Re: New vs old diodes
Hi Giannis,
I haven't come across the term "saturation" in this context before, but I think I now understand what you are getting at, although I don't know what, if any, sonic effect this would have.
I don't have access to any such sophisticated analyzers as you do, so similarly I have not seen the effect you now describe.
My (perhaps over simplistic) view is that if the diode's current and voltage ratings are adequate (also allowing for the normally recommended tolerance margin to ensure safety and handle the surge at switch-on), there should not be any 'electronic' problem.
If any member who *knows* better in this regard is reading this and I have overlooked something here, I should be grateful if he would correct me, for all of our sakes.
As far as the sonic results are concerned, as I have said in several posts during the past few days on this Forum (and as Jonathan Carr has just reminded me!), the only way to be sure is to arrange a realistic test of the devices, loaded in a similar way to how you would use them in a bridge, and listen to the results.
Being new to the Forum, I don't yet know how to make a reference here to my other posts, but you should be able to find them by searching. I'm doing my best, but there aren't that many yet to look through as I only joined on Xmas day!
In at least one of them I have explained how I carry out some of the listening tests, together with the importance of avoiding having any unwanted influences which will spoil the results, and you may find this of some help.
All it needs is a sensible methodology and a little patience and determination, and if you cannot hear any differences (or anything wrong with the chosen diodes), then I wouldn't worry about them, whatever your teacher says, as you are unlikely to hear any ill-effects in their use.
You will probably find it much easier to make a judgement if you compare these diodes with some others you know to be acceptable, by instantaneous switching between them, rather than merely listening to a setup where they are used throughout.
Hopefully they will either sound distinctly better, or worse, but if there is no difference, go for the cheapest ones!
Fortunately, with diodes (although I guess they will change a fraction during 'burning in' as all other SS devices seem to) I have never noticed any real change to their 'sound' when used over a period of time, unlike many other components. Therefore any conclusions you reach based on immediate direct comparisons, are likely to be reasonably fair and true over the long term.
Schottky devices should theoretically work well at high frequencies, although if the problem is only at say 26.5 GHz, I guess anything could happen here, but whether any abberations at these stratospheric frequencies will cause you any 'sonic' problems, I just don't know!
Normally, "ringing" is dealt with by using snubbers, which I said elsewhere I personally don't like the sound of, but with no reverse recovery transients to worry about (again, theoretically) with schottkys, I don't know what else to suggest.
Regards,
lll said:
Hi Giannis,
I haven't come across the term "saturation" in this context before, but I think I now understand what you are getting at, although I don't know what, if any, sonic effect this would have.
I don't have access to any such sophisticated analyzers as you do, so similarly I have not seen the effect you now describe.
My (perhaps over simplistic) view is that if the diode's current and voltage ratings are adequate (also allowing for the normally recommended tolerance margin to ensure safety and handle the surge at switch-on), there should not be any 'electronic' problem.
If any member who *knows* better in this regard is reading this and I have overlooked something here, I should be grateful if he would correct me, for all of our sakes.
As far as the sonic results are concerned, as I have said in several posts during the past few days on this Forum (and as Jonathan Carr has just reminded me!), the only way to be sure is to arrange a realistic test of the devices, loaded in a similar way to how you would use them in a bridge, and listen to the results.
Being new to the Forum, I don't yet know how to make a reference here to my other posts, but you should be able to find them by searching. I'm doing my best, but there aren't that many yet to look through as I only joined on Xmas day!
In at least one of them I have explained how I carry out some of the listening tests, together with the importance of avoiding having any unwanted influences which will spoil the results, and you may find this of some help.
All it needs is a sensible methodology and a little patience and determination, and if you cannot hear any differences (or anything wrong with the chosen diodes), then I wouldn't worry about them, whatever your teacher says, as you are unlikely to hear any ill-effects in their use.
You will probably find it much easier to make a judgement if you compare these diodes with some others you know to be acceptable, by instantaneous switching between them, rather than merely listening to a setup where they are used throughout.
Hopefully they will either sound distinctly better, or worse, but if there is no difference, go for the cheapest ones!
Fortunately, with diodes (although I guess they will change a fraction during 'burning in' as all other SS devices seem to) I have never noticed any real change to their 'sound' when used over a period of time, unlike many other components. Therefore any conclusions you reach based on immediate direct comparisons, are likely to be reasonably fair and true over the long term.
