Hi Chocky,
May I know why many prefer to use jfet for I/V instead of bipolar? Bipolar has much seperior gm compared to jfet for noise reduction and lower input impedance. What are other consideration in choosing a right transistors?
Thanks in advance.
May I know why many prefer to use jfet for I/V instead of bipolar? Bipolar has much seperior gm compared to jfet for noise reduction and lower input impedance. What are other consideration in choosing a right transistors?
Thanks in advance.
Ipanema said:
frankly - I don't have much xperience regarding I/V conversion , besides using plain passive I/V and xformer/buffer output (I was lucky to have some Plessey and Telefunken zformers , when needed)
anyway - at least as I see it - point is that you connect I out to some sort of high impedance CCS (variable , off course ) ;
thinking of that - CCS is CCS , pick your fave if you can squeeze it in .
rest of circuit , after that I/V conversion point .......... dunno , we'll see ;
but - don't expect any novelty from me , except in case that I choose to use toobz , in Pass playground 😉
Some reference i've looked at:
Haiku I/V
- Loosely base on Nelson Pass´s mosfet version, so says Russ White, and he knows i'm sure.
- Schematic of Rudolf Boetje's proposal for an I/V stage for a current output DAC ( see bottom of post ).
-Gerhold Dietmar's FET_DCout
...otherwise known as...
This thread might just develop into a very interesting discussion on the issue, culminating i hope on a practical implementation and from which i'll certainly learn a lot, already have.
But..if i was lost looking for a solution now i'm just plain confused.
ZM, you are too modest, or Manu is right and you just don't value what you have achieved in these pages.
I wish i had what you define as your lack of experience for this job.....
Haiku I/V
- Loosely base on Nelson Pass´s mosfet version, so says Russ White, and he knows i'm sure.
- Schematic of Rudolf Boetje's proposal for an I/V stage for a current output DAC ( see bottom of post ).
-Gerhold Dietmar's FET_DCout
...otherwise known as...
This thread might just develop into a very interesting discussion on the issue, culminating i hope on a practical implementation and from which i'll certainly learn a lot, already have.
But..if i was lost looking for a solution now i'm just plain confused.
ZM, you are too modest, or Manu is right and you just don't value what you have achieved in these pages.
I wish i had what you define as your lack of experience for this job.....
Attachments
CeeVee said:
as I said - we will find what's most interesting to you 😉
Haiku is interesting , I'll study it later ......
Dietmar's stage is nice , but Jfet BOZ is nicer ...... primary because Papreamp is made with more "proper" part .......
and - it's not I/V conversion circ , what we need .
CeeVee
thinkin' about that HF blurps .........
can you try to decrease these two resistors (between + and - I outs ) - put 330 Ohms , instead of 1K2
you can put 10n in parallel to both 330E resistors
I'm thinking about some crumbs .......
thinkin' about that HF blurps .........
can you try to decrease these two resistors (between + and - I outs ) - put 330 Ohms , instead of 1K2
you can put 10n in parallel to both 330E resistors
I'm thinking about some crumbs .......
..........Catching the plane in 5 minutes, will test after next week.
Hope you guys have a fruitful discussion this week while i'm away.
😎
Hope you guys have a fruitful discussion this week while i'm away.
😎
why reinventing the wheel
anyway - more I look , more I like it;
rudolf made it pretty clever ;
so - there it is , mirrored
Riv can be - for start, same as in Drekling ....... Civ , also same
you can also try also combination of 330E/10n
later , if you're in mood , you can try doubling 1N4148 (two in series , instead on one ..... in both positions)
anyway - more I look , more I like it;
rudolf made it pretty clever ;
so - there it is , mirrored
Riv can be - for start, same as in Drekling ....... Civ , also same
you can also try also combination of 330E/10n
later , if you're in mood , you can try doubling 1N4148 (two in series , instead on one ..... in both positions)
Attachments
Hi Zen Mod,
...no i was not swept out to sea in Oostende, ...almost though the weather was really bad the first few days.
I'm back and getting the components to try your sugestion.
I sent for 2 PCBs from rudolf, to test single ended.
I'm a bit confused though, what is the advantage of a mirrored version ?
Another question, what type caps do you sugest for output ?
😎
...no i was not swept out to sea in Oostende, ...almost though the weather was really bad the first few days.
I'm back and getting the components to try your sugestion.
I sent for 2 PCBs from rudolf, to test single ended.
I'm a bit confused though, what is the advantage of a mirrored version ?
Another question, what type caps do you sugest for output ?
