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Old 27th April 2013, 01:35 PM   #38641
SY is offline SY  United States
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Cool- here's my issue: I need low noise pFET pairs with matched Idss of 15-20mA for a project I've been trying to design. They have to be available to anyone building the project. Selected J74s in the right range would have been ideal but the available ones have a high percentage of fakes, and LS doesn't seem to be anywhere near production. Suggestions?
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Old 27th April 2013, 01:48 PM   #38642
Waly is offline Waly  United Kingdom
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No, it's a common writing error. "Complementary" is the right word unless the devices are telling you that you're a handsome and intelligent fellow.
Or free .
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Old 27th April 2013, 01:52 PM   #38643
Bonsai is offline Bonsai  Taiwan
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Go single ended JFET input. Very easy to get high loop gains ( or not if you don't want that), high slew rates and ultra low distortion. You can set the output stage up to run heavily into class A with all the attendant benefits. It seems to me that this fully balanced thing for small signal stages is totally overrated - its just not a prerequisite for top notch sound. LS LSK389C make a great input pair.
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Old 27th April 2013, 01:55 PM   #38644
SY is offline SY  United States
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Unfortunately, that won't work for this application. I absolutely need p-channel, unless you know about some positronic tubes. I prototyped it with parts on hand, and got stellar performance, but can't publish the design unless others can build it as well.
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Old 27th April 2013, 01:57 PM   #38645
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LS finally in production of j74
Not cheap at $6.37 each
Volume production in less than 12 weeks.
6 different idss levels
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Old 27th April 2013, 02:04 PM   #38646
SY is offline SY  United States
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You give me hope, but I've been disappointed by them before...
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Old 27th April 2013, 02:07 PM   #38647
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Wow a new element discovered
LSj74 - gone from unobtanium to unaffordium

I have Toshiba j74 I better use or my kids will throw them in the dumpster when I'm gone

Last edited by ticknpop; 27th April 2013 at 02:11 PM.
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Old 27th April 2013, 02:08 PM   #38648
dimitri is offline dimitri  United States
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Quote:
Selected J74s in the right range would have been ideal but the available ones have a high percentage of fakes, and LS doesn't seem to be anywhere near production. Suggestions?
Evaluate and review your goals and design spec, think out of the box, reevaluate n-ch FET designs, proposed by Scott Wurcer
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Old 27th April 2013, 02:12 PM   #38649
godfrey is offline godfrey  South Africa
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Originally Posted by SY View Post
low noise
How low is low? These J174-177 look like they could be good for something. Noise is too high for a phono stage, but should be OK for line level. (or am I being a cretin again)
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Old 27th April 2013, 02:22 PM   #38650
SY is offline SY  United States
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How low is low?
1.5nV/rt Hz or better. Yes, phono stage.
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