Best SiC rectifiers?

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A friend of me with valve amplifiers was using MUR860 diodes and I sent him a set of SiC diodes... He swapped all diodes from MUR860 to SiC and that resulted in a total disaster in fidelity...
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I am running EL84 SET as a computer multimedia on daily basis that is using using MUR860 rectifier. Yes MUR860 suits tube gear PSU as well as SiC since SiCs are high reverse voltage devices commonly.

However MUR860 has Vf =1.5V 1.2V while VS-90SQ045 delivers Vf=0.42V and 45V rectifier is well enough for let say LM3886 amp.

600V reverse voltage MUR860 has no sense for SS PSU
45V-60V-100V SCHOTTKY depending on B+ B- voltage would be cleverer approach.
 
I'm not so sure about using them in jfet amplifiers either - the forward voltage is high. These are only sensible as high voltage rectifiers

There are a number of reasons to use the SiC diodes.

And there are a huge range of different specified SiC diodes available with completely different forward voltages etc.. So it is just to pick the correct SiC for the circuit it will be used.. SiC diodes have a current range where the forward drop are close to constant over the full temperature range. This is one of selection criteria I use.

As I wrote previously it should be obvious that when you intend to replace a BJT transistor with a SiC JFET transistor that this requires additional circuit changes.
It should be just as obvious that if you intend to change the SiC JFET model that this also requires additional circuit changes.
And it should be just as obvious that both replacing a diode with a SiC diode and also replacing a SiC diode model may require circuit changes if the SiC diode are not selected because of its specifications fits the design...
 
Good outlined linear amp suppose linear voltage regulator implementation anyway so thermal stability of a rectifier at no concern.

As FoMoCo already mentioned on previous page SiC does suit switching PSU due to lower switching losses (that is hardly a real benefit at 50-60Hz) or ones may implement them if B+ is high as well (tube gear) at extra expense. Due to high Vout the Vf is not critical.

For a solid sate amp due to relatively low rectifier Vout lowest Vf Schottky make sense means no overkill reverse voltage rating as higher reverse voltage devices tend to have higher Vf or if Vf is the same they are pricier.
 
Thanks very much for your reply. This may explain why we are noticing this problem while others do not, as our power supply runs our tubed linestage preamplifier with < 0.5uF so the effect of the SiC's may be exaggerated.

-Hukk

You should use a SiC diode with the lowest possible current rating / highest possible forward voltage drop with the low current your circuit draws.

The diode impedance when conducting are together with the 0.5uF acting as a RC (or LC) filter. Actually you may also include the transformer secondary impedance into the equation. 0.5uF are a very small value....
I use a 100nF 630volt or 1200volt polypropylene capacitor (2000 V/uS slew rate or better) in parallel with the transformer secondary when using SiC diodes.
 
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You should use a SiC diode with the lowest possible current rating / highest possible forward voltage drop with the low current your circuit draws.

Interesting - so our plan of trying 8A instead of 1A will not be successful if what you say is correct. Well, I already ordered them from Mouser so I will still report back on the results. I looked for less than 1A but did not find.

Thanks again for your input.
 
Rectifiers do sound different. May be it is just because of build quality difference. So try to buy trusted brand from trusted supplier.

I have hundreds of power supply PCBs that I used to use to compare caps and rectifiers. Good sounding rectifiers tend to have good build quality. For example where the leg is round and yellowish (copper color), not silverish rectangular like most products today.

Switching is probably the biggest market for rectifiers. Not so surprising if many bad products float around in this highly competitive business.
 
Good sounding rectifiers tend to have good build quality. For example where the leg is round and yellowish (copper color), not silverish rectangular like most products today.
You have got to be kidding. Lead color influences sound?

Switching is probably the biggest market for rectifiers. Not so surprising if many bad products float around in this highly competitive business.
How exactly does a rectifier become bad because it is designed for switching? Rectifiers must switch to rectify!
 
You have got to be kidding. Lead color influences sound?

No, I was explaining how a well built rectifiers often look like. Or, how the good sounding rectifiers often look like.

How exactly does a rectifier become bad because it is designed for switching? Rectifiers must switch to rectify!

I live in a location where you can find many fake electronics products. Even fake products have grades (such as KW1, KW2, KW3, etc). I think, even original products have "grades", or at least, the ones produced in a plant in Japan may be different than the one produced in a plant in China.

