VOX AC30 Custom Classic High Gain design

[ppaappoo]

Hi, i want buil a Vox top boost usin the 4 triodes of 2 12ay7 tubes.
This is my design:
 

the tone sw is like the ac30 custom classic 2



Standard/Custom Switch

Standard: When this is selected the EQ (Treble and Bass) becomes very interactive and acts
like a standard AC30. As you increase the Treble or Bass, the mids are decreased and conversely,
as you decrease Treble or Bass, mids are increased.

Custom: When this is selected the EQ becomes less interactive like an AC30 Hand Wired or an
AC15TB.

It's based to the english channel from runoffgroove.com

 

It's ok? can you help me to find errors or mod.

[jhadhar65]

A few questions come to mind...

What do you mean by "High Gain"?

If the above answer is "High Distortion", why 12AY7's?

Further, why did you pick a 9V jfet design to stick tubes into?

What is your power supply plan?

This is only a suggestion, but you might think about saving yourself some grief by opting for a simpler, proven design or maybe just build the pedal as per the schem for the time being.

[OldHouseScott]

The tone stack as you've drawn it is not correct. Look at the runoffgroove diagram for the correct configuration. The lower 10k resistor should be separated from the upper 100k resistor by a 22n cap. The wiper for the bass pot then goes to the junction of the 10k resistor and the 22n cap. All the switch does is break the ground connection of the bass pot. It doesn't have to connect the wiper to the end of the pot, but it won't hurt.

Also, 47r as the cathode resistor of your final stage seems too low. I would go with something between 820 and 1k5 like the other gain stages.

[ppaappoo]

The tone stack as you've drawn it is not correct. Look at the runoffgroove diagram for the correct configuration. The lower 10k resistor should be separated from the upper 100k resistor by a 22n cap. The wiper for the bass pot then goes to the junction of the 10k resistor and the 22n cap. All the switch does is break the ground connection of the bass pot. It doesn't have to connect the wiper to the end of the pot, but it won't hurt.

Also, 47r as the cathode resistor of your final stage seems too low. I would go with something between 820 and 1k5 like the other gain stages.

Thanks, i'll make the changes!

[ppaappoo]

A few questions come to mind...

What do you mean by "High Gain"?

If the above answer is "High Distortion", why 12AY7's?

Further, why did you pick a 9V jfet design to stick tubes into?

What is your power supply plan?

This is only a suggestion, but you might think about saving yourself some grief by opting for a simpler, proven design or maybe just build the pedal as per the schem for the time being.

High gain: It is because AC30 only use two stages of amplification and it uses three. I use two 12ay7 because I have them but you can also use the 12AX7.

The English Channel is based on the AC30 preamps and thought it would be a good guide for choosing the third stage of amplification.
The power supply will be a 290v the Vox style but using diodes.

Thanks for your comments, all the information you give me is very helpful to me.

[ppaappoo]

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