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Old 6th September 2008, 11:40 AM   #11
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obviously, somebody designed and built it, so it must work. my question about it is whether the output devices have a problem with gain droop like bipolars do. these IGBTs in particular are designed as fast switching devices, so not a lot of thought was given to making them particularly linear.
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Old 6th September 2008, 12:10 PM   #12
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I believe you will have great trouble sourcing those output transistors.

And if you want an amp with bipolar transistors why don't build one with bipolar transistors instead of IGBTs? IGBT characteristics are more like MOSFETs than BJTs.
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Old 6th September 2008, 12:18 PM   #13
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I built this amp maybe 10 years back, and Im afraid to say that it has some goblins. Difficult to stabilise but it works fine once done. As for the sound, its good, there is something that sounds very right using IGBTs and its mabey its speed. Anyway i compensated it rather with small miller around the vas and some phase lead which turned it into a much better sounding amp.
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Old 6th September 2008, 06:22 PM   #14
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homemodder,
maybe your taste was modestly refined those days...
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Old 6th September 2008, 06:54 PM   #15
lineup is offline lineup  Sweden
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Quote:
Originally posted by Lumba Ogir
homemodder,
maybe your taste was modestly refined those days...
think homemodder has good taste
= similar taste as mine
for audio amplifiers
... at least i have encountered you, homemodder
in several topics already, so maybe we are interested in partly same stuff



regading use of IGBT, Insulated Gate Bipolar Transistors
i once asked Nelson Pass about those IGBT
if he would use them


his answer was:
>>>> they can be used for audio
but will not outperform neither MOSFET or BIPOLARS
... and what I can see, Nelson Pass has not published any IGBT Amp


The idea of IGBT
is to have the easy drive (lower current) of MOSFET
and at same time have low saturation voltage (voltage drop out across C-E at high current)
of bipolar power transistors

now, there are not many types of IGBT devices easily available for ordinary customers
as been pointed to in this topic already
this type of transistors has not been often used for audio
most probably because of the fact:

> there has not been any such made targetted for Audio use
> mainly, like for IRF HEXFET,
> IGBT has been made for high Current fast Switching purposes

... like for SMPS, Switching Mode Power Supply
here is where we can preferably use them
= lower power losses
= higher efficiency
<<<<<< LINEUP AUDIO LAB - not any smps circuits >>>>>>
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Old 6th September 2008, 11:36 PM   #16
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Those Toshiba IGBTs were actually made for audio. I haven't seen any other P-channel IGBTs ever.

AFAIK they are not made any longer, and you will probably find them almost impossible to find.
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Old 7th September 2008, 06:40 AM   #17
Mooly is offline Mooly  United Kingdom
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John Linsley Hood I believe did some consultancy work on behalf of Toshiba regarding IGBT's for audio about 15 years ago. There is a Toshiba application note floating around somewhere - can't remember the number.
I think the fact we have never seen them in any designs say's it all really.
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Old 16th October 2009, 02:29 AM   #18
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by SoundsGreat View Post
Hi,

I was doing some research and came across this circuit for a IGBT based amp !
It sounds from the responses so far that there isn't going to be much help available since this device is unusual and unpopular. If you really want to try it out then I would encourage you to go and try it by building a simple amplifier on a test board. You could check out the Zen amplifier by Nelson Pass and modify it to use a single IGBT in the output.

IF you can't find any IGBTs you could fake your own device by using a small signal MOSFET to drive a power Bipolar in a complimentary feedback pair (CFP) arrangement - also called sziklai arrangement.

If you built a Zen amplifier like this you would replace the lower output FET with the CFP. The input would drive the gate of the small signal FET, it's source would go to ground and the drain would connect to the base of the power BJT. The collector of the BJT would also go to ground and it's emitter to the constant current source / output. You would connect a resistor from the emitter of the BJT to the drain of the small signal FET - not sure what value would be best as it depends on the devices you choose.

You will learn a lot and possibly find yourself addicted to amplifier building !
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Old 30th October 2009, 07:30 AM   #19
radio is offline radio  Macedonia
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Exclamation PCB for DX HRII Audio Amplifier!?

Hello!
I need a PCB for audio amplifiers Dx HRII. If someone is made shall be placed on this web site!
Thank you in advance!

Last edited by radio; 30th October 2009 at 07:40 AM.
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Old 30th October 2009, 07:36 AM   #20
radio is offline radio  Macedonia
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Red face PCB for DX HRII Audio Amplifier!?

I have already started Quasi's Nmos Bi-Polor version ! and want to build this as a second amp ! have looked at his Nmos200 (still in the series consideration ),but it does not have a protection circuit added (DC detect or whatever you want to call it),so are most of others like Sysmasysm,DX HRII,ST151 etc etc !

Hello!
I need a PCB for audio amplifiers Dx HRII. If someone is made shall be placed on this web site!
Thank you in advance!

Last edited by radio; 30th October 2009 at 07:39 AM.
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