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Old 27th November 2012, 03:00 AM   #51
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Quote:
Originally Posted by Jon Lord View Post
Using an ordinary VMOS or a Power-J-FET
provokes Phase Intermodulation Distortion in the range of a microsecond or
so. Nobody would ever like to listen to digital Audio with a Jitter of 1us at
20kHz. PIM and Jitter have the same mechanisms behind of them and sound
very similar ...
Since there are examples of people who apparently like the sound of the
Zen, this doesn't make for a very strict argument against 1uS jitter.

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Old 27th November 2012, 04:23 AM   #52
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Quote:
Originally Posted by Jon Lord View Post
Btw.: I promoted the classic V-FET amplifier and the transistors for more than eight years (At times, when they weren't en vogue) on another forum, but only a few people believed me. Some also asked for a proof. My proof is that I listened to all commercially available classic V-FET amps and I drew my own independent conclusions ... I could even pretend that I listened to more different SIT amplifier designs than anybody else on this planet. Unfortunately this doesn't help to convince people, who didn't actually listen to any of these amplifiers.

Probably we need to wait until NP starts to promote LDMOS RF transistors in let's say five years (When perhaps the die attach solder of his SIT-1 transistors starts to get non RoHS compliant or the like), then the crowd of LDMOS believers will certainly grow but the number of people, who are looking into the future will still stay very small.
Guys, we do need advances in measurement approaches, that really correlate with sound perception. Otherwise, we cant proove anything to anybody, saying that it sounds good, except for a case, when GURU is saying something. But guru is not a god, he must not say absolute truth, he could have some hidden ideas behind his posts.

RD100HHF1 are not that expensive, around 30$, and I tested them at few designs. Jon Lord said: "Let me guess, the RD16HHF1-Version sounds more open, less blurry, much wider and deeper in sound stage etc., even when the 1 kHz THD is not (much) better ..."
That is also close to my impression. However, when an initial euphoria passes out, one could mention, that there are still differences at bass, depending on what kind of parts used at output stages.
With laterals, one can made Zout as low as 1mOhms, but bass perception can differ from that with bjt power transistors, and many will find the difference is not in favour of laterals. This is another puzzle of AUDIO, I can not explain it by measurements. In this respect, SITs are sitting somethere in between the laterals and bjts, but, there advantage, they provide an exceptional sound "purity" and easy to listen for long period, like NoGNFB designs.
To me, Ge BJTs are the best output transistors for proper bass reproduction, but, their specific properties (terrible thermal run away), that intuitively can help for proper bass, objectively look like a reason of "bad" thermal distortions.
SiC parts, except for applications at some specific schematics that need depletion mode parts, do not promise special benefits. I agree with Jon Lord, that LDMOS are generally superior to SiC parts.

Last edited by VladimirK; 27th November 2012 at 04:40 AM.
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Old 27th November 2012, 05:25 AM   #53
JZatopa is offline JZatopa  United States
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Quote:
Originally Posted by Jon Lord View Post
:The commercial SIT is dead: long live the V-FET !!!


How about LDMOS RF FETs like NXP BLF578XR ???

This 1000W-Transistor eats SiC-FETs and V-FETs for breakfast in Audio.
I would love to see someone make a stereo amp with these. I wonder how it would perform.
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Old 27th November 2012, 06:55 AM   #54
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Old 27th November 2012, 06:57 AM   #55
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Old 27th November 2012, 06:58 AM   #56
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is that yours? I contacted them about these some time ago, I would be interested to hear impressions on how they work/sound
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Old 27th November 2012, 07:21 AM   #57
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TranSiC was a Swedish company that supposedly developed an SiC bipolar transistor that had significant advantages over silicon transistors, though they never did so much as publish a data sheet to substantiate their claims. Fairchild acquired them (or their IP - they were small).
Given the difficulties in doing anything SiC-related, I won't hold my breath until I can buy some of their product with real money. People are still trying to figure out how to grow SiC wafers with low defect densities, and how to process the wafers once they have them. The 50 years or so experience with Si doesn't mean anything, as SiC is an entirely different ball game. Semisouth went under in part because they lost their process and couldn't get back to a decent product yield (that would have still been crappy compared to what is currently expected as a routine matter for Si). To add to the difficulty, the wafer sizes are much smaller with SiC (meaning that the "sweet spot" for high yield is proportionately much smaller, and the base material is much, much more expensive (at least 10X) than Si. I can't blame anyone in the SiC business for going slow and keeping their cards very close to their chests...
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Old 27th November 2012, 07:40 AM   #58
qusp is offline qusp  Australia
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they sent me datasheets back then when I asked, but I never got around to getting samples. I wasnt aware of semisouth losing their process, what exactly to you mean by that? they had to move fabs, or they sold the rights to the process they were using at MIT?

let me know if its still of any interest and i'll send you the datasheet. at least I think they did, i'll check. I have a folder with some files at the very least

yep I have one for BitSiC BT1212AC-P1

Last edited by qusp; 27th November 2012 at 07:44 AM.
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Old 4th December 2012, 07:01 PM   #59
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What about this? http://products.semelab-tt.com/pdf/f...L100M12MSF.pdf
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Old 4th December 2012, 07:09 PM   #60
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not bad.....!

the price too, at Mouser one around for 206 ....
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