mace said:
Thanks for the explanation. So... the channel MASTER controls the signal level going to the power section of the amp. And the OUTPUT knob controls how much amplification (work) is being done by the power section.
No.
Channel MASTERS attenuate the signal between the preamp output and the effects loop send.
The master OUTPUT attenuates the signal from effects loop return to the power amp input.
The POWER SOAK attenuates the signal between the power amp output and the speaker input.
So, cranking the channel MASTER will put a stronger signal into the power section, but will not have any affect on what the power section is doing with the signal.
No. Cranking the channel MASTER will send a stronger signal into the power section and will cause the overall output (volume) to be louder.
The OUTPUT knob controls how much the power section will amplify the signal.
No. The OUTPUT knob controls how much signal is sent into the power section. The easiest way to think about it is that an amplifier produces a relatively constant amount of amplification, and the variable is how much signal you feed into it. More signal in = more signal out (to a point *).
The MASTER and OUTPUT knobs both basically do the same thing (attenuate signal/adjust volume), but sit in a different part of the signal path in order to serve a different purpose in the overall design. In most Mesas the individual channel MASTERs are there balance the individual channel volumes whereas the OUTPUT is used to raise/lower amplifier's overall volume.
It's a relatively intuitive design. If the amp is too quiet you're likely to raise the OUTPUT rather than turning up all three MASTERS, however if your channel two is too quiet you'll probably raise the channel 2 MASTER rather than turning up the overall OUTPUT.
* More Signal In = More Signal Out is true until you reach the limits of an amplifier, at which point feeding more signal in drives the amplifier into distortion (aka, overdriving the amp). At this point More Signal In = More Distortion at the same overall output.
And, to your point about needing to really have the power tubes working, I take that to mean they need to be pushing high amounts of current out the back end to the speaker to really be working. In other words, setting a very, very low MASTER level and turning up the OUTPUT will maybe provide bedroom levels at high OUTPUT setting, but there really isn’t any current (voltage?) being pumped out of the power tubes and they will not sound optimal. Is that right?
No. It doesn't work that way. To get the power tubes really working the amplifier has to be loud as f*ck. If it's not getting the cops called on you and you don't live on a farm in the middle of nowhere then they're not working all that hard.
The one exception to this is a power soak. It attenuates the signal between the power amp and the speakers. Attenuation in this part of the signal path is the only way to reduce overall volume without reducing the stress on the power tubes. Every other method of reducing volume (in the case of the TC-50/100, the GAIN, MASTER and OUTPUT knobs) causes the stress on the power tubes to be reduced.
The power soak feature allows the power tubes to pump out a lot of current (voltage?) but not all of it goes to the speakers, so this prevents ear bleed.
This is correct. The Power Soak in a TC turns energy into heat via big resistors that can take the full output of the amp without burning up.
On the Mark V, if one turns off the EFX loop, the channel MASTER becomes the final stage. Does this mean that the OUTPUT knob is essentially “set to MAX” (or bypassed, I guess) when the EFX loop is off?
In simplistic terms, yes. In reality, it's removing a bunch of additional circuitry and gain stages from the signal path... so, in this case running the OUTPUT wide open is different from removing it completely since it's also removing gain stages from the signal path, which is why running the master OUTPUT wide open also tends to add a lot of extra noise when compared to bypassing the effects loop.
I tried to keep that simple. Hopefully it makes sense.