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When Does Balanced Matter?

A typical stereo cartridge has 4 pins, L and R, + and -. The signal appears "across" the +/- pins.

How is that not suitable for balanced operation?

If you ground the - (or the +) the signal appears on the other pin.

That can have the interpretation of unbalanced.

Take your pick, for whether you have a differential or single-ended input to your phono preamp.

View attachment 12417

An MC cartridge is inherently a balanced device, as the impedance to ground is pretty much equal on both wires of each channel, there may be a tiny capacitative and inductive difference due to the routing of the wires from the coils, but this is small.
However, a MM cartridge isn't balanced because the coils are large, and the outside of the coil, nearest the screening can, has a different impedance to the inner part which is sheiled from the can by the bulk of the coils. Furthermore, in many cartridges, the screening can is connected to the -ve pin of one channel, usually the left, so inherently unbalancing the cartridge.

Nevertheless, it's a continuing mystery to me why in home HiFi, MC phono stages which are the only part of a system which would benefit from a balanced input, very seldom is.
S.
 
I'm not sure what the situation is in US homes, but here in the UK all mains sockets have an earth/ground pin, and some equipment has the chassis earthed for safety but the audio ground is not connected to safety earth, others have the three core mains cable with the chassis connected to safety earth, and audio ground connected to chassis, others again have double insulation which only has a two wire mains cable so no safety earth, with the audio ground usually connected to chassis, but otherwise floating from safety earth.

The result in many a system is a mixture which can only result in hum loops. If everything were double-insulated with no safety earth, then there would be no benefit to balanced operation, but with the mixture we have, balanced gets rid of an awful lot of problems. It won't eliminate hum loops, but reduce their effect to the point where it's not an issue.

By the way, I tend to use the term 'earth' for mains safety earth, and 'ground' to indicated the 'zero' for audio.

S.
 
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I'm not sure what the situation is in US homes, but here in the UK all mains sockets have an earth/ground pin, and some equipment has the chassis earthed for safety but the audio ground is not connected to safety earth, others have the three core mains cable with the chassis connected to safety earth, and audio ground connected to chassis, others again have double insulation which only has a two wire mains cable so no safety earth, with the audio ground usually connected to chassis, but otherwise floating from safety earth.

The result in many a system is a mixture which can only result in hum loops. If everything were double-insulated with no safety earth, then there would be no benefit to balanced operation, but with the mixture we have, balanced gets rid of an awful lot of problems. It won't eliminate hum loops, but reduce their effect to the point where it's not an issue.

By the way, I tend to use the term 'earth' for mains safety earth, and 'ground' to indicated the 'zero' for audio.

S.
In the US, all mains sockets in homes have also required an earth/ground pin for many decades, at least 50 years or more. However, electrical codes are local and may have adopted the newest standards unevenly by area. Older homes wired before that are exempt from the requirement, using only 2 pin hot-neutral connectors. But, they have gradually grown ever fewer in number as homes are renovated and rewired. However, connecting that "earth ground" to the earth itself via a ground rod or copper water pipes is not universally a requirement. Some electrical panels merely connect the earth grounds to the neutral at the electrical panel.
 
However, a MM cartridge isn't balanced because the coils are large, and the outside of the coil, nearest the screening can, has a different impedance to the inner part which is sheiled from the can by the bulk of the coils. Furthermore, in many cartridges, the screening can is connected to the -ve pin of one channel, usually the left, so inherently unbalancing the cartridge.

Nevertheless, it's a continuing mystery to me why in home HiFi, MC phono stages which are the only part of a system which would benefit from a balanced input, very seldom is.
S.
For the first part, as I mentioned before, the grounding straps on a few cartridges (e.g., Shure) can be easily cut. I did some measurements with several different MMs (Shure, Grado, Technics, Audio-Technica, Stanton) and didn't see any significant differences between either pin and ground. I can see how there might be a pF or two (my resolution was more like 10pF) worst-case difference, but still, you have a device that for all intents and purposes is balanced.

For the second part, installed base and standardization- QWERTY, if you will. I don't know for sure, but I'll guess based on some Amazon searches that 90+% of new turntables are USB, making all of this a moot point outside of our tiny hobbyist niche.
 
For the first part, as I mentioned before, the grounding straps on a few cartridges (e.g., Shure) can be easily cut. I did some measurements with several different MMs (Shure, Grado, Technics, Audio-Technica, Stanton) and didn't see any significant differences between either pin and ground. I can see how there might be a pF or two (my resolution was more like 10pF) worst-case difference, but still, you have a device that for all intents and purposes is balanced.

For the second part, installed base and standardization- QWERTY, if you will. I don't know for sure, but I'll guess based on some Amazon searches that 90+% of new turntables are USB, making all of this a moot point outside of our tiny hobbyist niche.

