PMA said:
Am I missing something? AC coupling means zero current into gate resistors means Vgs =~0. FET's crash close enough to plus rail so Vds is low enough for .5mA at 0 Vgs? The distortion will be very bad at this operating point.
I general Hannes I agree the case for obsessive JFET matching is overstated. The folks that claim to get only 3 or 4 quads out of a bag of 1000 are shooting themselves in the pocket book.
Oh sorry, I forgot to post the link to above citations:
here it is:
http://www.diyaudio.com/forums/showthread.php?postid=1294772#post1294772
Have fun, Hannes
here it is:
http://www.diyaudio.com/forums/showthread.php?postid=1294772#post1294772
Have fun, Hannes
Hi Scott,
thanks for your comment!
Of course you're perfectly correct.
The circuit is mostly a result of my parts bin 😀 and I think it's sufficient for the comparison as absolute values are not of interest.
(Don't tell anyone I'm using old scrap parts out of 80ies vintage gear 😉 )*
See, I'm matching jfets myself. Still and even if it's only for the beauty of symmetry.
My original intention was never to show that it's overstated. That came out of the data.
I just wanted to get a grip on what it could bring. There's so much discussion and so little real data.
Somehow I thought there would be more curiosity in finding things out. After all we seek real improvements, no?
In the end, building amps as a hobby has for a lot of people more to do with emotions than with rationale - and I'm no exception 😉
Have fun, Hannes
*of course they get checked before use...
thanks for your comment!
Of course you're perfectly correct.
The circuit is mostly a result of my parts bin 😀 and I think it's sufficient for the comparison as absolute values are not of interest.
(Don't tell anyone I'm using old scrap parts out of 80ies vintage gear 😉 )*
See, I'm matching jfets myself. Still and even if it's only for the beauty of symmetry.
My original intention was never to show that it's overstated. That came out of the data.
I just wanted to get a grip on what it could bring. There's so much discussion and so little real data.
Somehow I thought there would be more curiosity in finding things out. After all we seek real improvements, no?
In the end, building amps as a hobby has for a lot of people more to do with emotions than with rationale - and I'm no exception 😉
Have fun, Hannes
*of course they get checked before use...
Gentlemen,
maybe it`s time to round off this well-founded discussion by saying that those nice Audio Precision distortion curves have no connection either with device matching or reality.
I can hardly wait for Part 3.
maybe it`s time to round off this well-founded discussion by saying that those nice Audio Precision distortion curves have no connection either with device matching or reality.
I can hardly wait for Part 3.
Hi Scott,
Crazy stuff! It would be interesting to see wether it also holds up on the bench 😀
EDIT: err, 10Meg resistors. Are these these little things that change resistance already when touched?
Have fun, Hannes
Maybe on your own, personal little planet orbiting sometimes near the earth 😉
Crazy stuff! It would be interesting to see wether it also holds up on the bench 😀
EDIT: err, 10Meg resistors. Are these these little things that change resistance already when touched?
Have fun, Hannes
Maybe on your own, personal little planet orbiting sometimes near the earth 😉
h_a said:
No, that's just so I don't have to use any dirty electrolytic coupling caps. 🙂 10M are the biggest RN55C's that come standard in the assortment kits.
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