Cathode boost question

[Colas LeGrippa]

Buenas tardes amigos !

I have been looking at many schematics concerning adding a footswitchable cathode boost. I made one, but it doesn't boost enough the signal for me. It is  audible, but the difference is not that big. 
Do you know if it gives better results at the cathode of the first or third stage ? And what is the best resistor/cap combination to give best results ?

Thanx

Colas

P.S: leave the girl next door alone.

[SILVERGUN]

My experience suggests that the first or second stage is a 'better' spot because by the tme you get to the third stage you are boosting/adding a lot more noise.
I have used this method at the second stage successfully.
The switch adds the bypass cap and changes the bias condition by lowering the cathode resistor value simultaneously. Note that the stage is cool biased and unbypassed to begin with.

[HotBluePlates]

... footswitchable cathode boost. I made one, but it doesn't boost enough the signal for me. ... what is the best resistor/cap combination to give best results ? ...

Best combination for what? How much boost do you need? Do you want this boost to be in the amp and take the place of, say, a boost pedal?

[HINT: You need to answer this first to know if you should even waste your time on "cathode boost".]

[PRR]

Cathode bypass gives roughly 2 times the gain of no-bypass.

It is a boost. It will never be a WOW boost.

[Colas LeGrippa]

Hola buddies !

I have precised my needs and realized I didn't need  extra gain , but extra volume ( in fact, less volume !!!! ). I have experimented all day and the best way to get a noticeable volume boost without boosting the gain is lowering the  original volume by sending to ground a second 68k input resistor as to form a voltage divider. Hooked up a foot switch with led and everything is fine. I ' had never thought of that before. I can't tell for the moment if it adds extra noise or if the footswitch cable capacitance acts as a low pass filter, but my day is over now !  Anyway I am satisfied with my experiments up to now. Thanx guys 

Colas LeGrippa

[kagliostro]

If I remember correctly this is from our friend Geezer



One other way may be to "play" with the bypass of the power tube/tubes





Ciao

Franco

p.s.: Download images for full resolution

[Colas LeGrippa]

Buon giorno Kagliostro !


The pseudo channel switch is very simple and interesting !!! ( BTW, I haven't seen Geezer for a long time 
I have downloaded the files and will study them much later !

Grazie mille fratello


Colas

[Colas LeGrippa]

hey Kag, I guess that in the case of the pseudo channel switch, we would need a relay to minimize hum and noise ?


Col

[kagliostro]

Ciao Colas

I think the same, not strictly necessary but the use of a relay could give better results, perhaps you must try

Franco

p.s.: I asked about Geezer and results that he was connected on febrary of this year, but he didn't post since september 2014