It sounds best when the amp is working a bit. The extra gain stage on the front end with its own volume control (i.e., the preamp gain control) is acting like a one-knob clean boost. It's also pretty much the sound of the JCM800. That's the sound of an old plexi or tweed or whatever, turn up about halfway or a bit more, and smashed in the front with a fuzz, or an OD, or a clean boost or something. This tips the whole amp right over the edge and you get that nice, full-spectrum, multifaceted distortion that sounds so good, but while the power amp is not so maxed out it's lost all dynamic range. However, a more tightly focused sound comes when you get the amp just up to the point of distortion - the tipping point - and then hit it with line level and square wave in the front end. When you just turn up the volume on an old tweed or something, the distortion you get is coming from the preamp, the PI, the power section, the power supply, the output transformer and probably the speakers, too. My 2 cents on this is that a classic amp cranked up to distort sounds good because it's distorting in lots of different places between the input and the speaker. CheersĮdit I should have also said that the distortion also gets progressively richer as the phase inverter is overdriven. Of course it will lack the dynamic response that comes from pushing the power tubes, but it illustrates that the phase inverter being overdriven plays a substantial role in what we think of as power stage distortion. Now start to raise the normal (pre phase inverter) master & you notice that as you crank it the tone will start to thicken up, & as it gets near maximum the tone will thicken a lot. Turn down the PPIMV to 3 or 4 (ideally shouldn't be below 7 but will go right down to bedroom level), turn down the normal master & crank the pre amp. This is easily proven with a 2203 or 2204 that has had a Post Phase Inverter Master Volume, or PPIMV added to it. A l fair bit of what people call "power stage distortion" is actually the phase inverter being overdriven.
Hi, I know this thread has been dormant for a few weeks but I find it interesting &'think I can add to it.
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