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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
pryso
1,936 posts
 
Hi Lew. I can solder but have no ability to design circuits.

I previously used a Threshold FET-10 (a unit I still endorse and a great bargain at $7-800) and an audio buddy built a regulated power supply for that for me. I changed to the JLTi mainly because it offers external gain and loading selection, but when he converted the RPS to my JLTi (which started life with a wall-wart), it offered some audible benefits as well. So yes it is custom and no I don't have a schematic.

The same friend with the EA phono stage just picked up an AT 170(something), one high on Raul's list.

Good luck in finding a few of these "hidden gems".
tketcham
291 posts
 
Hi, Axel. Given the replies to the original post, I'll let my first question stand: To what level of "top" phono stage are you referring?

The discussion seems to be about phono stages in the range of $1000 to $2000 USD and thus, the Graham Slee Reflex is an example of what you were asking about. (It's clearly designed for MM cartridges.) The Jadis phono stage reference was a bit misleading. Or is the Jadis the "top" level you were originally asking about?

Tom
fap
32 posts
 
G'day all, this quite simple to build design is amazing! This is my preferred MM phono preamp. http://sound.westhost.com/project06.htm I have built several of these. Regards, Fap.
axelwahl OP
788 posts
 
Hi Tketcham
>>> To what level of "top" phono stage are you referring? <<<
Simply the best, - second best I already have.

>>> ... is the Jadis the "top" level you were originally asking about? <<<
Raul got this, he is thinking "Essential 3160"...
The Jadis is a still current, just as an example, that's why I mentioned it.
There 'where' other great 40dB stages but ALL gone by now.
I'm really NOT asking about any 'wall-wart' power supply pre's. I thought that was implied. Why even bother to ask then? Like: "Go get one (any one) and call it a day..." :-)
Greetings,
Axel
PS: There are squat (current) 'top' 40dB tube phono-pres out there, and that is already something useful to know. Makes it a proposition to build one's own... a new market gap?
axelwahl OP
788 posts
 
Hi Fap, Tketcham
>>> ..this quite simple to build design is amazing! <<<

OP-Amps, not part of the spec I'm thinking of.

I realize it's maybe time to go into more detail.
Also, the 'Jadis' would be single-ended also not part of the idea, good as it my be.

Rough spec. would be:

- 40dB
- tube gain stage (max. to gain stages)
- 1 JFET gain-stage? Maybe, to get minimum tube-rush/noise
- or e.g. Lundal trannies to get the first 20dB?
- shunt regulated power supply
- differential circuit (XLR out-puts, differential wired RCA inputs)
- no volume control
- floating RIAA (between + and - of the differential circuit)
- one box design (if at all possible, by use of good screening)
- No PCBs, screened silver wire for internal wiring.
- Good,e.g. WBT connectors

That should cover the basics. What tubes to use, trannie, resistors (Tantalum, or?) is dependent on the circuit design and implementation.

Greetings,
Axel

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