Big glass, big iron & god?

[Mr Davison]

I wonder what the actual power output of this monster is?

It might be beyond the capabilities of most attenuators!

When Audio34 (amp tech) had the amp in for tube replacement they measured output as:
81 watts RMS clip point & 132 watts RMS max
So perhaps not as formidable as it may appear.

Interesting. I suspect the OT and/or B+ are the limiting factors here. The design is ultimately based on a 100W Marshall after all.

Very interesting considering the '84 Marshall 1987 I sold is able to milk 78w clip/144w max from a pair of EL34s

[wavesofffear]

I have a Park75 which contains 2 x Kt88's and it's waaay more civilized than the 100 watt 4 holers which preceded it. Decent MV too.

Nice! Is that an original or Mitch Colby reissue?

Park 75s are basically 1986s with KT88s, so you would expect them to be tamer. The KT88s aren't getting pushed much into overdrive by that circuit (EL34s break up earlier).

Very interesting considering the '84 Marshall 1987 I sold is able to milk 78w clip/144w max from a pair of EL34s

Is that peak or RMS? Note that 78/sqrt(2) ~ 55W, which sounds more reasonable (assuming "clip" means at the onset of clipping, i.e. "clean power").

Output power measurements tend to vary a little according to the method.

[RobRoyMcCoy]

DM's amp (JSN880) gets 100w rms at clip and 200w rms maximum power from a pair of KT88s.

However, it is running 630v DC on the plates, has a custom designed power supply including separate screen windings on the Power Transformers (PT) and custom OPT. We had to build 3 PT's (via Marque Magnetics) until we achieved this as a result of prototyping learnings.

[Bg]

DM's amp (JSN880) gets 100w rms at clip and 200w rms maximum power from a pair of KT88s.

However, it is running 630v DC on the plates, has a custom designed power supply including separate screen windings on the Power Transformers (PT) and custom OPT. We had to build 3 PT's (via Marque Magnetics) until we achieved this as a result of prototyping learnings.

Not sure what you just said but it makes me want to get in Greased Lightning and drive 1000 miles of straight US of A highway.

[Dharmajester]

Nice! Is that an original or Mitch Colby reissue?

Colby with a couple of modern appointments, MV, fx loop...