My question is: why are all the output sockets I see in all turntable phones all single-ended? Why are they not balanced?
I was under the impression that if
Yet, I find all turntables fitted with RCA sockets. None of them (that I've seen) are balanced. (I'm sure there are a few, but that's not my point.) Why? Is my understanding of what constitutes a balanced signal incorrect? Is there some other reason why all turntables and phono preamp inputs in the world do not do balanced connections?
I tried searching, but couldn't find anything which discusses this. Maybe my searching was inept.
I was under the impression that if
- you have a floating differential signal,
- the signal amplitude is low, thus making it vulnerable to noise pickup
Yet, I find all turntables fitted with RCA sockets. None of them (that I've seen) are balanced. (I'm sure there are a few, but that's not my point.) Why? Is my understanding of what constitutes a balanced signal incorrect? Is there some other reason why all turntables and phono preamp inputs in the world do not do balanced connections?
I tried searching, but couldn't find anything which discusses this. Maybe my searching was inept.
You will find that the ground connection of the RCA plug is floating wrt the earth wire, and that the phono input of many preamps has an AC coupled ground from the RCA socket.
Yes, I've seen that earth lug and wire, but is that connected to the two leads which emerge from the cartridge in any way? If not, then isn't the cartridge output still a pure differential output, and shouldn't it benefit from a balanced interconnect? The earth lug can then just connect to the shield of the balanced cable or something, remaining electrically isolated from the signal.
With little DIY you can modify your turntable and have balanced outputs.
See how it is done in this article.
Tube CAD Journal: Tube balanced phono stage, July 1999
Why manufacturers don`t do it? Probably costs. Balanced phono preamp, almost double the components.
See how it is done in this article.
Tube CAD Journal: Tube balanced phono stage, July 1999
Why manufacturers don`t do it? Probably costs. Balanced phono preamp, almost double the components.
Remember that almost any MM cartridge has it's case grounded through one channel's ground pin (either the green or the blue one). In this case balanced cabling isn't impossible, but requires micro surgery (cutting the connection, provide a fifth wire to ground the case).
Best regards!
Best regards!
Thanks, but that's not my aim right now. I just want to know why turntables don't come with XLR by default, the way mics do. Is there a technical reason?
Even today, with solid state opamps? I am not asking for a totally balanced internal circuit of the phono preamp (I am not sure there is anything to be gained from it, though some audiophiles will disagree). I'm just asking about the interconnects and the interfaces. I am not seeing XLR factory fitted on even $1,000 turntables. If my understanding is correct, there is absolutely no cost impact fitting an XLR on a turntable, because it's just the connector shape and wiring which will change -- there will be no electronics added.
This is the kind of thing I wanted to learn. Thanks. I didn't know that the body ground is connected to one of the channels' signal ground.
This will be very difficult to eliminate, right? Will we have to open the cartridge to cut this? Seems such a bad idea to do the grounding like this. Why does the cartridge industry "corrupt" the signal by connecting it with the cartridge body this way? I'm using the word "industry" because every MM cartridge is wired this way...?
I'm not too sure that any cart has a grounded case. There are even some carts with plastic bodies and no visible ground connections.
If you've got a cart with this connection, you don't need (and want!) to open and destroy it. Just get a microscope or a very good magnifying lens and cut the connection that is visible at the backside. If the case isn't grounded by the metal tonearm also, you'll need to solder a ground wire to the case or better the connector that hopefully you've remained long enough.
Best regards!
If you've got a cart with this connection, you don't need (and want!) to open and destroy it. Just get a microscope or a very good magnifying lens and cut the connection that is visible at the backside. If the case isn't grounded by the metal tonearm also, you'll need to solder a ground wire to the case or better the connector that hopefully you've remained long enough.
Best regards!
I could be wrong but I thought that the reason why most cartridges are wired single ended is because the i/p stage is single ended for noise and perhaps cost reasons.
