Its important to understand what I am saying with regard to IT's. All IT's and Input Transformers and even OT's are designed and measured in a very specific loading arrangement and they will only produce the measured results if those exact loads are duplicated. Drop in a IT into a different loading arrangement and they will either droop at the frequency extremes or ring or resonate in the bottom end.
So simply dropping in an IT into any old circuit will have unpredictable results regarding frequency response and you will need to measure that response and possibly adjust the loading of the IT to smooth it out. Companies like LLundahl specify a specific Zobel network for loading their secondaries and they will be specified for a specific output impedance of the driver valve. Alter either of these and the response will deviate from the manufacturers specification.
I have never used an Input Transformer which hasn't needed adjustment to its secondary loading in order to get a reasonably flat response.
Shoog
So simply dropping in an IT into any old circuit will have unpredictable results regarding frequency response and you will need to measure that response and possibly adjust the loading of the IT to smooth it out. Companies like LLundahl specify a specific Zobel network for loading their secondaries and they will be specified for a specific output impedance of the driver valve. Alter either of these and the response will deviate from the manufacturers specification.
I have never used an Input Transformer which hasn't needed adjustment to its secondary loading in order to get a reasonably flat response.
Shoog
Her the link where you can find your information ( sorry its dutch)
DHTRob - Vergelijking 1:1 interstage Tribute en AE-Europe op amorfe kern
DHTRob - Een Tribute 1:1 interstage met amorfe kern
En clearly he is speaking about resonances.
DHTRob - Vergelijking 1:1 interstage Tribute en AE-Europe op amorfe kern
DHTRob - Een Tribute 1:1 interstage met amorfe kern
En clearly he is speaking about resonances.
Haha,
You don't need to be able to read Dutch to see the results of this comparison bij checking the comparison table.
Both interstage transformers show HF -3 dB points around 350-400 kHz; is that enough
?
The AE interstage transformers show more HF resonance modes, however these are not graphically presented, and they are not harmful at all (as you are supposed to know....).
This despite the fact that the AE IT's are wound bifilar, whereas the Tribute IT's reach the same specifications with layer winding which minimizes the risk of shortage between the primary and secondary wires.
Also check the DC resistance of both interstage transformers; enough said??
You don't need to be able to read Dutch to see the results of this comparison bij checking the comparison table.
Both interstage transformers show HF -3 dB points around 350-400 kHz; is that enough
?The AE interstage transformers show more HF resonance modes, however these are not graphically presented, and they are not harmful at all (as you are supposed to know....).
This despite the fact that the AE IT's are wound bifilar, whereas the Tribute IT's reach the same specifications with layer winding which minimizes the risk of shortage between the primary and secondary wires.
Also check the DC resistance of both interstage transformers; enough said??
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Your IT is quite good but it does have a resonance as well in the 400-500 KHz range. You FR picture clearly shows a "double slope" in the high frequency range. This is not completely damped with the source impedance you used.
Although your understanding of physics in transformers is poor you have found a good recipe in making them.
This is not uncommon and at some point theory is not very useful anymore because of the lack of control on some parasitic phenomena which can be sorted only by trial and error. If the FR were optimally (i.e. Q= 0.71) or critically (i.e. Q < 0.7 ) damped then F3 (i.e. -3 dB point) would be quite less than 895 KHz.
In general, I would not be worried about some ringing above 40 KHz in zero fb amps. The only important thing is that ringing needs to be completely damped after few cycles.
Well a resonance at 200KHz and -3dB at 400kHz and again a resonace at 800kHz.
A graphic would be much better to see if it is a big problem or not but because of the lack of information i don't know. Not even a square wave.
Btw, low copper losses is nice but they don't give any data about signal level at 20Hz so both companies have a hugh lack of information.
A graphic would be much better to see if it is a big problem or not but because of the lack of information i don't know. Not even a square wave.
Btw, low copper losses is nice but they don't give any data about signal level at 20Hz so both companies have a hugh lack of information.
Haha,
You don't need to be able to read Dutch to see the results of this comparison bij checking the comparison table.
Both interstage transformers show HF -3 dB points around 350-400 kHz; is that enough
The AE interstage transformers show more HF resonance modes, however these are not graphically presented, and they are not harmful at all (as you are supposed to know....).
This despite the fact that the AE IT's are wound bifilar, whereas the Tribute IT's reach the same specifications with layer winding which minimizes the risk of shortage between the primary and secondary wires.
Also check the DC resistance of both interstage transformers; enough said??
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As i sad before: i found no problems.
Otherwise the sq would show.
Otherwise the sq would show.
Your IT is quite good but it does have a resonance as well in the 400-500 KHz range. You FR picture clearly shows a "double slope" in the high frequency range. This is not completely damped with the source impedance you used.
Although your understanding of physics in transformers is poor you have found a good recipe in making them.
If the FR were optimally (i.e. Q= 0.71) or critically (i.e. Q < 0.7 ) damped then F3 (i.e. -3 dB point) would be quite less than 895 KHz.
In general, I would not be worried about some ringing above 40 KHz in zero fb amps. The only important thing is that ringing needs to be completely damped after few cycles.
Attachments
From Tribute:
"Actually, different from what the tube community likes us to believe, interstage transformers with a 1:1 ratio are easy to wind with specifications easily surpassing those of output transformers for example. If someone on this forum comes up with this type of interstage transformer, yelling how good it performs, I'd say go back to your winding machine and wind a more difficult transformer with a step up or step down ratio, preferably for a high Rp tube. When measuring don't forget to implement the right source impedance.
That said, interstage transformers with a 1:1 ratio can be wound "on the cheap" (with a limited number of primary and secondary sections) or "more expensive" (with layer to layer primary/secondary sections or bifilar).
Properties of these different winding techniques are predictable and there is no voodoo involved.
If someone is not willing or able to spend more bucks for higher quality transformers it is perfectly possible to get decent results with cheaper ones; the Hammond 1:1 is a good example when taking care of feedback/phase shift issues in the tube circuit as pointed out by member 45.
By the way, this is neither about core geometry and core material and their influence on sound quality, nor on the everlasting and IMO totally senseless discussion on SE vs PP".
P.S. Thanks esltransformer for your positive PR by providing that link....
"Actually, different from what the tube community likes us to believe, interstage transformers with a 1:1 ratio are easy to wind with specifications easily surpassing those of output transformers for example. If someone on this forum comes up with this type of interstage transformer, yelling how good it performs, I'd say go back to your winding machine and wind a more difficult transformer with a step up or step down ratio, preferably for a high Rp tube. When measuring don't forget to implement the right source impedance.
That said, interstage transformers with a 1:1 ratio can be wound "on the cheap" (with a limited number of primary and secondary sections) or "more expensive" (with layer to layer primary/secondary sections or bifilar).
Properties of these different winding techniques are predictable and there is no voodoo involved.
If someone is not willing or able to spend more bucks for higher quality transformers it is perfectly possible to get decent results with cheaper ones; the Hammond 1:1 is a good example when taking care of feedback/phase shift issues in the tube circuit as pointed out by member 45.
By the way, this is neither about core geometry and core material and their influence on sound quality, nor on the everlasting and IMO totally senseless discussion on SE vs PP".
P.S. Thanks esltransformer for your positive PR by providing that link....
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zobel can fix it, opinions are that no big difference is heard. Who will care if small ringing at 50khz or so is present?
But dips/peaks in audio range will be heard.
I agree that zobels can fix it, but I repeat I can hear a big but subtle difference between a transformer that rings at 50khz and one that doesn't and it somewhat surprises me that others report not been able to hear it.
Shoog
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