@grunf,
Slightly off topic, but AD811 related.
Did you ever experiment with W. Jungs line amp/preamp AD744/AD811 circuit?
https://cfas.waltjung.org/High_Performance_Audio_Stages_Using_TransZ_Amps.pdf
Slightly off topic, but AD811 related.
Did you ever experiment with W. Jungs line amp/preamp AD744/AD811 circuit?
https://cfas.waltjung.org/High_Performance_Audio_Stages_Using_TransZ_Amps.pdf
Attachments
FFT, Phase and Transfer, Input impedance and output impedance.
Not Vin and Vout.
(Vout is in the form of db transfer with phase...)
No, iti is an option,
BUT i simulate with same sch as Jung did in AD811 IV aplication. And it giving some improvements...
.
Note that AD797 as IV not tolerate this "Jung" R in the input! (I simulated and it was a mess 🙁 ...)
Try to isolate the RC filter from direct output of IV OP. And from FB termination path...
I suggest to use some buffer, then You will have precise value of generator driving RC filter and You can dimension the values with more room?
You can use an LC filter too, I tried it and it sounds better than RC.
https://markimicrowave.com/technical-resources/tools/lc-filter-design-tool/
(5 order Bessel or Legendre or other options...)
You can match the values of L to as close to available comercial values.
@Zoran ,
What do you think about a crazy idea ? to enhance the CFA input, or at least any VFA ? Goal : lowish imedance input for the opamp and HF spead ruled partially by the input discrete JFET.
A Jfet miror input with a servo sub not in the audio path at the input like showed in the thread. The JFET (or MOSFET) input will be to avoid 10 uF bipolar at the output of the first Jfet.
Bad idea ?
What do you think about a crazy idea ? to enhance the CFA input, or at least any VFA ? Goal : lowish imedance input for the opamp and HF spead ruled partially by the input discrete JFET.
A Jfet miror input with a servo sub not in the audio path at the input like showed in the thread. The JFET (or MOSFET) input will be to avoid 10 uF bipolar at the output of the first Jfet.
Bad idea ?
It occurred to me to reverse the absolute polarity since I eliminated one stage. The effect was not night and day, but the sound seemed to be just a little cleaner if I'm hearing it correctly. This was after reading Ken Newton " I have found that the sometimes fuzzy/soft image character of NOS is affected by inverting the absolute polarity of the signal."
https://www.audiosciencereview.com/...d-different-to-oversampling-designs.86/page-3
I dont know, probably the idea is good?
Try to simulate first to see some results?
.
BTW
I found different circuit with OP amp and JFETs.
from
http://peufeu.free.fr/audio/extremist_dac/implement_4.html
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i was more thinking of J1 not closed on J2 gate but going like J2 source towards R1. But instead R1 a Jfet mirror to avoid serie caps on each branch, then the AD811 (not the passive I/V of above).
instead of J3/J4 : more a BJT (HN1A01/HN1C01) cascode like EUVL FC SEN. Perhaps these double BJT in smd package dissipate not enough heat vs a T092 here and like the BC559 from FC SEN genuine design ?!
instead of J3/J4 : more a BJT (HN1A01/HN1C01) cascode like EUVL FC SEN. Perhaps these double BJT in smd package dissipate not enough heat vs a T092 here and like the BC559 from FC SEN genuine design ?!
Fellas, the original design by Walt Jung, provided the best (by far) I/V stage for the PCM1704 dual differential DAC I played with for close to 2 years. The 1704 is both a notorious to implement and a legendary DAC IC. It really showed me what the CD could sound like once I used the AD811. The best by far spec is the close-to-zero dynamic impedance that AD811 was presenting to 2mA (on a good day), and the compliance requirements of the current-out pin coming from 1704... no other attempt provided such a low impedance. The staircase waveform at Iout pin was absolutely perfect with this circuit in its original form - amazing. An absolute pleasure to observe. I do not believe any further attempt is required in this regard.
@Extreme_Boky a link to a schematic?