Schottky devices should theoretically work well at high frequencies, although if the problem is only at say 26.5 GHz, I guess anything could happen here, but whether any abberations at these stratospheric frequencies will cause you any 'sonic' problems, I just don't know!
Normally, "ringing" is dealt with by using snubbers, which I said elsewhere I personally don't like the sound of, but with no reverse recovery transients to worry about (again, theoretically) with schottkys, I don't know what else to suggest.
Regards,
If we talk about tests, why not go on with this thread? :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=8683&perpage=15&pagenumber=1
Would be fine if somebody could make comments.
also crown posted a link to a document with related information in the thread.
Giannis:
While regular diodes are conducting, the junction builds up and stores a substantial charge. When the AC waveform and voltage reverse direction, the current also reverses, but until the junction charge is depleted, the diodes continue to conduct (now in the reverse direction). When the charge finally clears, the diodes turn off abruptly, creating a sharp wavefront with high-frequency content that can reach into the RF region, and the lead wires and transformer windings act as antennas to radiate this crud all over.
OTOH, Schottkys don't have any stored charge, and therefore should not cause this type of problem. However, Schottkys can also cause ringing, not in themselves, but in the power transformer. As long as the rectifiers are conducting, the transformer windings are loaded, but when the rectifiers stop conducting, the windings "lose" their termination and will ring. The solution is to add some sort of network (like a bleeder) across the secondaries so that the windings are always terminated, regardless of whether the rectifiers are conducting or not.
So much for the theory... When I actually do this I frequently end up deciding that I prefer the sound without the network in place. Ultimately, it is best to try it for yourself and make up your own mind.
hth, jonathan carr
While regular diodes are conducting, the junction builds up and stores a substantial charge. When the AC waveform and voltage reverse direction, the current also reverses, but until the junction charge is depleted, the diodes continue to conduct (now in the reverse direction). When the charge finally clears, the diodes turn off abruptly, creating a sharp wavefront with high-frequency content that can reach into the RF region, and the lead wires and transformer windings act as antennas to radiate this crud all over.
OTOH, Schottkys don't have any stored charge, and therefore should not cause this type of problem. However, Schottkys can also cause ringing, not in themselves, but in the power transformer. As long as the rectifiers are conducting, the transformer windings are loaded, but when the rectifiers stop conducting, the windings "lose" their termination and will ring. The solution is to add some sort of network (like a bleeder) across the secondaries so that the windings are always terminated, regardless of whether the rectifiers are conducting or not.
So much for the theory... When I actually do this I frequently end up deciding that I prefer the sound without the network in place. Ultimately, it is best to try it for yourself and make up your own mind.
hth, jonathan carr
till said:
Hi,
Actually, I was already aware of this thread, and the only comments I would make are that nowhere in the entire thread (that I could see) does it tell you anything very practical or positive about how these devices actually sound. i.e. does a particular type of diode sound good in use, or not, or better or worse than another?
Also (and I am not criticising him in any way, as I would be in exactly the same position) when questioned, Icceman, who kindly put up the original rather nice 'scope pictures, admitted that he didn't really know what they meant!
The earlier post I made was to share the results of many extended and carefully carried out 'listening' tests, and my conclusion that schottkys were universally the best I had tried was readily shared with everyone who might be interested.
Similarly, I admitted that I didn't care for the sonic results I had obtained from *any* of the snubber circuits I had also tried, which appear to agree with Wayne's recent objective test on snubbers. Regrettably, Wayne didn't comment on schottkys, which Nelson said (somewhere in the Forum) he also favoured.
Presently, I don't find it very convenient to replicate my earlier tests all over again, but soon I will do so to compare schottkys (my current favourites) with the newest diodes, and I will expose the findings to anyone who might be interested.
Unfortunately, my own diode 'listening' tests were done some years ago, and the latest fast/soft diodes were not then available, so I haven't tested them A/B yet, although I have just obtained some of them to try.
I still hope that someone may have done some of these listening tests and comparisons on the modern diodes and will be prepared to share the results with the rest of us.
Perhaps if Giannis adopts my suggestion, he will be kind enough to publish his findings, especially over the concerns his teacher has expressed. i.e. does the 'ringing', or whatever has been observed, have any bad affect on the sound?
