IRFP140 and IRFP9140...anyone tried them in Aleph J or F5T? - diyAudio
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Old 22nd July 2013, 12:36 AM   #1
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Default IRFP140 and IRFP9140...anyone tried them in Aleph J or F5T?

Hi Guys,

I have a line on some freebie parts...which is always good, and am wondering if the IRFP140 would be okay in the Aleph J, I am thinking it will be fine as the main difference is in voltage rating, Ciss is about the same @1400pF. Second, would this pair work in the F5T V2 or V3 if I keep the rails below 50VDC? I would like to build the V3 with the 8 outputs per channel. I know the 240/9240 are available, but the Fairchild parts are EOL and when free stuff comes along, it's nice to be able to use 'em.

Your thoughts?

Cheers

Paul
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Old 22nd July 2013, 01:47 AM   #2
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Perfectly fine if the rails don't exceed 100V.

Last time I looked they have a slightly greater transconductance, but not
enough to get excited about.

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Old 22nd July 2013, 02:35 AM   #3
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Ahhh, Nelson,

Thank you so much for stopping in and letting us know we have options. Much appreciated. I have many torroids from past projects, mostly the same dual 17VAC @ 6A and 24 VAC @ 8A windings, tag says 200 and 319 watts, so I can parallel or series them as required for the Aleph J or F5T V3. Should see about +/- 30VDC for the Aleph J and either +/- 35 or 60VDC for the F5T. Here is the thread I started, trying to decide what to build next, Aleph J, F5T etc.

Catching up on 15 years of PASSt projects...which amp to build first!


So on another note, I am still about to rebuild the Stasis II, which I have had apart for over a year now. Finally have all the new 48 outputs and drivers etc. See my other thread...

Threshold Stasis II help needed please

Also sometime this fall/winter, I need to build a preamp based on one of your designs, be it a BA-3 line stage or ???

I must restrict myself to only 3 projects at a time.

Thanks again!

Cheers

Paul

Last edited by kilohertz; 22nd July 2013 at 02:58 AM.
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Old 22nd July 2013, 05:13 AM   #4
Gyuri is offline Gyuri  Hungary
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My four channel F4 uses IRFP240/IRFP9140 pairs in two channels.
They are fine.
I'm raised PSU voltages to +/- 35V without hassle.
If we don't mind the exceeding heat.

Best regards,

Gyuri
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Old 22nd July 2013, 09:58 AM   #5
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by Gyuri View Post
My four channel F4 uses IRFP240/IRFP9140 pairs in two channels.
Gyuri has chosen the mixed pair which are recommended as better complementary pairs.
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Old 22nd July 2013, 01:05 PM   #6
Gyuri is offline Gyuri  Hungary
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Yes, I read it somewhere earlier.
And datasheets also show this to me.
As much as possible with my runted brain as I can judge it.
I must have to say, I don't experienced any differences between 240/9240 and 240/9140 pairs.

Regards,

Gyuri
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Old 27th July 2013, 03:09 AM   #7
Bikeman is offline Bikeman  Australia
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Hmmm,

I managed to score a bunch of FET's at a good price.

I have IFRP9240 and IRFP340.

http://www.irf.com/product-info/data...a/irfp9240.pdf
http://www.irf.com/product-info/data...ta/irfp340.pdf

They look to be fairly complementary, would anyone be able to take a look at confirm (or deny!) that they might be suitable for an aleph-J or F5.
I've only got half an idea of what I'm looking at...

Thanks if you can help,

Mark
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Old 27th July 2013, 08:47 PM   #8
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Quote:
Originally Posted by Gyuri View Post
My four channel F4 uses IRFP240/IRFP9140 pairs in two channels.
They are fine.
I'm raised PSU voltages to +/- 35V without hassle.
If we don't mind the exceeding heat.

Best regards,

Gyuri
So is the front end is the same at 35 volts ? That is about 50 watts per channel in to 8 ohm class A is it not ?
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Old 28th July 2013, 03:20 PM   #9
Gyuri is offline Gyuri  Hungary
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Yes. I'm a fearless burning amplifier builder.
I'm worried about the 2SJ74/2SJ108 JFETs because of 25V GDS.
I don't have countless pieces of them.
But they are survive.
I must to say, I can't perform a comprehensive test with this configuration, depending lack of a proper preamp. It wasn't a really dynamic condition test.
So, perhaps these delicious devices don't survive, if I can put to them a full voltage swing.
I can say, I never ever burned any of Pass designs.
Despite of that I always push the limits.


I think, IFRP9240 and IRFP340 will be fine.
But I'm not an expert.
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Old 28th July 2013, 08:08 PM   #10
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Quote:
Originally Posted by Gyuri View Post
Yes. I'm a fearless burning amplifier builder.
I'm worried about the 2SJ74/2SJ108 JFETs because of 25V GDS.
I don't have countless pieces of them.
But they are survive.
I must to say, I can't perform a comprehensive test with this configuration, depending lack of a proper preamp. It wasn't a really dynamic condition test.
So, perhaps these delicious devices don't survive, if I can put to them a full voltage swing.
I can say, I never ever burned any of Pass designs.
Despite of that I always push the limits.


I think, IFRP9240 and IRFP340 will be fine.
But I'm not an expert.
On the youtube video of burning anp thing in 2010 Papa states that the absolute max on the 2sj74 is 43 not 25 volts so I think you are well with in the real limits on it as well as the for the 170 . For that mater neither an I the expert on this.
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