OTL Asylum

OTL, Output Transformerless Amplifier User Group.

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RE: Help with Autotransformers

Posted by Cory M. on June 16, 2019 at 14:06:49:
Hi CB,

Thanks for the reply. I wasn't quite sure what to expect, actually- possibly more effortless dynamics, maybe a greater sense of "ease-" both qualities that this amp/ speaker interface already excels at. Definitely not less bass and lower volume, though.

I'm new to the OTL party, and have read that a few folks have had success with autotransformers (The Zeros, in particular) to match their speaker's reflected impedance to the tubes more closely.

The builder of this OTL, Craig Merz, spec'd power ratings at 100 WPC into 8 ohms, and 75 WPC into 4 ohms. This amp uses 10 6AS7Gs per channel in a modified totem-pole configuration, so the output stage's impedance may already be where it needs to be to drive my 8 ohm nominal KEF LS-50 speakers at their best.

I'm planning on trying it with 'stat panels soon, which may be an entirely different story.

Best,