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 ..?
i an currently building holton AV400 amp. with 2x50 v 1KVA transformer
my question is can i use IRF640/IRF9640 instead of IRFP240/IRFP9240 ..?
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. 😉
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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.
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.
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<<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" ... http://www.diyaudio.com/forums/solid-state/164531-another-one-build-av800-av1000.html
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
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
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
They are around £3 each at Cricklewood electronics.
Cricklewood Electronics CCTV and Electronic Components
I didn't intend to travel to Egypt to hand them out to you. 😉
(However, I've been there last December...)
I just asked to get an idea where you could source parts from.
For matching the IRFPs I used the way A.H. proposed and it worked well.
Here you find the full documentation of the AV400 including advice how to match the IRFPs:
http://www.diyaudio.com/forums/atta...2-need-scheme-400w-mosfet-amplifier-av400.zip
Note that when buying IRFPs you should take care to get them from the same batch, preferably from the same tube. This makes it more likely to find some matching ones. You need to buy a lot more than you actually need for your amp because they must match close in order to share the load.
That's why I offered you matched ones. 😉
Here you find my experience with matching the IRFPs:
http://www.diyaudio.com/forums/solid-state/164531-another-one-build-av800-av1000-8.html#post2334814
Where do you have the pcb artwork from? Is is from A.H.?
I can't tell you whether it's correct, sorry.
One thing I like to add is that I recommend to buy some IRF610 to replace Q10 if you experience overcompensated bias.
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ok thanks so much Mr. LEE and i hope to c u in egypt next time u r there
regards,
SHADY
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