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Dedicated phono-pre for MM only?

Hi All,
the subject of phono-pres, specifically 'adapted' to MM came up in some related postings.

IF, and only if, MMs are much to ones liking --- why spend your buck on some 'halve backed' 60dB plus, MC gain requirement, stage? Why not consider put the $$$ into a TOP 40dB gain stage of either SS or tube?

Raul had more thoughs on the subject as he mentioned before, and might share, why he knows that a TOP MM compared to MC stage circuit requirement might NOT be -one suit fits all-.

There could even be a nice argument to fit a tube gain stage only into an otherwise SS only system!?

Again, the $buck saved on the 20dB plus circuitry could be translated into the BEST circuit for an MM.
I realise, that most such stages were simply fitted inside some older TOP pre-amps, (e.g. Jadis...).
I have not come across a **dedicated** , current 40dB stage neither in nor outside a pre-amp.

Thank you,
Axel
axelwahl
lewm
13,150 posts
 
Axel, You wrote:
"As to hum caused by 'unbalanced' MM cart output impedance. Well, I think that the more expensive carts we are speaking of (Raul mostly), those have always excellent channel balance, often better than more main-stream MCs with an e.g. <1.5dB spec."

I am pretty sure that Kirkus was not referring to differences between channels in his comments on the impedance properties of MM cartridges. I think he was referring to the generally much higher and more reactive impedance of MMs and the fact that these parameters may not be identical for each phase of the output in a SINGLE channel, using a balanced circuit. This creates a noise that cannot be cancelled by the balanced topology and is instead amplified. Channel balance has nothing to do with it. If I am full of baloney, perhaps Kirkus will correct me.
axelwahl OP
788 posts
 
Lewm,
of course you are right! We are talking one channel at a time, sorry.
>>> ... he was referring to the generally much higher and more reactive impedance of MMs and the fact that these parameters may not be identical for each phase of the output in a SINGLE channel, using a balanced circuit <<<

I see, but then this would be a GENERAL issue with every kind of MM?!
They ALL have a much higher reactive component than any MC.

Now why do you think, do I have NO hum what so ever with a FULLY opened pre, going balanced into a balanced phono-line-pre?

Maybe the answer lies with ML's balanced design then?

Axel
Ag insider logo xs@2x
rauliruegas
13,101 posts
 
Dear Axel: ++++ " Balanced = Hyper-clean and dynamic vs. unbalanced = naturalness, less clean, and better harmonic completeness " +++++

IMHO I think there is no trade off but different quality level designs, that's all.

Regards and enjoy the music,
Raul.
axelwahl OP
788 posts
 
Well Raul,
my own findings really concur with Martin Colloms', but so be it :-)
A.
kirkus
502 posts
 
I think he was referring to the generally much higher and more reactive impedance of MMs and the fact that these parameters may not be identical for each phase of the output in a SINGLE channel, using a balanced circuit. This creates a noise that cannot be cancelled by the balanced topology and is instead amplified. Channel balance has nothing to do with it. If I am full of baloney, perhaps Kirkus will correct me.
Actually Lewm, you got it exactly.
Now why do you think, do I have NO hum what so ever with a FULLY opened pre, going balanced into a balanced phono-line-pre?
Well I'd say that you happen to have good synergy between the cartridge, tonearm wiring, and preamp input stage, at least in the sense that its noise-rejection happens to be sufficient to completely eliminate interference from the particular amount of mains-frequency magnetic flux to which it is being subjected.

Now whether or not the ML engineers anticipated/designed for a similar level of performance in other situations or environments, I have no idea . . . but for yours, they got it right.
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