Thanks, all. I’m experimenting with the two inputs, and whilst both sound remarkably nice, the low/47Ω input sounds as if it has a richer, fuller bass than the high/100Ω input (maybe I’m being fooled by an increase in volume: 17.3dB vs. 10.9dB). In neither case am I aware of any excessive top end, but then again, I probably can’t hear it if present!
I bought this transformer many years ago as the pre-amp I used at that time (Copland CTA-301) only had an MM phono section. I don’t think I want to dive into fine-tuning via a choice of SUTs. This arose again now as the MC input of my phono stage has some hum, and this cures it. I think it sounds better, but we all know how easily we can think something new or different can sound better, and the proof of the pudding will be in whether the benefits last.
I read that phono stage impedance/turns ratio squared = Impedance apparent on primary coil.
Phono stage impedance =47kΩ
turns ratio = x (not given on VAS website)
primary coil impedance 47Ω
Which should make x = 21.7, probably 1:20. Similarly the high/100Ω input should have a turns ration of ~1:30 by that calculation. But I’m doing something wrong, as the high impedance input has a 10dB gain vs. 17dB for the low, and surely a higher turns ratio should result in the higher gain, not the other way round?
I was also reading that getting the output voltage of the SUT to match the input of the phono stage is what matters. I can select input sensitivity of the phono stage as 1.3mV, 2.6mV or 5.2mV. That complicates it further!
Don’t worry if you can’t drum sense into my thick skull—I’m only going to use what sounds best anyway!
Chris
