IXYS depletion MOSFETs: What are they good for? - Page 2

wrenchone · 28th October 2009, 02:56 AM

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.

Nelson Pass · 28th October 2009, 04:13 AM

I think Hiraga did one of those...

wrenchone · 28th October 2009, 05:15 AM

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.

flg · 28th October 2009, 10:23 AM

I suppose the lowish idle current you would want for the typical transformer might contradict the highish idle current you would want for the MOSFET to be in a linear area? Unless maybe a para-feed type topology were used

Ejam · 28th October 2009, 11:25 AM

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

Ejam · 28th October 2009, 11:34 AM

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

jan.didden · 28th October 2009, 12:22 PM

Quote:

Originally Posted by Ejam

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

Zen Mod · 01:10 PM

janneman - have you any info about these xformers ?

winding ratio etc ?

edit : I forgot that in original schematic is written 64:8 ohms

any other info , besides that ?

Gordy · 28th October 2009, 01:03 PM

Quote:

Originally Posted by Nelson Pass

I think Hiraga did one of those...

This one perhaps...

" Schematic by Jean Hiraga published in "L'Audiophile" named Némésis. "

2SK135 SE Amp

tubesguy · 28th October 2009, 01:24 PM

Zeus.

28th October 2009, 10:23 AM	#14
flg diyAudio Member Join Date: Jul 2005 Location: North East	I suppose the lowish idle current you would want for the typical transformer might contradict the highish idle current you would want for the MOSFET to be in a linear area? Unless maybe a para-feed type topology were used __________________ “Be who you are and say what you feel because those who mind don't matter and those who matter don't mind.” Dr. Seuss

28th October 2009, 11:25 AM	#15
Ejam diyAudio Member Join Date: Aug 2004 Location: Queensland	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

28th October 2009, 11:34 AM	#16
Ejam diyAudio Member Join Date: Aug 2004 Location: Queensland	Wrong Spelling 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

28th October 2009, 12:42 PM	#18
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	janneman - have you any info about these xformers ? winding ratio etc ? edit : I forgot that in original schematic is written 64:8 ohms any other info , besides that ? __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb Last edited by Zen Mod; 28th October 2009 at 01:10 PM.

28th October 2009, 01:24 PM	#20
tubesguy diyAudio Member Join Date: May 2002 Location: Madison, WI	Zeus. __________________ www.buyoutdickvitale.com: Pledge money to enable ESPN to get Dickie V off the air


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28th October 2009, 02:56 AM	#11
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	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.

28th October 2009, 04:13 AM	#12
Nelson Pass The one and only Join Date: Mar 2001	I think Hiraga did one of those...

28th October 2009, 05:15 AM	#13
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	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.

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