Building a tube pre/amp copy (6V6)

cancon · 29th August 2011, 11:39 PM

Ahoy,

I'm trying to copy the design of a Herzog/Champ (single 12AX7 & 6V6) into a convenient tube preamp for instrument > amp purposes, as well as optional drive power. There is no schematic but I suppose the Champ schematic would serve as a good reference point, however there is no tone stack aside from a Deep/High tone switch on the copy.

Only other controls are the separate input and output volume pots. Both are 500K pots. Presently the design outputs nothing but drive - which is awesome - but I would like the option of deriving a cleaner signal as well (i.e. clone Hammond keyboards to tube Leslie applications).

My only idea thus far is to up the Input volume pot to 1M. Can anyone suggest alternate or additional measures to allow for more control of the signal drive?

Not sure if its helpful but the PT/OT specs are as follows - PT: 205VAC secondary (rated at 115V input, so it actually measures at 225VAC today). 5K/8ohm OT.

Thank you!
Adam

VictoriaGuy · 30th August 2011, 05:03 AM

Do you have a schematic of your planned build?

It sounds like you are trying to take the output from a Champ (SE 6V6 amp) and plug it into the input of a second guitar amp?

It might be better to copy a preamp design, but I don't understand exactly what you are trying to accomplish.

cancon · 30th August 2011, 05:24 AM

I'm copying a Champ copy that a friend lent me, so the schematic is similar to that.
You are correct about running it into a 2nd amp - the OT has a 10ohm 5W resistor across the secondary.
My objective is to make it do what it is originally designed for - drive an amp to bits, and in addition to serve as a pre for passive gear such as a rhodes or drive a leslie tube amp (leslie's don't have built in pre's). In those later examples i'd want to achieve a cleaner tone - something I can't get the thing to do now.

I thought this could act as a preamp already - even though it has a 6V6 there must be a way to allow it to be clean.

29th August 2011, 11:39 PM	#1
cancon diyAudio Member Join Date: Mar 2011	Building a tube pre/amp copy (6V6) Ahoy, I'm trying to copy the design of a Herzog/Champ (single 12AX7 & 6V6) into a convenient tube preamp for instrument > amp purposes, as well as optional drive power. There is no schematic but I suppose the Champ schematic would serve as a good reference point, however there is no tone stack aside from a Deep/High tone switch on the copy. Only other controls are the separate input and output volume pots. Both are 500K pots. Presently the design outputs nothing but drive - which is awesome - but I would like the option of deriving a cleaner signal as well (i.e. clone Hammond keyboards to tube Leslie applications). My only idea thus far is to up the Input volume pot to 1M. Can anyone suggest alternate or additional measures to allow for more control of the signal drive? Not sure if its helpful but the PT/OT specs are as follows - PT: 205VAC secondary (rated at 115V input, so it actually measures at 225VAC today). 5K/8ohm OT. Thank you! Adam

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30th August 2011, 05:03 AM	#2
VictoriaGuy diyAudio Member Join Date: Dec 2008 Location: Victoria, BC	Do you have a schematic of your planned build? It sounds like you are trying to take the output from a Champ (SE 6V6 amp) and plug it into the input of a second guitar amp? It might be better to copy a preamp design, but I don't understand exactly what you are trying to accomplish.

30th August 2011, 05:24 AM	#3
cancon diyAudio Member Join Date: Mar 2011	I'm copying a Champ copy that a friend lent me, so the schematic is similar to that. You are correct about running it into a 2nd amp - the OT has a 10ohm 5W resistor across the secondary. My objective is to make it do what it is originally designed for - drive an amp to bits, and in addition to serve as a pre for passive gear such as a rhodes or drive a leslie tube amp (leslie's don't have built in pre's). In those later examples i'd want to achieve a cleaner tone - something I can't get the thing to do now. I thought this could act as a preamp already - even though it has a 6V6 there must be a way to allow it to be clean.

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