Mosfet replacement

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In the book High power amplifier design there is a very simple project for small amplifiers. Here 2SJ 162/2SK 1058 mosfets are used in the output stage. They are difficult to get. Hence i will like to replace it with IRF series. Is this possible or not, and if yes then which mosfets i should use. The amp will drive 50W/4 ohms load for small subwoofer.
Mahendra Palesha

I stay in Malaysia and the mosfets you've mentioned are quite readily available over here at around USD8/- per piece depending on the quantity. I've tried direct substitution of the Hitachi Mosfets with various IRF types and the results were not too good. If you need help to get some Hitachi parts, let me know and I may be able to help.

BTW, is Farnell available at your place? They stock this parts too although the price may be a bit more expensive.

Thanks for ur suggestion.
It is available in my country also. But they are expensive. Hence i was looking whether they can be replaced with IRF. IRF devices are available in very big range. Hence I can use them parallel to get more output. They are cheap and easily available also.

Exicon has a a cross reference list on their web site. Unlike IRF devices these are specifically designed for audio use and available in complementary pairs. Perhaps the list below will be usefull to some one.

Data sheets are available from the Exicon web site and Spice models are supplied by request.

I intend to try some of the Exicon and Magantec devices shortly. These both appear to come from England and may be similar.

Data on Magnetec MOSFETS is also available on the web and they also supply spice models on request.

Changing devices, even though they say they are compatibile may require small to substantial bias changes to obtain similar performance. This is something to keep in mind.

Hitachi / industry part Replacement

N Channels 2SK to Exicon part number

2SK133 - TO3 metal ECF10N16
2SK134 - TO3 metal ECF10N16
2SK135 - TO3 metal ECF10N16
2SK175 - TO3 metal ECF10N20
2SK176 - TO3 metal ECF10N20
2SK1056 - plastic ECX10N16
2SK1057 - plastic ECX10N16
2SK1058 - plastic ECX10N16
2SK2220 - plastic ECX10N20
2SK2221 - plastic ECX10N20

P Channels 2SJ to Exicon part number

2SJ48 - TO3 metal ECF10P16
2SJ49 - TO3 metal ECF10P16
2SJ50 - TO3 metal ECF10P16
2SJ55 - TO3 metal ECF10P20
2SJ56 - TO3 metal ECF10P20
2SJ160 - plastic ECX10P16
2SJ161 - plastic ECX10P16
2SJ162 - plastic ECX10P16
2SJ351 - plastic ECX10P20
2SJ352 - plastic ECX10P20

John Fassotte
Alaskan Audio
subbing IR MOSFETs for Hitachi-like MOSFETs

Regarding the direct substitution of IR devices for "Hitachi-like" devices, it's not so simple. The Hitachi devices are lateral devices, built to have a zero tempco bias point at around 100mA drain current. So, they are easy to apply to class a/b or class b amps. The IRs are HEXFETs. The zero tempco bias point for the HEXFETs is MUCH higher (amps I think instead of milliamps), so you should probably have some sort of bias servo scheme if you want to do class a/b or class b with them. HEXFETs are great for class A though.

I won't even touch on the other device characteristics, like Gm, capacitance, etc.

The 2SJ162 - 2SK1058 are not to difficult to get and the price are low here is the price
2SK1058 = $1.16 and for 25off is $1.05
2SJ162 = $8.30 and for 25off is $7.77
you buy them at Futurlec Electronic

Hi Rambo900,

The price for the 2SK1058 seems too good to be true at Futurlec.

I recently bought some 2SK1058 & 2SJ162 from Tayda for $3.50 a piece, delivery took more than a month though. I used them to build Dr. Bora's Sigma Amp & they are the geniune Renesas parts & the amp sounds fantastic.

2SK1058 N-Channel MOSFET 160V 7A

Cheers, Stanley
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