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Old 24th May 2007, 12:03 AM   #1
antomas is offline antomas  Europe
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Default 2SK389 for left and right channels

Hi everybody!
Anyone knows if there is any pitfall in using a 2SK389 dual fet (on a common substrate) for left and right channed of a preamplifier?
Crosstalk? Anything else?

Thanks very much to anyone willing to answer.
Massimo
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Old 24th May 2007, 10:51 AM   #2
AndrewT is online now AndrewT  Scotland
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Hi,
389 as a single ended FET for the front end of a power amp?
How do you stabilise the DC voltages?

I think it would be better the use the matched pairs as both sides of an LTP input. Then the electrical match is some use and the thermal coupling works to the amps' benefit as well. That's the sort of application it was designed for.
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Old 24th May 2007, 10:58 AM   #3
Zen Mod is offline Zen Mod  Serbia
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Default Re: 2SK389 for left and right channels

Quote:
Originally posted by antomas
Hi everybody!
Anyone knows if there is any pitfall in using a 2SK389 dual fet (on a common substrate) for left and right channed of a preamplifier?
Crosstalk? Anything else?

Thanks very much to anyone willing to answer.
Massimo

without any comment about actual project ( why should I) I can tell that's waste ;

keep it for something where you'll need dual jfet; use instead any single jfet you can easily find........2SJ74 , J309,j310
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Old 24th May 2007, 11:14 AM   #4
antomas is offline antomas  Europe
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Sorry Gentlemen for having been imprecise and thanks for your answers.

I'd like to use these dual fet for R & L channels in a phono preamp (the Pacific RIAA discussed here and elsewhere).
Reasons for using the 2sk389 are:
1. I already have some;
2. I wouldn't like to purchase several 2sk170 just to find two decently matched couples (I'm aware some vendor on the net sells matched pairs).
Thanks a lot once again,
Massimo
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Old 24th May 2007, 11:30 AM   #5
AndrewT is online now AndrewT  Scotland
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Hi,
if you don't NEED the 389 then sell/swap them for dozens of 170/74.
Now that the obsolete stocks are running low the retail price has jumped a factor of ten times in just 12months.
Don't waste them on single ended.

You don't need to match 170 across the two channels.
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Old 24th May 2007, 11:47 AM   #6
GuidoR is offline GuidoR  Italy
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Massimo,
I totally agree with AndrewT, 2sk170 are so cheap, and trust me, matching is absolutely not a problem.
From lelettronicaasti.it (yes, Asti) you should buy 2sk170 @ 0,418
Euro each + VAT.

Guido
(now living in Bergamo, but coming from Turin)
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Old 24th May 2007, 11:52 AM   #7
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Anyone mention GR yet ?

Monsieur Walter will live forever, so it seems.
Altogether now : Hummmmmm !
L' Elettronica Spumante ?
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Old 24th May 2007, 12:02 PM   #8
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Aside from price it is a good idea, they will have similar transconductance and gain.
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Old 24th May 2007, 12:02 PM   #9
GuidoR is offline GuidoR  Italy
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Yes, for sparkling circuits.
Matching taste of audio circuits with wine's taste is more difficult than matching jfets.... but is muuuch better!!!

They are "BL"
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Old 24th May 2007, 12:22 PM   #10
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Quote:
Originally posted by GuidoR
They are "BL"
Ding Dong : 5mA * 2K4= 12 Volts
Idss range of BL is ?

(ps: as a veteran customer and Pacific constructor i'd like to add that it is Mr Walter, not Walters, and LA Maison de L'A)
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