His Master's Noise: A Thoroughly Modern Tube Phono Preamp

Brinkman

Member
Paid Member
2007-08-17 5:48 pm
Oakland, CA
I have purchased from his eBay store. Are you referring to his mute circuit PCB when you say “switch circuit”? I’m not trying to be pushy, I am genuinely curious about the PCBs you are using. For instance, the Elliot Sounds bleeder circuit; is that something you DIY’d or is that a project he offers (yes, I looked)?
 
Can I calculate the value of R1?

Tube resistance = 65R
Source resistance of the transformed cartridge = 500R (5Rx100) Ortofon MC Quintet Black S x Sowter 1480
Transformer secondary resistance = 60R
Grid stops = 100R

Total resistance = 725R
Hi, I also used one of these transformers. At the time there was a note saying to use a 47k loading resistor eg r1.
However, I hooked up a signal generator and scope with the setup suggested in the artical and devised (largely through experimentation) a zobel network to try and get the best square response and Max signal transfer out of a benz Wood sl.
There is an excellent artical at http://www.rothwellaudioproducts.co.uk/html/mc_step-up_transformers_explai.html
Which you should read.
Also unsure why you have just added up those resistances?
Anyway, if unsure, stick with the 6k8 as stock and then try a 47k in r1.
If you don't have a scope and thoroughly understand the testing setup, don't bother as you may damage the transformer putting too much current through it.
 
Hi, I also used one of these transformers. At the time there was a note saying to use a 47k loading resistor eg r1.
However, I hooked up a signal generator and scope with the setup suggested in the artical and devised (largely through experimentation) a zobel network to try and get the best square response and Max signal transfer out of a benz Wood sl.
There is an excellent artical at http://www.rothwellaudioproducts.co.uk/html/mc_step-up_transformers_explai.html
Which you should read.
Also unsure why you have just added up those resistances?
Anyway, if unsure, stick with the 6k8 as stock and then try a 47k in r1.
If you don't have a scope and thoroughly understand the testing setup, don't bother as you may damage the transformer putting too much current through it.
Thanks for the answer. The article was very interesting :)