L’Amp: A Simple SIT Amp: Part Deux - Page 2

14th December 2011, 11:57 AM
Michael Rothacher AudioMaker.Tech diyAudio Member Join Date: May 2001	L’Amp: A Simple SIT Amp: Part Deux Introduction In the first L’Amp article, we built-up a simple Class A amplifier using a not-quite-unobtainable Static Induction Transistor. It’s a nice amp but doesn’t have a lot of power or voltage gain. In this little vignette, we’ll examine a simple option for improvement. An... Click here to read the entire article Last edited by Michael Rothacher; 17th October 2013 at 11:53 AM.

8th February 2012

putko

diyAudio Member

Hi

Michael Rothacher mentions in L'Amp CCS Addendum that

"So, I tried (D). It uses a self-biased IXYS depletion mode MOSFET
IXTH6N50D2. "

That beast is not easily available (at least in Finland). Could somebody say, is there anything special in IXTH6N50D2 (irreplaceable), or can it be replaced with some other bug (I understand semiconductors but cannot evaluate them)

Best wishes HPu

8th February 2012

putko

diyAudio Member

Hi

Michael mentions in "L'Amp CCS Addendum" that "So, I tried (D). It uses a self-biased IXYS depletion mode MOSFET IXTH6N50D2. "

The IXTH6N50D in almost impossible to buy. Is there some other bug that does its work

Best wishes HPu

7th December 2012

Garuda77

diyAudio Member

Hi,

Could anyone suggest the correct/minimum size/value for the CSS heatsink please? also @ putko found this:

IXTH6N50D2 IXYS | IXTH6N50D2-ND | DigiKey

not sure if they ship to you though?

Thanks Terry

7th December 2012

putko

diyAudio Member

Hi All

I just want add this fact to IXYS and Europe. I found out that they have an importer in Swizerland. When I asked them how to get one pair of IXTH6N50D2.

They said it's ok. Minimum ordes is around €200. When I explained the story (I would like do some testing for myself)m, they organized the thing that I could purchase one pair with normal sneding costs. This was well below €200.

So all kudos (praise!) to this company's representatives in Europe.

best wishes HPU
PS
This is meant to be helpful, if somebody else is in the same situation, when I was.

PPS
For various reasons I have not had oppoturnity to build the thing.

25th April 2014

johnyradio

diyAudio Member

hi Michael, can your addendum version run on batteries?

thx

1st November 2016

Aboulafia

diyAudio Member

Hi,
A similar idea of one transistor amp was presented in the french "revue du son" some years ago. The active part was a more common 2SK135 (which has pentode like curves) with drain to grid feedback, that made it behave like a triode. Different circuits were built using this method, some based on the NEMESIS amp.
This very simple topology is well suited to high impedance headphones for instance.

13th April 2017

triode_al

diyAudio Member

Michael,
you mention a hefty bump possibility when turning on off. Is that due to the inductance?
How about a diode across the choke (inverse)? This is done with solenoids. == or one in series. So no energy goes to the power supply. I have seen this in tube amps. Only for the turn-off bump, to prevent Tesla's energy spike from developing.

just a few ¢.
I have a pair of TO-3 SITs and I am sitting on them. And I have huge 110 mH multitapped chokes.

SPU --> tube MM/RIAA; Kaneda pre; 300B SE driven by ECC35; Open Baffle PM2A, 2A9

13th April 2017

Michael Rothacher

AudioMaker.Tech

diyAudio Member

I said doesn't have a significant turn-on thump. Have fun

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13th April 2017

triode_al

diyAudio Member

Michael,
In fact this is what triggered me:

Quote:

NOTE: The author suggests that you should always have a speaker or dummy load connected when powering the amp on and off.

I shouldn't mess around with designs. albert

SPU --> tube MM/RIAA; Kaneda pre; 300B SE driven by ECC35; Open Baffle PM2A, 2A9

13th April 2017

Michael Rothacher

AudioMaker.Tech

diyAudio Member

Nothing to do with bump. I was addressing the accidental omission of a bleeder resistor in the drawing. Here's the entire quote:

NOTE: The author suggests that you should always have a speaker or dummy load connected when powering the amp on and off. Furthermore, you may wish to install a 200 Ohm, 3 Watt bleeder resistor from output to ground to safely discharge the coupling capacitor in case you should forget the foregoing.

I don't think your music would appreciate the diode. Have fun

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