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audiodan 25th March 2009 08:17 PM

2SK170 matching

Whats the best... easiest way to match these puppies.
Done some searching but links I found just dont work:(

Gonna attempt the pearl and maybe waynes new design.


Nelson Pass 25th March 2009 08:42 PM

Get a 5 to 13 volt supply and a DC voltmeter. Connect the +V to the
Drain, connect the Gate and Source together to a 100 ohm resistor,
and connect the other lead of the resistor to ground.

Measure the voltage across the resistor, which gives the Idss. 1 volt
= 10 mA of current.

Try to measure all devices under the same conditions, temperature,
and duration of test.


jackinnj 25th March 2009 08:53 PM

Erno Borbely also wrote a pair of very nice articles on JFET matching, optimizing performance and it's free and on his website --


audiodan 25th March 2009 10:29 PM

Once again, Thanks Mr Pass
....and you to jackinnj:)

h_a 26th March 2009 10:23 AM

Just be aware you don't need to match the jfets for the pearl ;)

If you can, just select the higher current parts as this will lower the distortion a tiny bit, but otherwise also not necessary.

Have fun, Hannes

Rick NL 26th March 2009 02:05 PM

BF862 Matching result
2 Attachment(s)
I just bought 50 BF862's (see also the B1 Turbo on a chip thread
and the result is that at least 30 are very well matchable in pairs and even one almost perfect double quad.
You don't need to buy big numbers to get decent matching.

An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.


audiodan 27th March 2009 05:42 AM

So Hannes, nothing need matching on the pearl then?

MRupp 27th March 2009 08:14 AM

Real matching may not be required. But it does not do any harm if you have both channels very close in overall Idss distribution, so do not put all 6mA Idss devices in one channel and the 12 mA devices in the other.

Close matching of the filter cap values channel to channel is also a good thing, btw..

h_a 27th March 2009 08:53 AM


So Hannes, nothing need matching on the pearl then?

Of course you can do it if you want, it won't hurt.

Have fun, Hannes

Rick NL 27th March 2009 09:24 AM

Only in the capacitor less dual supply versions matching is required.

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