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Old 4th June 2008, 04:36 PM   #6121
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Please, Lumanauw. I cannot answer questions posed at this level. It just confuses the issue.
 
Old 4th June 2008, 04:40 PM   #6122
zinsula is offline zinsula  Switzerland
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Thank you for your efforts PMA. I have learned something.
And thank you for your great circuit ideas and hints, John.

Despite many useless posts, s/n ratio is still ok here due to these two contributors.

Tino
 
Old 4th June 2008, 04:51 PM   #6123
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It is s/n ratio of the circuit itself that I am most concerned about.
 
Old 4th June 2008, 04:52 PM   #6124
PMA is offline PMA  Europe
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Quote:
Originally posted by john curl
PMA, you should try the full differential version without caps, running about 2.5ma on each side.

Quote:
Originally posted by zinsula
Thank you for your efforts PMA. I have learned something.
And thank you for your great circuit ideas and hints, John.

Despite many useless posts, s/n ratio is still ok here due to these two contributors.

Tino
Thanks for your support. I need to take a break now and continue on my business projects. I will be back tomorrow on the hint that John has mentioned.
 
Old 4th June 2008, 04:54 PM   #6125
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Thanks, PMA I really like your circuit emulations. I suspect they are better than typical SPICE for some reason.
 
Old 4th June 2008, 05:06 PM   #6126
syn08 is offline syn08  Canada
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Quote:
Originally posted by john curl
But, how quiet is it? NOISE is EVERYTHING with MC input.
Well, I don't know and honestly I don't care. I'll leave the MC/MM user market in your trustful hands and stick myself with the Linn studio digital recordings. If one would use the new generation of dirty sand extra contaminated with germanium high speed ICs from TI then I guess it would be quiet enough for me. Which doesn't mean much for you or anybody else.
 
Old 4th June 2008, 05:15 PM   #6127
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Low noise design is a specialized topic of which I am an expert. Your interests may vary.
P.S. Do you know Ivor? We have been good friends for 1/3 century. I own a Linn Sondek turntable, which is my 3'rd. I purchased the first in 1974. Ever been to the factory? Had a beer or two with Ivor? He exports great Scotch!
 
Old 4th June 2008, 05:20 PM   #6128
dimitri is offline dimitri  United States
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Quote:
Now, try to figure out how it works,
Composite op amp - so what? Better tell us what buffer will you use in front of this, which wouldn't degrade the overall performance?
 
Old 4th June 2008, 05:22 PM   #6129
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Quote:
Originally posted by john curl
Out of nothing else to do, let us take apart SE's question. How quiet is good enough? What is good enough for me, an old man? What about a young woman? What about a really low output MC cartridge like the original Ortofon cartridges, that this design was originally made for?
Why do you think that I chose 2 ohms as the input? That is the DCR of the Ortofon cartridge. Yes, it is the cartridge itself that sets the gain. What is the noise figure of this preamp with an Ortofon cartridge? Is it 3dB, 6dB, 10dB? Something else? Hint: With a 10 ohm cartridge, it is 3dB.
3dB?

Not bad.

And what was it you said? "NOISE is EVERYTHING," right?

I just calculated the noise figure for one of Jensen's dedicated MC step-up transformers.

It'll give you about 30dB of voltage gain and with a 10 ohm cartridge and loaded by a MM input's 47.5k ohms, has a noise figure of...

1.6dB.

So, if as John says, "NOISE is EVERYTHING with MC input," you can do better with a transformer.

se
 
Old 4th June 2008, 05:25 PM   #6130
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What is the DCR of the transformer referred to the input? You have to add that in, you know!

Wow, no mention of the referred DCR of the transformers on the spec sheet? They must run in liquid nitrogen, or use superconductiong wire, or both! Bill, shame on you.
 

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