OO so when can we expect to be able to buy these new AJ boards, ZM? Greedy Boyz got to know
same as never-to-be-seen Iron Pre, this one is my gift to Boyz organizing Store, so for all Greedy Boyz
ask them
though, we see them having hands full, with last PapaVFet frenzy
I'm using model from Michael Rothacher, but added some capacitances, for P-channel it's the same symmetrical JFET model - with opposite sign.
I think, I've sent you some ASC file some time ago that includes these models, not sure if they are with capacitances.
Ahh I see. Fair enough, it is really awesome of you, Nelson, Mark, Jim, Jason, Gianlucia, and everyone else involved to donate all the time and effort on that project. Kudos to you all
I'm using model from Michael Rothacher, but added some capacitances, for P-channel it's the same symmetrical JFET model - with opposite sign.
I think, I've sent you some ASC file some time ago that includes these models, not sure if they are with capacitances.
feed me
when LTSpice is in case, I'm twice the Typewriter Monkey Army
send me two LTSpice files, each having one Sony VFet nested, ready for sim
edit: found files you sent - CSX-1 and CSX-2
will play with, these days
now I' Happy Camper, on her shoulder
ZM, also IMO these VFETs models are pretty accurate, Pa said CSX1 has 4 Ohms output impedance, I measured in simulation output voltage drop with 8 Ohm resistor and calculated 4.16 Ohms, Sony VFETs have low transconductance, got 8-9dB gain in CSX1 pretty much the same as real VFETs in Common Source. So I think Mr. Mike did a great job
Cross-posted from another discussion, so apologies for the duplicate.
After a couple of glorious weeks of listening, I think it’s time to check the biasing. The amp has been on for the entire period, staying nice and warm and dutifully trying to keep the basement temperatures stable. Yesterday while listening, I found that I had to bump my interim preamp (Pioneer AV integrated) up +2dB on the right main to center the image. I presume this will be resolved with biasing adjustment? I recall that this is actually a CCS adjustment more than an amplifier stage. So hoping one cascades into the other.
I haven’t pulled the amp out to check it yet, but thought I’d pose the question.
After a couple of glorious weeks of listening, I think it’s time to check the biasing. The amp has been on for the entire period, staying nice and warm and dutifully trying to keep the basement temperatures stable. Yesterday while listening, I found that I had to bump my interim preamp (Pioneer AV integrated) up +2dB on the right main to center the image. I presume this will be resolved with biasing adjustment? I recall that this is actually a CCS adjustment more than an amplifier stage. So hoping one cascades into the other.
I haven’t pulled the amp out to check it yet, but thought I’d pose the question.
Thanks. I haven’t checked things yet, but will soon. May be my room, may be my hearing. I did just move the speakers a bit for soundstage adjustment, so it’s entirely possible the right side is reflecting (or not) differently.
ZM, also IMO these VFETs models are pretty accurate, Pa said CSX1 has 4 Ohms output impedance, I measured in simulation output voltage drop with 8 Ohm resistor and calculated 4.16 Ohms, Sony VFETs have low transconductance, got 8-9dB gain in CSX1 pretty much the same as real VFETs in Common Source. So I think Mr. Mike did a great job
one thing - you're aware of fact that anything I'm able to end with, is not going to be simple as usual Papawork........
had some fun tonight with Aleph J Sonyfication, of course just in LTSpice
need to check latest Sit data thread and my files, to see how far I'm from melting
EUVL's solution with aux neg-neg rail and small CCS is working as charm in Spice, no doubt it'll work in vivo, but I'm not exactly happy driving VFet gate in A2 region with puny 2SJ74BL drain directly, so some additional complication inevitable
now , polylemma- tossin' on ya, in few days, what I have in sim .... or trying at least simplest solution EUVL gave, to decide do I like how it sounds...... or to make proper ikebana proto on T-Bed .......
Attachments
Thanks for finding that ZM.
