I've seen several posts about the best audio quality diodes to use, but I get a little bit of contradiction between didoe types:
Schottky diodes seem to be more audio quality than standard, but do we want to use fast recovery or soft recovery?
==> Similar note, has anyone tried Fairchild's stealth diodes?
Schottky diodes seem to be more audio quality than standard, but do we want to use fast recovery or soft recovery?
==> Similar note, has anyone tried Fairchild's stealth diodes?
Try both and see if you can tell a difference. You won't need fast recovery for dealing with 60Hz line frequencies. Diodes used in a switching supply are a different story...
Its not the speed of fast diodes that matters at 60hz, its thier better recovery giving less HF noise when they are shutting off.
I wish I could convince myself that fast recovery is an issue at 60 hertz...
This is one of those things I guess I'm just going to have to try myself and compare.
This is one of those things I guess I'm just going to have to try myself and compare.
This diode story is one of those placebo effects in audio.
You can use chicken fence wire to connect speakers to an amp. Then tell a guy it's gold plated solid silver $300 mega-monster interconnects, and he'll swear he can hear profound presence, soubtle overtones, rich full-bodied sound that envelops you like the flavor of fine cognanc...blah, blah, blah, ... you know the drill...
Then tell him it's chicken wire, and he can suddenly hear the rough, jagged, scratchy granularity caused by the myriad diodes formed by the cheap iron molecules in the cable...
There's never been any evidence, measured objectively with instruments, to suggest that any power supply rectifier diodes used in place of the 1N400x will provide any significant improvement in sound parameters.
The drive to substitute more expensive alternatives for all components in a power amp stems from a desire to improve the design without an actual knowledge of how to improve the design.
It demonstrates complete unawareness of a fundamental principle of electronic design:
The topology must factor out component characteristics,
so that overall quality of result depends on circuit arrangement, not on individual component properties and tolerances.
The sound of an amplifier should not depend on the quality of components, but on the arrangement of those components. With few exceptions, this design goal is to a large extent achieved in most designs today.
So you're trying to improve something which has already been rendered irrelevant by the design.
This in turn causes an individual to convince themselves they can "hear" an improvement, in order to achieve self-justification. Communicating with others who have done the same modification provides reassurance through cross-confirmation. So now you have a club of believers. Something like this:
http://www.alaska.net/~clund/e_djublonskopf/Flatearthsociety.htm
You can use chicken fence wire to connect speakers to an amp. Then tell a guy it's gold plated solid silver $300 mega-monster interconnects, and he'll swear he can hear profound presence, soubtle overtones, rich full-bodied sound that envelops you like the flavor of fine cognanc...blah, blah, blah, ... you know the drill...
Then tell him it's chicken wire, and he can suddenly hear the rough, jagged, scratchy granularity caused by the myriad diodes formed by the cheap iron molecules in the cable...
There's never been any evidence, measured objectively with instruments, to suggest that any power supply rectifier diodes used in place of the 1N400x will provide any significant improvement in sound parameters.
The drive to substitute more expensive alternatives for all components in a power amp stems from a desire to improve the design without an actual knowledge of how to improve the design.
It demonstrates complete unawareness of a fundamental principle of electronic design:
The topology must factor out component characteristics,
so that overall quality of result depends on circuit arrangement, not on individual component properties and tolerances.
The sound of an amplifier should not depend on the quality of components, but on the arrangement of those components. With few exceptions, this design goal is to a large extent achieved in most designs today.
So you're trying to improve something which has already been rendered irrelevant by the design.
This in turn causes an individual to convince themselves they can "hear" an improvement, in order to achieve self-justification. Communicating with others who have done the same modification provides reassurance through cross-confirmation. So now you have a club of believers. Something like this:
http://www.alaska.net/~clund/e_djublonskopf/Flatearthsociety.htm
A spike (as can be seen across the diodes when they turn off), is energy with a uniform frequency distribution. That is it may set off resonances throughout the power supply if they exist.
Fairly easily fixed though, put some snubbers across the diodes, and place small resistances between stages in the ps.
I believe Nelson Pass has a few good things to say on his web site on this subject too. I seem to recall him recommending which diodes to use.
