Looks like the 78 is regular production now…

[beaubrummels]

Not sure I buy that. Ed was using it with those things. Why would it be designed to compensate for them?

I’m just stating my direct experience with mine. No one has to buy it. It’s just my experience.

Do you suppose Ed had a Variac set to 85 watts on each of all 12 of his Marshalls when he played live?

[Demanic]

Why would anyone in their right mind purposely run starved plate?
Yuck

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[dystrust]

Why would anyone in their right mind purposely run starved plate?
Yuck

Generally I agree with you, but turning down the input voltage to your Plexi isn't the same thing. A starved plate design in a pedal uses the tube as a clipping device if it uses the tube at all; some of these pedals still work if the tube is removed.

When you brown out your Plexi at 90v or so, the tubes still work but they have less headroom. The biggest benefit as a guitar player is that you get more distortion at less ear-splitting volume. The bass response is looser and the amp is less bright, but those are likely the result of power amp clipping rather than directly due to the voltage drop. Power scaling amps have this sort of voltage reduction built into the power supply with a very important difference. Your Plexi will stop passing signal when you drop the input to around 90v (or slightly less) because the tube heaters no longer get enough voltage to operate properly. Power scaling amps don't drop heater voltage, so you can reduce the amp's output to the point that it's no longer audible. The new 20w mini Marshalls work similarly; they drop the plate voltage to the power tubes only, thereby reducing wattage while still running the power tubes in pentode. The difference here is that you have only two settings (20w/5w) instead of being continuously variable down to 0.

[Cynical]

The new 20w mini Marshalls work similarly; they drop the plate voltage to the power tubes only, thereby reducing wattage while still running the power tubes in pentode. The difference here is that you have only two settings (20w/5w) instead of being continuously variable down to 0.

My understanding of those amps is that only the 20w is pentode; the 5w setting runs the EL34s as triodes.

[dystrust]

My understanding of those amps is that only the 20w is pentode; the 5w setting runs the EL34s as triodes.

The original 1987 Marshall Jubilees and JCM900s have a pentode / triode switch, and it definitely works to reduce wattage and volume. It also makes the amp sound like spongy crap IMO, so I always run my 2555 at full power.

I don't have a way to measure it (and not sure I want to try) but my understanding is that the new Minis drop the plate voltage to the power tubes in 5w mode, but they're cathode bias which solves the issue of needing to rebias. However they accomplish it, the lower power option on the 2525H doesn't compromise on the core tone of the amp. It still sounds basically the same, albeit much less loud and a bit lighter on bass response.

[Demanic]

I tend to get the distortion that I want from a pedal, preferably into the cleanest amp sound that I can get. Once again, preferably with as much headroom as possible. If I want old school distortion, I'll run a top boost into my 5 watt Picovalve with the pre gain on 3 and the master on 5.
But to each their own.

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[misterwhizzy]

I think this thread has been derailed.

[Mincer]

That's Ok, there is another thread about the new pickup releases.

[Hehasthejazzhands]

Medium-Low output, rolled off bass, bright and clear... Sounds like I need to try it out.

[philthis]

I have an Eric Johnson guitar that I absolutely love. I'm thinking about putting in the 78 in the bridge. How does the 78 clean up? Does it still have a nice clean quack when mixed with the neck single?

[Mincer]

I have an Eric Johnson guitar that I absolutely love. I'm thinking about putting in the 78 in the bridge. How does the 78 clean up? Does it still have a nice clean quack when mixed with the neck single?

It is not so high of an output that it is compressed sounding/feeling, so it does clean up well. As far as quack, it is better if you split it and combine it with a neck single...however the best quack would come from a middle single with a split 78.