cabsvrt - please take it down a notch and be civil. Calling the participants in this thread "fools" and *******???? does not advance your case and is not in the spirit of the forum.
It was mentioned in a private discussion, so no names.
However, if I were shopping for a cartridge I would specifically ask the dealer if the cartridge I was interested in could be run balanced. Barring that, the importer should be honest in telling you.
Putting in some series resistance (this is important!) you could measure this with a cheap ohm-meter.
I've never run a balanced phono set-up, but it's something that I've been leaning to for a long time. Guess I'm going to have to sell off the Deccas!
D2TG;
What is the price of their "buy up" cartridge? Most of us Diy either for fun or for cost.........most likely both, which would eliminate the Ultra pricey MCs like ZYX or Koetsu products. $15,000 for a Cartridge???
From the Pearl 2 thread;
Originally Posted by orpheus
"There don't seem to be a lot of true balanced designs for phono preamps available to the DIY community, it must be a difficult to design and implement."
Papa said.
"The difficulty is that they don't make balanced cartridges, and
without a center-tap ground, the problems with input common
mode noise render it impractical unless you use an input
transformer."
So, help me understand this please.
The input common mode is the neutral from each moving coil which is tied to the grounded head shell, which is then in turn the outside conductor of a RCA jack. So far so good, Right?
OK, an Input transformer would then separate the L&R grounds from each other and provide balanced outputs. Is that right?
Is the input transformer the same as a step up transformer? Could it be?
Help me to understand. No sarcasm intended on my part.
Ron
Ron
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The input transformer is very often a step-up as well (see my recent article on a vacuum tube phono stage). But I have to, on this rare occasion, disagree with Nelson, if I understand correctly what he's saying. The phono cartridge does not need to be centertapped, nor does the transformer. In fact, that would be detrimental. As long as the grounds (or - leads or whatever they're called) of each channel of the cartridge are separate and not connected to the cartridge metal case, the cartridge will be balanced. When used in conjunction with an input transformer or active stage with high common-mode rejection, the noise pickup from the connections will be minimized.
If the cartridge connects those grounds together internally, this won't work- you can either use a different cartridge, or if you're brave, you can do some surgery and separate them yourself.
If the cartridge connects those grounds together internally, this won't work- you can either use a different cartridge, or if you're brave, you can do some surgery and separate them yourself.
I could be wrong, but I'm probably not. A cartridge is by it's nature a balanced source. This is for any cartridge with four pins. Is there any other kind?.
Turning a tonearms single ended RCA cable connector into a balanced one is not difficult. Buy the least expensive plastic connector. Do not buy the metal ones (Cardas), do not buy the gold plated ones.
Pin 1 is ground. This connects to the ground of the tonearm/headshell/cable outer shielding.
Pin 2 is hot. This is from the +ve lead of the cartridge. Obviously there is a right and a left channel, each going to it's own connector.
Pin 3 is neutral. This is from the -ve lead of the cartridge, one per connector.
It is that simple.
When using a step up transformer you obviously need another set of XLR/Neutrik connectors; the tranny's internal ground is connected to one connector, and a seperate wire needs to be added which is connected to the casing of the tranny and subsequently to the other connector, pin 1.
Turning a tonearms single ended RCA cable connector into a balanced one is not difficult. Buy the least expensive plastic connector. Do not buy the metal ones (Cardas), do not buy the gold plated ones.
Pin 1 is ground. This connects to the ground of the tonearm/headshell/cable outer shielding.
Pin 2 is hot. This is from the +ve lead of the cartridge. Obviously there is a right and a left channel, each going to it's own connector.
Pin 3 is neutral. This is from the -ve lead of the cartridge, one per connector.
It is that simple.
When using a step up transformer you obviously need another set of XLR/Neutrik connectors; the tranny's internal ground is connected to one connector, and a seperate wire needs to be added which is connected to the casing of the tranny and subsequently to the other connector, pin 1.
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I have two carts with 3 pins, and one cart with two pins.
I think what you're saying goes in contradiction to what SY has suggested.
In any case, you could always just leave the connectors as RCA's, with barrels floating and a separate ground. I guess this just wouldn't look as cool.
I actually like cardas connectors. They have good 'feel' as I plug and unplug and mess around with my system. The last thing I want to do is spend time wiggling connectors. I've given serious thought to moving to BNC. (I'd do LEMO, but they make cardas look cheap).
OK, you lost me there. Why not?
A normal balanced-input pre-amp (without transformer) would have some input impedance between each input (i.e. inverting and non-inverting) and earth.
Do you not have any DC path to earth from the cartridge anywhere?
Or is this for when the "-" pins of the cartridge are grounded to the headshell?
Center Tap of a transformer winding.
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It would have to be mono, then?
The only three pin ones I know of are Deccas, and the wires are the least of the problem.
True and gloriously true. However, you haven't heard phono playback until you've heard a Decca in its glory. Trouble is, owning a Decca is 9/10ths frustration, 1/10 glory.
You're talking to a former owner of a 4RC. Lovely sound, colored but fun, but seeing the little curls of vinyl being shaved off was alarming.
godfrey:
http://www.diyaudio.com/forums/tubes-valves/92766-l-pad-instead-h-pad.html#post1091266
Besides the issue of noise injection from ground that EC8010 mentioned, there's also the imperfection of center-taps; you're essentially degrading the CMR to the accuracy of where that tap is paced in the winding.
Ron , koetsu ?
simple,buy 10year old fom ebay like me
As of right now, Fleabay has a (headshell only) for the ridiculously cheap price of $350 and cartridge at $1759.99, a bit steep for my budget, but thanks anyway.
I was thinking more like a new Denon R103. $305
Ron
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