I'm more concerned concerned with "jitter", translating even the best tables to CD terms is rather eye opening (so to speak). I might be able to repeat the experiment with a Thorens TD160 is that good enough? Is there anyone who would try this with an SP10 and make the files available, just a couple of minutes with a few seconds of noisy leadin groove should do it.
I may be of help here.
Synchronous motor, belt driven Thorens TD160 is good enough to demonstrate the effect.
Servo motor direct driven Kenwood KD-3100 is not much better, sorry.
I have some 44.1/16 files (music) from my past experiments with cartridges.
I can also digitize some tracks with test tones from two test records (HFN 002 Test LP and The Ultimate Analogue Test LP from Analogue Productions)
Tell me what would best suit your needs and where should I upload the wav. files
George
OK, I have a question about the circuit you posted in post 43907. R17/18 and R13/14 -- why are there 2 resistors instead of one? Nothing is connected to the node between R17 and R18, so why are there 2 resistors? Was that just for visual symmetry?
OK, let's look at the biasing of the INPUT jfet. It is essentially, the Idss of the input jfet- the IR degeneration across the 5 ohm resistor, to give an Id slightly lower than Idss. It takes a lot of Gm to make the 5 ohm resistor useful, but it works OK.
Also, note: ALL of the current drive is in the input jfet. Low Idss won't give very much peak output current. This is important.
Also, note: ALL of the current drive is in the input jfet. Low Idss won't give very much peak output current. This is important.
Now, what about the 2'nd stage? The second stage gets the difference between the first stage current and the current supplied by the feed resistor (here being 300 ohms)
Now how much current is that? In this example, the feed current is about 25ma., so if the input jfet is operating at 13ma, then the second stage will operate at 25-13ma, or 12ma.
Can everyone see how jfet selection for Idss is so important in this circuit?
Now how much current is that? In this example, the feed current is about 25ma., so if the input jfet is operating at 13ma, then the second stage will operate at 25-13ma, or 12ma.
Can everyone see how jfet selection for Idss is so important in this circuit?
They bothered with complimentary JFET's must have not made the text books. John with all due respect for your audio adventures this stuff has no larger commercial value, it simply does not solve any other signal processing problem in a more cost effective maner.
Personally I think dwelling on the fashion/big money aspect of this is too negative. I have always thought you, Nelson, and Charles Hansen fall more in the ritualistic aspect of audio. All the fussing with details or simplicity is part of the experience.
Yes John you are the Zen priest guiding us on the proper trimming of our
bonsai trees for the next 100 years.
Unfortunately, the "fussing with details" is what's required - until the 'other side' evolve the mechanisms that test completed systems in the areas relevant to subjective performance ...
I follow this thread, among others, so that I can hopefully learn something about the use of electronics in audio. Sadly, I don't give a dam about zen priests or bonsai trees. Is there some useful comparison to audio here which I have missed? or is it just a personal grudge type thing which again I could not give a dam about?
Depends on what you want to learn. This thread mostly deals with circuit design from 30-40 years ago and the application to fashion audio. Modern designers with the goals of performance and reliability would (and do) make use of technology that wasn't available then, but there's lot of other threads about that. Take your choice.
I guess we will like to know about a way to measure the "subjective performance" when people is worried... or is happy... or has a headache... or is tired...
It would be very interesting if you could explain how to measure "the love for a girl" or any other emotion... as it is the same that you are proposing as an evolution
I just in the last 24 hours mentioned a technically possible way of measuring one parameter of performance relevant to what I'm talking about. Of course, this was completely ignored - yes, it's messy, not fall off a log easy to do, hence will be considered 'useless', - therefore, more 'intelligent' ways of measuring need to be devised ...
- therefore, more 'intelligent' ways of measuring need to be devised ... - Status
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