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.
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.
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!
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! '-)
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! '-)
Please everyone, I am only trying to save concerned amateurs of audio DIY the money that they might invest in transformers, to try NOT using transformers and getting the same measured results, as well as maybe a new approach in phono playback design that seems to work, at least, for many people.
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Any audio input transformer experts out there? I'm sorry if I overlooked you, perhaps you can present your credentials and your measurements of different transformers? I would certainly appreciate it, and everyone else would too. Please give us your input. We need it to make an intelligent discussion out of a series of opinions.
Ask Pieter T. Or Bud. Or maybe try measuring a few yourself. The results might be interesting.
There's a pretty complete set of independent measurements of the Sowter I use on their website- Morgan Jones did those and wrote some nice text on how to optimize them.
There's a pretty complete set of independent measurements of the Sowter I use on their website- Morgan Jones did those and wrote some nice text on how to optimize them.
Morgan Jones compares the Sowter 8055 to the Jensen JT - 346 - AX - 1. Both need a Zobel network parallel to the secondary. It depends on cartridge DC resistance. So the first i can learn here is that there is no universal transformer and overshot depends on the particular cartridge and the Zobel. Fig. 7.37 in his book "Valve Amplifiers" third edition says : Jensen : 1dB extra gain, 2 x ringing frequency, 1/4 ringing amplitude, 4 x price against the 8055.
Yeah, the price differential is less here, thanks to the weak dollar. The economics have probably changed in Europe as well. Morgan's writeup on zobels vs cartridge type on the Sowter site is a bit more comprehensive than in his book. But that's an important point that can't be underestimated- the circuit has to accommodate the transformer- just drop the iron in without attention to what it wants to see as far as secondary load and the performance will be mediocre at best.
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