mini high gain amplifier

[robson73]

I've been thinking about a small high-gain amplifier for some time and I've asked friends, would it be possible to combine a lead channel from a well-known amp (for example, Carvin Legacy, Engl Fireball) with a low-power single-ended?

 

[rayma]

Sure, can you give more details of what you are looking for?
This is a guitar amp?

 

[robson73]

Exactly, a low power guitar amplifier! Maybe a 25L6, or one with a little more power. The preamp would be a lead channel from a known high gain amp, and only with two 12AX7s.

 

[rayma]

More members will see this thread in the instruments and amps forum, I'll move it there.
Can you post the preamp schematic you want here?

You'd still need at least a driver stage for the output tube, though.

 

[robson73]

Could you add a high gain pre with this power?

 

[rayma]

Sure. Which preamp circuit?

 

[robson73]

I thought about maybe this one! I know I should adjust the voltages, or would a different power valve than the 25L6 be better? A 6V6, EL84?

 

[rayma]

Should be ok, just remember the tone circuit has a 6dB loss.
Also the 25L6 has a max allowable 500k grid resistance.

 

[robson73]

In your opinion, what would be a better alternative than the 25L6?

 

[rayma]

It's mostly personal preference, best to copy a known existing amp circuit that has available output and power transformers.
Those are the hard parts to get.

 

[robson73]

But what could be a model? With high gain pre amp and low power! The ones I know are not high gain enough!

 

[rayma]

Do you know how much gain you need in the power amp section?

 

[robson73]

I would like gain only in the pre-amp section, in the power part a single ended output, class A. In the style of the amplifiers on the AX84 website.

 

[rayma]

Then most tube output stages will have low gain, if any.
Just make sure the amp uses available power and output transformers.

 

[robson73]

An output power of between 2 and 10W would be enough, as for transformers, it is not difficult to find them. The main part for me is the high gain preamp! I'm a big fan of this type of amplifier (Carvin Legacy, Engls, Mesa Rectifier, SLO).

 

[rayma]

The preamp in post #7 should be straightforward to build. You just need a couple of sockets, the pots, and the standard small parts.
The other preamps will be pretty similar.

 

[robson73]

There are two more preamps that could be options.

 

[rayma]

Sure, these are all pretty similar. Maybe someone who has built various circuits like these can comment.

 

[robson73]

Thank you very much for the advice, friend Rayma, if others could give me other opinions it would be of great importance!

 

[JMFahey]

I would like gain only in the pre-amp section, in the power part a single ended output, class A. In the style of the amplifiers on the AX84 website.

Just build an AX84 project, the simplest one, one EL84 + 1/2 12AX7.
You need only one triode to drive EL84.