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SoundsGreat 5th September 2008 09:14 AM

Any Idea or help with this Amp ??

I was doing some research and came across this circuit for a IGBT based amp !

I thought to post it here and ask for some suggestions and opinions !! Am planning to build a 100 -150 W (4/8 R) and need some suggestions !!

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 !

Also after discussing a bit on the amp's sound with Quasi (in his thread) I've now made to believe that Bi-Polor sounds better then Mosfet ! So this also the reason for me to select this !

This is a old elektor design and seems to be very very good since its by the famous Tony Giesberts.

So guys please share your thoughts on this !!

This circuit was on a public domain and was not having any copyright or any warning as to its reproduction

So please let me know if I've violated any rules that Am not aware of ! I don't want to repeat the same thing thats being scrutinised by mods in other threads !!

[SIZE=3]Again the Circuit design and etc is,if copyrighted then belong to the them and full credit goes to them ![SIZE=3]

I have no way of contacting them as the site in this page thats linked to the main (or atleast what I think is main) leads to a German or Dutch lang site, which I have no idea and no means to communicate to ask the permission ! So inspite all my explanations if someone has a problem I cannot help it !!

Hoping to see some responses soon !

unclejed613 5th September 2008 11:20 AM

you probably don't need high current drivers as shown here. IGBT's have similar gate drive requirements as MOSFETs. looks like a bipolar design adapted to IGBTs without any changes.

Markus2006 5th September 2008 11:41 AM

This is amp from Elektor magazine (I think from 1997). Some people succeeded building it but many have not. It was discussed many times on this (and many other) forums.


SoundsGreat 5th September 2008 05:04 PM

Well !

Thanks for replying !!

Yes I said so myself its elektor ! but I searched the forum could not get a info on this !!

Could you be kind enough to post the links ?? also any other similar amps that I can build with the said parameters ??

Thanks again !!


Mooly 5th September 2008 05:29 PM

Are you determined to use IGBT's. They are peculiar devices, never seen much on them applicable to audio. They are a bit like a high voltage BJT but like a MOSFET to drive. The gate/base resistor is needed for stability just like a MOSFET but it also determines the "short circuit" current of the device.
They were more for switching applications really, audio wise you can do much better I think.

SoundsGreat 5th September 2008 06:45 PM

Noway !

Mooly thanks for the reply ! But I think I've mentioned the reason for choosing this design ! May it has gone without your notice !;) !

So anyway no worries, I have no fixation to use these devices ! and absolutely does not want to use something which will not serve the purpose !

So again here's why I chose this !

1.Simple to build (both in terms of circuit design and implementation on the PCB)
2.Small PCB (which most essential as this is a second amp !! the main is as already said Quasi's Nmos Bi-Polor which I've already started to build !)
3.Had the protection circuit which is again a must !
4.As I've learnt in the past days of exchanging idea's on the quasi's thread,The Bi-Polor tends to be better for sound quality then Mos
5.Last but most certainly not the least the cost !!

So based on the above points and also based on the previous posts, I request you and others to recommend a suitable amp !!

Thanks a lot again !


Mooly 6th September 2008 06:46 AM

Looked at your profile :) If audio is your life, and do you mean music by that as well -- the two are not always perhaps the same -- I have to say try something like my MOSFET amp, which you have probably seen on this forum.
It does use Lateral FET's ( would that alone rule it out ? ).
It is small, it's very stable, I would say it's easy to build -- no oddball parts, but it does sound amazing, better than any commercial amp I have heard.
I use it with a Micromega Stage 2 CD player and B&W 703's and for sheer musicallity nothing I have heard has come close.
Adding DC protection and a delay is easy and essential really on any DC coupled design.
Regards Karl

Have a read at post #107

Markus2006 6th September 2008 07:06 AM

Instead of providing links I suggest to search in Google for the following phrase: "giesberts amp". Giesberts is the name of the author of the amp. You may also look for "Elektor amp" but this one will return much more results (also for many other amps published in Elektor).


lineup 6th September 2008 07:12 AM



Also have a look at
this latest update of
Mooly's MOSFET Amp for MUSIC!!!



Lumba Ogir 6th September 2008 08:57 AM


Any Idea or help with this Amp ??
Forget about it. (Go for the Mooly amp).

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