Kalcium wrote: I realise there have been quite a few questions regarding overdrive pedals into an amp recently and the difference to amp overdrive so Im hoping my question hasn't already been answered else im wasting ur time....

If you have an overdrive pedal going into and amp with the amp set virtually clean the signal gets driven and then sent to the amps preamp as a bigger signal which makes the preamp tubes work harder while with an overdrive channel the preamp tubes are set to work harder to get a drive. Would the amp just drive the signal before it enters the tubes as with a drive pedal? Also how much a difference is there between driving a signal then sending it to a preamp as to driving it in the preamp itself? Would the tonal characteristics be similar in that even though ur using a pedal with its own characteristics it is still pretty much doing the job of making ur amps preamp tubes work harder so assuming the pedal doesn't add too much color would the amps voice still be there for the most part? I mean if you could get a pedal with virtually the same characteristics as the drive channel on the amp would it sound virtually the same even though its getting driven and then still amplified a bit in the amp itself? The last question is, with a 1 channel amp that gets driven with volume does it only have minimal preamp distortion or is it half power amp and half preamp when u crank it?

I would assume the preamp and power amp both get driven about the same...but i dont know.
Appreciate all info ? Thanks in advance ?

Most drive pedals use diodes to clip the signal, i.e. it takes the highest and lowest points of the waveform and flattens them or compress them, this gives that overdrive sound. In solid state amps it is much the same. In most valve amps the preamp valves are are made to do this, you set the gain high enough to run the valve outside of its linear operating region and it compresses the signal, giving overdrive again. Some valve amps uses clipper diodes (Marshall JCM900, JMP1).

You need to differentiate between an overdrive sound and signal strength. An overdriven sound coming from a pedal may not be strong enough to make the preamp in the amp overdrive too. An overdriven sound is one that has been compressed/clipped. This is usually independent of its level. Sending a weakish overdriven sound into a very clean valve amp will sound much the same as sending it to a SS amp (given the same speakers and other factors). Sending a strong overdriven signal into a valve amp will make the amp drive a bit and add more harmonics/drive to the mix.

Regarding single channel amps. Your question is formulated to sound like you don't mean single channel amps but non master volume amps (like your Class 5). So the general answer is, it depends. In some non master volume amps when you turn the volume up high enough all the tube stages drive but in most it'll be the phase inverter and power stage only (This is the case with my Marshall(knockoff(TM)))



In short, pedals into amps sound different to amp drive only and sounds very different to properly overdriven valve amps.

Thanks very much, very informative ? I kinda wish I knew more about amp circuits and how they work but it seems like a lot to learn and i still wanna focus on learning to play, but maybe some day i'll learn, thanks for the info ?