Giesberts IGBT amplifier Elektor 1995

[kibi]

Hi

I have decided to build some of these amplifiers. I last built them 13 years ago and liked them very much.
My question is, what LED's do you use? I don't have any more of the ones that I used originally and I want to order the correct ones.
Thanks

[Bigun]

I've no idea what this amplifier looks like, can you post some details, it sounds interesting.

LEDs - can't see that this is very critical. There are some tests somewhere showing noise levels for different brands and colours, but if anybody is brave enough to tell me they can hear a difference I'll consider buying them a beer

[wahab]

from this times, there s two schematics at elektor using IGBTs...
one use a complementary differential and the other one
is a current feedback amp..it seems that the former is
the 1995 model...

[wahab]

hope this will help..

[meanman1964]

There is a kind of update of this amp that uses the IRFP240 and the IRFP9240 mosfets instead the IGBT.I can send you the update if you want.With the update no more worries about oscillation-probs

[AMV8]

Meanman 1964
I built the original amp. I was not aware of an update using the IRFP mosfets. I would like a copy if possible so as I have lots of the IRFP mosfets and I would like to build the updated model to compare the sound. PLease either post here or send to my e mail address.
Don

[meanman1964]

Originally Posted by AMV8

Meanman 1964
I built the original amp. I was not aware of an update using the IRFP mosfets. I would like a copy if possible so as I have lots of the IRFP mosfets and I would like to build the updated model to compare the sound. PLease either post here or send to my e mail address.
Don

It isn't an update from elector but from someone who had probs with this amp caused by oscillations of the IGBT.Did you have those probs too?the schematic is called the Hexfet amplifier but it's from the IGBT version.All what's in orange is the update but look out the partnumbers on the updated schematic ain't number the same as the original IGBT schematic.

[BMW850]

Another one scheme , from Analog Devices.

http://www.analog.com/static/importe...17334AN211.pdf

[AMV8]

Thanks for the replies.
I have never had any problems with the original amplifier with IGBT's. It seems to work fine. My speaker loads are around 4 ohms and with little/no crossovers.
I also have a couple of Forte amps that use IGBT's and no problems from them either.
However I am interested in listening to the difference if the output devices are changed to IRFP devices. I would like to see if the IGBT's improve anything or make things worse or make no difference. The theory behind IGBT's seemed ok but I am not sure if they really work in practice. I will have a go over Christmas and let you know how it sounds.

Thanks
Don

[kibi]

Originally Posted by Bigun

I've no idea what this amplifier looks like, can you post some details, it sounds interesting.

LEDs - can't see that this is very critical. There are some tests somewhere showing noise levels for different brands and colours, but if anybody is brave enough to tell me they can hear a difference I'll consider buying them a beer

The LED's in question are thermally coupled to T5 and T6 in the circuit diagram that wahab attached earlier in this thread. They are supposed to have a 1.6V drop at 3mA. Trying to find an LED with those specifications is proving to be difficult for me.

Thanks