Two preamps in the same power amp

[Sirion]

Quite simply: If one has a amplifier head and a pre-amp, would it be possible to split the guitar signal before the pre-amps and join them together so that they go into the head's power amp together? I might be interested in trying to combine clean and distorted tones in this way, and was merely wondering if there might be any problems associated with such a set-up.

 

[Vasshu the humanoid typhoon]

Re: Two preamps in the same power amp

Well you need a parallel mixer for line level signal...nothing hard in that
But I think that you will dislike the sound....
There are better results in using two different amps instead.

 

[GilmourD]

Re: Two preamps in the same power amp

Technically that's how Fender amps from the '60s on (and even non master volume Marshall and the Tweed Fenders they were based on, to an extent) amps work. There are two separate preamps. If you look at, say, a Fender Twin Reverb schematic there's the Normal channel and the Vibrato channel. At the end of them there's a resistor (called the mixing resistor) and they connect to the input on the phase inverter.

 

[Edgecrusher]

Re: Two preamps in the same power amp

Technically that's how Fender amps from the '60s on (and even non master volume Marshall and the Tweed Fenders they were based on, to an extent) amps work. There are two separate preamps. If you look at, say, a Fender Twin Reverb schematic there's the Normal channel and the Vibrato channel. At the end of them there's a resistor (called the mixing resistor) and they connect to the input on the phase inverter.

Marshals don't have separate preamps they have separate inputs, fenders you are right though.

 

[guitfiddle]

Re: Two preamps in the same power amp

With my old Bassman, I used to jumper the channels together, but run an OD into only one side. That way I could get the amount of overdrive I wanted, and then mix in as much or as little of the clean channel with it. It works with my Music Man HD-150 as well.

 

[Sirion]

Re: Two preamps in the same power amp

Well you need a parallel mixer for line level signal...nothing hard in that
But I think that you will dislike the sound....
There are better results in using two different amps instead.

Thanks! Any particular reason why you think I would dislike the result?

 

[GilmourD]

Re: Two preamps in the same power amp

Marshals don't have separate preamps they have separate inputs, fenders you are right though.

They have two channels which end in the same way, two parallel gain stages that each end in a mixing resistor (470K resistors after each channel volume) and meet at a common point. They just happen to have more preamp after that point, but the general idea is the same.

 

[Dave Locher]

Re: Two preamps in the same power amp

My old Randall amp let's me do this. Two channels, voiced differently, with preamp and master volume for each channel. I mix in the lower-gain vhannel just enough to really thicken the overall sound. But really clean and really distorted together sounds too odd. You don't get the best of both, you get odd spikes of clean on top of the distortion.