Ultrasimple mm/mc RIAA preamp 2 - Page 4

Mad_K · 11th September 2007, 08:25 PM

LSK170 should be equvivalent, just go ahead!

scott wurcer · 11th September 2007, 11:58 PM

BTW you should be able to build a small adjustable -Vgs biaser with a single 1.5V cell and some BIG resistors. You could then adjust each FET for equal Id, obviating the selection/matching requrements. A 1Meg pot between ground and -1.5V and a 10Meg resistor to the gate on each should do. The same geometry FET has about the same gm at a given Id with very little sensitivity to Idss.

wrenchone · 12th September 2007, 06:20 AM

I was amazed to get an email about this thread after all this time. If you're curious about what I finally did, check out the thread "open loop follies" (use search, it works).

Stanco · 14th November 2007, 05:47 PM

Nothing! The 2sk170-GR not find them .... Argh!
Maybe I am stupid ... But where you have taken them?

gaborbela · 19th May 2008, 08:19 PM

HI
Did someone made a PC board lay out for these MM preamp I would be imterested .
Madd K did you com pared these RIA with the Atlantic if yes wich one sound better .
Dou you have PC board for the Atlantic ,I would be intrested on a sett if that is the better one ..

Thanks for sharing with us your designs .

Greetings

Mad_K · 20th May 2008, 05:46 AM

I have boards for both. Send me an email

GlidingDutchman · 20th May 2008, 02:12 PM

Hi there

I cant find any FETs (as listed here) in South Africa. What other FET's can be used?

D

Zigis · 23rd May 2008, 10:53 PM

Very interesting design!

I just win in ebay great LP collection with Jimi Hendrix, English 60' blues, Woodstock records , and now I need new, better phono corrector.

Problem is - I can't find 2SK170.

Is it possible to replace this JFETs with other, preferable available from elfa.se or digikey.com ?

GlidingDutchman · 24th May 2008, 06:33 AM

Zigis... that is also what I like to know! Isnt there a modern eqivalent for these transistors?

D

EC8010 · 24th May 2008, 05:33 PM

Quote:

Originally posted by Zigis
Is it possible to replace this JFET with another, preferably available from elfa.se or digikey.com?

No. The 2SK170 or LSK170 are quite special. They have low voltage noise and a low (for a FET) 1/f corner frequency. They are also high transconductance (which is why they are low noise). You need to get on to Linear Systems for the LSK170.

11th September 2007, 08:25 PM	#31
Mad_K diyAudio Member Join Date: Sep 2002 Location: Norway	LSK170 should be equvivalent, just go ahead! __________________ Mads K

11th September 2007, 11:58 PM	#32
scott wurcer diyAudio Member Join Date: Jan 2004 Location: cambridge ma	BTW you should be able to build a small adjustable -Vgs biaser with a single 1.5V cell and some BIG resistors. You could then adjust each FET for equal Id, obviating the selection/matching requrements. A 1Meg pot between ground and -1.5V and a 10Meg resistor to the gate on each should do. The same geometry FET has about the same gm at a given Id with very little sensitivity to Idss. __________________ Clay is embedded in our subconscious. It has been there for at least 50,000 years.

20th May 2008, 05:46 AM	#36
Mad_K diyAudio Member Join Date: Sep 2002 Location: Norway	I have boards for both. Send me an email __________________ Mads K

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12th September 2007, 06:20 AM	#33
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	I was amazed to get an email about this thread after all this time. If you're curious about what I finally did, check out the thread "open loop follies" (use search, it works).

14th November 2007, 05:47 PM	#34
Stanco diyAudio Member Join Date: Apr 2006 Location: Rome-Italy	Nothing! The 2sk170-GR not find them .... Argh! Maybe I am stupid ... But where you have taken them?

19th May 2008, 08:19 PM	#35
gaborbela diyAudio Member Join Date: Sep 2005	HI Did someone made a PC board lay out for these MM preamp I would be imterested . Madd K did you com pared these RIA with the Atlantic if yes wich one sound better . Dou you have PC board for the Atlantic ,I would be intrested on a sett if that is the better one .. Thanks for sharing with us your designs . Greetings

20th May 2008, 02:12 PM	#37
GlidingDutchman diyAudio Member Join Date: Nov 2007	Hi there I cant find any FETs (as listed here) in South Africa. What other FET's can be used? D

23rd May 2008, 10:53 PM	#38
Zigis diyAudio Member Join Date: May 2005 Location: Riga, Latvia	Very interesting design! I just win in ebay great LP collection with Jimi Hendrix, English 60' blues, Woodstock records , and now I need new, better phono corrector. Problem is - I can't find 2SK170. Is it possible to replace this JFETs with other, preferable available from elfa.se or digikey.com ?

24th May 2008, 06:33 AM	#39
GlidingDutchman diyAudio Member Join Date: Nov 2007	Zigis... that is also what I like to know! Isnt there a modern eqivalent for these transistors? D

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