Mario wrote:
dtp wrote:
Master volume does not affect whether or not you can use VRM/VVR/Power Scaling. MV in all of its forms can be used with voltage reduction in all of its forms.
Since the 18 watt design gets pretty much all of its distortion from the power tubes a master volume of any type will have what most people feel is a negative affect on tone. This is where voltage reduction schemes shine because they have minimal if any affect on tone.
Ok, but you can get
power tube distorsion only when cracking the amp to MAX, correct?
Instaling an VRM to this amp would enable you to have:
1) Power distorsion coming from the normal chanel at lower volumes
2.) Power and preamp distorsion for the TMB chanel at lower volumes.
Basicly this MV on the TMB chanel controls the distrsion from the preamp tubes, correct?
You don't NEED to have your amp maxed-out to get power amp distortion - it really depends on how the amp is designed. There is a whole "inexact science" to finding an amp's "sweet spot" when balancing volume vs power distortion. Some amps have it at full blast, some don't. Some people's sweet spots are different than others'.
But, as we've been saying, VRM allows you to have nearly the full tone of the amp at lower volumes. There is lots and lots of theory involved in this that is explained all over the web. The 18watt.com forums would be a great place to look for that if it interests you to see the "why" behind it all. Unless you want to dig into that theory yourself or just go ahead and build it and hear for yourself, you are going to just have to take our word for it that for 1) and 2) above... yes. Compared to the overall cost of the amp, $45 for the VRM add-on is a "safe" investment and very easy to remove if you don't like it but it works wonders on an 18-watt design.
For your third question, a master volume does not lower the amount of distortion created anywhere before it in the chain. Once it's made, its there for good - no master volume can take that away it can only make that distortion quieter. (Well, you could take some away with a feedback loop, but that's a whole other topic unrealated to this one and if you put one in an "18 watt" amp it would not be an "18 watter" anymore.)
The MV on the TMB channel is most likely there to balance the output levels of the two channels when using an A/B/Y switch in front of the amp, nothing else.
However, that master volume on the TMB channel CAN affect how much power tube distortion you get from that channel only because turning it down will then hit the phase-inverter with a lower input voltage.
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