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Toroidal transformer on tube amp

Why are toroids so popular in solid-state amplifiers but so uncommon in tube amplifiers?
They are said to send less EMI and interference to nearby components, among other benefits.

Is there a reason why solid-state designs are "so good" but tube amplifiers aren't?
Why not use them as output transformers?


I've never used EI transformers and have always relied on toroidals.
But, in any case, I've never built a tube amplifier.

128x128runnaway
deludedaudiophile
493 posts
 

@dafox 

From BAT’s website for one model:

VK-90t also means there are no tubes to bias; no fuses to replace; no pentodes imitating triodes; and no direct current at the tube output stage. VK-90t is the sound of the future—and musical truth.

I don’t know if the no-DC is a feature of the circuit, or if they have a circuit that adjusts to prevent DC? I am sure there are some tube hacks that can weigh in.

 

alucard19
355 posts
 

Primaluna uses toroidal transformers in their integrated amps and power amps, just check their website.

larryi
3,718 posts
 

There can never be dc at the output of any amp with output transformers.  Current is induced in the secondary (output side of the transformer) by the changing magnetic field induced by the primary; if the current on the primary is not changing (dc), there is no induced current in the secondary.

As far as I can tell from the Primaluna site, they use toroidal transformers only in the power supply to their hybrid and all of the output transformers are not toroidal types.

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