IXYS depletion MOSFETs: What are they good for?

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O.K. I think we've all seen the Depletion Mode MOSFET Zen Lite variant displayed by N.P. at BA'09. Personally, I did not know that part existed? But, it appears to have some quite conveniant qualities:
Suitable Voltage rating, Current rating, self biasing like the LU1014D, "Idss" of about 2.5A, Rthjc .31 C/W, plenty of S.O.A., fairly linear C in our typical operating range, and by all accounts so far, fairly linear and good sounding. Oh yea, affordable price in small enough orders. Did I miss something?
I'm not so interested in another Zen Lite but as I've seen recently, I'm not the only one interested in creating a monster B1 circuit. I was thinking of paralelled LU1014Ds with car battery rails. This device can take that idea further and easier as Paul Hynes did a few years ago (someone posted an AudioCircle link around here somewhere). I've also played with the Circlotron circuit quite a bit and it's very nice but, with self biasing and ground refrenced input as Paul Hynes has already done also wow :)
Personally, I can't wait to play with this part. There is a GB thread started to research the interest in obtaining some.
So, I thought I'ld get us all started on a discussion for everyone's benifit. Oh, yea, another great quality, N.P. seems to like this part too...
Any other comments? questions? previous experiance? Ideas?
 

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I don't mean to misslead anyone or anyhing but first I must say this: I've done some data sheet tests myself, mostly because my Boss always responds to my reasoning gathered from datasheets with "Data Sheets Lie".
Having said that, I realized recently that I have 2 copies of the datasheet for this device. One of them from 2006??? And the other is current on the IXYS website(2009). I may not have been thoughtfull enough with looking at them? or posting accurately.
I have one other peice of info I was going by. The Link I posted refrencing Paul Hynes work states that in his application, at his temps etc. he see's about 2.5A.
All in all, I think it's a very interesting part and I would not even know about it's existance without The One And Only sharing with us. Thanks Nelson.
 
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Let us know when you figure out the name... The use of a depletion mode FET simplifies the design and makes it more tube-like in concept, if not in sound. I prefer to view the Ixys depletion mode fets as pentodes without heaters and extra annoying pins. Treating them as such may prove to be interesting.
 
I nosed around a bit in the forums devoted to Hiraga's works, and haven't seen mention of a transformer coupled amp yet (not that that means a whole lot). The concept is so obvious, I can't believe no one's done it before. The addition of a deplection mode output device adds a touch of innovation, but not a whole lot, Anyway, it's an excuse to dust off the pair of One Electron UBT-1s that have been gathering dust, because this application is made to order for them.
 
Hiraga Amp

Hiraga's SE Mosfet amp (called the Nemisis) from memory used a Hitachi lateral mosfet (2SK135) and an output transformer (64 ohm primary winding). The mosfet had 1A of current running through it. So I think the UBT-1 would be well cooked, even fried. Also if you check Bonavolt's website you should find a circuit of the Nemisis there. Hope this helps.

Regards

Ejam
 
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Sorry, got the spelling wrong, it should be "Nemesis". Jan Didden at Linear Audio has a few words about rebuilding one of these amps. Try http://www.linearaudio.nl/nemesis-1.htm

The original output transformer is no longer available, but I have a prototype from another manufacturer on order. As soon as I get it, I will test it in the original Nemesis and with one of these depletion mode MOSFETs. I'll keep you guys posted.

I am currently using the ECF10N16 from Exicon, but the new device should make the circuit even simpler. Maybe even beat Nelson at his own game ;)

jd
 
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