Nelson-
Is there any way to see where this sweet spot would be by looking at the graphs on the data sheets? Or is something you find by trying different Vds's and measuring the results?
I've poured over the ZV8 articles and ZV9 articles, and I haven't been able to come away with anything that I could apply to a different jfet. Same thing goes for cascode modulation.
JJ
jupiterjune said:
not exactly Nelson , but sorta never adopted orphan
😀 .......
it's probably easier with THD meter , varying cascode element bias ( height, whatever) .......... Papa probably just feels this things , but we others must lean on more profan ways of finding this things ........
This week I had the pleasure of putting together this preamp. Fired it up today .😀
Been trying it on my wife's setup (no research in the living room....). Certainly did bring life to the sound.
The living room setup is JBL Sovereign speakers, a class a/b power amp(http://www.diyaudio.com/forums/showthread.php?s=&threadid=65286&highlight=) and a low/mid-end Sony cd-player. Other sources are a Pioneer tuner and the TV. Preamp is normally a Doxa 012(Norwegian).
This JBoz's impact on the setup is incredible.
Attached is the circuit with the built resistor/cap values.
Now back to the workshop - input selector necessary.
Been trying it on my wife's setup (no research in the living room....). Certainly did bring life to the sound.
The living room setup is JBL Sovereign speakers, a class a/b power amp(http://www.diyaudio.com/forums/showthread.php?s=&threadid=65286&highlight=) and a low/mid-end Sony cd-player. Other sources are a Pioneer tuner and the TV. Preamp is normally a Doxa 012(Norwegian).
This JBoz's impact on the setup is incredible.
Attached is the circuit with the built resistor/cap values.
Now back to the workshop - input selector necessary.
Attachments
yggdrasil : welcome to the JBOZ lovers club 😉
refering to your schematic, may I ask you with which value of Idss/Rs
you did get the sweet pot?
Manu
refering to your schematic, may I ask you with which value of Idss/Rs
you did get the sweet pot?
Manu
... and if you add 0.1 - 0.47ohms in series with the 1uF cap as your bipass device usually results in cleaner and more accurate mids/top end - maybe smaller value, too.
Manu said:
Well I haven't really done much measuring, nor have I done any hunting for the sweet spot.... Yet.
I got ~7V at the drain, and 100mV at the source of the jfet. Then it was time to start listening.
There was some variation between the channels, so I'll have to match some devices before next run.
"Really"
Yeah Carpenter,
Works like magic, nearly everytime, with very different ccts, too!
- 0.1 ohm (+,-) in series with 0.1uF cap (propylene, or better)as a bipass to any electro for example, is a good starting point.
- simple to try - maybe easier to get low ohm SMD resistors
- try it on your 2246 driver Xover cap.
See also "Capacitor bipass" thread - interesting.
Yeah Carpenter,
Works like magic, nearly everytime, with very different ccts, too!
- 0.1 ohm (+,-) in series with 0.1uF cap (propylene, or better)as a bipass to any electro for example, is a good starting point.
- simple to try - maybe easier to get low ohm SMD resistors
- try it on your 2246 driver Xover cap.
See also "Capacitor bipass" thread - interesting.
A practical adventure of capacitor bipassing -
I'm optomising an F3 amp (Peter Daniel pcbs) and the o/p cap started off as a Rifa 15,000 (C1), Pana FC 220 (C10), plus 4.7uF Solen (C8). Well, the Rifa's are excellent for power caps but lousy for signal - replaced by 4 x 2200 Pans FC (excellent) + 1000 Nicki Gold (Curiosly - maybe slightly heavier sound, maybe b.s. too) C10 became 220 B/Gate (much better everything) and C8 became 4.7uF ICW Clarity cap (better small signal, brighter, etc but a noticable mid/treble smearing).
Adding the series R (0.25R) removed all "smearing" but rolled off some tops, so added another parallel "string of [0.15R + 100nF] styrene (like Rel caps) = incredibly treble increase, and so on, and on, ...
This particular one ended up with both the film caps in parallel [4.7uF//87nF + 0.1R] as a bipass across the group of 5 electros which suits my perception of a reasonable balanced sound, for the present system setup and my no doubt, imperfect hearing.
