Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Colas LeGrippa on January 18, 2012, 12:03:10 pm

Title: TREBLE ATTENUATION by cap. shunt method at the power tubes plates
Post by: Colas LeGrippa on January 18, 2012, 12:03:10 pm

I'd like to know if someone here has ever tried to shunt the plates of the power tubes of a guitar amplifier to ground through a cap ( .022 or so ) in series with a variable pot, as a tone control ( or rather a treble cut control ).

Colaslalalalalala

Title: Re: TREBLE ATTENUATION by cap. shunt method at the power tubes plates
Post by: kagliostro on January 18, 2012, 12:43:17 pm

Hi Colas

No to ground not

this is similar but in order to simulate UL taps

(http://locofonic.alphalink.com.au/pix/ultrick1.png)

http://locofonic.alphalink.com.au/valves.htm (http://locofonic.alphalink.com.au/valves.htm)

Kagliostro

Title: Re: TREBLE ATTENUATION by cap. shunt method at the power tubes plates
Post by: PRR on January 18, 2012, 02:38:36 pm

Cap at power plate is common in small 1 Watt radios.

At guitar amplifier powers, the _power_ in the cap and pot is significant, and burns-up the cap and pot in loud playing.

Title: Re: TREBLE ATTENUATION by cap. shunt method at the power tubes plates
Post by: kagliostro on January 18, 2012, 03:31:15 pm

this seems to have something to do with your request

but I'm not able to give you any info

Kagliostro

Title: Re: TREBLE ATTENUATION by cap. shunt method at the power tubes plates
Post by: Colas LeGrippa on January 18, 2012, 03:37:24 pm

Grazie, fratello !

Title: Re: TREBLE ATTENUATION by cap. shunt method at the power tubes plates
Post by: stratele52 on January 18, 2012, 03:57:03 pm

Like PRR said in small radio.

Kagliostro shematic show a 50C5 tube , this is a 2.3 watts tube at maximum power output signal

Title: Re: TREBLE ATTENUATION by cap. shunt method at the power tubes plates
Post by: Colas LeGrippa on January 18, 2012, 07:21:55 pm

PRR, what about using two 630V caps in series, choosen according to the total capacitance needed ? Voltage up to 1200V, protecting the pot as well ? I like this arrangement because the tone is smoother. I read it has something to do with intermodulation cancelling ?

Colas