Preamp pedal into icepower power amp

[rainywish]

Hi all,

After building a few guitar tube amplifiers (mostly old tweed designs), I now want to try my hand at putting together a solid state amp. My idea is to use a preamp pedal (eg this one or this one) and feed its output directly to an Icepower 100AS1 power amp.

I have drawn up the following layout to make this idea a bit more concrete:





What am i missing here? It seems a bit too simple to work...

[ElectricDruid]

I don't see why it would need to be much more complicated than that, really. Maybe if you start adding multiple input channels, reverb, switching, etc etc.
But the basics are Input->PreAmp->Power Amp->Speaker, and that's what you've got.

The only thing I noticed is that the Preamps you linked to run on +/-15V (or +/-9V, maybe), but you've got it marked as a 9V power input to the board. Perhaps the Aion board uses a convertor to boost the power? If it does, I'd bypass it and provide the right voltage directly if you can. Converting down to then convert back up again sounds like an accident waiting to happen, with whining convertors fighting with each other.

[marcelomd]

I did something similar for the 125ASX2, but added a differential driver. It might work.

Things to take note:
- Mind the input signal level 1: Icepower modules only take 3.3V to the inputs. Don't know if they have any protection.
- Mind the input signal level 2: In my case, max clean power was achieved with only ~1.8V input signal.
- There's a few extra control signals in my unit, like "enable", "over temperature", etc. Check if you need to connect any of it.
- Be very careful because there's real high voltage there.

[antonis]

Minor annonations: 

Power ON-OFF switch should be a DPST one..
(with X2 cap across lugs..)

Audio ground and Safety earth must be seperated..

In1- & GNDA could be shorted inside power amp

Master Volume pot outer lugs should be reversed..

[R.G.]

Humh. I just finished layouts for the UK Vox UL700 series vibrato and normal channel preamps, and the Thomas Organ Vox normal, brilliant, and bass preamps . Well, actually, I did the Thomas ones in both smd and through hole. They run to about 3.8" by 1.25" on average.

You might be a good vict... er... early tester. :-)

I've always intended to do something l like this, just never bought the power amps.

Oh, another thought. I also did a board for the 3-channel mixer and limiter for the Thomas amps. I personally believe that the limiter ahead of the power amps gave Thomas Vox amps a soft distortion overload, unlike a lot of the early solid state amps.

[rainywish]

Minor annonations: 

Power ON-OFF switch should be a DPST one..
(with X2 cap across lugs..)

Audio ground and Safety earth must be seperated..

In1- & GNDA could be shorted inside power amp

Master Volume pot outer lugs should be reversed..

Thanks for all the suggestions. Concerning the separation of the audio ground and safety earth: how would one go about this? I have read about a "ground loop hum eliminator circuit" which has four parallel components: Two diodes opposite direction, 10R 3W resistor and 100nF X-class capacitor. Is this the way to go?

Humh. I just finished layouts for the UK Vox UL700 series vibrato and normal channel preamps, and the Thomas Organ Vox normal, brilliant, and bass preamps . Well, actually, I did the Thomas ones in both smd and through hole. They run to about 3.8" by 1.25" on average.

You might be a good vict... er... early tester. :-)

I've always intended to do something l like this, just never bought the power amps.

Oh, another thought. I also did a board for the 3-channel mixer and limiter for the Thomas amps. I personally believe that the limiter ahead of the power amps gave Thomas Vox amps a soft distortion overload, unlike a lot of the early solid state amps.

sounds interesting 

[antonis]

Concerning the separation of the audio ground and safety earth: how would one go about this? I have read about a "ground loop hum eliminator circuit" which has four parallel components: Two diodes opposite direction, 10R 3W resistor and 100nF X-class capacitor. Is this the way to go?

More or less, yes..
(X or Y class cap isn't essential..)



from here

[R.G.]

That's the usual circuit. There's some fine print.
Safety standards require that the chassis to safety ground wire on the AC cable be able to conduct 2A with less than ... um, I forget, but it's a small voltage. What's really needed is that the diodes be able to conduct enough current to blow the AC mains breakers in case of a line-to-chassis short. So those diodes need to be big ones. A good choice would be a 25A or higher bridge rectifier with a heavy wire between the + and - pins.