IRFP9240/IRFP240 vs 2SJ201/2SK1530 Mosfets

[Daniel(Del)]

Hi there!

Is it worth replacing IRFP9240/IRFP240 Mosfets by the Toshiba 2SJ201/2SK1530 Mosfet pair when it comes to sound quality? Has anyone already compared them?

Thanks!

[kacernator]

According to Pass Labs forum IRFP9240 or more generally speaking only IRF P-channel mosfets have some distortion in the audio midband which makes them sound more tubey (more 2nd harmonic distortion). People say it is not problem sonic wise, just different, some don´t notice, some do even like that effect.
So, you can make very good sounding amp with both of them, it is mainly your preference.

If you search F4 and F5 threads you will find more detailed reports of direct comparison between these two devices.

[nigelwright7557]

I hae used the irfp240/9240 is numerous amp designs and always been pleased with the results. So long as you use a Vbe multiplier with the transistor on the heatsink they are pretty reliable.

[Daniel(Del)]

Thanks everyone for the answers!
Is it ok to use unmatched Toshiba devices? They are quite expensive to buy a lot of them and use only 10. I'll post the design so that you can see if it's feasible to use the Toshiba pair instead of the IRF devices.
Shouldn't IRF9610/IRF610 be also replaced?

[bigpanda]

And please don't forget they have a different pin-out. Special care when soldering them directly on pcbs.

[bigpanda]

IRFP price is only 1/3 that of the 2Ss, right?

[Daniel(Del)]

Originally Posted by bigpanda

IRFP price is only 1/3 that of the 2Ss, right?

Yes, but on Ebay I could find some chinese sellers and their price is almost 2x that of the IRFPs, and I have never heard of fake Mosfets... Anything to worry here?

Originally Posted by bigpanda

And please don't forget they have a different pin-out. Special care when soldering them directly on pcbs.

It seemed to be the same when I looked at the datasheets. What about modifications on the bias circuitry?

Thanks!

[bigpanda]

Hope I did not get it wrong :

IRFP240 - left to right : GDS
2SK1058 - left to right : GSD



I think we can use IRFPs for the AV1000 w/o bias modification (make sure please, don't set a CNY firework show) I had used it for AV400. Only the pin-out is different. There seems to be no indication of the pin-out in the original IR datasheet but the one from Fairchild shows it.



I would try to avoid these from China. Some EBAYers from HongKong should be OK. But I get them from authorized distributors in hundred. Not too much problem for me.

BP

[Daniel(Del)]

Originally Posted by bigpanda

Hope I did not get it wrong :

IRFP240 - left to right : GDS
2SK1058 - left to right : GSD



I think we can use IRFPs for the AV1000 w/o bias modification (make sure please, don't set a CNY firework show) I had used it for AV400. Only the pin-out is different. There seems to be no indication of the pin-out in the original IR datasheet but the one from Fairchild shows it.



I would try to avoid these from China. Some EBAYers from HongKong should be OK. But I get them from authorized distributors in hundred. Not too much problem for me.

BP

I was talking about 2SK1530, not 2SK1058
Also, AV1000 was originally projected to be used with the IRFP devices, not the Toshiba ones.