I think rectifiers and power supply parts have high demand in electronics industry. The higher the demand, the higher the probability of people making the counterfeit product. Or, to provide less than sufficient quality product to target the "cheap" market segment.
 
Yes counterfeited parts are no good. BTW SS devices are made 99% from sand with very little amount of dopes so technology is the limiting factor not sands shortages.

The subject related issue however that when linear amp is on AC supply there are 100-120 times per second when receptacle delivers 0 voltage (means no energy is coming from receptacle) while linear amp might need to deliver a burst on energy at the moment for let say low octave note.

Basically proper designed linear amp should not "see" receptacle, power cord, fuse, diode bridge - the AC - at all (all they should be in working order and no counterfeited quality however).

It is possible to make a story when tweaking proper low Vf diodes with audiophile grade ones with high Vf (like MUR860) might decrease the room for linear voltage regulators that is true and that kind of tweak might make an amp sounds different.
 
why so much concentration on the 'huge differences' in different diodes, and not so much comment about the incorrect placement of them in the circuit. 2 before and 2 after the caps? either you are not reading the schematic or board layout correctly, or its an incompetent design. its mental...

SiC, just like GaN, still need to be applied properly and just dropping different diodes into the circuit without any regard to matching them to the application, is as bereft of common sense as rolling opamps without knowing the differences in operating conditions, maybe less.

schematic please, so we can see if the bridge should be thrown out and a new design added.

if your PSRR is so bad that changing one diode for another similarly specced diode brings big changes, then it needs more attention than changing diodes.

Sic Diodes do indeed switch very well, thats the point of them, they are often built to switch faster than required for non-switching/linear amps, but thats just a design factor that you need to keep in mind and lay your bridge out well on the PCB
 
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incorrect placement of them in the circuit.

either you are not reading the schematic or board layout correctly, or its an incompetent design. its mental...

Well I'm sorry to inspire a lack of faith, but I can assure you that our circuit is not incompetent. i am pretty sure my partner will not want me posting a schematic on the internet.

In the meantime I am still interested if you or anyone else has a favorite SiC rectifier. Thanks,

Hukk
 
Well I'm sorry to inspire a lack of faith, but I can assure you that our circuit is not incompetent.

Your report of sonic differences is a strong indication that it is.

Without a schematic, a parts recommendation for band-aiding a faulty circuit is totally useless. Different types of circuit faults have different requirements for repair. I'm afraid that you and your partner are on your own here.
 
Hi,

The only thing I am seeking is a discussion about your favorite kind of SiC rectifiers. I was not trying to show how we did our circuit. Sorry if it came across this way. I only mentioned the circuit design as a follow-up, because somebody complained that I had not given a description of anything.

I think if we could hear people's opinions on which SiC rectifier they think sounds best, it would be very helpful to all DIY'ers.

But, if it turns out that the consensus is "they all sound the same," that's also very helpful -- in that case, we can all just select the least expensive option and not worry that we are missing out on something.

Thanks,
Hukk
 
I DON'T believe that there are significant sound attributes of a SiC rectifier or any rectifier for that matter as long as layout, reverse recovery, etc. are taken into account.

People swear about Panasonic FC series capacitor sound after reading another's comment, the demand is artificial that it drives Digikey's pricing of this average cap higher. Same thing goes with the use of Schottky diodes for almost everything for some DIY when a 10nF capacitor across a standard recovery diode is sufficient to tame the buzz it creates all the way to the HF band.

If you are designing a commercial product and asking for technical help on this forum,.e.g. "best Sic rectifiers", "favorite volume control" but adamantly refuse to divulge design "secrets'. Go somewhere else!

One more thing, do yourself a favor and invest in test equipment, e.g. LCR meter, curve tracer, FFT analyzer, spectrum analyzer, etc. so you can actually measure capacitor dissipation factor, diode leakage, switching noise from diodes, etc. instead of buying random samples and trying them out with your ear.

Hi,

The only thing I am seeking is a discussion about your favorite kind of SiC rectifiers. I was not trying to show how we did our circuit. Sorry if it came across this way. I only mentioned the circuit design as a follow-up, because somebody complained that I had not given a description of anything.

I think if we could hear people's opinions on which SiC rectifier they think sounds best, it would be very helpful to all DIY'ers.

But, if it turns out that the consensus is "they all sound the same," that's also very helpful -- in that case, we can all just select the least expensive option and not worry that we are missing out on something.

Thanks,
Hukk
 
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