OK, to get back on the topic ...
using Carlos' snubber will lower the impedance an amount "negligible" from a measurement standpoint, but apparently some can hear a difference.
the point which I try to make is that the utility of the capacitors is greatest when they are immediately adjacent to the Overture Series chip -- there is also some utility to having a cap on the supply board -- this way the leads from the power supply to the chip pcb are less likely to pick up stray emissions -- EMI from various sources. If you are using a transformer with significant coupling capacitance then you are essentially putting an RFI/EMI radiator into the box (I think that Eva has made this point, it has also been discussed in some of the low noise measurement articles on Linear Tech's website.)
i drew the resonant circuit for y'all a few days ago -- depending on the transformer you are using (and the diode, and the voltage across the diode) you have the potential for nasty RFI generation which will affect the gain linearity of the Overture chip. you get a nice oscillatory phase reversal.
well, in the past I have shown pix taken from my oscilloscope which demonstrate the problem -- it's a real life problem, not one we just simulate in SwitcherCAD. tackling it changes the supply impedance somewhat. as in life, there aren't any free lunches.
and to get to the matter of regulating the supply and placing another control loop...fodder for another day.
using Carlos' snubber will lower the impedance an amount "negligible" from a measurement standpoint, but apparently some can hear a difference.
the point which I try to make is that the utility of the capacitors is greatest when they are immediately adjacent to the Overture Series chip -- there is also some utility to having a cap on the supply board -- this way the leads from the power supply to the chip pcb are less likely to pick up stray emissions -- EMI from various sources. If you are using a transformer with significant coupling capacitance then you are essentially putting an RFI/EMI radiator into the box (I think that Eva has made this point, it has also been discussed in some of the low noise measurement articles on Linear Tech's website.)
i drew the resonant circuit for y'all a few days ago -- depending on the transformer you are using (and the diode, and the voltage across the diode) you have the potential for nasty RFI generation which will affect the gain linearity of the Overture chip. you get a nice oscillatory phase reversal.
well, in the past I have shown pix taken from my oscilloscope which demonstrate the problem -- it's a real life problem, not one we just simulate in SwitcherCAD. tackling it changes the supply impedance somewhat. as in life, there aren't any free lunches.
and to get to the matter of regulating the supply and placing another control loop...fodder for another day.
Jeez!
Peter, its amazing how you try to make it seem like your some kind of victim here, no offence(ok, a litle), but your simply full of c*ap.
oh, and before you reply, take a moment reviewing the tone of your posts.
your post have a "hint" of arogancy and better-knowing, and at the same time the darting "back and forth" of a man who know that whats he's accused of is true.
as jocco say, as long as you speak english, you kind of get what others say between the lines as well as the black-on-white.
-and, why the last post?
can you see what makes me and others tic about this place?
I'd like to agree with nuuk, but sometimes shuting up and playing nice just dont get the work done.
stagnant forums?
I can see why few people wound subject their eventual finds to the s*itstorms that strike here.. carlos has taken a lot of beating for his snubber.
edit: and oh, by beating i dont mean people trying to find out how\why it works\dont work. I think that should fall second nature to any diy'er. after all, this IS science, not fiction\snake oil.
Peter, its amazing how you try to make it seem like your some kind of victim here, no offence(ok, a litle), but your simply full of c*ap.
oh, and before you reply, take a moment reviewing the tone of your posts.
your post have a "hint" of arogancy and better-knowing, and at the same time the darting "back and forth" of a man who know that whats he's accused of is true.
as jocco say, as long as you speak english, you kind of get what others say between the lines as well as the black-on-white.
-and, why the last post?
can you see what makes me and others tic about this place?
I'd like to agree with nuuk, but sometimes shuting up and playing nice just dont get the work done.
stagnant forums?
I can see why few people wound subject their eventual finds to the s*itstorms that strike here.. carlos has taken a lot of beating for his snubber.
edit: and oh, by beating i dont mean people trying to find out how\why it works\dont work. I think that should fall second nature to any diy'er. after all, this IS science, not fiction\snake oil.
Peter Daniel said:
I don't believe it.
You aren't supposed to pick the speaker you think that may work well with the amp for a test.
Just try everything you can.
From a B&W 601 / 2, Dali 3-way floorstander, B&W Nautilus 805, Epos, JMLab, Rega Ela, everything that you can.
Don't play games here making people believe that the low-cap amp can drive these kind of speakers.
You are into SET territory to match that amp with a pair of speakers.
What really bugs me is that you are being fooled by the previous components in the chain (like the source), because it seems you are artificially "removing" the dynamics from the amp due to a jittery source and/or your beloved NOS passive-output TDA1543 dacs.
Also, this kind of NOS dac with uncompensated passive output has a marked high-frequency roll-off, it sounds shut-in, so it's really surprizing to see you claiming very good sound out of this. Then you go fiddling with other components on your system to compensate.
The amp sounds "faster" to you because you have a flaw on a previous component.
Better no bass than untight bass.
Oh, and don't come with Mark Levinson gear, you could do much better.
demogorgon said:Jeez!
