22 watt amp (how can I get it to sound good?)

[doug0147]

Hi,

I built this power amp circuit

http://www.aaroncake.net/Circuits/amp20w.asp

I'm only using one chanel right now, so it's just a 22 watt mono amp. I'm using it with a guitar speaker (not HI FI).

So I tried putting a couple different preamps in front of it. Both from RunOffGroove.com

Tone Mender - http://runoffgroove.com/tonemender.html

Professor Tweed - http://runoffgroove.com/professor.html

Both sound great into my regular amp, but they don't quite turn the 22 watt circuit I made into a real guitar amp. The make a huge improvement over the power amp alone though.

My question is, is there anything I should do to the power amp circuit to make it more like a guitar amp?

Does anyone have any sugestions for pre-amps or a combination of pre-amps?

My goal in the end is to have a 2 chanel (clean & distortion) amp with master volume.

Thanks, Doug

[Iron Code Monkey]

Try a clean preamp, like the ROG Fetzer Valve.

[dschwartz]

please explain what you mean when you say "more like a guitar amp"..that will help us help you

[doug0147]

I mean the amp has no tone realy. A guitar amp has a nice ballance of treble, bass, and mids. This amp by itself has no bite or clarity.

[MikeH]

Really, some sort of preamp is needed.  FETs will work ok (as you have found out) but tubes would be better, although I don't think low voltage tube applications will be much better.  You might try some of the submini designs that have been posted lately, a lot of them run a 50V B+.  Not exactly high voltage, but a little better.

[ninjaaron]

I mean the amp has no tone realy. A guitar amp has a nice ballance of treble, bass, and mids. This amp by itself has no bite or clarity.

Most guitar amps significantly boost treble, cut the lowest bass, and drop the lower mids a bit. You will proably also want to attenuate some of the highest frequencies completely off for a smoother sound.

You might get some good results if you use the Tone Mender and the Professor tweed together... probably tweed first and Tone Mender second. You might also want to look into the biasing the first FET on the tweed according to the advanced techniques described in the 'Fetzer Valve,' for a more tube-like harmonic responce.

[Mark Hammer]

A nicely tuned midscoop filter in the right place can do a lot for the resulting tone.  Keep in mind that the usual Fender or Marshall tonestack does not really "boost" treble, mids or bass.  rather, the bass and treble are often already boosted by other parts of the circuit, and what the tonestack does is either let that boost remain in place or "tame" it so that it starts to sound flat or even cut.

[doug0147]

So from what you guys are saying, it sounds like all the tone shaping, frequency boosting, and cutting needs to be done in the preamp. What ever that turns out to be. It doesn't seem like there is any tweeking to be done in the actual power amp circuit itself. Am I getting this right?

Thanks for the advice so far.

I had another idea, I don't know if it validated though. I plugged my CD player into the power amp and it sounded great. Which makes sense, since that's probably what the amp was designed for. So I was thinking, a speaker cab sim might be like the direct out from a CD player. It's supposed to go to a line in on a mixer or power amp (I think). Would it make any sense to use the ROG Condor cab simulator as the last stage in my preamp?

[dschwartz]

i think that will help a LOT..try putting a mix control between the dry and the condor signals and you´ll have best of both worlds