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Old 31st March 2005, 11:54 PM   #1
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Default SiC Schotkys rectifiers .

Just for telling you that , after 6 years of GZ37 and GZ34 i decided to try SiC Schottkys , two 600v in series . I will keep them for the superior high frequency performance , and clean sound .
Of course i have a BG WKZ 2x100uf 500v as reservoir .
Who else had tried them in valve systems ?

Peace to all

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Old 1st April 2005, 02:15 AM   #2
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Silicon rectifiers in Valve amps will almost kill the valves by COLD CAThODe EMMISSION..unless some delay circuit is used in the HV DC supply..about 1 to 2 minute delay is required..until the filaments heat up well...
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Old 1st April 2005, 07:36 AM   #3
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Quote:
Originally posted by sivan_and
Silicon rectifiers in Valve amps will almost kill the valves by COLD CAThODe EMMISSION..
OMG! These diodes will increase your supply voltage fifty-fold?! I need some for HV experiments then! Wow!

Quote:
unless some delay circuit is used in the HV DC supply..about 1 to 2 minute delay is required..until the filaments heat up well...
Also obviously false, since tube rectifiers heat up in four seconds...LOL

Tim
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Old 1st April 2005, 10:31 AM   #4
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Default SiC Schottkys rectifiers

I know an Audionote power that has silicon too , i m not seeing them unavoiding the problem . In the long term i believe the valve can have his life shortened . But in this case , the superior sound , worths the little damage .
The B+ was 364v , now 429v , not a problem for me , i m using
TT22 ( KT88 equiv. ) which can hold 1000v i think , all HT caps are 450v Audience brand . I bought them in USA from Tubebuilder .
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Old 1st April 2005, 11:13 AM   #5
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Quote:
the superior sound

Would you say the sound is superior in every way? I generally hate tubes and only put up with them because of the sound. Rectifier tubes i hate even more - extra transformers, heat, mercury... But so far nothing has offered comparable sound.

If the SiCs are even close to mercury they will be worth their value in gold. Where can one get these wonders?
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Old 1st April 2005, 11:45 AM   #6
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silicon carbide rectifiers... this is the state of the art rectification today... do you use the adjustable ixys bridge (5pin), that allows adjustment of the settling time?... they re expensive though...
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Old 1st April 2005, 02:04 PM   #7
MelB is offline MelB  Canada
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I'm looking at digi-key part # SDT04S60IN @www.digikey.com about $4 each Data: http://rocky.digikey.com/WebLib/Infi...P_D_T04S60.pdf are these the ones you mean?
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Old 2nd April 2005, 12:14 AM   #8
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These are Infineon ( Siemens) , and they are similar .
I tried other silicon but always seemed to me hearing some harsh
in the vocals . What i find superb , the SiCS deliver incredible highs without dryness . I have fited them in the Audionote PS2 amp too instead of 1N400X diodes , and his owner was delighted .
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Old 2nd April 2005, 12:38 AM   #9
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ALL PN junction diodes exhibit a reverse recovery spike (switching noise). Schottky diodes don't exhibit the switching noise. Until the relatively recent introduction of Silicon Carbide (SiC) parts, Schottky diodes were unusable in B+ PSUs due to PIV limitations. So, the switching noise problem with SS rectification has been solved.

As was pointed out in a previous post, directly heated vacuum rectifiers turn on very quickly. Only vacuum rectifiers with cathode sleeves turn on slowly. A simple way to slow the B+ rise down when SS diodes are employed is to use negative temperature coefficient (NTC) thermistors. Jim McShane installed NTC inrush current limiters in my H/K Cit. 2 when he overhauled it. The thermistors get the job done. No more bangs come out of the power trafo at turn on. While the thermistors only provide a few seconds delay, that's enough for the bias supply to charge up and protect the "finals" from cathode stripping.

FWIW, the "book" on Schottky diodes is that they should not be stacked. However, a Schottky diode and a FAST PN junction diode can be stacked. The combination works well. The Schottky diode blocks PN switching noise and the junction diode protects the Schottky from overvoltage. Thanks go to AA "inmate" Volt Second for the stacking synergy concept.
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Old 28th June 2005, 09:36 PM   #10
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Quote:
Originally posted by Eli Duttman
FWIW, the "book" on Schottky diodes is that they should not be stacked. However, a Schottky diode and a FAST PN junction diode can be stacked. The combination works well. The Schottky diode blocks PN switching noise and the junction diode protects the Schottky from overvoltage. Thanks go to AA "inmate" Volt Second for the stacking synergy concept.
I think I want to use this in the amp I am currently building. Can someone recommend a junction diode to use with the Infineon SiC diodes? Or, anything wrong with a MURxxxx?

And the junction diode is on the secondary side and the Schottky on the filter cap side, right?
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