Mesa Boogie Nomad 55 OT

[Helmholtz]

[ATTACH]55491[/ATTACH]

Thanks! The power stage looks straight forward, even has some HF lag compensation. So I have nothing to add.
Interesting: For EL34 operation an additional screen filter/dropping resistor is switched in to relieve the pentode screens and increase/match output impedance.

[Helmholtz]

It has a somewhat complicated location and is fixed only at two points, but I would measure it to find a substitute.

Like this for example:

https://www.hammfg.com/files/parts/pdf/1750M.pdf

[ATTACH=CONFIG]55492[/ATTACH]

The OT in the picture doesn't look as if it could put out more than 40W before clipping/saturation (similar to a Fender Vibrolux OT).

[Leo_Gnardo]

The OT in the picture doesn't look as if it could put out more than 40W before clipping/saturation (similar to a Fender Vibrolux OT).

I agree. Either $155 or 130 is too much for that kind of OT, unless it can't be had elsewhere.

Back to Amp Parts Direct, we're looking at any of the following ClassicTone models: 40-18006, 40-18105 , 40-18088 all under $60. I've bought iron from them before, it's always worked out fine.

Mesa makes a habit of boasting about their output power, they must measure at 20-30% distortion. I doubt the Nomad made 55W before clipping, even if you drove it off a cliff, with the wind at its back. That's what I used to say about my 62 Volkswagen, with a speedo that read up to 85 mph. Expect more like 40.

https://shop.amppartsdirect.com/Transformers_c2.htm