John Curl's Blowtorch preamplifier part II

[john curl]

Is everybody ready to make Werner's circuit? I think it is a GREAT example of a DIY design. I couldn't do better, myself. Then, someone out there should compare the single stage VW design that we did earlier, with this design. I think that many here would be surprised. Of course, that is only my opinion, yet this is what I do for living, and I seem to do pretty well with it.

[Rod Coleman]

Originally Posted by john curl

Is everybody ready to make Werner's circuit? I think it is a GREAT example of a DIY design. I couldn't do better, myself. Then, someone out there should compare the single stage VW design that we did earlier, with this design. I think that many here would be surprised. Of course, that is only my opinion, yet this is what I do for living, and I seem to do pretty well with it.

I am ready. I have already been using the JFET shunt-cascode stage almost exactly as drawn here, but with the opamp stage replaced by a triode.

It is low noise, using Lyra cartridges. The gain is flexible, and can be traded for low output impedance. And - the sound is superb, notably more enjoyable than any other solution I've tried.

And yes, with the input and output both referred to ground, the EMI rejection is excellent: you can hold telecom handsets or 50Hz transformers very close before perceptible pickup.

Also, since the instantaneous AND average supply current is constant, you can feed it from a current source, shunted by a resistor, for extra supply isolation.

Not to mention that it costs pennies to make DIY, and the board can be carved out of a piece of FR4 by hand.

[Rod Coleman]

O, and yes, I use the K369. They are perfectly low enough noise in my application, and you don't even need to run them at Idss to get it: a small source resistor brings them under better control.

[SY]

Originally Posted by Steve Eddy

Huh?

Kevin's selling the LL1931 and 1933 for $225.00 and $185.00 respectively.

se

Those are "each." I think John was talking about "per pair."

[Steve Eddy]

Originally Posted by SY

Those are "each." I think John was talking about "per pair."

The only people crazy enough to pay that much for a single pair are the Japanese.

And what's produce have to do with transformers?

se

[SY]

Originally Posted by Steve Eddy

And what's produce have to do with transformers?

Excellent quality isn't cheap, but once one reaches a certain level, additional money is just for fashion. Hey, go for the Jensen at $500 the pair. It's gotta be 20% better than Lundahl and 40% better than Sowter!

[john curl]

Jensen is even more expensive? Good to know.

[john curl]

Let's forget transformers for the moment, everybody. It is obvious that there are no transformer experts here, and most can't tell the difference between good ones.
Let's talk about cost effective phono reproduce design, instead. Werner's basic circuit was also in the JC-80, designed about 30 years ago. Just goes to show that good designs keep their reputation, even over time. We got 'preamp of the year' in Japan. Try for that, you amateurs! '-)

[gpapag]

Let's forget transformers for the moment, everybody. It is obvious that there are no transformer experts here, and most can't tell the difference between good ones.
Let's talk about cost effective phono reproduce design, instead. Werner's basic circuit was also in the JC-80, designed about 30 years ago. Just goes to show that good designs keep their reputation, even over time. We got 'preamp of the year' in Japan. Try for that, you amateurs! '-)

YouTube - Monty Python - The man who is alternately rude and polite

Regards
George

[SY]

Originally Posted by john curl

Let's forget transformers for the moment, everybody. It is obvious that there are no transformer experts here, and most can't tell the difference between good ones.

OK, we'll continue to look at the ground and drool.