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Old 3rd December 2011, 06:07 PM   #3261
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Ok, i build it. Send me the circuit you like best. I have a strange idea. Sampler could build his one and i build yours. Then, after testing and listening i can ship him yours and he ships his to me for comparison.
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Old 3rd December 2011, 06:56 PM   #3262
MiiB is online now MiiB  Denmark
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Cool....what a support...... I'll just go over the working points and currents and then send you the schematics, and post it here as well

Michael Børresen
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Old 3rd December 2011, 06:59 PM   #3263
sampler is offline sampler  Lithuania
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Sounds cool to me, but I would not hold my breath for my version build if I were you Joachim And I know how fast you are with proto builds, so I will feel really bad and obligated.
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Old 3rd December 2011, 07:14 PM   #3264
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OK, i easy your pain. I build Michaels circuit and send it to you and you compare.
Do we have a deal ?
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Old 3rd December 2011, 07:36 PM   #3265
sampler is offline sampler  Lithuania
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What can I say, that's a deal ! I'm really speechless... There is really not much people around that would go through such hassle to help others. I really admire your enthusiasm
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Old 3rd December 2011, 07:49 PM   #3266
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No, this is not a hassle, it is about the music. May it play for ever.
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Old 4th December 2011, 09:34 AM   #3267
MiiB is online now MiiB  Denmark
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This is the circuit I have in mind...

Quite sure that the servo can be made different...where it is less in the signal path.. but this will work...only must the fundamental offset in the summing node be adjusted so it' close to zero before engaging the servo..

The showed resistor voltage reduction for the servo opamp is not good enough. think that a 15 V zener solution would be better, but for sims this works OK

The gain here is 56 dB, but can be adjusted by adjusting Riaa network values.
The circuit is extremely fast and has a bandwidth of more than 30 MHz.

Can be used with an octet of BF862. without changing the currents, then noise will be extremely low as well...But for ease and proof of concept i think that the SK170 will be good enough
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Old 4th December 2011, 02:45 PM   #3268
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OK, i got it. Will build this in the next 2 weeks.
I found an interesting input stage that avoids common mode distortion. It is described as multi tan-h. It is from the ADA4898 that i tried successful some time ago. For me that also looks like a driven cascode, this time in the current sources.
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Old 4th December 2011, 05:46 PM   #3269
MiiB is online now MiiB  Denmark
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How to get the signal out....two left branches..??
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Old 4th December 2011, 05:49 PM   #3270
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Good question. Id1 -, Id1+, Id2-, Id2+ may need a mirror. There is more in the patent.
I will post a link.
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