Except for transformer i/p differential i/ps are potentially 3db (or is it 6db) noisier because you are effectively doubling the i/p connections. I remember seeing mention of this in one of Erno Borbely's designs but it didnt stop him from using a balanced i/p.
Except for transformer i/p differential i/ps are potentially 3db (or is it 6db) noisier because you are effectively doubling the i/p connections. I remember seeing mention of this in one of Erno Borbely's designs but it didnt stop him from using a balanced i/p.
The "ground strap" on cartridges is removable by the installer if needed to eliminate any ground loops that may happen, depending on the turntable wiring setup.
For instance, if a Pickering cartridge was mounted on a metal headshell that was already grounded via a seperate wire to the amp chassis.
The Pickering's metal body would ground itself via the screws to the metal headshell.
But an Audio Technica with a plastic outer case would need that strap in the same headshell.
All MMs have a grounded case. Just look at the back and you can see the tab connecting to one of the ground pins, which can be lifted but is a pain. Early Philips MMs had 5 pins so you could control grounding.
Confession time. All my MM and MC stages are balanced. Mainly because I can rather than any huge technical benefit. The cartridge, lacking a centre tap is not truly differential. Any stray fields picked up by the coils in the cartridge (which make quite a good antenna) are not cancelled out as they are not normally common mode. But you might get a few dB (I have seen 10 recorded) reduction in noise pickup.
Balanced interconnect with a good screen is readily available and that is an attraction for me as it removes all cable angst and I can use the same cable across the system with no worries. Also I am carp at properly terminating coax into RCAs so chose the easier option.
You should look at many things considering their history.
Originally record players where installed in radio consoles that used tubes.
Consumer goods did not use balanced lines. Those were reserved for telephone lines and large PA systems. Balancing was accomplished, into and out of the equipment rack using transformers.
Compatibility demanded that various pieces of equipment could work together, especially in the consumer industry.
One of the best examples (both NTSC and PAL) are the necessary engineering contortions to fit colour into the existing B&W TV signal. It would have been better, but far to expensive, to start fresh with a new standard. E
Originally record players where installed in radio consoles that used tubes.
Consumer goods did not use balanced lines. Those were reserved for telephone lines and large PA systems. Balancing was accomplished, into and out of the equipment rack using transformers.
Compatibility demanded that various pieces of equipment could work together, especially in the consumer industry.
One of the best examples (both NTSC and PAL) are the necessary engineering contortions to fit colour into the existing B&W TV signal. It would have been better, but far to expensive, to start fresh with a new standard. E
Hey TCPIP, I modified my MM phono years ago to balanced. Had to separate the earthed "centre tap" of the L and R coils where the tone arm terminates under the turntable. So that 5 connections go out to my amp. L+, L-, Earth, R+ and R-. The earth wire simply connects both chassis together.
Now quiet like a mouse and I couldn't be happier.
Now quiet like a mouse and I couldn't be happier.
Backward compatibility with different cartridges, NonMetalic/Metalic Tonearms, Non-DIYers user friendly or already having unbalanced Phono Preamplifier or Integrated Amplifier may be the reasons.
Thanks, all. A lot of valuable perspective, including historical reasons. This is what I wanted to learn.
I wonder how difficult it will be for a DIYer to cut the cartridge case grounding and try balanced connections to a balanced preamp. But I now remember that a differential input is a bit more noisy than single-ended, all things considered. So, it's a question of input noise vs common-mode noise picked up by the cable.
I wonder how difficult it will be for a DIYer to cut the cartridge case grounding and try balanced connections to a balanced preamp. But I now remember that a differential input is a bit more noisy than single-ended, all things considered. So, it's a question of input noise vs common-mode noise picked up by the cable.
Interestingly, although voltage mode differential inputs are noisier, current mode inputs are quieter when diff. Current mode MC stages are back in vogue at the moment but current mode MM is a rather esoteric beast for a number of reasons and I wouldn't recommend that unless you limit yourself to AT and Ortofon cartridges.