holton AV400 help..??

PROFESSOUR2003 · 2nd January 2011, 02:48 PM

Hi guys,

i an currently building holton AV400 amp. with 2x50 v 1KVA transformer
my question is can i use IRF640/IRF9640 instead of IRFP240/IRFP9240 ..?

khalsa · 2nd January 2011, 03:51 PM

use IRFP240/IRFP9240 is ok minimam 4pair for good results

PROFESSOUR2003 · 2nd January 2011, 04:06 PM

ok but what about using IRF640/IRF9640 instead of IRFP240/IRFP9240..??!!

HighTec · 04:19 PM

Yes, you can use them but they have a maximum power dissipation around 125w so you'll need to use at least 6-7 pairs per channel. Especially if you wanna drive loads under 8 ohms.

nigelwright7557 · 2nd January 2011, 04:34 PM

I found irfp240/9240 to be more available.

jaycee · 08:17 PM

You're building a high power amp. Don't try to skimp on the cost, build it as the designer intended, unless you want it to blow up in your face.

Look at the difference between the two devices. IRFP240's are capable of 20A and dissipating 150W in their TO-247 casings. The IRF640 does 18A, but it is a TO-220 case that will only dissipate 125W. You will be reducing the dissipation of the amp to the point where it will blow up. If you use more devices, then you are making a harder load to drive, which will result in instability.

PROFESSOUR2003 · 2nd January 2011, 10:30 PM

<<unless you want it to blow up in your face.>> u r right jaycee,i think i missed this point ..

ostripper · 3rd January 2011, 01:06 AM

Quote:

Originally Posted by PROFESSOUR2003

<<unless you want it to blow up in your face.>> u r right jaycee,i think i missed this point ..

Here is someone who DID build it and did not go "BANG" ... another one to build an AV800 / AV1000

It depends on the end use and how much money you want to spend. Vertical OPS = GOBS of power (PA use)... lateral OPS= nicer sound , less power - simpler biasing.

OS

Lee Knatta · 3rd January 2011, 08:53 AM

Hi

You can find IRFP240 and IRFP9240 at DigiKey or Mouser but they are expensive there.

Where are you from?

I could help you out. I bought 100 each for my project and could sell you 2x4 matched devices.

Regards,
Lee

PROFESSOUR2003 · 3rd January 2011, 01:13 PM

Quote:

Originally Posted by Lee Knatta

Hi

You can find IRFP240 and IRFP9240 at DigiKey or Mouser but they are expensive there.

Where are you from?

I could help you out. I bought 100 each for my project and could sell you 2x4 matched devices.

Regards,
Lee

hii lee,
i am from egypt too far from u

but any way thnx 4 trying 2 help me.

and what`s the best way to match these mosfets ??

regards,
shady

2nd January 2011, 02:48 PM	#1
PROFESSOUR2003 diyAudio Member Join Date: Nov 2009	holton AV400 help..?? Hi guys, i an currently building holton AV400 amp. with 2x50 v 1KVA transformer my question is can i use IRF640/IRF9640 instead of IRFP240/IRFP9240 ..?

2nd January 2011, 04:15 PM	#4
HighTec diyAudio Member Join Date: Mar 2003 Location: Sibenik, Croatia	Yes, you can use them but they have a maximum power dissipation around 125w so you'll need to use at least 6-7 pairs per channel. Especially if you wanna drive loads under 8 ohms. Last edited by HighTec; 2nd January 2011 at 04:19 PM.

2nd January 2011, 04:34 PM	#5
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	I found irfp240/9240 to be more available. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

2nd January 2011, 08:12 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	You're building a high power amp. Don't try to skimp on the cost, build it as the designer intended, unless you want it to blow up in your face. Look at the difference between the two devices. IRFP240's are capable of 20A and dissipating 150W in their TO-247 casings. The IRF640 does 18A, but it is a TO-220 case that will only dissipate 125W. You will be reducing the dissipation of the amp to the point where it will blow up. If you use more devices, then you are making a harder load to drive, which will result in instability. Last edited by jaycee; 2nd January 2011 at 08:17 PM.

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2nd January 2011, 03:51 PM	#2
khalsa diyAudio Member Join Date: Dec 2007	use IRFP240/IRFP9240 is ok minimam 4pair for good results

2nd January 2011, 04:06 PM	#3
PROFESSOUR2003 diyAudio Member Join Date: Nov 2009	ok but what about using IRF640/IRF9640 instead of IRFP240/IRFP9240..??!!

2nd January 2011, 10:30 PM	#7
PROFESSOUR2003 diyAudio Member Join Date: Nov 2009	<<unless you want it to blow up in your face.>> u r right jaycee,i think i missed this point ..

3rd January 2011, 08:53 AM	#9
Lee Knatta diyAudio Member Join Date: Apr 2010 Location: Germany	Hi You can find IRFP240 and IRFP9240 at DigiKey or Mouser but they are expensive there. Where are you from? I could help you out. I bought 100 each for my project and could sell you 2x4 matched devices. Regards, Lee

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