I need some advice on selecting the right schottkys for my power amp and cd player.
My power amp at the moment uses IN 5402 - 3 A / 200 volt
alongside 4 old Aerovox 10,000 uf 63 volt caps.
I wish to replace the existing PS caps with something bigger like 15,000 uf @ 63 volt or maybe 100.
From comments read my understanding is that I will also need to up the value of the diodes if I am to safely increase the value of the main PS Caps.
Can anyone confirm and suggest which value schottky's to buy.
Is 6 amps and 1000 volts just too far ?
The Tranny has a 420 VA rating on a protection relay that opens after 10 seconds.
Finally then, which values of schottkys do I need for the PS stage of the Alpha 5 plus CD player please ?
Thanks in advance
Andrew
My power amp at the moment uses IN 5402 - 3 A / 200 volt
alongside 4 old Aerovox 10,000 uf 63 volt caps.
I wish to replace the existing PS caps with something bigger like 15,000 uf @ 63 volt or maybe 100.
From comments read my understanding is that I will also need to up the value of the diodes if I am to safely increase the value of the main PS Caps.
Can anyone confirm and suggest which value schottky's to buy.
Is 6 amps and 1000 volts just too far ?
The Tranny has a 420 VA rating on a protection relay that opens after 10 seconds.
Finally then, which values of schottkys do I need for the PS stage of the Alpha 5 plus CD player please ?
Thanks in advance
Andrew
Member
Joined 2009
Paid Member
There are many types of high speed low noise diodes available at the current and voltage ratings you need. ON diodes, which were motorola, still produce the MUR high speed, low noise soft recovery types are still available. Vishay also makes very nice shattky type diodes. There are many others. You are looking for a D 41 type axial diodes. At least that is what I remember.
That's what I needed !
Someone who just knows.
So, going from 10,000 uf to 15,000 uf is OK and safe
and I can maybe leave the existing IN 5402 rect diodes in place
( 3 amp 200 V )
That would be great and less work !
Presumably the voltage rating is less important providing it's not lower than the exisitng caps ?
Thanks again !
Andrew
Someone who just knows.
So, going from 10,000 uf to 15,000 uf is OK and safe
and I can maybe leave the existing IN 5402 rect diodes in place
( 3 amp 200 V )
That would be great and less work !
Presumably the voltage rating is less important providing it's not lower than the exisitng caps ?
Thanks again !
Andrew
Hi
Johnny X : Thanks I'll look those up asap.
I have access to RS up here too - Cheers
Mr Evil : Do they ? Blimey - I didn't see that in the spec !
200 A is probably more than OK. The Aerovox caps were fitted
in 1997 - so it's probably time for them to be changed plus all the Rubycons I put on the input and output stages. Like Andy Bartha said, while I've got it stripped down again I may as well do the other bits too. I was just worried that I may damage the recti diodes by upping the capacitance to 15 K x 4 ( there are 4 )
But from your advice - it won't matter.
Of course I've got ' fast recovery Schottky = sonic gain ' in my head too - which may be wrong - don't laugh !!
I've made loads of probably time wasting tweaks to things after I've read something here in the forums.
That's why I like it !
Appreciate everyones help here
Andrew
Johnny X : Thanks I'll look those up asap.
I have access to RS up here too - Cheers
Mr Evil : Do they ? Blimey - I didn't see that in the spec !
200 A is probably more than OK. The Aerovox caps were fitted
in 1997 - so it's probably time for them to be changed plus all the Rubycons I put on the input and output stages. Like Andy Bartha said, while I've got it stripped down again I may as well do the other bits too. I was just worried that I may damage the recti diodes by upping the capacitance to 15 K x 4 ( there are 4 )
But from your advice - it won't matter.
Of course I've got ' fast recovery Schottky = sonic gain ' in my head too - which may be wrong - don't laugh !!
I've made loads of probably time wasting tweaks to things after I've read something here in the forums.
That's why I like it !
Appreciate everyones help here
Andrew
I've never seen (or heard) anything to convince me that fast recovery diodes are or could be beneficial. I think Schottky diodes would be better in that respect anyway, since they don't suffer from reverse recovery problems. Also, I personally prefer Schottky diodes because they are that little bit more efficient (but watch for the reverse leakage current, which can be quite large for some types).AndrewGM said:
http://www.cree.com/products/power_docs2.asp
SiC (silicon carbide) schottky diodes up to 20A and voltages of 600 and 1200. if you're operating rail voltages of +/-60V or so, you only need 200V rated devices though... between 20 and 60V are where most standard schottky diodes are rated. "high voltage" schottky diodes are in the range of 80 to 200V, and SiC diodes are mostly in the 200-1200V range. the intermediate schottky diodes are most likely 2 standard schottky dies in series, based on their forward voltage drop of 1.4V and SiC diodes in any voltage/current range are about 2V forward drop per junction. SiC definitely has the fastest recovery time and lowest capacitance.
with SiC there are no reverse current spikes (which is generally where a lot of RF noise is generated in silicon rectifiers)
SiC (silicon carbide) schottky diodes up to 20A and voltages of 600 and 1200. if you're operating rail voltages of +/-60V or so, you only need 200V rated devices though... between 20 and 60V are where most standard schottky diodes are rated. "high voltage" schottky diodes are in the range of 80 to 200V, and SiC diodes are mostly in the 200-1200V range. the intermediate schottky diodes are most likely 2 standard schottky dies in series, based on their forward voltage drop of 1.4V and SiC diodes in any voltage/current range are about 2V forward drop per junction. SiC definitely has the fastest recovery time and lowest capacitance.
with SiC there are no reverse current spikes (which is generally where a lot of RF noise is generated in silicon rectifiers)
1st - Dr Evil - understood.
Not sure about Reverse Leakage Current or when/how it may occur.I will look at the spec sheets now you've pointed it out - before I just throw them in.
Extra efficiency....I'll take that as positive
Thank you again
Uncle Jed - I had to read that three times !
No reverse current spikes = no RF noise ....I'll take that as a gain too !
I do however need to check the rail voltages to be sure and I will.
Thank you for your advice
In fact thanks to you all
Andrew
Not sure about Reverse Leakage Current or when/how it may occur.I will look at the spec sheets now you've pointed it out - before I just throw them in.
Extra efficiency....I'll take that as positive
Thank you again
Uncle Jed - I had to read that three times !
No reverse current spikes = no RF noise ....I'll take that as a gain too !
I do however need to check the rail voltages to be sure and I will.
Thank you for your advice
In fact thanks to you all
Andrew
I use I/R 30EPH06 fore poweramps with very good results, I think they are called "hyper-fast"
No snubber, coupling caps or anything, just a couple of Jensen 4-pole, 15.000uf fore 50watt mono
Rectifers are x4 each rail, so a total of 16 fore two monoamps
Amps have really super nice sonics, if the speakers are up to it
Also have smaller ones of same kind, to use fore preamp or such, I/R 8ETH06
I expect them to be equally good, but cant say yet
Well, I looked them up, and seems they are no longer available
No snubber, coupling caps or anything, just a couple of Jensen 4-pole, 15.000uf fore 50watt mono
Rectifers are x4 each rail, so a total of 16 fore two monoamps
Amps have really super nice sonics, if the speakers are up to it
Also have smaller ones of same kind, to use fore preamp or such, I/R 8ETH06
I expect them to be equally good, but cant say yet
Well, I looked them up, and seems they are no longer available
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