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FS: Matched Vishay IRFP240 and Harris IRFP9240

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chromenuts

chromenuts

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I’d love to have some of these. Enough for four stereo amps (8 pair or preferably 4 quads)

Like others have said...it is kind of hard to commit to something you don’t know the price of.

The last time I ordered 2 matched quads from Aleweit on fleaBay I paid $30. Are we talking twice the price?
 
Tea-Bag

Tea-Bag

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Joined 2006
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chromenuts said:
I’d love to have some of these. Enough for four stereo amps (8 pair or preferably 4 quads)

Like others have said...it is kind of hard to commit to something you don’t know the price of.

The last time I ordered 2 matched quads from Aleweit on fleaBay I paid $30. Are we talking twice the price?
Click to expand...

I am still working on the pricing of them. I have to make sure I am not doing stupid math and not even paying for parts costs.

The difference I think is likely using NOS Harris cost substantially more than the Vishay counterparts (but not insane). But I think your looking at 2 matched 240 and 2 matched 9240 in 18-20usd range (4 fets). I will have to charge a bit more to match say quads NNNN and PPPP (say enough for a F5Tv3 one channel). I will probably top it off with matched quads.

Keep in mind, we dont need to match between channels. It doesn't really buy you much IMO. You guys can argue otherwise. But having close matched on same rail V+ or V- keeps them 'load sharing' in output best.

Don't worry, there is no commitment to purchase.
 
Tea-Bag

Tea-Bag

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silasmellor said:
Alright, i must've gotten my wires crossed there. But in any case isn't matched better (if only in terms of transistor lifetime)? Or is matching irrelevant since they are on separate rails?
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Transistor lifetime? I am not sure I have heard of transitors failing over a amount of time, but I am sure all devices will have a MTBF to them.

Matching N and P in most designs is not needed, and often the parts have different ranges altogether.

Further, I am matching for VGS, not trans-conductance. So they may 'express' a little differently under load. If this is audible, I am not certain.

What I can say is that I did not like the M2 or F5 with standard IR or Vishay IRFP9240 in them. I preferred Fairchild (now really hard to find) or Harris parts on the P-channel by a long shot. I can hear the difference. I am not sure others would. But I don't think my ears are special. Just trained maybe over the years. I think there are plenty of studies that show people can hear differences, even subtle ones between sources and signal chain. Now sometimes we think the cheaper option is better. It's not perfect, but people often do know a difference. Not that I am an authority on sound quality, but I have not heard anyone tell me my initial impressions were the opposite of theirs. Maybe they just have not felt inclined to do so. :) I don't consider myself an authority on anything here. So take that with a grain of salt.
 
S

silasmellor

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Joined 2016
For lifetime, i had understood that when you had unmatched devices sharing the load unequally would lead to one device potentially failing prematurely (in the extreme case). But it makes sense that this would probably only be relevant for NN or PP (i heard this in relation to whether or not to match IRFP240s for an F6).

I do not doubt the notion that choice of transistor manufacturer can make an audible difference, though i am well aware that opinions expressed on audio-related forums should be taken with a grain of salt :)

I will discreetly sidle over to the M2 signup page instead now and leave you good gentleman to your matched FETs:cool:
 
Tea-Bag

Tea-Bag

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Joined 2006
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chromenuts said:
Signed up...will you be contacting us for payment arrangements?
Click to expand...

Yes, I will be contacting you as soon as I am done with final sorting and packaging.
I have locked down the spreadsheet from more buyers. I am already commited to more than I have in stock (including unmatched in another spreadsheet) so I am going to lock this spreadsheet down until I can get more supply in.

You can PM me for signup, and I will put you on new list if you are not in current one.
 
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