IGBTs

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#3
Hello!

There are many valid reasons for NOT using IGBT in audio amplifiers. A IGBT is a MOSFET and a bipolar device etched on the same substrate. One of the more obvious drwabacks are the fact that you can NOT bias them independently.
Other probelms include matching probelms and so on........

There is however one reason for using them: novelty😀 😀

best regards😎
 
#5
"im interested in building a class d sub wif dem since dey are cheap"

Go for it. IGBTs are of little worth for a linear amplifier due to poor seconday breakdown specs, they are designed for low speed switching.

Apex builds some switching amplifiers with IGBTs that do 5~10KW that are suitable for subwoofer use (20Khz clock). The SA18 is $181.55, not bad for 10KW!

Apex also builds some hi-fi designs with FETs and 250Khz clock

http://www.theriver.com/apexmicrotech/products/pages/pwm_amps/sa18.html
 
#8
"the main question is still not answered?

can in interchange IGBTs with mosfets for the power stages?"

Yes, you can build an amplifier with IGBTs.

You can also put a saddle on a zebra and ride him to work too!

You are obsessed with IGBTs. They cost more than MOSFETs, are slower, and have no SOA.

The only valid use for IGBTs is high voltage, low frequency switching.
 
#9
If you want to use IGBT's then do it! You don't need the approval of people who say it won't work. If it turns out that it doesn't work as well as you hoped you will have gained useful experience and understanding. You will be able to speak with confidence and authority about this. Anyway, there are some pretty fast IGBT's like for instance Warp Speed ones available nowadays. AFAIK the SOAR is fet-like or thereabouts, not yucky bipolar-like. I have a pair of 600v 60amp 540w TO-247 yummies that I will try I my class A someday.

Go for it hacknet! Try it and see. If you like IGBT's that much, then psychology being what it is, provided it isn't downright rotten, you will probably enjoy the sound even more once you have these jiggers installed.
 
#11
i would very much like to run down to the store to buy a tray of IGBTs to fit around but i do not have the cash..


for some reason here in singapore... RS sells IGBTs at unbelieveably low prices...

like 1 pcs for $3... 600v 18amps....
190w....

so i thought why not use IGBTs instead of MOSFETS dat cost $12 each....

i was looking at the 17w mosfet amp at elliots sound...

could i use a igbt inplace of the mosfet?
 
#12
If you want to use IGBTs then check if you can find the project in Elektor which used them. They had a project called "IGBT Amplifier" could be 1992-1995 somewhere. Contact them for a copy. http://www.elektor-electronics.co.uk

Try for the Elektor amplifier:

http://steve.sky.net.ua/Audio/semi/IGBT/igbt.htm

http://www.audiocircuit.com/9121-solidsamplifier-circuit/Diy/Projects/Giesberts-TG/9121DPTG.htm

Nueva Electronica had one for 20 W Class A in 1998 I think.

I am not sure but it may also be that the Titan 2000 by Elektor used IGBT. That wopuld be in the 1999 magazines I think.

/UrSv
 
#13
"AFAIK the SOAR is fet-like or thereabouts, not yucky bipolar-like. I have a pair of 600v 60amp 540w TO-247 yummies that I will try I my class A someday. "

There is not one piece of data published on the forward biased safe area of these large IGBTs.

http://www.irf.com/product-info/datasheets/data/irg4pc60f.pdf

That is because they are not designed for linear use. The SOA is just like that of a BJT switching transistor, NONEXISTENT !!!

How nonexistent is nonexistent? I have some 50A continuous, 100A peak, 150V, 250W 30Mhz "designed for use in industrial-millitary power amplifier and switching circuit applications".

They can switch 15,000W (100A @ 150V).

Forward biased at 100V what do you think they will do?

At 25*C they will do 10W (JEDEC registered data for the 2N6277)

If they get hotter than that you have to derate them.

The trade-offs made for speed and low saturation voltage in BJTs cause the forward biased secondary breakdown voltage to be in the 10V range. An IGBT is essentially a small MOSFET driving a big BJT. It has less gate capacitance than a big MOSFET and less voltage drop at high voltages because of the BJT.
 
#14
are there any high eff. igbt amps?

like abt 70% eff....

it wud be nice if it was abt 100w rms...

i intend it to be a monoblock for a sub...

so quality doent matter..

linear or not... i cant really bother cuz cost is the main concern...

i cant affort krell standards and will do with the cheaps alternative.....

simplicity iz another issue....

i heard of class d amps but they are a hell of a difficult to put together....
 
#16
Has anyone here tried the IGBT pair from Toshiba meant for Audio use; they are GT20D101 and GT20D201.

By the way, it is slower IGBTs that are good for audio work, not the fast ones, according to an editorial in Elektor.

Elektor has published two different amplifiers using the above mentioned IGBTs. One is an upgraded version of an earlier HEXFET 63w 8ohm/105w 4ohm amp. The IGBT version delivers 90w 8ohm and 146w 4ohm power.

The other design was called "A Compact Amplifier" that uses current feedback, rather than voltage feedback. It puts out about 50w 8ohm/ 85w 4ohm and is to date probably the best amplifier that Elektor has published. The Titan amp from Elektor is much based on the same topology as the Compact Amp but uses BJTs.

Hope that helps and encourages you to give it a try. The IGBTs sold by RS may not be useful in this regard.
 
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