😎
CeeVee said:
as I wrote before -
try that first , then you can try Rudolf's variant ; it's simple enough to try on any protoboard .
with question
you mean generally , or why I mean that Rudolf's variant is better in mirrored fashion ?
Made nice balanced cables, checked again....and realized i had it connected wrong all along.
Connected again : between pin 2 of op-amp 1 and pin 2 of op-amp 2
( neg input ).
Op-amps are out, so it's just for convenience i use the IC socket.
...sound is great ! no HF rasping....it's cleaner and more open than with all the original op-amps.
Conclusion is that i had 6 op-amps too many.
Values i have now are 1k and 2n7 with 3u3 output caps.
...I don't think i need to test the 330R/10n option, but i'll do it just for curiosity's sake.
CeeVee said:
Made nice balanced cables, checked again....and realized i had it connected wrong all along.
Connected again : between pin 2 of op-amp 1 and pin 2 of op-amp 2
( neg input ).
Op-amps are out, so it's just for convenience i use the IC socket.
...sound is great ! no HF rasping....it's cleaner and more open than with all the original op-amps.
Conclusion is that i had 6 op-amps too many.
Values i have now are 1k and 2n7 with 3u3 output caps.
...I don't think i need to test the 330R/10n option, but i'll do it just for curiosity's sake.
now we all have learn something 😉
if you're in ballpark with output level - comparing to original , then you don't need to try lover resistor values .
next - for fun , try Rudolf's mirrored version ; if I'm not mistaking , that can be definitive , with tweak or two .
edit:
gimme ( when you can ) few more characteristics/differences to previous (stock) sound ; seems that my ears can't cope with all these miles between us
...hehe yeah even if you were Mr. golden ears..it is kind of far.
comparing what i get in terms of sound:
Before, with stock thingie sound was dull, i referenced Diana Krall's piano as not "real", it was "veiled".
Now it seems crystal clear and tone is true in comparison, if not in absolute value.
and i'm sure it will be better with the mirrored schematic you put up.😉
I should refer that i'm trying to follow Siegfried Linkwitz's advice and compare with the real thing ( piano in this case).
comparing what i get in terms of sound:
Before, with stock thingie sound was dull, i referenced Diana Krall's piano as not "real", it was "veiled".
Now it seems crystal clear and tone is true in comparison, if not in absolute value.
and i'm sure it will be better with the mirrored schematic you put up.😉
I should refer that i'm trying to follow Siegfried Linkwitz's advice and compare with the real thing ( piano in this case).
yup ;
human voice and natural instruments are best for evaluating ;
even if too many FiFi gadgets nowadays aren't capable to pass voice test
human voice and natural instruments are best for evaluating ;
even if too many FiFi gadgets nowadays aren't capable to pass voice test
Hi,
I'm also thinking about a similar mod, albeit on my Rotel rcd-02 player. This cdp was the biggest waste of money, and it's just collecting dust (I am still listening to an old Denon cdp).
Unfortunately, Rcd-02 uses PCM1732 dac, which provides only Vout...
The question is: Is it worth fiddling with, or shall I just forgetaboutit...
Regards,
Vix
I'm also thinking about a similar mod, albeit on my Rotel rcd-02 player. This cdp was the biggest waste of money, and it's just collecting dust (I am still listening to an old Denon cdp).
Unfortunately, Rcd-02 uses PCM1732 dac, which provides only Vout...
The question is: Is it worth fiddling with, or shall I just forgetaboutit...
Regards,
Vix
Vix said:
besides googling for recipe , you can do few more things - try to find schematic , take digicam and make few macros , make a new thread .... so we can have funnnnnn
Somewhere I had found the relevant part of the schematics...
For the rest.. this player is free to play with! 😀
Internal photos may be done sometime nest week...actually I already tried something on this cdp...I had hooked a Jfet boz directly to the Vout of dac, but it didn't sound good...I even don't know how to describe the sound...somehow weird...now I'm thinking that I may have had some HF junk passing through....
So, I'm am willing to give it a second chance, with with some Hp filtering or whatever...
Vix
For the rest.. this player is free to play with! 😀
Internal photos may be done sometime nest week...actually I already tried something on this cdp...I had hooked a Jfet boz directly to the Vout of dac, but it didn't sound good...I even don't know how to describe the sound...somehow weird...now I'm thinking that I may have had some HF junk passing through....
So, I'm am willing to give it a second chance, with with some Hp filtering or whatever...
Vix
Attachments
- Status
- Not open for further replies.