has anyone tried On-Semi's MOSFETS in place if IRF's?

bigparsnip · 27th February 2004, 02:15 PM

Hi, I was just having a look about to see what transistors to use in my aleph-x, and I was looking on the on-semi site ofr compatable products, and it came up with their MTW32N20E as a compatable for the IRF240. At first glance this seems to be a slightly higher specced device, with a curent ratting of 32A compared to 20 for the IRF part, and an on resistance of only 0.075 ohms, compared to the 0.18 for the IRF240.

So, I was wondering if anyone had heard any of these devices before, and if it would be worth givingthem a try to see what they sound like.

???

Alain Dupont · 27th February 2004, 03:17 PM

bigparsnip,

There is quite a pb with the Input capacitance

IRF240 InCap 1300 pF

MTW32N20E InCap 3600 pF

Well for a compatible.... can do better.
You'll have to find a device with a lower Input capacitance.

Regards.

Alain.

bigparsnip · 27th February 2004, 03:19 PM

Hm, I didn't check that, but as people have parlelled up quite a lot of output devices on the aleph series in the past (I'm sure I have seen over six at least), in theory the driver circuits in most designs should still be ok driving two of these without any noticable drop on HF quality right?

Alain Dupont · 27th February 2004, 04:00 PM

bigparsnip,

I am building a CCS-X-BOSOZ
now, And I could take a try as it's used IRF244's in the Aleph P ; a similar setup...

I'll check where to find a pair of MTW32N20E to insert in the CCS-X-BOSOZ

they are available at DigiKey, I'll order a few on my next order , they are 8.18 cad$ each.

I expect you receive comments from other DIYer's on this.

Regards.

Alain.

stefanobilliani · 27th February 2004, 04:23 PM

Quote:

Originally posted by bigparsnip
in theory the driver circuits in most designs should still be ok driving two of these without any noticable drop on HF quality right?

Thats right , and probably 2 semis will do the job of 3 irfp240 (?).

An experience: I tried Toshiba(tm) 2SK1029 ( very cheap in an electronic show) as gain device in ZENV2 and find out they were a lot more noisy than the IRFP044.

Nelson Pass · 27th February 2004, 06:39 PM

Probably the ratio is more like 2 to 1. The MTW32N20E
is more like an IRF250.

Brian Donaldson · 28th February 2004, 03:49 AM

The IRFP244 is somewhere around $1.50 ea by the 100s from Future Active if I remember correctly. Minimum on resistance below .25 ohms is wasted unless you're building a smps for low voltages, and you'll never be able to run anywhere near the maximum current in a class A amp due to max dissapation.
Sorry, didn't mean that as a smack down, I like to think out of the box as well.

bigparsnip · 28th February 2004, 01:30 PM

The low on resistance was for my aleph-x, which will only have piddly little 17V rails (probably), so I was looking to get as much out of the device as I could (although the IRF044 has an even lower on of about 28milli ohms if I rember right, but I can't find any of those at RS).

I guess I will just have to see if I can get enough parts together to build up all four of the boards that I have, to see if I can hear any differences between the two devices. But that could take some time ...

27th February 2004, 02:15 PM	#1
bigparsnip diyAudio Member Join Date: Apr 2003 Location: Cambridge	has anyone tried On-Semi's MOSFETS in place if IRF's? Hi, I was just having a look about to see what transistors to use in my aleph-x, and I was looking on the on-semi site ofr compatable products, and it came up with their MTW32N20E as a compatable for the IRF240. At first glance this seems to be a slightly higher specced device, with a curent ratting of 32A compared to 20 for the IRF part, and an on resistance of only 0.075 ohms, compared to the 0.18 for the IRF240. So, I was wondering if anyone had heard any of these devices before, and if it would be worth givingthem a try to see what they sound like. ???

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27th February 2004, 03:17 PM	#2
Alain Dupont diyAudio Member Join Date: Sep 2003 Location: Paris - France	bigparsnip, There is quite a pb with the Input capacitance IRF240 InCap 1300 pF MTW32N20E InCap 3600 pF Well for a compatible.... can do better. You'll have to find a device with a lower Input capacitance. Regards. Alain.

27th February 2004, 03:19 PM	#3
bigparsnip diyAudio Member Join Date: Apr 2003 Location: Cambridge	Hm, I didn't check that, but as people have parlelled up quite a lot of output devices on the aleph series in the past (I'm sure I have seen over six at least), in theory the driver circuits in most designs should still be ok driving two of these without any noticable drop on HF quality right?

27th February 2004, 04:00 PM	#4
Alain Dupont diyAudio Member Join Date: Sep 2003 Location: Paris - France	bigparsnip, I am building a CCS-X-BOSOZ now, And I could take a try as it's used IRF244's in the Aleph P ; a similar setup... I'll check where to find a pair of MTW32N20E to insert in the CCS-X-BOSOZ they are available at DigiKey, I'll order a few on my next order , they are 8.18 cad$ each. I expect you receive comments from other DIYer's on this. Regards. Alain.

27th February 2004, 06:39 PM	#6
Nelson Pass The one and only Join Date: Mar 2001	Probably the ratio is more like 2 to 1. The MTW32N20E is more like an IRF250.

28th February 2004, 03:49 AM	#7
Brian Donaldson diyAudio Member Join Date: Jan 2003 Location: Texas, Love it or leave it	The IRFP244 is somewhere around $1.50 ea by the 100s from Future Active if I remember correctly. Minimum on resistance below .25 ohms is wasted unless you're building a smps for low voltages, and you'll never be able to run anywhere near the maximum current in a class A amp due to max dissapation. Sorry, didn't mean that as a smack down, I like to think out of the box as well.

28th February 2004, 01:30 PM	#8
bigparsnip diyAudio Member Join Date: Apr 2003 Location: Cambridge	The low on resistance was for my aleph-x, which will only have piddly little 17V rails (probably), so I was looking to get as much out of the device as I could (although the IRF044 has an even lower on of about 28milli ohms if I rember right, but I can't find any of those at RS). I guess I will just have to see if I can get enough parts together to build up all four of the boards that I have, to see if I can hear any differences between the two devices. But that could take some time ...

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