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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
intactaudio
301 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
301 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
onemug
784 posts
 
Intactaudio (Dave) is brilliant and balanced. Read his posts a couple of times to make sure your getting what he is saying.

Charles1dad,
from what you have experienced with the Duelund caps, what do you think a "cap coupled" amp using a cap that was that good do for a challenge to the same amp with an IT? Theorize of course.
charles1dad's avatar
charles1dad
10,250 posts
 
Onemug,
I've had the same hypothetical thoughts.I believe either one can be done with a fine result.Given my deep satisfaction with the use of IT in my Coincident components, I'd probably favor the transformer approach.It's so wonderfully natural .For all I know it could be as good with CAST caps in their place.It would be fun to build both examples and listen.It's interesting to note that many cost no object designs choose the IT when they could use the best capacitors money can buy.
Regards,
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