[aos]

As usual, different pros have different opinions

. The point to make here is, though, we don't care about slowing down of the diode - which capacitor would certainly do to a Schottky - all we care IN THIS APPLICATION is to minimize (high frequency) noise since integrated voltage regulators are unable to regulate at more than couple of MHz. It's possible that snubber is useful only on regular diodes, while Schottky and FRED types don't need them. Obviously a snubber won't turn a standard diode into Schottky as a general rule, but it might achieve the same desired effect in a rectifier bridge application.

 

[ppl]

An instructive test of just how low of noise your rectifier is is to get an AM pocket radio battery operated. Turn to a point of no station and place the receiver in and around the rectifiers and hear how much garbage is coming through and trust me you will hear it. The softer the noise the better the Rectifier is. aos also has a point all radios use a cap across the rectifiers to suppress noise. The MUR diodes in the above pdf were originally Motorola Fast recovery types. Remember all those fancy fast recovery diodes are intended to be used at switching frequencies way higher than the nominal 50 or 60 Hz they are going to be used at in the above application.

Another bit of info mark levinson uses 1N4936 in low power apps this is a standard soft recovery Diode. They also use 35MB40A for High Current Bridge rectifier apps this is a 400 PIV 35 Amp Bridge. Oh yes ML also bypasses the secondary of the Power transformer from center tap to each side with 0.1uF/500 Volt Film caps designed for across the line use. Since the Big Electrolytes are on the output of the Rectifiers no additional caps are used. This is good engineering and is standard practice in almost all quality Equipment.

Dose the Type of diode make a difference and dose snubbers matter, ya they do but you should concentrate on verifiable measurable solutions rather than voodoo or snake oil propagated by people that most likely have no idea of what they are doing or are governed by there own personal Bias.

Now for My personal Bias on Rectifiers. I use the Base and collector junctions of PNP/NPN Bipolar Power transistors as rectifiers without any snubber caps. I thought the caps degraded the sound. Besides would not this method continue Kevin’s Complimentary topology all the way to the Power supply? I must admit i was heavily medicated at the time I listened to this vs. the standard 1N4000 & 1N5400 series

 

[BoyElroy]

Here are a couple of pics. from the diyaudio thread comparing the waveforms from a Schottky psu and "standard" psu:

Quote:

Difference between normal and schottky bridge rectifier:

Normal Rectifier

Schottky Rectifier

 

[morsel]

Surprisingly dramatic, but I wonder if those were measured under load.

 

[ppl]

somthing is wrong with those two photos. the upper one is a clear high res image that is showing less than a complete cycle. the Bottom one is a low res blury image showing about 1.5 cycles. now i am sure the person that posted this image was just not being accurate enough and also left out critical info like what time base the measurements were taken. still it is these inconsistencies that make me qusetion the validity of the comparrison since the raggeg edje could have easaly been obsured in the lower different time base image.

If this were photos of a U.F.O. the debunkers would be all over it. I would also like to mention that i am not questioning wether one type of rectifier is going to perform better than another in any given application I am just sugesting to test for yourself and see if you can hear and or measure the difference. Afterall that is not only part of the Fun of DIY but you gain personal insight into the how and why of Circuit design and thus you will not have to just rely on what someone elce sed to prove your ideas. I recomend that you take peoples sugestions Including Mine as a start to allow you to futher your own investigation of the subject. in that way You will Know for sure what the real Deal is.

 

[ppl]

many thanks to our long Time head-Fier and the Person who posted a list of Links at the top of the DIY fourm (ricker) I present this artical on Wonder Diodes that tends to agree with what i sed above but Is more inline to what Morsel points out It Dosen't matter http://www.zero-distortion.com/techn...owersup_04.htm

 

[Tomo]

Hey,

Make sure read some about different FREDs at AudioDIY as Possum suggests. Appearently, not all FRED are good.

IXYS FREDs, I hear, is actually pretty bad. They say HEXFRED and that should never be mixed. (Doh! for me because my four FREDs are from IXYS. So much for that!)

I use normal rectifier bridges. I get freaky and use something rated like 10~20A because I like to install lotta caps. (I think I got fetsh for bolting stuffs onto chasis like FETs and Bridges.

)

Cheers,

T

P.S. I am supposed to know about Schottky diodes, but I am not sure why it is "low" noise. I do understand why it's faster. ... (Induge me, please?)

 

[wallijonn]

thanks guys. i'm learning a lot.

can a MUR801 replace a regular iN10001 to 1N1004, if it is not being used as a bridge rectifier?

 

[Stager]

re:
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."

update- article moved to: https://www.passdiy.com/project/articles/power-supplies

 

[Nisbeth]

You're resurrecting a thread that's more than six years old - that has got to be some kind of record!

/U.