2SK170 matching

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#2
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.

😎
 
#5
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
 
#6

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#8
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..
 
#11
Hello All

Thanks for your knowledge 🙂 Much Appreciated !

Another Question.🙄
I see that a dual supply is needed but I was gonna use the same transformer used with my AP1.7, have the 1.7 and pearl in one box and power supply in another. Supply is 30-0-30v 160VA. Yes i know its overkill but the price was right.
Should I swap for two 0-30 transformers, in which series them up and power ap1.7 and use seperately for pearl?

Cheers
 
#12
What really needs matching in the Pearl (as with all RIAA's ) is the equalization components. Those parts are mainly R19, R22, R23, R24, C10, C13, C11 and C12. The main concern is to match them so they are the excact same in each channel. Doing this will greatly add to the soundstage, both in width and depth. The Pearl is capable of delivering an great soundstage, if this is taken care of. The excact value is not as important as being the same between channels. Mrupp mentioned this, and I think it deserves to be repeated😉
You would also do good by matching at least Q8-Q11 to some degree, since they sit in //. Not really needed though, as mentioned above.

🙂
 
#14
Nelson Pass said:
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.

😎
Click to expand...

Mr Pass,

I know this is an old thread but would you mind checking the attached circuit to see if this is what you mean in the post regarding checking Idss?

Thanks!
 

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#17
Nelson Pass said:
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.

😎
Click to expand...

Zen Mod said:
trick question - what is voltage between gate and source , on that picture ?

:clown:
Click to expand...


ZM,

Not a trick question, only following papa's instruction as highlighted above in his message.
 
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