Maybe both, with a little magic, too!
I’m publishing this Misho Myronov’s short article about his handmade transformers, the heart of his amazing, unique gears: his phono stage and other amps and preamps are able of truly remarkable musical performances and are in some of the best audio systems worldwide
I’m re-publishing on my blog because - same as per Misho’s strong will - I don’t want his wise words and concepts went lost.
“My reply to a good friend question about Wooden output transformer - just do not want it to be lost 🙂
There is nothing unusual - since the transformer behaves as a “normal” transformer, just designed for a different frequency range.
Cores of different types should be applied where needed, and if needed, no doubt - but if we can avoid to use it - why not? 🙂
As I’ve said, the coil should be designed as any audio frequency range output transformer - it should have the required properties 🙂
There is no self resonances in the audible frequency range (and not even close to it - otherwise it will be terrible design 🙂 and the only real issue that we should consider - we should not feed the signal considerably lower than the lowest transformer frequency in to it - since at the lower frequencies the transformer impedance drops and if unwanted signal is present - it will not be passed, but will saturate the signal with the distortions (higher harmonics will pass) - same as with any amp, do not feed the much lower than designed frequencies in to the output stage - at this frequencies the transformer will be not seen as a load by the tube, but as a short 🙂
Nothing new, actually - but people dealing strictly with audio some time thinking too limited - only in a comfort zone they are used to 🙂
Forget about core - it’s just a trick in order to provide our coil with the higher impedance and lower dcr - any transformer can be done without core - but the coil can become enormous in size, and dcr of the windings will (can) rise much higher that it can be allowed. So, core helps to make the transformer smaller, and realistically workable. The lower frequency is - the higher our needs in core.
The higher frequency is - the lower our need in the same core.
In fact, most popular high silicone steel cores - the ones that has higher of all saturation level - the most important parameter for the high dynamic range output transformer (think hysteresis, think useful dynamic range - the undistorted range, the effective range the core actually work - nothing can beat the silicone steel 🙂 - but back to out topic - frequency range. Silicone steel core is not effective at the higher frequencies. It’s useless at 2 kHz and higher. It not help any more. Transformer designer should think about different approach at those frequencies. And here comes the magic of the audio transformers.
Bad designer gladly using the cores effective at wider frequency ranges - like permalloy, metglass, etc - core helps his bad design to pass higher frequencies, but the main issue - dynamic range - is forgotten.
Oh, well… where are we? Coreless - and I want to be short… each frequency range has its own rules. And own problems. And different instruments to solve it 🙂 and what is good for one range - is enemy for another.
The World is full of the coreless transformers and coils. Many just do not realise it 🙂
Ps(added later):
And of course (it was not mentioned as it was no asked) - the main benefit of the coreless transformer - the lack of ALL the issues associated with the core - core saturation, core distortions, core losses…. You just free of all those garbage!
Ps: but the coil has to be good, very good 🙂 as always!”
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