GoodSoundClub - Romy the Cat's Audio Site - Uber-tweeky phono topologies deconstructed

03-01-2010

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Romy the Cat

Boston, MA
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An interesting Russian pnonocorrector.

Guys from a Russian audio site come up with an idea of MM corrector that I find very interesting, take a look – it is self-explanatory. The firs tube is Russian equivalent of 7788. The second is “my” 6E5P, though I would use 7721 – sounds better in output if no drive in required.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-02-2010

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cv
Derby, United Kingdom
Posts 173
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Novel MM corrector

Hi Romy
How very strange you mention this... Dave and Jeffrey have been working with a somewhat similar concept.

The design you have doesn't look right - it's missing a time constant; you need another cap there. Where did you find this schematic?

03-02-2010

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Romy the Cat

Boston, MA
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The kinky Russky phonostages

Nope, it does not miss anything. They offset the 75msec in input using the inductance of cartage’s coil (I quess they do not use MC). Below is the original thread. You need to buy a chocolate cake and to do a foot massage to your Russian mistress to read it. In personaly I do not see a lot of useful written at this thread. I think the idea is well highlighted and the rest is secondary.

http://hiend.borda.ru/?1-7-0-00000010-000-10001-0

If I had any interests in phonostages then I would prototype the concept to see how it works. But what is the point – the “End of the Life Phonostage” will blow it up anyhow… Again…

The caT

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-03-2010

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cv
Derby, United Kingdom
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Inductance cartidge equalisation what?

I don't see how the cartridge inductance is doing anything as far as that schematic goes.
There's another thing *very* wrong with it as well, but as you're not going to pursue it, we can leave it at that.

03-03-2010

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Romy the Cat

Boston, MA
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No claims about sonic advantages of this method.

cv wrote:
I don't see how the cartridge inductance is doing anything as far as that schematic goes.
There's another thing *very* wrong with it as well, but as you're not going to pursue it, we can leave it at that.

Possible, I posted it more as an idea not as source for replication. In that site they claim that they built it “as is” and that work and measure fine. It is irrelevant what they claim, even thigh it might be true. The concept is still elegant and different and this is all that sounds. Sure there are no claims about sonic advantages of this way…

The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-03-2010

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Romy the Cat

Boston, MA
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The same corrector from the same site.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-04-2010

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cv
Derby, United Kingdom
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Corrected corrector...

That makes more sense, though I must admit, Dave corrected me regarding how the first scheme might work (I had forgotten MM cartridges had such high inductances).

03-04-2010

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Romy the Cat

Boston, MA
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Why do not use this method on DSETs?

Yes, I knew that you were not accurate with your assumption that MM cannot run 75mSec offset.I am not a big fun of this method as no sane person would use MM cartridges. However, what I find is very attractive in this phonocorrector is to employ SOME of those ideas for DSET applications and to filter DSET via plate voltages on driver of power stages. I do not care about the phonostages but I think for DSET it might open some room. You for instance would like to write a line level filter but you too hectic about keeping the grid impedances low and input impedance high. Here is an option of massaging the plate voltage…The Cat

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-04-2010

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

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Interesting in 2-D

This appears to put the internal values of its gain stages into play, which in turn appears to cut the signal path parts count, all right. Since we are not given the (presumed "dedicated") cartridge H, did anyone run reverse numbers to see if this path also includes the tubes' Miller capacitance?

I forget which tubes they used as I post this, but how much does a design like this depend on the absolute stability of the gain stages, ie, how much slop is built in, or where would one go to tweak it without effing up turnover?

Overall, is there sufficient isolation here, or is there classic tank circuit co-dependency/bleed-through?

...put a DACT PS on that puppy...

Paul S

03-04-2010

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cv
Derby, United Kingdom
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Uber-tweeky phono topologies deconstructed

Hello Paul,
The first stage is a pentode, so the Miller cap is negligible. As for the other things you mentioned, there is a detailed exploration, which covers some of your points, by Dave Slagle at:

http://www.intactaudio.com/forum/viewtopic.php?t=1026

I do highly recommend LTSpice (free download) for answering such engineering-type questions... plenty of tube-oriented info and fairly accurate tube models available from the above website. Takes a wee bit of time to setup but well worth it.

best,
cv

	Target	Threads for related reading	Most recent post in related threads	Forum	Replies	Views	Started
»	New	7788 tube mic pre design..	Read my leaps: Absorb-GEL...	Analog Playback Forum	38	373555	02-14-2006
»	New	The LCR RIAA correctors..	Inductive RIAA link...	Analog Playback Forum	57	721213	07-11-2007
»	New	The last phonocorrector: “End of Life" Phonostage..	Big cap banks...	Analog Playback Forum	310	1973243	11-13-2007
»	New	Another interesting corrector: Likhnitsky's RX correcto..	Again, the capacitors...	Analog Playback Forum	6	70742	02-10-2005
»	New	Where are our good phonostages?..	Omnigon Tubes...	Analog Playback Forum	61	665178	05-31-2004
»	New	Incorporating active crossovers into DSET..	Thanks...	Melquiades Amplifier Forum	2	46059	07-22-2008

	Target	Threads for related reading	Most recent post in related threads	Forum	Replies	Views	Started
»	New	7788 tube mic pre design..	Read my leaps: Absorb-GEL...	Analog Playback Forum	38	373555	02-14-2006
»	New	The LCR RIAA correctors..	Inductive RIAA link...	Analog Playback Forum	57	721213	07-11-2007
»	New	The last phonocorrector: “End of Life" Phonostage..	Big cap banks...	Analog Playback Forum	310	1973243	11-13-2007
»	New	Another interesting corrector: Likhnitsky's RX correcto..	Again, the capacitors...	Analog Playback Forum	6	70742	02-10-2005
»	New	Where are our good phonostages?..	Omnigon Tubes...	Analog Playback Forum	61	665178	05-31-2004
»	New	Incorporating active crossovers into DSET..	Thanks...	Melquiades Amplifier Forum	2	46059	07-22-2008