Also, maybe if I am patient, Wayne might comment on whether or not he carried out any objective tests on schottkys with their sophisticated equipment, and if so what his findings were, which will be useful to compare with my subjective trials, to see if we are also in general greement here as well.
Regards,
OK, i try to find the difference in an objective way, but i don´t know if the difference in the scope pics is what we search for. I recived a lot of samples / super fast / soft etc. recovery and schottky diode samples from different companys and will use them in the alephx. I have to admit i´m not able to hear the differnce between diodes. This may be because my speakers are not good enough or because i´m simply pysicaly not able to. I´m bale to hear differnces between door open or colsed in listening room but not between caps or diodes. Maybe this will change with other speakers or not. What i understand is there is an aestethical reason for usage of schottkys. This is my main reason to do so. From my experience, and thats subjective and not much, i have to build another listening room when the new speakers are ready, far more important than diodes, caps, induction free resistors and what ever.
Sorry that I cannot provide an answer that is succinct and neatly packaged, but that's life for you...
Hi Jonathan,
Thanks a lot for such a comprehensive reply.
I fully understand what you say, and I should have known better than to have asked such a direct question about these diodes, or at least to have expected an all-encompassing answer, as I know full well that few things in life are that easy.
Reading what you have written, it seems that we must have trodden many similar paths over the years, although, in my case, I am some way behind you as my interest in electronics and audio is entirely non-commercial.
I don't have the advantages of doing these kinds of tests (amongst other things) full-time like I guess you do, but I don't need to make a living out of it like yourself, the pressures of which I imagine must take much of the fun out of it.
I hoped perhaps in a similar way to what I have found with say MIT Multicaps, which all seem to me to have a family semblance (although I only happen to like the rather limited [and pricey!] RTX series myself), that you may have reached a similar conclusion with regard to different makes of diodes etc.
I noticed the same kind of situation with each of the many generations of TRT's Wondercaps, Ultracaps, and Infinicaps etc, to use another example, and most other passive components I have tried do appear to exibit many similarities.
In general with active devices, I have not seen the same well-defined situation, and I maybe wrongly thought from your other post, that your findings were rather different from mine in this area and that you had your favourites as far as semi-conductors go.
From what I now understand, this is not the case, and (like me) you have found some which are favourite in some locations, and some which are better used elsewhere.
Probably the greatest benefit to me from your carefully worded reply, is that you don't appear to have reached many conclusions which differ greatly from my own, and I am encouraged by that.
As you say, it is always far better to know if someone has (genuinely) come to a different conclusion, since that way you can think afresh or carry out some tests again, and by so doing learn something valuable and new from the exercise.
I don't wish to go through life with a blinkered approach, nor in thinking that I know everything (because I don't), but I have always had an insatiable curiosity about mechanical, electrical, and electronic devices of all kinds, and have tinkered about with many of them.
At sixty years of age, I have by now gained a fair amount of confidence through experience and will therefore try anything (legal!), and never a day goes by without my learning something new and worthwhile, which is a very enriching experience in life.
What I find aggravating (and, not unexpectedly, I have already seen a little of this in only a couple of days of posting at this Forum) are those armchair experts who spout off about all and sundry when it is clear they have done absolutely nothing on their own by way of any trials or tests in the areas I have 'dared' to make some comments on, and they really don't have anything worthwhile to comment upon, themselves.
I don't mind the irritation from a personal point of view, but such juvenile acts do unfortunately inevitably tend to cast some overall doubts upon what has been said in good faith, and this may discourage some inexperienced DIYers from having a go for themselves.
This is sad, I think, as very few of us are one hundred per cent 'original thinkers', and it is frequently the spark of an idea or a comment from someone else which has set me on a new path to try something out which might not be intuitively sensible to do.
No-one likes to waste time (or money!) unnecessarily, and, as you know, some of these comparisons can take up an inordinate amount of time to do thoroughly which many cannot readily spare, but if an experimenter thinks he stands at least a fair chance of success, if he is anything like me, he will have go for himself and see what the results are.
However, if some misguided idiot has slagged the suggestion off in an apparently authoritative manner, with the support of some bogus or irrelevant facts, I guess many hopefuls will simply not bother and they will miss out on the potential benefits.
