Best SiC rectifiers?

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hukkfinn

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#1
What is the best-sounding SiC rectifier you have heard?

Not "bridge" rectifier - just, rectifier.

We tried some $1.06 Cree SiC rectifiers in our power supply and it sounded pretty bad -- weird treble problems -- not as good as our old trusty Hexfreds.

-Hukk
 
#2
Unexpected!

How odd! This is the last thing I would have expected, HF should be if anything cleaner than all other SS rectifiers, I was about to order two types for my first tryout with SICs. Sick SICs, I can't imagine what the problem might be.
RC 🙁
 
#4
Not sure what the suspicion is all about, but we used them in a power supply for a tubed home stereo preamplifier. The circuit calls for 4 of them, 2 prior to the power supply capacitors, and 2 after. The power supply is brand new and very unusual, however, the SiC rectifiers were performing typical AC to DC duty.

We used 1A Cree schottky rectifiers. Maybe the 1A was too low.

The preamp sounded bad, so we replaced them with Hexfreds and it went back to sounding good again, with no weird problems in the highs.

So, just wanted to see if others have had this problem -- maybe somebody would say "oh those cheap Cree's. . . no good . . . you have to get the ________ kind" ?
 
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#7
Rundmaus said:
if changing one type of SS rectifier against another and it makes your amp sound "really bad", there is something seriously wrong with that amplifier circuit. Or with your ears and your imagination.

Andreas
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Thanks for your reply. Your observation is incorrect in this case, as there is nothing wrong with the amplifier circuit, or my ears, etc.

Please note that I didn't say anything sounded "really bad," so I'm not sure what you're quoting there.

If you have used any SiC non-bridge rectifiers that sounded good, I would still appreciate knowing which ones they were. So far, the advice I have gotten led me to the 8A Infineons but I'm open to others as well.

Cheers,
Hukk
 
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#8
hukkfinn said:
We tried some $1.06 Cree SiC rectifiers in our power supply and it sounded pretty bad -- weird treble problems --
Click to expand...

I didn't know that the difference between 'really bad' and 'pretty bad' is so large. 🙄

And again, if the choice of rectifier changes the sound of your amplifier more than just marginally, there is something seriously wrong with that amp, or more probably, with its power supply.

Andreas
 
#9
It is the transformer rectifier combination that can ring. So just changing rectifiers can give quite interesting results. one turn off time may be very close to the resonance of the transformer and the other a bit away.

You might try adding an RC network across the transformer secondary.
 
#11
hukkfinn said:
We tried some $1.06 Cree SiC rectifiers in our power supply and it sounded pretty bad -- weird treble problems -- not as good as our old trusty Hexfreds.
Click to expand...



I've been saying this for years and every time there is a team of physicists and EEs screaming i am delusional. The SIC shottkys sound ok as forward biased dc references but definitely hate switching. Btw, there is a pronounced break-in period after which they seem to mellow down a bit.
 
#17
analog_sa said:
The SIC shottkys sound ok as forward biased dc references but definitely hate switching. Btw, there is a pronounced break-in period after which they seem to mellow down a bit.
Click to expand...

When components start 'hating' something and then 'mellow down a bit', I think it is time for me to leave this thread alone. I don't like the absence of logic and common sense.

Have fun!
 
#18
IMHO for a proper designed PSU of a linear power amplifier type of rectifier should be irrelevant either kenotron or vacuum diode or Schottky once it's supplies sufficient power. Caps, chokes, linear voltage regulation that would a be concern.

SiC delivers better power efficiency less heat dissipation in a PSU. However SiC diodes are costly yet so they fit better tube gear assembly budget.
 
#19
analog_sa said:
I've been saying this for years and every time there is a team of physicists and EEs screaming i am delusional. The SIC shottkys sound ok as forward biased dc references but definitely hate switching. Btw, there is a pronounced break-in period after which they seem to mellow down a bit.
Click to expand...

The day I replaced MUR860 with SiC diodes in my JFET amplifiers was a rememberable event.
The overall improvements in fidelity was above all expectations.

However I discovered that this first test for some reason was very optimal..

When I replaced MUR860 with SiC diodes in other units I discovered that a direct replacement was not always optimal and I needed to change / adapt the circuits / components before and after the SiCs.

If a BJT transistor are replaced with a SiC JFET in a circuit most individuals understand that this requires additional changes.

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...

So my experience are that the higher the impedances (transformer secondaries etc..) and the lower the capacitance values a circuit have - the larger the impact of the SiC diodes. And the larger the needed changes of the circuit.
 
#20
analog_sa said:
The SIC shottkys sound ok as forward biased dc references but definitely hate switching.
Click to expand...
I must disagree. I've used the Cree parts (and the equivalents from Infineon) in PFCs that switch around 100kHz and the switching waveform is textbook perfect without snubbers. Switching is where these diodes excel. But, this can mean high dV/dT and your layout should be up to the task.

analog_sa said:
... Btw, there is a pronounced break-in period after which they seem to mellow down a bit.
Click to expand...
You can get past that break-in period by using a green highlighter on the tabs. It works as well as it does for CDs. 😀
 
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