Yeah.
I have done one such basic buffer circuit already.
Even posted it here in Pass forum ...
And I know just what the circuit will be like. It is in my head.
The hard part is to find that N-JFET with like 5-10 mA at Vgs ~0.7 Volt.
And that qualifies good for Audio use (low noise etc)
Last time I tested some N-JFETs in my sim library, I did not run in to one suitable.
But I only had patients to try like 5% of all available.
Will take half a day to try all
I have done one such basic buffer circuit already.
Even posted it here in Pass forum ...
And I know just what the circuit will be like. It is in my head.
The hard part is to find that N-JFET with like 5-10 mA at Vgs ~0.7 Volt.
And that qualifies good for Audio use (low noise etc)
Last time I tested some N-JFETs in my sim library, I did not run in to one suitable.
But I only had patients to try like 5% of all available.
Will take half a day to try all
Lineup shot me down..........
Dear Lineup,
............you mean two more reasons.
Well in some people think Mr.Pass is god (notice I spelled that with a small 'g' ),and that sould be reason enough but it would be nice to do a comparison of your respective topologies.
Best regards,
Jam
Dear Lineup,
............you mean two more reasons.
Well in some people think Mr.Pass is god (notice I spelled that with a small 'g' ),and that sould be reason enough but it would be nice to do a comparison of your respective topologies.
Best regards,
Jam
Tolu said:
The question is if the 45k of the DS1802 is input or output impedance!
Never looked at the Datasheet until just now - it's here
http://datasheets.maxim-ic.com/en/ds/DS1802.pdf
Looks to me like you treat it just like a 45K pot with 400 ohm wiper resistance. Unless I'm missing something, the max. source impedance is 45K/4 + 400 = 11.65K ohms. Should be fine.
Professor Smith
I have split off many of Professor Smith's questions and the answers to here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=130708&perpage=25&pagenumber=1
The new thread should be used for all questions by Professor Smith and the answers to them. Prof Smith, don't post more questions in this thread, that way they will all be in one place and be of the most use to other people starting out, and this thread won't be so scattered.
Variac
I have split off many of Professor Smith's questions and the answers to here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=130708&perpage=25&pagenumber=1
The new thread should be used for all questions by Professor Smith and the answers to them. Prof Smith, don't post more questions in this thread, that way they will all be in one place and be of the most use to other people starting out, and this thread won't be so scattered.
Variac
Absolutely nothing wrong with this implementation
It's ZMs modified schematic with dip-8 sockets for the jfets and 9V battery power. I was going to try 2SJ108 GR in there, but I broke the tabs off the pot (fake alps) and haven't gotten around to replacing it, so it's out of commission at the moment
(AP 1.7 on the left, F4 on the right)
Thank you Nelson Pass
It's ZMs modified schematic with dip-8 sockets for the jfets and 9V battery power. I was going to try 2SJ108 GR in there, but I broke the tabs off the pot (fake alps) and haven't gotten around to replacing it, so it's out of commission at the moment
(AP 1.7 on the left, F4 on the right)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Thank you Nelson Pass
twitchie said:Absolutely nothing wrong with this implementation
It's ZMs modified schematic with dip-8 sockets for the jfets and 9V battery power. I was going to try 2SJ108 GR in there, but I broke the tabs off the pot (fake alps) and haven't gotten around to replacing it, so it's out of commission at the moment
Thank you Nelson Pass
Very nice, did you listen to it? See about offset before the output capacitors. Should be minimal with matched fets. Tap off from there to output and listen without them caps too. It sounds better.
Had a discussion with John Curl about that recently. We concluded that it must be some Idss related sweet spot. For 7mA Idss that I used (most common mean average is 7-8mA for BL batches in my experience) it is subjective performance wise valid. I have carefully arrived to +/- 10V. For other Idss picked devices it may be a bit different. Since I haven't made another non caps B1 to compare with say 10mA devices, I just recommend trimmers for the supplies and some auditioning with different symmetric voltages. It pays off.
salas said:Had a discussion with John Curl about that recently. We concluded that it must be some Idss related sweet spot. For 7mA Idss that I used (most common mean average is 7-8mA for BL batches in my experience) it is subjective performance wise valid. I have carefully arrived to +/- 10V. For other Idss picked devices it may be a bit different. Since I haven't made another non caps B1 to compare with say 10mA devices, I just recommend trimmers for the supplies and some auditioning with different symmetric voltages. It pays off.
You are quite right. I have data on that subject, as probably does John,
although you need not assume symmetric voltages.
salas said:Its more than nice, but I wonder if there will be successors to them, or it will be like CD and vinyl.
As much as I'm an admirer of his work and his aesthetic, and as much as I thank him for sharing with the community and allowing me access to audio that would otherwise be beyond my means, I don't think even Mr. Pass could replace vinyl.
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