Fairly easily fixed though, put some snubbers across the diodes, and place small resistances between stages in the ps.
I believe Nelson Pass has a few good things to say on his web site on this subject too. I seem to recall him recommending which diodes to use.
Schottky diodes have the smoothest recovery of them all, but they are not as robust nor available in as high PIV rating as other types.
My own opinion is that with massive cap banks etc the conduction angle of the diodes becomes smaller so any recovery time will become more important. I use Schottky's, I like to over engineer.
My own opinion is that with massive cap banks etc the conduction angle of the diodes becomes smaller so any recovery time will become more important. I use Schottky's, I like to over engineer.
I recently started using UF5408 diodes, they are good for 1000V 3A, and are wicked fast for the price, they are also quite large, wich I like.
They may be fast, but their recovery - which is the most important parameter on 50/60Hz mains - is poor. I would not use these diodes.
Upupa Epops said:
Some people claim to notice a difference. That aside, there are also EMC/RFI issues to take into account.
It is confusing of reason and result - low PSRR, amp on border of stability, wrong design of PCB, sensitivity for HF disturbing at input etc... Isn't problem to get with normal diodes SNR over 120-125 dB, with any special low noise devices ( at line levels... ), if all is correct designed .... 😉
Diode commutation noise is not like common thermal/resistance noise which is usually relatively quiet and resembles white noise.
Diode noise is short spikes that on their own are largely inaudible, but they are very high in level. It takes this wideband high voltage spike to ring the power supply.
Diode noise is short spikes that on their own are largely inaudible, but they are very high in level. It takes this wideband high voltage spike to ring the power supply.
Hello,
there is no current recovery problem, but in some cases hf-generation can occur if one uses diodes with higher capacities together with a transformer with some leakage inductance.
In this case there is one (not four!) small snubber the problem solver!
The "funny" thing is that usually schottkey´s have bigger capacities!
You can start read about from here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=66542&perpage=10&highlight=&pagenumber=5
Regards
Heinz!
there is no current recovery problem, but in some cases hf-generation can occur if one uses diodes with higher capacities together with a transformer with some leakage inductance.
In this case there is one (not four!) small snubber the problem solver!
The "funny" thing is that usually schottkey´s have bigger capacities!
You can start read about from here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=66542&perpage=10&highlight=&pagenumber=5
Regards
Heinz!
I'm sure I read somewhere that people were using Switching Mode Power Supplies and Microcontrollers in their Hi-Fi designs... all of which, in my mind, do WAYYY more to induce HF noise than a Power Diode like a 1N4004 could ever hope to do.
I realize that a lot of designs, especially Gainclones, like to use those really cool looking fast diodes in TO-220 cases... but WELL FILTERED DC power (both HF and RIPPLE filtered) would seem to be able to completely overcome anything a "standard" diode could do while changing state.
I'd be more worried about what a local FM radio tower could induce into my amp than what the diode might do...
So... I guess I remain unconvinced it makes a difference... still haven't lab tested though.
I realize that a lot of designs, especially Gainclones, like to use those really cool looking fast diodes in TO-220 cases... but WELL FILTERED DC power (both HF and RIPPLE filtered) would seem to be able to completely overcome anything a "standard" diode could do while changing state.
I'd be more worried about what a local FM radio tower could induce into my amp than what the diode might do...
So... I guess I remain unconvinced it makes a difference... still haven't lab tested though.
pwillard said:
Not me...
Yes, but the trouble is getting there. Filtering requires resonant circuits, and whilst we try to have them behave themselves and to act at infrasonic frequencies, there are always parasitics.
Electrolytics in particular usually have an inductive component due to their plates being rolled, that when combined with their capacitance, resonates in the upper midrange.
When you mention "very high in level" you must put this into perspective, compared to what? Bear in mind that 99.99% of all high-end gear have regular diodes.lndm said:
peranders said:
No I don't. I understand the problem conceptually as I'm sure you do too. I'm explaining it conceptually. I build according to guidelines, common sense, and my training. If it's broken I fix it and I enjoy much success. Therefore I speak from experience.
Not interested in specifics here.
http://www.passlabs.com/downloads/articles/powersupply.pdf
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