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Anybody used a Class A solidstate amp for clean sounds?

Started by mandu, March 07, 2010, 04:11:47 AM

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mandu

I never had a chance to use a class A solidstate amp with guitar.
Anybody has experience trying a guitar with such an amp?

Thanks in advance.
Mandu

Enzo


ll81

You should certainly get a very clean sound from a class A amp, of course the drawback being the limited power output. It really depends on the volume levels you wish to play clean at, if using SS then there's no reason why a well designed class B amp operated below clipping won't sound clean.

If you want a good easy to build Class A SS design then I have plenty kicking about, just add pre-amp of choice and away you go.

mandu

Thanks for the feedback.
I am not aware of any branded class A amp in the market, but looking into building a 30 - 40 watts amp (pushpull, with output transformer)
I play cleanonly.
regards,
mandu

rowdy_riemer

Maybe you should check out the Nelson Pass's "Zen" amplifier. www.passdiy.com/pdf/zenamp.pdf. You might can bridge a couple of these for 40 watts.

E

Quote from: rowdy_riemer on March 08, 2010, 10:28:30 AM
Maybe you should check out the Nelson Pass's "Zen" amplifier. www.passdiy.com/pdf/zenamp.pdf. You might can bridge a couple of these for 40 watts.

www.passdiy.com/pdf/retofzen.pdf

Some 'improvements' in there. I'm interested to see how this turns out actually, what would you use for a preamp?

Minion

You can also Bias Chip amps to Class A , Or so I hear .....

rowdy_riemer

I've got a two-stage "fetzer valve" jfet preamp setup that I like, but I'm sure a simple op-amp stage would work at least as well. Check out this thread, http://www.ssguitar.com/index.php?topic=1426.0 . J M Fahey's suggestion about the "Rod Elliott project 27" sounds interesting.

rowdy_riemer

If going with a Class A power amp, I'd definitely use discrete components, especially since Class A stages are very simple. Even if you found a way to make a chip amp operate as a Class A amp, it might sound like crap. One of the supposed  benefits of a class A amp is having fewer components to distort the sound (Teemuk's book has made me doubt the veracity of this claim). Whatever the case, unless a chip amp is designed for class A output, forcing it to behave that way doesn't sound like a good plan.

Check out http://www.ssguitar.com/index.php?topic=861.0. While I'm sure there are many better class a amp designs(like the zen), my source follower design demonstrates how simple a class A amp can be. If you have high wattage resistors, you can obviously get much simpler. I've seen one design that used an LM317 in a current limiting configuration as the load for a source follower stage. If you're going for class A, theres no need for chips.

mandu

Thank you all for so many guide lines. About 12 years before I have built 20+20 watts class A amp with sucess. For the heat sink I used a VSD chassis. That time I did not have the guitar to test. I gave it as a present to one of my friends. I believe that design was from Elector magazine, with two 2n3055 at the output with upper transistor acting as a current source.
I am looking into a good heatsink now, I may go with a fan cooling if I get a smaller one. This will be all descrete amp. Since mechanical construction is a pain, I believe could be done in a months time. This will be a amp head only, difficult as a combo.

For the preamp, I would like to use all FET preamp.
Thank you all once again.

E

Well keep us posted.

Would using solid capacitors have any effect?