Grounding straps on Shure cartridges are easy to remove, others less so when the connection to the can is internal. As to the balance of an MM cartridge, I haven't measured the CMR, but I would be surprised if it was very good, given that one part of the coil is pretty much up against the can, which if the strap is removed has to be grounded through the arm, and the other end of the coil is buried inside. You may be right, but I would be surprised.

As to QWERTY, that I agree is the most common, but French keyboards are AZERTY, Croatian, Hungarian, Polish and German keyboards are QWERTZ.

S
.
 
An MC cartridge is inherently a balanced device, as the impedance to ground is pretty much equal on both wires of each channel, there may be a tiny capacitative and inductive difference due to the routing of the wires from the coils, but this is small.
However, a MM cartridge isn't balanced because the coils are large, and the outside of the coil, nearest the screening can, has a different impedance to the inner part which is sheiled from the can by the bulk of the coils. Furthermore, in many cartridges, the screening can is connected to the -ve pin of one channel, usually the left, so inherently unbalancing the cartridge.

Nevertheless, it's a continuing mystery to me why in home HiFi, MC phono stages which are the only part of a system which would benefit from a balanced input, very seldom is.
S.

Ditto...I have no idea why XLR phono connections aren't the norm.

I can get a DIN->XLR phono cable for my tonearm fairly easily. Sadly, there are very few, even in the high end, phono stages that accept XLR input. Weirdly, many have XLR out.

For me, personally, I use the DSP-based phono input on my Devialet, which has so far smacked the crap out of any standalone phono stage I've ever owned, both in terms of lack of noise and configurability.
 
For me, personally, I use the DSP-based phono input on my Devialet, which has so far smacked the crap out of any standalone phono stage I've ever owned, both in terms of lack of noise and configurability.
What cart are you using? I love the Devialet Phono stage for everything but noise, with a low output MC it hisses a little more than it could, but everything else about it more than makes up for it.
To my ears it's getting things right other stages mess up, I'd like to see in-depth measurements of it vs conventional to see what's going on.
 
What cart are you using? I love the Devialet Phono stage for everything but noise, with a low output MC it hisses a little more than it could, but everything else about it more than makes up for it.
To my ears it's getting things right other stages mess up, I'd like to see in-depth measurements of it vs conventional to see what's going on.

Nagaoka MP-500 MM/MP type cartridge, 3mV output.
 
What cart are you using? I love the Devialet Phono stage for everything but noise, with a low output MC it hisses a little more than it could, but everything else about it more than makes up for it.
To my ears it's getting things right other stages mess up, I'd like to see in-depth measurements of it vs conventional to see what's going on.

As far as measurements go, have you seen this?

https://www.stereophile.com/content/devialet-d-premier-da-integrated-amplifier-phono-stage
 
Please describe the "speaker cable effect" you measured , explain methodology and results and provide corroboration in literature and/or peer conducted experiments.

You are asking for a lot from someone else. Perhaps you could apply the same standards to your own posts.
 
You are asking for a lot from someone else. Perhaps you could apply the same standards to your own posts.
It was a rhetorical question. I kind of expected the answer that came: "I don't care...I'm not going to...no shit Sherlock". It can happen when foolishly one (me) asks about "cables effect" in audio. I am sorry, I should have known better. If I can answer any of your questions about my posts I'll try to do it diligently.
 
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There's lots of literature on the effect of speaker cables modifying frequency response. See Fred Davis and Dick Greiner's papers, for example. It seems to me that if frequency response is modified to an extent well above well-established audible thresholds, there's no need to beat the equine corpse any further.
 
One of the advantages of doing your own designs and builds is that you don't have to worry about mixing and matching random commercial equipment, you can do an optimized system design. My next step, after I get this fershlugginer SP10 Mk2 turntable working again, is to build an instrumentation amp directly into the turntable plinth using some very cool AD8229 chips I got from Scott Wurcer (late of Analog Devices).

Spendy little buggers. Mine's (http://www.ka-electronics.com/kaelectronics/Phono_Transfer_System/PT_System.htm) hanging off 5" of cable behind the plinth. Love to see how the AD8229 solution turns out.

Good to see you, Stuart.
 
I see you also got trapped by the three letter handle minimum. :cool:

Fortunately, my cost on these was zero. If you want a couple, let me know, I owe you a lot of favors.

Seems to be the default with most forum software. I've gotten a couple to change mine. Haven't asked here.

They'd need to come with a design as I'm fairly useless at that stuff. If you've time (and care) I can send you one of the units I'm using to measure as I'm curious. I've four plinth feet on my bench I need to send you anyway.
 
I'll tuck a copy of my schematic into the package.
 
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