VAS is alive and well
Steve and son Ray Leung are terrific people, certainly can answer your questions
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VAS MC One Transformer
I bought this years ago, and I think a MkII has come out since. Since I'm currently using two MC cartridges, and there's a bit of hum using the Quad 24p phono stage in MC mode, I found it and slipped it in and switched the Quad to MM. Certainly cures the hum!
A question re loading. As I understand it the 47kΩ of the MM input of the phono stage is now irrelevant, only the low (47Ω) or high (100Ω) inputs of the transformer matter?
Showing 2 responses by elliottbnewcombjr
lewm is right, my Fidelity Research FRT-4 settings are not what you might think:
3Ω:31.1dB(x factor: 35.84 times); 10Ω:26.3dB(x factor: 20.68x); 30Ω:25.2dB(x factor: 18.27 times) 100Ω:20.0dB(x factor: 10.55 times) it gets a bit complicated, you need to balance: desired impedance (guide: cartridge’s coil resistance x 10, get close to that is all it means) with enough/too high resultant signal strength. ...................................... My AT33PTGII: coil 10 ohms; signal strength 0.3mv FRT-4 setting 10 ohms = x factor 20.68. signal strength 0.3mv x 20.68 = 6.2mV. allow for some loss, guess 5.8mv signal strength. (not too high) RESULTANT impedance is 47,000 divided by x factor squared. thus setting 10 ohms 20.68 x factor squared is 428. 47,000 divided by 428 is 110 ohms RESULTANT impedance. Guide for my cartridge: 10 ohm coil x 10 is 100 ohm guidance. .................................................... As mentioned: listen, find what seems right. Avoiding too high signal strength, thus overload of phono stage’s input is important.
Long article, interesting chart simplifies recommendations http://www.rothwellaudioproducts.co.uk/html/mc_step-up_transformers_explai.html I found this which, if you scroll down has a chart for many cartridges by model 3, and a calculator where you plug your #s in |