#1
I have a 2 part question
1) when you have a tube amp the power tubes are driven by cranking the amp but if you have a tube amp that has a gain knob I've noticed you can get a driven tone without cranking it so are you actually driving the power tubes or are you driving the pre amp tubes by doing that?

2) say I have 2 tube amps both have the same tubes say 1x 12ax7 and 1x el84 and are the same wattage same speaker size but they are different brands and one is say $100 more shouldn't they sound the same regardless of price?
#2
1. preamp

2. No.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#4
No. They are both volume controls, they just sit in different spots. Turn either down to zero and no sound will come out. To turn a master volume amp into a non-mv amp, you turn the master volume up to 10 and use the gain knob as your volume control.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#6
You can get distortion out of the preamp or the output section. In the old days, they started by just turning up the amps real loud (the non-mv - non-master-volume days). I think the the early BOC sound represents that type of sound. It's distorted, but lacks the sizzle.

Then they added a pot before the output stage so you could instead overdrive the preamp (with a an overdrive pedal for example). The old Boston group's sound introduced a "power soak" - they put some big resistor divider on the output so that they could also push the output stage all out, but not have the amps real loud. I think there's some affect on your amp's life by doing that and I haven't seen the power soakers around these days.

So anyways, yes, there's two types of dirt you can get out of the amp head. You might want earplugs for the one
#7
Quote by USMC_VET_ROCKER
So how can you get power tube distortion in those types of amps instead of per amp tube
The way i just told you. You will still get some preamp distortion but most will come from the power amp.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
So about the second part of my question... why if your sound comes from the tubes and out the speaker and those are the same in both amps why are they not the same
#9
Amps aren't just tubes wires and a speaker. If you had the same tires on two cars that were otherwise different, would you expect them to drive the same? Similar idea. The circuit is what determines how the tubes sound, and amp circuits vary quite a lot. Tubes are just one small part of the circuit.

The sound "comes" from the tubes in the way that your car's speed and handling "come" from the tires; they are a crucial part of how your car translates your input into the car's motion, but they are definitely not the only part of that equation. Tubes do nothing on their own, just like tires.
#10
Change the value of one resistor and you can radically change the sound of the amp.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#11
To a certain extent, if you were to just have an amp that was meant to drive the speakers with the sound from the guitar pickups, then the amp head would have less of an affect on the sound. But amps, and in particular tube amps, are meant to add some "color" to the sound. The amp designers can choose to emphasize different aspects of the sound (regardless of the tone controls). When you bring distortion into the picture, then things can get very complicated and the manner of how they distort and the coloring of the sound depends a lot on the amp designer.

There is a lot of common aspects to what's going on. But there are enough subtle things that can make different amps more desirable - it's all a matter of taste (and $)