I personally don't care if anyone else's system doesn't sound as good as it might, after all there is nothing in it for me, but having discovered a few good things as a result of my efforts, I will willingly share them with anyone who is interested and who has an open mind.
When I first discovered (quite by chance) some 35 years ago that not all similar components sound the same in use, I simply couldn't believe it, and neither could the few people I spoke to about it who clearly thought I had a screw loose!
However, I couldn't deny it (since it was so blatantly obvious to me, once noticed) in spite of what the conventional wisdom said at that time, so I thought it might just be sensible to take advantage of the fact and improve the overall sound of my equipment.
I have therefore spent the last 35 years doing just that, with the first ten or so of those years in virtually complete isolation, because no-one wanted to listen to what I had to say about such apparently ridiculous beliefs.
Fortunately, in more recent times, the 'rags' began to run articles which made it obvious that, however misguided people thought I was, I was clearly not alone in my discoveries, and the rest is history, as they say!
One of the most exciting times I have had for many years, was when, relatively recently I built a computer, and then soon discovered the Internet and DIY audio forums etc.
I could hardly believe it and the generous exchange of information, especially from professionals such as yourself and Nelson, who must be a little concerned not to dilute your livelihoods too much, and I applaud you all for what you have done.
Thank you, again, for your kind response, and a very happy and prosperous New Year to you.
Regards,
Hi Jonathan,
Thanks a lot for such a comprehensive reply.
I fully understand what you say, and I should have known better than to have asked such a direct question about these diodes, or at least to have expected an all-encompassing answer, as I know full well that few things in life are that easy.
Reading what you have written, it seems that we must have trodden many similar paths over the years, although, in my case, I am some way behind you as my interest in electronics and audio is entirely non-commercial.
I don't have the advantages of doing these kinds of tests (amongst other things) full-time like I guess you do, but I don't need to make a living out of it like yourself, the pressures of which I imagine must take much of the fun out of it.
I hoped perhaps in a similar way to what I have found with say MIT Multicaps, which all seem to me to have a family semblance (although I only happen to like the rather limited [and pricey!] RTX series myself), that you may have reached a similar conclusion with regard to different makes of diodes etc.
I noticed the same kind of situation with each of the many generations of TRT's Wondercaps, Ultracaps, and Infinicaps etc, to use another example, and most other passive components I have tried do appear to exibit many similarities.
In general with active devices, I have not seen the same well-defined situation, and I maybe wrongly thought from your other post, that your findings were rather different from mine in this area and that you had your favourites as far as semi-conductors go.
From what I now understand, this is not the case, and (like me) you have found some which are favourite in some locations, and some which are better used elsewhere.
Probably the greatest benefit to me from your carefully worded reply, is that you don't appear to have reached many conclusions which differ greatly from my own, and I am encouraged by that.
As you say, it is always far better to know if someone has (genuinely) come to a different conclusion, since that way you can think afresh or carry out some tests again, and by so doing learn something valuable and new from the exercise.
I don't wish to go through life with a blinkered approach, nor in thinking that I know everything (because I don't), but I have always had an insatiable curiosity about mechanical, electrical, and electronic devices of all kinds, and have tinkered about with many of them.
At sixty years of age, I have by now gained a fair amount of confidence through experience and will therefore try anything (legal!), and never a day goes by without my learning something new and worthwhile, which is a very enriching experience in life.
What I find aggravating (and, not unexpectedly, I have already seen a little of this in only a couple of days of posting at this Forum) are those armchair experts who spout off about all and sundry when it is clear they have done absolutely nothing on their own by way of any trials or tests in the areas I have 'dared' to make some comments on, and they really don't have anything worthwhile to comment upon, themselves.
I don't mind the irritation from a personal point of view, but such juvenile acts do unfortunately inevitably tend to cast some overall doubts upon what has been said in good faith, and this may discourage some inexperienced DIYers from having a go for themselves.
This is sad, I think, as very few of us are one hundred per cent 'original thinkers', and it is frequently the spark of an idea or a comment from someone else which has set me on a new path to try something out which might not be intuitively sensible to do.
No-one likes to waste time (or money!) unnecessarily, and, as you know, some of these comparisons can take up an inordinate amount of time to do thoroughly which many cannot readily spare, but if an experimenter thinks he stands at least a fair chance of success, if he is anything like me, he will have go for himself and see what the results are.
