John Curl's Blowtorch preamplifier part II

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Of course, I apologize. I was concerned with lamination thickness, and its effect on ultimate transformer importance. Whatever the rest of you were debating was 'off-topic' as far as I am concerned. I am trying to discuss low noise audio design, and deviation from this topic, should have been dealt with by others, I should think. What does everyone else think?

Yes, the principles of physics are usually OT here.
 
Layer winding of audio transformers causes electrical resonance.....bundle winding helps to cure the resonance problem.

Care to elaborate on that?

What do you mean by "bundle winding"? Are you using that term to mean the same as random winding or scramble winding?

High frequency resonance is the result of leakage inductance and winding capacitance. Layer winding keeps winding capacitances very low.

Here's a CineMag CMLI-15/15B which is a layer wound transformer. No resonance problems there.

An externally hosted image should be here but it was not working when we last tested it.


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resonance "Q" measurements can be very sensitive, but it helps to have a model to put those sensitive measurement numerical results into

for MC step up I think we're talking about ~10 Ohm source Z from the cart, and pretty much 1st order pre-emphasized signal from the disc


within the xfmr bandwidth you need the source impedance of these noise mechanisms to calculate their significance when paralleled with the cart R

the step up ratio shouldn't be too large, giving poor bandwidth, large leakage, which could "decouple" the source Z image at the secondary from the noise "at resonance" beyond the xfmr bandwidth
if it is then you have the bigger issue of not enough bandwidth for audio

I also really doubt any xfmr lamination "eddy current loss noise" will be increasing faster than the RIAA pre emphasized signal with increasing frequency
 
As far as core losses are concerned: Quote without comment.
"Then if an eddy-current loss of 6dB is acceptable at 16kc/s (Hz) the lamination thickness must not exceed 6 mils, and for the same loss at 600Kc/s it must not be more than 1 mil." p.50 'A Survey of Factors Limiting the Performance of Magnetic Recording Systems'
JAES, Jan. 1957 E. D. Daniel et al. Most authors were with the BBC. Daniel was with National Bureau of Standards, Wash. D.C.

Hopefully you will get a copy and believe what they say. Equations are provided, on a previous page.
 
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