john curl said:
Won't a current source add 2nd harmonic distortion? Not that second's all that evil in the overall scheme of things, but to the extent that I can cancel it, why not?
I specifically mentioned in the accompanying post that you could pass on the front pair if you had a well behaved load; a decent value straight resistive pot definitely qualifies. I use the same board for several things, one being as a crossover module for which isolation from level controls, siblings, and personalized current are pluses.
The front buffer also gives me the option of evaluating volume controls without worrying about interactions with the input cable due to different impedance/resistance. I don't want to have to force everything I try into the same impedance value, be it 5k, 10k, 100k, whatever. A buffer ahead keeps the variables down.
Grey
john curl said:
(You posted while I was writing...)
Hmmm...comparing this post to your previous one leaves me a bit perplexed.
I got fortunate and was able to match N-ch and P-ch devices to each other...no servo required. In fact, the 10 Ohm pot I'm using for DC offset adjustment is nearly dead center. Not too bad. I also have a somewhat larger number that can be used together with only modest resistances. One of the few times I can say that I got lucky on parts.
Any hints on the right CCS to null 2nd?
Grey
In exploring the proposals for possible servo configurations by Pavel, Charles and John my current servo configuration shows reasonable results. I have the feeling it can be taken a step further which, for me, is a challenge. There have been many examples and hints to come up with ones own solution, so I will not display the schematic. One learns by exploring and sometimes trial and error.
I have used somewhat extreme DC values which in real life certainly will not be present if devices are matched properly I guess.
I have used somewhat extreme DC values which in real life certainly will not be present if devices are matched properly I guess.
Attachments
GRollins said:
Of course, except for educational purposes, it would be pointless
to simply present a JFET follower (TaaDaa!!).
But it turns out that you can play a couple of tricks, ones that I
haven't seen exploited.
Now Grey, I know that your mind is already racing, so chill for a
bit and let me finish writing it
😎
john curl said:
Nelson Pass said:
You guys need to remember that between the fellas here at work bringing me problems to solve, Logan crying because Wyatt took the truck he was playing with, and my wife adding entries to my fix-it list...thinking is 'bout near all I can do! Don't take my last remaining audio pleasure away from me. At least you can get to soldering irons when you want to.
Jeez, and listen, too...
Grey
P.S.: I've got a circuit on my to-try pile of notes that uses opposing current sources in addition to the JFET follower. That one I can remember pretty clearly. There are at least two other variations on the JFET follower in the pile, but I can't remember the details for the life of me. That's why I sketch these things out while they're fresh in my mind--otherwise I lose them during the weeks or months between when I think of them and when I finally get to try them out.
GRollins said:
Oh Yeah?
To quote Cassandra Peterson ( AKA Elvira, Mistress of the Dark) :
Just stay away from the front of my car.
😎
In an interview, Elvira was asked if she had any advice for aspiring
young actresses in Hollywood.
She responded, "Yeah. Stay away from the front of my car."
young actresses in Hollywood.
She responded, "Yeah. Stay away from the front of my car."
If she's the one I'm thinking of, she had fairly nice headlights herself.
(I may not be tracking on the right girl...bear in mind I've only watched TV twice in the last thirty years--when the Challenger blew up and during Gulf War I.)
Grey
(I may not be tracking on the right girl...bear in mind I've only watched TV twice in the last thirty years--when the Challenger blew up and during Gulf War I.)
Grey
Grey,
...............maybe it is best you wait for Mr.Pass's article rather than try to second guess him or steal his thunder, better yet come out with some orignal work of your own..........an article or project, perhaps.
Regards,
Jam
...............maybe it is best you wait for Mr.Pass's article rather than try to second guess him or steal his thunder, better yet come out with some orignal work of your own..........an article or project, perhaps.
Regards,
Jam
I don't even know whether the things in my to-try pile work or not. I think about them when I'm driving sometimes, but that's not quite the same as actually putting things to the test. It's exactly what it sounds like...a stack of little scribbly pieces of paper with sundry ideas on them. They sit there collecting dust until I get a chance to fiddle with them...which I haven't yet, in this case.
Grey
Grey
My sincere apologies Mr.Curl, I should have waited for you to ask the question...............
Jam
Jam
The Parasound JC2 seems more populated, I speak mainly of the line circuit. Why? Is this an improvement on sound quality or purely on specifications?
Just stuff to give ease in operation. The heart of the preamp is more complex, but only to add feedback and great specs. Take that, you feedback nuts!
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