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Tube amplifiers and interstage transformers

Hi,

I have seen that a lot of very expensive tube amplifiers use interstage transformers to handle impedance between stages. There are other two methods to handle impedance between stages: capacitor coupling and RC. I would like to know if somebody with more knowledge can explain the difference in the sound of these 3 styles.

Somehow, it looks like some of the most expensive SET amplifiers have interstage transformers like Audio Note or Shindo.

I also read about the highly regarded amity and karna amplifiers that D Olsen built and they have also interstage transformers.

So, what are the benefits of using interstage transformers?

Thanks

Alan
128x128alanbrain
charles1dad's avatar
charles1dad
10,250 posts
 
Alan,
As is usually the case the key is execution. A top quality IT used by a talented builder and placed in a good circuit will turn out fine.I certainly can't offer an explanation but this proper use of IT yields such naturalness and striking realism.My amp's builder Israel Blume much prefers the IT rather than a capacitor in the signal path. Of course other builder/designers will feel the opposite and have their own approach.I heard my amp paired with the Atma-Sphere MP-1 and the sound was also fabulous. My line stage has an IT and is sublime with this amplifier.There's always different paths to great results.
Regards,
alanbrain's avatar
alanbrain OP
69 posts
 
Regardless of the technical hows, that is the bottom line: it depends on the implementation.

Maybe I could ask Bob Danielak to build a SET IT amplifier for me so I can compare for myself at home. Maybe one with the darling 1626, which by all accounts looks like a "magical" tube in the presence and soundstage area.
intactaudio
300 posts
 
The use of the term "impedance matching" isn't really appropriate for the majority of interstage transformer usage.

Typically output transformers are used to "match" the high impedance of a tube to the low impedance of a speaker so they usually have rather large stepdown ratios.

In the case interstage coupling, tranformers with ratios around unity are typically used. A 1:1 doesn't help with impedance matching, Small step up ratios make the impedance matching worse and it is only the transformers with a stepdown ratio that help in the impedance matching situation and you typically see them used for the drive of an A2 grid.

dave
alanbrain's avatar
alanbrain OP
69 posts
 
Thanks for jumping in Dave with a real technical explanation. Could you help us here giving us an idea why interstage transformers when properly implemented add a kind of natural and openness to the sound?

Alan
intactaudio
300 posts
 
This might not be an appropriate response but system synergy is the only thing that can give you what you want.

The problem is, you need to know what you want prior to asking the question or you risk a 1000 post thread from others telling you what they think you need.

dave
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