Peter, its amazing how you try to make it seem like your some kind of victim here, no offence(ok, a litle), but your simply full of c*ap.
oh, and before you reply, take a moment reviewing the tone of your posts.
your post have a "hint" of arogancy and better-knowing, and at the same time the darting "back and forth" of a man who know that whats he's accused of is true.
as jocco say, as long as you speak english, you kind of get what others say between the lines as well as the black-on-white.
-and, why the last post?
can you see what makes me and others tic about this place?
I'd like to agree with nuuk, but sometimes shuting up and playing nice just dont get the work done.
stagnant forums?
I can see why few people wound subject their eventual finds to the s*itstorms that strike here.. carlos has taken a lot of beating for his snubber.
edit: and oh, by beating i dont mean people trying to find out how\why it works\dont work. I think that should fall second nature to any diy'er. after all, this IS science, not fiction\snake oil.
Don't start things up again. If you don't have anything constructive to say, say nothing. This has been hashed and rehashed. Things were starting to settle down. We don't need you to start the whole thing over again.
If i may add water to the fire:
i starting following the development of the snubber back when carlos had posted his discovery. i also closely followed peter's developments with brian of their board revisions and especially peter's opinions and experience with gainclone component choice. since i was a newbie (and still am), both peter and carlos were my sources of experience and knowledge. i learned many things from both just by following things as they developed.
there was a side effect of learning about chip amps with these two, i ended up learning about their audio philosophies and "beliefs" too.
the way I see it pretty simple: (emphasis is on I, im sorry if this isnt exactly what you think carlos and peter)
carlos' audio goal:
make the best sounding chip amp that will work consistently well in any setup. (with special emphasis on driving his hard to drive epos) For carlos, an amp that sounds good in setup A but oscilates in setup B is not a good amp, regardless of how good in sounds in A. If it cant perform in B, it has failed.
peter's audio goal:
tweak the hell of the gainclone concept until his prime gainclone sounds as best it can to him. For peter, sacrificing components (ie. zobel, input res, input cap) in the name of sound quality is the name of the game. doesnt matter if it doesnt play as well in another setup, as long as for his uses it sounds the best it can. (more recently, sounds the best for the active speakers he is designing).
So now i think its pretty obvious were the friction comes in. Peter is trying to design a chip amp for those active speakers. So im guessing his design process involves changing variables, listening through HIS speakers, determining improvement or none, moving on to another variable and so on. To peter, the snubber does not sound better on HIS setups, to HIS tastes, therefore he is disregarding it.
As for carlos, he is designing something that sounds good and can drive anything you throw at it. i think the snubber is successful in this aim, even though it may take away in certain very specific situations (ie. peter's easy to drive speakers), it can add in other situations (hard to drive epos). hell, peter even recommended to me that according to my music tastes, i should consider trying the snubber! (this was after he posted his reviewed results about how the snubber isnt necessarily an upgrade)
I think both Peter and Carlos have succeeded in their goals, and because their goals differ, so do the results. No one argues if you prefer brunettes or blondes, coffee or tea, sugar or no sugar. this is no different!
different tastes, different goals, different results.
i starting following the development of the snubber back when carlos had posted his discovery. i also closely followed peter's developments with brian of their board revisions and especially peter's opinions and experience with gainclone component choice. since i was a newbie (and still am), both peter and carlos were my sources of experience and knowledge. i learned many things from both just by following things as they developed.
there was a side effect of learning about chip amps with these two, i ended up learning about their audio philosophies and "beliefs" too.
the way I see it pretty simple: (emphasis is on I, im sorry if this isnt exactly what you think carlos and peter)
carlos' audio goal:
make the best sounding chip amp that will work consistently well in any setup. (with special emphasis on driving his hard to drive epos) For carlos, an amp that sounds good in setup A but oscilates in setup B is not a good amp, regardless of how good in sounds in A. If it cant perform in B, it has failed.
peter's audio goal:
tweak the hell of the gainclone concept until his prime gainclone sounds as best it can to him. For peter, sacrificing components (ie. zobel, input res, input cap) in the name of sound quality is the name of the game. doesnt matter if it doesnt play as well in another setup, as long as for his uses it sounds the best it can. (more recently, sounds the best for the active speakers he is designing).
So now i think its pretty obvious were the friction comes in. Peter is trying to design a chip amp for those active speakers. So im guessing his design process involves changing variables, listening through HIS speakers, determining improvement or none, moving on to another variable and so on. To peter, the snubber does not sound better on HIS setups, to HIS tastes, therefore he is disregarding it.
As for carlos, he is designing something that sounds good and can drive anything you throw at it. i think the snubber is successful in this aim, even though it may take away in certain very specific situations (ie. peter's easy to drive speakers), it can add in other situations (hard to drive epos). hell, peter even recommended to me that according to my music tastes, i should consider trying the snubber! (this was after he posted his reviewed results about how the snubber isnt necessarily an upgrade)
I think both Peter and Carlos have succeeded in their goals, and because their goals differ, so do the results. No one argues if you prefer brunettes or blondes, coffee or tea, sugar or no sugar. this is no different!
different tastes, different goals, different results.
