The 18W amps that Trinity sell don't have any Master Volume control - at least not in the true sense of the word. In the TMB channel there is a Gain control, which is exactly what it says. It alters the preamp gain of that channel. After that comes a Volume control, which sets the volume level of the TMB channel through the power amp. It's not a Master Volume control, and to refer to it as one is misleading. The Normal channel has a regular vintage style Marshall 18W preamp, which lacks any Gain control, but also has a Volume control. You use the Volume controls of each channel to adjust the output level and hence the volume levels of each channel, and relative to each other. In the case of both channels, increasing the volume level also increases power amp distortion. All 18W amps, even the original vintage Marshall ones have this Volume control on the output of each preamp channel, feeding to the phase invertor. So there isn't any MV, although some folks add one as a mod.
The Normal channel relies almost totally on the power amp for distortion, while the TMB channel can also add some extra preamp distortion (of the good kind) to the power amp distortion. The cool thing with these amps is that you can jumper the two channels together, or use an ABY box, to get a whole variety of different clean and overdriven tones.
Stoo wrote:
Over on 18watt.com there is a version called Ritchies and another called JA's and they both have a gain/master setup similar to Stephens.
Yes, and both are misnamed, and hence misleading. Thankfully Trinity straightened that out, at the same time as using a simpler and more foolproof layout. This is no disrespect to either Richie Hall or Jersey Aaron, who are both real awesome guys. Richie was one of the founders of the 18W community.