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Old 21st April 2010, 12:00 PM  
SY is offline SY  United States
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Join Date: Oct 2002
Location: Chicagoland
Default His Master's Noise: A Thoroughly Modern Tube Phono Preamp

After more than 25 years of faithful service, it seemed that it might be time to redo my phono system. After all, I like to think that I've picked up a few tricks in the intervening years... The old system consisted of a VPI HW17-II, a Linn Ittok LVII tonearm, and a Troika cartridge. The Troika was...

Last edited by Variac; 2nd April 2011 at 12:17 AM.
 
21st April 2010
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SY
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Well, a shunt regulator is a preferred choice for circuits where PSR has been traded off for gain or linearity. In this case, because of every stage being CCSed to the max and the plate impedances being very low, the PSR is outstanding and the limitations are not in the regulator.

dh, I don't have data on that configuration, but it certainly may be worth trying. That does reduce the source impedance of the CCS (as seen by the tube), but how much and how serious I just don't know. Nor do I know the sonic effects, if any. I'd be interested in your results if you do that.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
21st April 2010
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jlsem
diyAudio Member
Very nice article, but I'm confused. Has it really been online for a month and I just missed it?

John
21st April 2010
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SY
On Hiatus
Are you using aluminum cookware?
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
21st April 2010
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jlsem
diyAudio Member
No, but I'm sure the spoonfuls of live-monkey head cheese isn't helping.

Seriously, though, the article is dated March 21, 2010. Admittedly, I don't spend much time in the articles section.

John (Cookware? What's cookware?)
21st April 2010
gingertube
diyAudio Member
Page 4 - Mate!!

"So for example, suppose one has three uncorrelated noise sources in series of 1mV, 0.5mV, and 0.1mV. The total equivalent noise voltage is then √(12 + 0.52 + 0.12) = 1.12mV."

Right answer BUT wrong expression.

I did a random sampling maths checks and did'nt see any other "clangers".

Cheers,
Ian
22nd April 2010
Sheldon
diyAudio Member
Regarding the mu follower. I'm cooking up this project: http://www.diyaudio.com/forums/tubes...ml#post2157086

I was planning a cathode follower stage, but decided for a few reasons that the mu follower on the output tube would work out better. Will probably make it a gyrator, though will probably try both.

Salas, you may recognize certain elements.

Sheldon
22nd April 2010
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Salas
diyAudio Chief Moderator
Yes. Good research.
22nd April 2010
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SY
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Ian, the superscript tags got lost. All those trailing "2s" should be superscripted (squares), i.e., 1 squared + 0.5 squared + 0.1 squared. That's why the answer worked out correctly. I'll fix that tomorrow. Thanks for the close reading.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
22nd April 2010
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grufti
diyAudio Member
Great reading, even better amplifier.

The numbering of the figure captions way at the end of the article on page 14 in messed up, not that it matters much. The table of contents numbering [repeated on every page top right] is also interesting in that it is single digit only and starts repeating at 10 [or zero, if you are so inclined].
22nd April 2010
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Pano
diyAudio Moderator
Very nice SY, bravo!

I think I might like to hear Brubeck's version of "These are a Few of My Favorite Things" played thru it. Why? Cause you put in a few of my favorite things. =)
  • Balanced, transformer input
  • Passive RIAA
  • Output buffer
  • A neon tube!

I've never understood why most phono cartridges are not run balanced. It seems a natural. Mics are...

Only ever built one tube phono preamp and it was passive RIAA, I loved it.

One thing I would love to see is a MM version of this. Not all of us are brave enough to use MC carts, but we MM guys could use a good input stage, too.
Perhaps a "Voice 2000"? (a pun)




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