Banned
Joined 2002
Banned
Joined 2002
homer09 said:
I didn't want to join heated discussion, but this post describe it in the best way. I have similar experience: I started with basic GC 3875 and enjoyed it a lot, than I added more capacitance and the bass worsen. I tried snubberized PSU an it was better driving my speakers with full crossover. Finally I tried snubberized regulated PSU and there was another improvement. None of this sounded bad, it was just GC evolution.
Small tube amps such as 2A3 or 300B are great, but they have hard time driving complex or not very sensitive speakers. That is why so many people are trying horns, transmission lines, e.t.c. It is same with GC - in some setups, original GC design with dual 1500 uF caps on board works well, I have it on my ribbon tweeters in three way system.
For full range speakers I have in my second set up, snubbers are great and necessity for me.
On another note, I am very sadden with this state of DIY audio. It is my site for morning and evening reading, it is a place where I could learn so much, and I am doing it. Heated discussions such as this one already chased away so many great and knowledagble people. They even started another forum because they felt abused here. I think we all lost.
Peter and Carlos, thank you for all you did for this forum. I have been following your posts, like many others, and I learned so much from you. Please, if there is disagreement or misunderstanding between you guys or between anyone else, settle it outside of forum by private mail. If Carlos felt neglected by someone else using, or just perceived using his ideas, what better way than settling it one on one? It will be much easier for both sides in reaching any agreement without all of us giving our opinion or taking sides,
It is just amazing how many treads regarding snubbers have been started and than ended up in fight. I also think Carlos that you sometimes reacted with high temper, even do I do agree that many people went in discussion without even trying it, which for sure is irritating. But many people wanted to know what is logic behind, or theory so they could understand it better and use it in various situations. My feeling is that you never fully described or welcomed this kind of questions. I could be wrong, but that is my feeling. I truly agree that there is a benefit of using snubber in PSU (as you discovered and shared it with us) because I tried it. But I do not know how to calculate values if I want to use it differently. I am sure many people feel the same way, and many discussions would be prevented if it was fully described. Again I apologize if I am wrong, or if I missed your description in somewhere. Without that please accept this as a friendly note as I am always looking for your submissions as a prime reading and learning material.
Stay well
AR2
homer09 said:
Excellent post, its good to see one level head! My feelings exactly, plus.....its interesting to see the interaction of these two personalities, this is the issue not just technology.
I can't quite figure why other posters fill so strongly that they have to support one over the other (even, if they haven't been active here for months).
There seems to be so many (mis)interpretations of the facts.
Greg Erskine said:
Excellent post, its good to see one level head! My feelings exactly, plus.....its interesting to see the interaction of these two personalities, this is the issue not just technology.
I can't quite figure why other posters fill so strongly that they have to support one over the other (even, if they haven't been active here for months).
This forum somewhat different from others that I found it has certain emotional attachment involve.. like a giant international family that one associate oneself with. I remember the first time that I could not access the site due to whatever reason my heart sank like a ship heading the sea bed..felt like a big family lost..
Why did you lower the impedance at such a higher frequency with the unregulated psu? The unregulated has it's impedance lowered in the 1mhz range, but the regulated is lowered in the 10khz range. At 10khz, the regulated psu's impedance is about .02 ohms. Wouldn't a snubber be better implemented at, say, 100khz, where the impedance is .1 ohms?
Just curious, because I've been testing out different snubber configurations. Not that I doubt your values or anything, I just like messing around with things.
Just curious, because I've been testing out different snubber configurations. Not that I doubt your values or anything, I just like messing around with things.
mateo88 said:
At 100Khz the impedance is 1R, not .1R.
I decided to point to around 10Khz, where the impedance starts climbing to "alarming" levels.
I used 0.47R but as I said, it can be beneficial to go even lower (like 0.22R or even 0.1R), increasing the value of the cap accordingly.
I just haven't found the time yet, because of lots of things, including spanking defense here.
mateo88 said:Just curious, because I've been testing out different snubber configurations. Not that I doubt your values or anything, I just like messing around with things.
At last!!!
At last someone that just doesn't stick to a schematic, studies, builds, thinks, tries to improve.
Go on Mateo, keep testing.
I never said these are the definitive values.
carlosfm said:
Is this true even when (looking at figure 3 in the lm338 datasheet) C2 is 10uf? I have my regulators constructed according to that schematic, and I just assumed that the "Cadj" that is refferred to in the impedance graph is the same thing as C2. If I am mistaken here, this would probably explain the not-so-substantial results I've been getting with different values.
That or you already found the good values! 
I believe that a significant improvement would be to use a .1 or .22 ohm resistor, as you stated, coupled with a capacitor around 100uf or so.
mateo88 said:
Yes, it's the same thing.
I use 47uf there, so things are not so bad as a starting point.
With Cadj. as 10uf, the impedance at 100Khz is around 1R, not .1R.
mateo88 said:That or you already found the good values!
Probably.
mateo88 said:
Maybe not a substantial improvement now, but yes, that's what I meant, you can test it.
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