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 distort first, then the PI, then the cold clipper stage before the PI, and finally the 2nd preamp stage (at which point it's super compressed and loud).