If the same, I've now the ad811 on ad1862 and 1865, don't want to back or beyond anymore.
If the same, I've now the ad811 on ad1862 and 1865, don't want to back or beyond anymore.
Yes, I know by heart that article, but I experienced that also the power supply makes a difference, if you haven't tried it, try the grunf board done by Vunce, you'll love the silence
Yes, I know. It's a great circuit. I think I already provided my opinion & praise earlier in this thread 🙂
I used my own power supply design.... and worked hard for close to two years on minimising the ground-fill noise as well...
I used my own power supply design.... and worked hard for close to two years on minimising the ground-fill noise as well...
The waveform and the said input impedance > 1Khz in this design don't say all about the sound of it.
OPA861 : 7 ohms impedance input, no feedback, perfect wveform too (see the Pedja Rogic paper and not the copies poping up by unexperienced enthusiasts), so better spec and some people report it doesn't sound as good (I mean their design). @Zoran for instance ! Mine with the opa861 TDA1541 Rogic's pcb, tunned is a killer from the people whom listened to it.... Go figure !
FC SEN from EUVL : some says it is the best, silicon wise.
So I wondered in my post from above if the impedance could be lowered according the paper from @EUVL in the FC SEN by using a jfet op amp helper for lowering the impedance from 2SK170/2SJ74 which is already low at 15 ohms to lowish it a near the milli ohms figure... which many DAC IC current output needs or like.
All the DAC i<c are not made equals for that low impedance need. For illustration at the end of the WJ paper sligthy tunned by Grunf, it is said the AD811 would not like impedance source as great as 2K and more. 2K is rigth at 2K R output. So more Diy more fun.
But indeed, don't mortgage your house for that... IIRC, @Extreme_Boky , your quest was better achieved by the purchase of the Holo May that won with a good margin after years of DIY. I was very intrigued by that and find it to be a good reminder about what is DIY and audio for each of us : fun of designing and building or just listening to music at the best total cost of the ownership.
Btw, do people made experience between PS 2 from @miro1360 VS Waltjung Super Reg with that same AD811 ? Or with WaltJung Super Reg Super grunf but with an opa861 proper layouted ?
I miss the good sounding reviews from Fran , @woodturner-fran .
Btw didn't listen PCM1704 from many years, but I remember I liked long ago the AD1862 better. But I listen 16/44 material mostly.
OPA861 : 7 ohms impedance input, no feedback, perfect wveform too (see the Pedja Rogic paper and not the copies poping up by unexperienced enthusiasts), so better spec and some people report it doesn't sound as good (I mean their design). @Zoran for instance ! Mine with the opa861 TDA1541 Rogic's pcb, tunned is a killer from the people whom listened to it.... Go figure !
FC SEN from EUVL : some says it is the best, silicon wise.
So I wondered in my post from above if the impedance could be lowered according the paper from @EUVL in the FC SEN by using a jfet op amp helper for lowering the impedance from 2SK170/2SJ74 which is already low at 15 ohms to lowish it a near the milli ohms figure... which many DAC IC current output needs or like.
All the DAC i<c are not made equals for that low impedance need. For illustration at the end of the WJ paper sligthy tunned by Grunf, it is said the AD811 would not like impedance source as great as 2K and more. 2K is rigth at 2K R output. So more Diy more fun.
But indeed, don't mortgage your house for that... IIRC, @Extreme_Boky , your quest was better achieved by the purchase of the Holo May that won with a good margin after years of DIY. I was very intrigued by that and find it to be a good reminder about what is DIY and audio for each of us : fun of designing and building or just listening to music at the best total cost of the ownership.
Btw, do people made experience between PS 2 from @miro1360 VS Waltjung Super Reg with that same AD811 ? Or with WaltJung Super Reg Super grunf but with an opa861 proper layouted ?
I miss the good sounding reviews from Fran , @woodturner-fran .
Btw didn't listen PCM1704 from many years, but I remember I liked long ago the AD1862 better. But I listen 16/44 material mostly.
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