Simplistic NJFET RIAA - Page 511

keantoken · 16th October 2010, 04:54 AM

It's one of those modern record players, from Technics. Has one of those snap-on plastic cartridges. It doesn't say.

- keantoken

Joao@AltheaMusica · 16th October 2010, 09:02 AM

Salas

did you experiment with BJT / FET current source in the 2nd / output stage as well and what are your results? Thinking of using an ZTX450 as current source...

Salas · 16th October 2010, 10:41 AM

Quote:

Originally Posted by keantoken

It's one of those modern record players, from Technics. Has one of those snap-on plastic cartridges. It doesn't say.

- keantoken

Do you have the model number so we can check better? It is most probably an MM cart. One SRPP simple one for you is Alex Nikitin's that I have tweaked the published values so to simulate nice for Riaa, and to use film cap couplers. Don't change any values. It has been used in various guises for Creek as OBH-8, and from Cambridge Audio in A3i. Also presented in 2003 here from Alex (member X-Pro) as well as in Radio Hobby magazine of Kiev. So its an Anglo-Russian theme with a Greek Tweak, as good as a vintage double-o seven flick as they come.

Salas · 16th October 2010, 10:48 AM

Quote:

Originally Posted by Joao@AltheaMusica

Salas

did you experiment with BJT / FET current source in the 2nd / output stage as well and what are your results? Thinking of using an ZTX450 as current source...

Have cascoded the second stage, didn't like it. No CCS load test.

Joao@AltheaMusica · 17th October 2010, 10:42 AM

Quote:

Originally Posted by Salas

Have cascoded the second stage, didn't like it. No CCS load test.

Cascoded like in the first stage? What about using a simple current source in the source of the stage?

Salas · 17th October 2010, 01:35 PM

What you have made up to now post it so I can sim it with and without, see the FFT and let you know.

keantoken · 18th October 2010, 12:34 AM

Mine is the Technics SL-Q300.

How do Technics products fare? I've heard there's some good Technics stuff, and I see the name a lot in pawn shops.

- keantoken

Salas · 18th October 2010, 12:54 AM

Much better arms and drive than others in same category. Its a decent consumer one. Cart is MM 2.5mV.
Doing that phono with BC550 I posted for you they match well. It is not a difficult CCT to find parts for I believe.
http://www.youtube.com/watch?v=mK8QpXP3inc

sonata149 · 27th October 2010, 08:49 PM

I'm new to fets and as I'm interested in this project I bought 10 pieces 2SK170 and checked them using the method described earlier in this thread: Transistor matching They all measured between 3.5 and 4.5mA. Now Salas's circuits specify 7-8mA. Does this mean they can / should not be used here in the gain stages? Are they at least good for the buffer and the Zener CCS fets or are they to 'weak' to complement the gain stages.

Sorry for the newbie questions but this is how I learned a lot from this Forum.

Regards,
JA

Salas · 27th October 2010, 08:59 PM

Are your parts having the description ''GR'' on them?

16th October 2010, 04:54 AM	#5101
keantoken diyAudio Member Join Date: Aug 2006 Location: Texas Blog Entries: 1	It's one of those modern record players, from Technics. Has one of those snap-on plastic cartridges. It doesn't say. - keantoken __________________ Contribute to the DIYAudio WIKI! http://www.diyaudio.com/forums/every...p-sign-up.html LTSpice wiki with special attention to new users' troubles

18th October 2010, 12:34 AM	#5107
keantoken diyAudio Member Join Date: Aug 2006 Location: Texas Blog Entries: 1	Mine is the Technics SL-Q300. How do Technics products fare? I've heard there's some good Technics stuff, and I see the name a lot in pawn shops. - keantoken __________________ Contribute to the DIYAudio WIKI! http://www.diyaudio.com/forums/every...p-sign-up.html LTSpice wiki with special attention to new users' troubles

27th October 2010, 08:49 PM	#5109
sonata149 diyAudio Member Join Date: Sep 2006 Location: Malta, Europe	Are these FETs too weak? I'm new to fets and as I'm interested in this project I bought 10 pieces 2SK170 and checked them using the method described earlier in this thread: Transistor matching They all measured between 3.5 and 4.5mA. Now Salas's circuits specify 7-8mA. Does this mean they can / should not be used here in the gain stages? Are they at least good for the buffer and the Zener CCS fets or are they to 'weak' to complement the gain stages. Sorry for the newbie questions but this is how I learned a lot from this Forum. Regards, JA

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16th October 2010, 09:02 AM	#5102
Joao@AltheaMusica diyAudio Member Join Date: Aug 2009	Salas did you experiment with BJT / FET current source in the 2nd / output stage as well and what are your results? Thinking of using an ZTX450 as current source...

17th October 2010, 01:35 PM	#5106
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	What you have made up to now post it so I can sim it with and without, see the FFT and let you know.

27th October 2010, 08:59 PM	#5110
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Are your parts having the description ''GR'' on them?

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