This is awesome, after so many years (I can see you post - at least - back in 2007) you are still having fun
I was wondering if your complication involve also adding cascode... you know NFB
Mr. Pass added 22k on the JFET gate, using I assume JFET input capacitance as a LP filter to prevent oscillations...
yeah, cascodes for input JFets are already customary for me, you know - ZM Chicken
also, nested current mirror in between input LTP and rest of circuit, to isolate weeny JFet, and increase gain without too much fuss, there is no other way to compensate missing gain than gaining the same ( gain
) in sole place where you can ...... without that, OLG dropped down to simple SET territory, that's no good
VFet gate modulation going deep to A2 Class ( again tube domain classification) which means positive Ugs, which means inevitable gate current, which simulation is not showing
eh, you can't expect everything, especially counting on fact that nice ppl who gave us free models, did that job for free
checked everything, don't have official datasheet for 2SJ28/2SK82
bits and pieces here and there, including Mr. MR's article ( as always, great work by our Mr. Nice Guy) but no hard numbers regarding absolute max values etc.
and, as Pa is saying - specimens are welcome, but don't expect them back
edit: though, same circuit - I'm expecting - applicable to Sonys, LU1014, Big Tokins ; however, now I can't contemplate about results ...... need checking
also, nested current mirror in between input LTP and rest of circuit, to isolate weeny JFet, and increase gain without too much fuss, there is no other way to compensate missing gain than gaining the same ( gain
) in sole place where you can ...... without that, OLG dropped down to simple SET territory, that's no goodVFet gate modulation going deep to A2 Class ( again tube domain classification) which means positive Ugs, which means inevitable gate current, which simulation is not showing
eh, you can't expect everything, especially counting on fact that nice ppl who gave us free models, did that job for free
checked everything, don't have official datasheet for 2SJ28/2SK82
bits and pieces here and there, including Mr. MR's article ( as always, great work by our Mr. Nice Guy) but no hard numbers regarding absolute max values etc.
and, as Pa is saying - specimens are welcome, but don't expect them back
edit: though, same circuit - I'm expecting - applicable to Sonys, LU1014, Big Tokins ; however, now I can't contemplate about results ...... need checking
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If I'm not mistaken ZM you have already built a few of them, so if you are going to build another one, you are going to have a great point of reference
Definitely please let us know what is your impression of your Sonyficated Aleph J
PS. ...and what speakers have you used if it isn't classified
PS2: I've received today transformer for (Zen_V5/CSX1)-ish project: 2x0-115V - 4x24VAC 600W
Definitely please let us know what is your impression of your Sonyficated Aleph J
PS. ...and what speakers have you used if it isn't classified
PS2: I've received today transformer for (Zen_V5/CSX1)-ish project: 2x0-115V - 4x24VAC 600W
If I'm not mistaken ZM you have already built a few of them, so if you are going to build another one, you are going to have a great point of reference
Definitely please let us know what is your impression of your Sonyficated Aleph J
PS. ...and what speakers have you used if it isn't classified
PS2: I've received today transformer for (Zen_V5/CSX1)-ish project: 2x0-115V - 4x24VAC 600W
refer - "them"
yup , I built few of them whatever that "them" is ......
but , if you think on amps with Sony VFets, I have some boxes of parts stashed away, in ZM's Cave; I got two precious gifts - got CSX1 package ( pcbs by Permaneder) as gift from my Bruder Generg, along with Jensens and Sonys; then I got a gift from our DiyA Boyz Team ( Iguana Cronander mostly to blame) - full kit of Papa's second Sony VFet PP amp (smaller one , with one pair of cans per channel) , supposedly to make a review/sorta build guide, but it seems I flawed with that , never fulfilled my side of bargain :bawlling:
anyway - had both amps on plank, more or less concoction-ed, for few weeks, then dismantled and put in cardbox, starting to scavenge all parts and mechanicals for them
but, had a stint of my own amps ( sorta) following that , so Kudos project inevitably postponed
as things are developing , it'll need some considerable time to get to Kudos amps again (even if Big Ones I really need to make)
frankly, think that I'm not going to put my Sony VFets in prototype, not having spares; you can expect some sort of contribution from me in form of schematic ( which is most probably going to work with no or minimal problems) , but without surplus Sony cans I'm not able to develop it in vivo
I'm considerably confident that nothing will go in flames ( sand is rarely doing that
) nor smoke ( at my bench, sand is also rarely doing that ), but Gremlins are always around, if nothing else demanding few last fine tuning of some part valuesedit: my speakers ...... I'm sucker for speakers, having and most important - enjoying all sorts of them
though, my reference are mostly dual concentrics, big ones, RCA and Tannoys ..... using them either OB or in fridge sized MLTL
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