However, if some misguided idiot has slagged the suggestion off in an apparently authoritative manner, with the support of some bogus or irrelevant facts, I guess many hopefuls will simply not bother and they will miss out on the potential benefits.
I personally don't care if anyone else's system doesn't sound as good as it might, after all there is nothing in it for me, but having discovered a few good things as a result of my efforts, I will willingly share them with anyone who is interested and who has an open mind.
When I first discovered (quite by chance) some 35 years ago that not all similar components sound the same in use, I simply couldn't believe it, and neither could the few people I spoke to about it who clearly thought I had a screw loose!
However, I couldn't deny it (since it was so blatantly obvious to me, once noticed) in spite of what the conventional wisdom said at that time, so I thought it might just be sensible to take advantage of the fact and improve the overall sound of my equipment.
I have therefore spent the last 35 years doing just that, with the first ten or so of those years in virtually complete isolation, because no-one wanted to listen to what I had to say about such apparently ridiculous beliefs.
Fortunately, in more recent times, the 'rags' began to run articles which made it obvious that, however misguided people thought I was, I was clearly not alone in my discoveries, and the rest is history, as they say!
One of the most exciting times I have had for many years, was when, relatively recently I built a computer, and then soon discovered the Internet and DIY audio forums etc.
I could hardly believe it and the generous exchange of information, especially from professionals such as yourself and Nelson, who must be a little concerned not to dilute your livelihoods too much, and I applaud you all for what you have done.
Thank you, again, for your kind response, and a very happy and prosperous New Year to you.
Regards,
Jonathan
Interesting, can I assume this is a properly designed snubber network designed to damp the self-resonance of the mains transformer secondaries?
I've not played with this in depth, but do know that, to my ears at least, the common (and incorrect) approach of putting caps across the rectifiers does sound worse.
Just curious, as I have every intent of trying a proper snubbing network, after I've played with rectifiers a bit.
Andy.
Interesting, can I assume this is a properly designed snubber network designed to damp the self-resonance of the mains transformer secondaries?
I've not played with this in depth, but do know that, to my ears at least, the common (and incorrect) approach of putting caps across the rectifiers does sound worse.
Just curious, as I have every intent of trying a proper snubbing network, after I've played with rectifiers a bit.
Andy.
Hi,
Thanks to all of you for the information.
When i found the time i try to figure out what really happen
with this diodes ( I work the most of the time out of Athens).
I d'ont now if the "ringing" create problems but i think the
real test is as Bob says.
Any way just i want to share any information i have in order to help if i can and to get information of course.
I d'ont now if can check sonically the diodes with super twetter.
Giannis
Thanks to all of you for the information.
When i found the time i try to figure out what really happen
with this diodes ( I work the most of the time out of Athens).
I d'ont now if the "ringing" create problems but i think the
real test is as Bob says.
Any way just i want to share any information i have in order to help if i can and to get information of course.
I d'ont now if can check sonically the diodes with super twetter.
Giannis
lll said:
Hi Giannis,
You are quite right in that 'listening' is the only definitve way to be sure in a case like this.
Since I started posting here on Xmas day, I have been amazed at the number of others who have related similar experiences to those I have experienced when 'listening' to components, and in some cases, measurements, which also seem to be generally in accordance.
Many of these observations don't seem to agree very well with theory, or what some other people have described, or what seems to be currently fashionable, but I cannot help that.
I will 'go with my ears', since these are what I use to enjoy music with, and I recommend you to do the same!
Please share any results with us in due course, as other people's views (based on *their* experiences, not hearsay) are always valuable to me.
You have a lovely Country, by the way, and I have enjoyed many wonderful holidays there.
Regards,
Hi,
i built such a bridge using 3 doublediodes. But then i noticed that the two diodes in one housing got much warmer than the others. Therefore they had a higher forward voltage drop and the ripple wasnt symmetric at all. By the way, with heatsinks you can keep their temperature equal..
Regards,
Smithers
i built such a bridge using 3 doublediodes. But then i noticed that the two diodes in one housing got much warmer than the others. Therefore they had a higher forward voltage drop and the ripple wasnt symmetric at all. By the way, with heatsinks you can keep their temperature equal..
Regards,
Smithers
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