it would be nice
if people who try the "no feedback mod" report here about their experiences.
Wouldn't it be also a nice idea to make of version of the dispre-2 which can be used for a "bi-ampli" option (I mean one output for the low frequencies and one for the highs).
if people who try the "no feedback mod" report here about their experiences.
Wouldn't it be also a nice idea to make of version of the dispre-2 which can be used for a "bi-ampli" option (I mean one output for the low frequencies and one for the highs).
Thanks for the hint.
It would also be nice if those who built their preamp according to Assembly Instructions and schematics provided wrote their listening impressions here.
I would prefer to build the preamp as in the documentation, the "no global FB mod" just for those who are curious.
It would also be nice if those who built their preamp according to Assembly Instructions and schematics provided wrote their listening impressions here.
I would prefer to build the preamp as in the documentation, the "no global FB mod" just for those who are curious.
"Today, I would say that the discrete design sounds better"
Pavel, you, JC, CH and one or two others have been making this claim here for quite a while.
Can you explain in rational terms what you mean by this.
Do you have proof that this statment is true and how do you reconcile this with the fact that most CD players employ IC technology to convert digital to analog, or that some highly regarded high end components use IC technology in the signal path.
Pavel, you, JC, CH and one or two others have been making this claim here for quite a while.
Can you explain in rational terms what you mean by this.
Do you have proof that this statment is true and how do you reconcile this with the fact that most CD players employ IC technology to convert digital to analog, or that some highly regarded high end components use IC technology in the signal path.
The only proof I can tell you is that I have performed numerous comparative listening tests. Also, I can hear different sound coloration of any opamp I have tried, though THD is negligible. I do not know if distortion spectrum is an answer
http://web.telecom.cz/macura/dispre2_thd.GIF
but according to my experience any trace of high order harmonics is a problem.
IMHO, it is a dynamic behaviour of opamps and low bias current of their output stages that make them not a superior part for audio.
You can find recordings with almost no opamps used and you can find digital players with no opamps used.
This is a tiring theme. I would suggest anyone to make his own sound conclusions, these everlasting debates do not help.
http://web.telecom.cz/macura/dispre2_thd.GIF
but according to my experience any trace of high order harmonics is a problem.
IMHO, it is a dynamic behaviour of opamps and low bias current of their output stages that make them not a superior part for audio.
You can find recordings with almost no opamps used and you can find digital players with no opamps used.
This is a tiring theme. I would suggest anyone to make his own sound conclusions, these everlasting debates do not help.
PMA said:
:bs:
I have nothing against a personal preference, and I would agree that a discrete designs may offer a wide range of optimization opportunities. But bringing the GEB escape pod to the rescue and then trying to wrap a personal preference (and I'm not discussing here the reasons) in a shell of techno-babble like "the dynamic behaviour of opamps" is... <snip>
Hi Pavel
What effect does the no-feedback mod have on gain and distortion? Have you measured this yet?
Sorry I've been so slow to build mine - I've been waiting on some parts from Farnell, but I think they've forgotten about me.
That, plus working myself to death has got in the way somewhat..
What effect does the no-feedback mod have on gain and distortion? Have you measured this yet?
Sorry I've been so slow to build mine - I've been waiting on some parts from Farnell, but I think they've forgotten about me.
That, plus working myself to death has got in the way somewhat..
What has output stage bias current got to do with it Pavel? Scott has commented on this non-issue. And, if you are not happy with the class B output stage, load it with a current source to V-!
I cannot believe this is an issue when a lot of these newer op-amps can drive 600 Ohms at 1ppm distortion. As for higher order distortion, well there is none - zip - you cannot measure it and you certanly cannot hear it if its -130db down. So this is not the reason. Is it your personal preference - then just say so.
Finally, don't pass comments about op-amps and then dismiss the discussion around IC's vs discrete designs as tiresome. As mentioned one or two posts above, kindly preface your comments with 'in my opiniom . . . '
We already have an anti feedback school that has poisoned the whole audio debate so lets not allow ourselves to drift into this IC vs discrete nonsense as well.
I cannot believe this is an issue when a lot of these newer op-amps can drive 600 Ohms at 1ppm distortion. As for higher order distortion, well there is none - zip - you cannot measure it and you certanly cannot hear it if its -130db down. So this is not the reason. Is it your personal preference - then just say so.
Finally, don't pass comments about op-amps and then dismiss the discussion around IC's vs discrete designs as tiresome. As mentioned one or two posts above, kindly preface your comments with 'in my opiniom . . . '
We already have an anti feedback school that has poisoned the whole audio debate so lets not allow ourselves to drift into this IC vs discrete nonsense as well.
Bonsai said:
The ever repeating theme. Someone makes an honest effort and then offers it to the public domain, gaining nothing. Then the engineering crowd comes down heavy. Prove this, prove that... Its ugly, isn't it?
An MP3 player and a properly measuring $100 receiver is OK in any ABX test. Lets use such instead. Why we bother here? I sometimes wonder if those interrogators listen to music everyday at home or what systems they use.
salas said:
You asked for this...
This preamp is a commercial effort and it is offered to the public for profit. The full schematic was never disclosed in public and the measured results were (to me) incomplete. No complete and objective comparison with any other solutions was ever done.
So if there's anything ugly it's not the "proof" request. I personally don't have a problem with any commercial enterprise, but I do have a problem with disguising it.
Ok, I rephrase... Someone makes a high value kit effort. Not that ugly to interrogate then. Semi ugly.
P.S. It should have been under the commercial section then. Why is it in solid state?
P.S. It should have been under the commercial section then. Why is it in solid state?
Why is it in solid state?
I'm sure, Pavel has also the intention to disclose the full schematic after first interest has gone.
I'm sure, Pavel has also the intention to disclose the full schematic after first interest has gone.
float: the non-NFB mod has higher distortion, about 0.01%/1V
syn 08: what measurements are you missing? What are YOUR intentions? Just to annoy? I can see nothing else in your posts, just annoying negativism.
syn 08: what measurements are you missing? What are YOUR intentions? Just to annoy? I can see nothing else in your posts, just annoying negativism.
I can tell you, syn 08, why the values are not released. The 1st Dispre was an open project. Very soon in another country another guy made his PCBs and started to sell them. This is very fine isn it?? I sold about 20 PCBs (not kits) to DIY audio community here and you speak about profit!! One PCB = packaging, documentation, shipment = profit?? You try to play a game of an honest man? So I have to open it for someone to make his profit? That would be fine, yeah??
I'll guess commercial is the level "pizza and beer money" and profit is hardly the right word. I think there are pretty many around here that have no problems with Pavel's profit levels.syn08 said:
Pavel doesn't have to show us anything really but to me he has revealed quite much here and at his homepage.syn08 said:
Pavel doesn't have to show us anything really but to me he has revealed quite much here and at his homepage.
Really. I can't figure out what resistor values to use by reading this thread or anything on his webpage.
I'm still waiting for the next batch of boards.... hurry Pavel.
Really. I can't figure out what resistor values to use by reading this thread or anything on his webpage.
I'm still waiting for the next batch of boards.... hurry Pavel.
Most probably next week into production. You were interested in the 1st batch, AFAIK, but did not follow the procedure to the end?
