FWIW, the Sowter 1:10 stepup I used in my phono stage has an input-referred ENR of under 1R5. It's not cheap, but compared to an inch of Bybee wire, it starts looking pretty good.
The input-referred ENR of the Lundahl LL1931, that we will probably use is 1.72 ohms. However, there is still lead wiring, etc.
Well, the only real issue with wiring is on the primary side. I suspect you know how to make that pretty negligible.
Nope, the paper is on Dr. Hill's site (as in Horowitz and Hill). This is achieved at low frequencies.
I really want to see about this transformer. Without liquid nitrogen cooling, I can't see that it would be possible to make an audio quality transformer anywhere near this effective resistance.
It's all in your mind you know. Solid high end engineering has always been irrelevent why would that change? You make an interesting observation without even the slightest idea of what they did. Talk about condemnation without observation.
I know it's difficult to deal with someone "not of the cloth" designing circuits.
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Scott, please tell me about the transformer. I searched out Hill's website, but I didn't find anything relevant to transformers.
What I am trying to do here is to show the real tradeoffs in low noise design, nothing else. I have never found a perfect transformer, and the good ones are very expensive. If someone can show me how you can make or buy a wide band transformer with almost no intrinsic resistivity, please show me the way. Of course, we can always just parallel a bunch of fets, and sooner or later get pretty darn low voltage noise, especially if we also have variable temperature control.
Would it not be better, Scott, to give your expertise to the other low noise thread, and help them get below 0.4nV/rt-Hz?
What I am trying to do here is to show the real tradeoffs in low noise design, nothing else. I have never found a perfect transformer, and the good ones are very expensive. If someone can show me how you can make or buy a wide band transformer with almost no intrinsic resistivity, please show me the way. Of course, we can always just parallel a bunch of fets, and sooner or later get pretty darn low voltage noise, especially if we also have variable temperature control.
Would it not be better, Scott, to give your expertise to the other low noise thread, and help them get below 0.4nV/rt-Hz?
Nothing stops you either, John, from helping me get below 0.43nV/rtHz 🙂 in the "other" thread.
Seriously now, I find it more difficult than just paralleling a bunch of jfets, but then, I'm just a beginner, so it's to be expected.
Seriously now, I find it more difficult than just paralleling a bunch of jfets, but then, I'm just a beginner, so it's to be expected.
Iko, I try to stay with this thread, if I can. However, I did look at your recent circuit, and I don't see anything obvious, except perhaps for the current source load. That can contribute noise, if you are not careful.
WRT 0.065nV - how about an autoformer for a ribbon mic. I believe the
Royer ribbons have something like a 1:40 step up ratio with very good FR.
That would have to be getting to around 0.1nV/rt Hz at the ribbon.
There you go John, why not try something different for that balanced IP
phono. An autoformer or multifilar IP transformer feeding fully differential
IP stage.
T
Sowter 8055x, which I cited before, has 0.17nV/rtHz, input referred, and 20dB of gain. Costs about $100 in onesy-twosey. In this context, that's hardly "very expensive."
Gents,
I have my doubts about using transformers at the input of a MC phono pre. According to Prof Hawksford's math in his "Fuzzy Distortion paper, a vinyl record and a good MC cart are down at the resolution level of +/- ONE ELECTRON!
I cannot believe any magnetic device can accurately transmit this signal level /difference accurately, and that's what my ears tell me, transformers just ignore the ultra subtile information of the music, and there goes the accurate portrayal of space and downward dynamic range.
Noise? I use a single MAT02 dual at 10mA/side in my big differential phono section, under a 6DJ8 tube, so lets be generous and say 1nV rt/Hz - and NO ONE has ever complained about phono noise - even with a 100uV IKEDA cart. I believe hunting for the noise levels you all are wanting could be a triumph of engineering over usability, but if a transformer is involved, maybe throwing the musical baby out with the bathwater?
Regards, Allen
I have my doubts about using transformers at the input of a MC phono pre. According to Prof Hawksford's math in his "Fuzzy Distortion paper, a vinyl record and a good MC cart are down at the resolution level of +/- ONE ELECTRON!
I cannot believe any magnetic device can accurately transmit this signal level /difference accurately, and that's what my ears tell me, transformers just ignore the ultra subtile information of the music, and there goes the accurate portrayal of space and downward dynamic range.
Noise? I use a single MAT02 dual at 10mA/side in my big differential phono section, under a 6DJ8 tube, so lets be generous and say 1nV rt/Hz - and NO ONE has ever complained about phono noise - even with a 100uV IKEDA cart. I believe hunting for the noise levels you all are wanting could be a triumph of engineering over usability, but if a transformer is involved, maybe throwing the musical baby out with the bathwater?
Regards, Allen
Clearly, subjectively, I disagree. 😀 And the actual experimental data (rather than theoretical speculation) give a rather different picture.
SY, who or what do you disagree with? Me I guess.
Seems like we will have to have a shootout between our creations, or we won't ever understand what each other believes/experiences.
But check this review for another's experience:
6moons audio reviews: Vacuum State RTP3D
Regards, Allen
Regards, Allen
Seems like we will have to have a shootout between our creations, or we won't ever understand what each other believes/experiences.
But check this review for another's experience:
6moons audio reviews: Vacuum State RTP3D
Regards, Allen
Regards, Allen
I was giving my own uncontrolled, subjective experience: that transformers are a positive. On the topic, I was also pointing out that the noise from the transformer is negligible, and that superb units are not horribly expensive.
If the Hawksford paper you referred to is the JAES 31, 745 (1983) paper, then I don't see what you claim is in there, in there. In fact, reading through that paper, one is struck with the idea that running an MC signal directly into the bases of the transistors is more problematic than interfacing via a transformer.
If the Hawksford paper you referred to is the JAES 31, 745 (1983) paper, then I don't see what you claim is in there, in there. In fact, reading through that paper, one is struck with the idea that running an MC signal directly into the bases of the transistors is more problematic than interfacing via a transformer.
The one I have is "Fuzzy Distortion in Analog Amplifiers: A Limit to Information Transmission?" which is an actual peer-reviewed and interesting paper.
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