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Old 4th October 2004, 03:59 AM   #21
SY is offline SY  United States
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A FET is just a pentode without the partition noise.
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Old 4th October 2004, 08:00 AM   #22
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Hi,

Quote:
A FET is just a pentode without the partition noise.
Not so sure we'd all agree on that...
If you'd were to say: a cascode instead of a FET then, yes. Sort of.

While both cascode and penthodes sport very high gain, you're still stuck with the fact that they're not the most linear devices either.
Which is probably where the SLCF comes in, to kill a few birds with one stone. So to speak.

Quote:
(just ignore the line stage bit)
I wouldn't do that. If it's for the sake of showing the frontend of an MC capable phonostage, O.K.
However if you'd want to build it I'd recommend adding the SLCF or another buffer.
Since the RIAA type used is of the split, fully passive type, you just can't leave the last stage open ended; it requires a defined g' to work against.

Cheers,
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Old 6th October 2004, 07:18 PM   #23
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Default More schematics

Hello,

donīt know what to do. Are there more schematics,
Conrad johnson, Audio research?

Reinhard
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Old 7th October 2004, 06:42 PM   #24
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Hi

Here you will find the Conrad Johnson Premier Six head amp and a lot of other things: http://www.pi.infn.it/~federico/further.htm

I have a Music Reference RM4 head amp schematic somewhere. It uses parallelled 6DJ8 halves (one Tube per channel). I can try to find it if anybody is interested.

Torben
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Old 9th October 2004, 09:19 AM   #25
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Default mc step up

Hallo,

thank you hermann,

can anybody help with schematics of Aesthtix I/O or Rhea?

Reinhard
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Old 9th October 2004, 04:53 PM   #26
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Default Head amp!

Quote:
Originally posted by Herrmann
Hi

Here you will find the Conrad Johnson Premier Six head amp and a lot of other things: http://www.pi.infn.it/~federico/further.htm

I have a Music Reference RM4 head amp schematic somewhere. It uses parallelled 6DJ8 halves (one Tube per channel). I can try to find it if anybody is interested.

Torben

Herrman,
Would you be so kind to post sch. of MR's RM4 head amp?
Regards,
Yugovitz
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Old 9th October 2004, 05:38 PM   #27
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Default rm4

Yawn...
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File Type: jpg rm4a.jpg (54.2 KB, 1064 views)
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Old 9th October 2004, 05:57 PM   #28
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Default Re: rm4

Quote:
Originally posted by analog_sa
Yawn...

Thanks,analog_sa!
Regards,
Yugovitz
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Old 17th December 2005, 05:46 PM   #29
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Hello,

are there more step upīs out there, what about Bob Carverīs
Sunfire solution

Reinhard
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Old 17th December 2005, 11:19 PM   #30
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Default Caution on direct coupling grid to MC

Quote:
If the curves are linear at Vg0 you can ground the cathode and couple the tube straight to the cartridge, one less cap in the signal path.
I've played with high transconductance tubes at low Vgk for MC use. The grid current becomes a real problem if you direct couple to the MC. If you calculate the tiny signal currents that an MC makes, this grid current is a huge relative DC bias on the MC coils. For example, an MC which makes 0.5mV at 5cm/s (a very high musical level, nevermind at -90dB below this level) will deliver 5 microamps rms into a 100 ohm load. Grid current for a 6C45/6S45 at small negative grid bias can approach this value. Better to run larger negative Vgk which means (for the same Ia) higher Va, and unfortunately higher Pa. But much lower grid current.
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