How to get loud and clean sound?

[Tdale]

I sometimes wonder a little about the 50 watts of two 6L6 tubes. I find it kind of strage that they don't produce a louder sound, without distorting. After all, 50W is pretty muc, and I would expect that it would be louder.

Hi-Fi amps for instance, can play pretty lound, and VERY clean, with much less than 50W.

Is it because of the way guitar amps are designed? If so, what do I need to change, to make it play louder, while still being pretty clean (not hi-fi clean though)

Tommy

[mlp-mx6]

My first thought is that if you're getting distorted tone at a lower volume than you would like then it is most likely preamp distortion, or PI distortion. If you have access to a scope then find out where in the chain the distortion is being generated, and try to clean up that stage or before.

50W is indeed capable of significant volume.

[Tdale]

I understand that. But how do I clean it up?

And it's not a specific problem in my amp, but I think quite alot of amps distorts pretty early. It might be intended, but is there any reason that it has to be that way?

Tommy

[David Root]

No it doesn't. You can either reduce the stage gain by altering plate and cathode caps, or by soaking out the interstage gain with voltage dividers/pots to ground....or both, which is the most flexible way.

Take a look at early BF Twin schematics. There are also some very useful examples of two and three stage clean circuits in TUT 1, I think.

How do you calculate the gain so you can't possibly turn the grids positive? Capacitor coupled grounded cathode gain stages are usually AC coupled and as such are subject to blocking distortion. There are DC components such as Vth (idle current divided by transconductance) and it gets pretty complex real quick. If you examine the circuit on a scope you don't have to do the math, that's a really good practical suggestion.

I have found TubeCad software to be a real boon in preamp design and I highly recommend it as one of the best $40.00 you'll ever spend.

[908ssp]

Turn your guitar volume down. Modern pickups are easily powerful enough to drive the preamp into distortion when you turn up the gain on a non master volume amp the volume is the gain and the master is full up all the time.

[dragonbat13]

you could try a lower gain tube in the first stage also. Maybe a 5751 instead of a 12ax7?

[drz400]

I understand that. But how do I clean it up?

And it's not a specific problem in my amp, but I think quite alot of amps distorts pretty early. It might be intended, but is there any reason that it has to be that way?

Tommy

12AT7 in the phase inverter

[Tdale]

Thanks, I'll try that.

Tommy