Power Transformer For Marshall 18 Watt

[CJ]

Interesting blurb on the Trainwreck amps, i think they are talking about an EL34 model but the concept remains the sdame>

"The secret to a Trainwreck is the output transformer. The impedance ratio is about twice that of other amps. I.e. typical 50W Marshall has a primary impedance of about 3200 ohms. A Trainwreck is about 6500 ohms. The causes the power tubes to clip much sooner."


had a Hohner Contessa CA-100 with 6BQ5's on the bench a while back, it had a crazy 18K : 8 ohm output, no NFB line,

75 EI, about 100 Henries

you can see what it does to the transfer function vs a 7.6K:8 here>

 

[capacitorless]

I've wondered if plugging a 16 ohm load into an 8 ohm tap would roughly accomplish the same thing.

As you likely already know, the Express is set up to have the power tubes overdrive first, then the PI, then a cold clipper stage (3rd preamp stage), then the 2nd preamp stage - at which point it's super compressed and loud.