[BoyElroy]

I can't say that I'm not a bit confused here. I had originally thought that I was going to use one type of rectifier diode, then I changed my mind, now I'm changing it again. I don't think I'm alone when I say that the large number of choices here presents a selection problem.

Does anyone have any opinions on which type of rectifying device would work best with the Gilmore power supply?

The choices that I know of at this point are as follows:

Standard Recovery silicon
FREDs
HEXFREDS
Fast Recovery Silicons
Schottkys
Ultrasofts
Ultrafasts

Would greatly appreciate any opinions on this matter!

Thanks--

 

[goon-heaven]

Thats why I asked if you had heard FRED, especially as that glowing quote came from a tuber, and you have sand.
Perhaps you could modify your PS circuit board to plant sockets for mounting the diodes, and get samples of eight, samples of eight and do a review. I would like to know too.
The other thought I have is that Kevin just specc'ed std diodes, which considering some OTT aspects of his design, lead me to suspect there may not be that much mileage.
BTW, what is the spec of your transformer?

 

[Joe Lau]

Quote:

Originally posted by BoyElroy I can't say that I'm not a bit confused here. I had originally thought that I was going to use one type of rectifier diode, then I changed my mind, now I'm changing it again. I don't think I'm alone when I say that the large number of choices here presents a selection problem. Does anyone have any opinions on which type of rectifying device would work best with the Gilmore power supply? The choices that I know of at this point are as follows: Standard Recovery silicon FREDs HEXFREDS Fast Recovery Silicons Schottkys Ultrasofts Ultrafasts Would greatly appreciate any opinions on this matter! Thanks--

As I know the best is Hexfred type & most of the UltraFast Superfast, Ultrasoft is also FREDs Structure.

So I suggest Hexfred if you don't care about the cost.

Freds is not so expensive compare to standard or Fast Recovery Silicon , Just 3 to 5 times higher but HexFred is too enpensive. I suggest FREDs even Silicon Fast recovery is not bad.

 

[morsel]

I am unconvinced that there are sonic improvements to be gained by using high performance rectifiers. If you have sufficient filtering, regulation, and shielding, the cheapest or most convenient rectifiers that will do the job should be fine.

 

[Possum]

There were some good responses to BoyElroy's question on www.diyaudio.com (http://www.diyaudio.com/forums/showt...?threadid=8683) for those of you who don't truly understand the differences.

 

[BoyElroy]

Hi Joe,

Thanks for your info. I've also received a couple of other recommendations on using Hexfreds as well. JWB and others over at DIYAudio suggest the International Rectifier Hexfreds and I've put together a quick list of Ultrafast, soft recovery T0-220AC two-lead packaged Hexfreds that should fit in the Fred Gilmore psu:

HFA04TB60 4A/600V
Newark part #07B790
$2.10 each/$1.88 per 10-24
http://www.irf.com/product-info/data.../hfa04tb60.pdf

HFA08PB60 8A/600V
Digikey part #HFA08PB60-ND
$2.20 each/$1.76 per 10
Newark part #07B800
$3.34 each/$3.00 per 10-24
http://www.irf.com/product-info/data.../hfa08pb60.pdf

HFA08TB60 8A/600V
Digikey part #HFA08TB60-ND
$1.58 each/$1.35 per 10
Newark part #16F6711
$2.30 each/$2.06 per 10-24
http://www.irf.com/product-info/data.../hfa08tb60.pdf

HFA15TB60 15A/600V
Digikey part #HFA15TB60-ND
$3.04 each/$2.13 per 10
Newark part#06F5976
$3.40 each/$3.06 per 10-24
http://www.irf.com/product-info/data.../hfa15tb60.pdf

HFA15PB60 15A/600V
Digikey part # HFA15PB60-ND
$2.36 each/$2.01 per 10
Newark part#16F6714
$4.53 each/$4.07 per 10-24
http://www.irf.com/product-info/data.../hfa15pb60.pdf

Circlotron at Diyaudio has also pointed out this link http://www.irf.com/technical-info/wh.../murdiodes.pdf for some good info on ultrafast/soft recovery specifics.

 

[BoyElroy]

Well, having just said that, I just got a response from Nelson Pass saying that he believes 50V Schottkys are "the absolute best".

 

[puppyslugg]

It was John Curl who suggested using Schotky's for low voltage apps. and hexfreds for high voltage. He felt the best diode for high voltages were the Fairchild Stealth diodes. Problem is, you can't get them small quanities. Minimum is 500 pieces.

 

[antness]

puppyslugg,

is it possible you can provide me with a part number for that diode?

 

[aos]

Similar effect can be achieved by bypassing a diode with a small capacitor (with maybe a series resistor). That will soften the spikes due to stored charge. I've seen this in some high end designs so I use it myself all the time. I do still use Schottky diodes if the rail voltage allows it. FRED diodes are TO-220 and take a lot of space, and cost a good deal of money. Some of them come in dual packages (i.e. TO-220 with two diodes in one package) and those are probably the best to use for bridge rectification.

 

[puppyslugg]

This one is rated for 4A@600v:

http://fairchildsemi.com/pf/IS/ISL9R460P2.html

There are others, up to 1200v. Check out Fairchild's site:
http://fairchildsemi.com/

 

[puppyslugg]

aos:

There is much discussion re: the use of snubbers over at audioasylum.

A veteran audio ee told me: "Absolutely not! Using a snubber creates a tank circuit and slows down the Schotttky's. Negating the benefit of using Schottkys."

Here's a link for calculating the value of the snubber components:

http://www.hagtech.com/pdf/snubber.pdf

 

[Possum]

I believe (I'm going from memory), during a search last year, I read from Nelson Pass' posts that he wasn't a fan of the ultra-fast/soft, HEXFRED, etc. diodes and preferred to use common rectifying diodes with capacitors as snubbers.

 

[puppyslugg]

Quote:

Originally posted by Possum I believe (I'm going from memory), during a search last year, I read from Nelson Pass' posts that he wasn't a fan of the ultra-fast/soft, HEXFRED, etc. diodes and preferred to use common rectifying diodes with capacitors as snubbers.

http://diyaudio.com/forums/showthrea...&threadid=8683

 

[Possum]

Ah, here's where I read it - an article by Nelson Pass about basic power supply design:

http://www.passlabs.com/pdf/powersupply.pdf

Under the section "Rectifiers."