tonestack but also reduces the effect of the controls.

+1. It's basically a frequency sensitive voltage divider and the source impedance determines the degree of attenuation. (Well, that and the load and the slope resistor and....) Lower losses= less possibility of "boost" or attenuation. So a CF driven tonestack should have a smaller range.

[Sir Cuitous]

Yes, my amp is SE, but no, I do not dime it, at least not all the time . It's loud enough - really too much gain which I will also address.

Right now the tone controls do have an effect. As I said, I'm not looking to the CF alone to fix the tone issues, but if I am going to make major mods, I want to start with that.

So what is the real story? Isn't the Fender 5F6A circuit renowned for it's tone? What is point of driving the tone stack in a Bassman with a CF if there wasn't some benefit? Doesn't the lower impedance of the CF mean that the tone controls won't drag down the voltage gains from the previous stages?