Unfortunately the p/supply is still growing up and this is causing different bipass adventures, particularly with the smaller values of final p/s cap. That "Carlos" snubber is useful here, too!
- Multibit NOS Dac + D1 O/P stage into X2.5 preamp (original) driving A.A Domestic Monitors - nowhere to hide here!
[The reference is Slee, etc into AKG 701's, 880's and the Stax.]
Ran 15" base + 4 way trax horns awhile ago - big room, too!
Hope this is of some relevance and brightens up your week!
Cheers
I'm optomising an F3 amp (Peter Daniel pcbs) and the o/p cap started off as a Rifa 15,000 (C1), Pana FC 220 (C10), plus 4.7uF Solen (C8). Well, the Rifa's are excellent for power caps but lousy for signal - replaced by 4 x 2200 Pans FC (excellent) + 1000 Nicki Gold (Curiosly - maybe slightly heavier sound, maybe b.s. too) C10 became 220 B/Gate (much better everything) and C8 became 4.7uF ICW Clarity cap (better small signal, brighter, etc but a noticable mid/treble smearing).
Adding the series R (0.25R) removed all "smearing" but rolled off some tops, so added another parallel "string of [0.15R + 100nF] styrene (like Rel caps) = incredibly treble increase, and so on, and on, ...
This particular one ended up with both the film caps in parallel [4.7uF//87nF + 0.1R] as a bipass across the group of 5 electros which suits my perception of a reasonable balanced sound, for the present system setup and my no doubt, imperfect hearing.
Unfortunately the p/supply is still growing up and this is causing different bipass adventures, particularly with the smaller values of final p/s cap. That "Carlos" snubber is useful here, too!
- Multibit NOS Dac + D1 O/P stage into X2.5 preamp (original) driving A.A Domestic Monitors - nowhere to hide here!
[The reference is Slee, etc into AKG 701's, 880's and the Stax.]
Ran 15" base + 4 way trax horns awhile ago - big room, too!
Hope this is of some relevance and brightens up your week!
Cheers
jh, would you mind posting a drawing? The various combos sound interesting. I want to be certain that I have the correct mental picture.
In gain stage coupling with caps, do you use the same procedure, or is this reserved for output caps only?🙂
In gain stage coupling with caps, do you use the same procedure, or is this reserved for output caps only?🙂
Woody (if I may be so bold!)
Will send you an email with scanned attachment later and perhaps you can get it posted here for me - lacking a certain computer "moxy"!
The bipass approach is one solution to some of the shortcomings of electros, particularly good quality ones, for both high & low signal and in power supplies.
In gain stage coupling, I use v. good quality film caps and just parallel different ones "to taste", as it were - easy to sort out - nothing really scientific about it at all, I'm afraid, apart from the usual sig gen, CRO, etc.
I hadn't thought about "R loading coupling filmcaps" for sound, though - thank you - must try this - pretty sure someone has tried this before, yes?
For some people and systems, good electros sound better if you leave them alone, thus "end of story"! No probrem!
For now -
Will send you an email with scanned attachment later and perhaps you can get it posted here for me - lacking a certain computer "moxy"!
The bipass approach is one solution to some of the shortcomings of electros, particularly good quality ones, for both high & low signal and in power supplies.
In gain stage coupling, I use v. good quality film caps and just parallel different ones "to taste", as it were - easy to sort out - nothing really scientific about it at all, I'm afraid, apart from the usual sig gen, CRO, etc.
I hadn't thought about "R loading coupling filmcaps" for sound, though - thank you - must try this - pretty sure someone has tried this before, yes?
For some people and systems, good electros sound better if you leave them alone, thus "end of story"! No probrem!
For now -
jameshillj said:
I'm actually getting to like my nickname, seems fitting--also describes my true talent. If only electronics and engineering came as naturally.😀
I'll be happy to post your email graphic. It's interesting to learn other techniques.
Did I see somewhere that you have a R.Cuff injury? Sorry to hear about it - had similar (squash injury) and b. painful - took ages to come good even with physio and work.
Cranking up the scanner - page soon.
Cranking up the scanner - page soon.
jameshillj said:
Yeah, that's the problem: Severe R. Cuff strain. MRI makes my shoulder look like a battlefield. Of course, everyone over 50 looks that way, according to the specialist.
Thanks for the scan. No hurry, though...🙂