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Old 25th March 2009, 08:17 PM   #1
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Default 2SK170 matching

Hello

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.

Cheers
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Old 25th March 2009, 08:42 PM   #2
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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.

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Old 25th March 2009, 08:53 PM   #3
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Erno Borbely also wrote a pair of very nice articles on JFET matching, optimizing performance and it's free and on his website --

http://www.borbelyaudio.com/adobe/ae599bor.pdf

and

http://www.borbelyaudio.com/adobe/ae699bor.pdf
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Old 25th March 2009, 10:29 PM   #4
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Once again, Thanks Mr Pass
....and you to jackinnj
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Old 26th March 2009, 10:23 AM   #5
h_a is offline h_a  Europe
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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
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Old 26th March 2009, 02:05 PM   #6
Rick NL is offline Rick NL  Netherlands
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Default BF862 Matching result

I just bought 50 BF862's (see also the B1 Turbo on a chip thread B1-Turbo on a Chip)
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.

[IMG]http://[/IMG]

Rick
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Old 27th March 2009, 05:42 AM   #7
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So Hannes, nothing need matching on the pearl then?
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Old 27th March 2009, 08:14 AM   #8
MRupp is offline MRupp  Germany
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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..
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Old 27th March 2009, 08:53 AM   #9
h_a is offline h_a  Europe
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Quote:
So Hannes, nothing need matching on the pearl then?
Exactly!

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

Have fun, Hannes
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Old 27th March 2009, 09:24 AM   #10
Rick NL is offline Rick NL  Netherlands
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Default Matching

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