Hi team,
I want to do a little experiment for my own interest.
I'd like to see how a balanced connection from an MC phono cartridge compares to an unbalanced connection when picking up noise.
I figure I can get an old, broken MC cart and then wire the right side to an XLR cable and the left side to another XLR but drop one of the pins. I could then run the cable over a transformer or similar and see what I hear out the other end.
My question is - how do I go about connecting grounds here? Or is my experiment doomed to fail?
Thanks!
I want to do a little experiment for my own interest.
I'd like to see how a balanced connection from an MC phono cartridge compares to an unbalanced connection when picking up noise.
I figure I can get an old, broken MC cart and then wire the right side to an XLR cable and the left side to another XLR but drop one of the pins. I could then run the cable over a transformer or similar and see what I hear out the other end.
My question is - how do I go about connecting grounds here? Or is my experiment doomed to fail?
Thanks!
Don't forget, if the cause of the noise(hum) is a field being induced into the cartridge coil, the induced voltage will look like signal. Some cartridges seem to be more susceptible to magnetic fields. I've got a grado and the hum varies depending on where on the record the cart is located. I am thinking of getting an AT just to see if it is better. After I got the grado and noticed the problem, I saw online reports that grado's are bad about picking up stray fields.
Doesn't seem like you have noise issues, you just want to try a balanced topology...?
The MC (like MM) output is single-ended, so not balanced. But connecting the coil's output directly to a transformer will keep the signal isolated and floating which may or may not be a benefit. The transformer may have a center tapped secondary giving balanced signals on the sec side for the rest of the signal path, or some portion of it.
The MC (like MM) output is single-ended, so not balanced. But connecting the coil's output directly to a transformer will keep the signal isolated and floating which may or may not be a benefit. The transformer may have a center tapped secondary giving balanced signals on the sec side for the rest of the signal path, or some portion of it.
Yeah, no noise issues, I just want to experiment with an old dead (generator is fine, just the cantilever is damaged) Supex MC I have and see how less prone it is to noise from switch mode PSU's in super close proximity with a balanced connection. I thought if I could do it with a spare loom then I wouldn't need to remove my 2M Black from my turntable and then set it up again after I was satisfied.
FYI as there seems to be some confusion, MC carts are inherently balanced by design. There is usually a ground wire on the tonearm, I was wondering if not having this (as there would be no tonearm) would throw off the experiment at all.
Sounds like it would be easier to just do it on a turntable and swap between a balanced and single ended DIN cable (going into my phono stage, which has both balanced and single ended inputs obviously).
FYI as there seems to be some confusion, MC carts are inherently balanced by design. There is usually a ground wire on the tonearm, I was wondering if not having this (as there would be no tonearm) would throw off the experiment at all.
Sounds like it would be easier to just do it on a turntable and swap between a balanced and single ended DIN cable (going into my phono stage, which has both balanced and single ended inputs obviously).
I don't know many MC cartridges at all, but don't they just have the four connectors? L+, L-, R+, and R-? The x+ is usually used as 'signal' and the x- is then the 'signal return' aka 'GND'. If they are balanced through ground wire, then they will no longer be stereo since there is only one GND and both left and right is connected.
Sorry, but they are single ended.
Removing the GND is removing the shield, and you really don't want that if you are worried about switch mode psu noise, which is hf and definitely needs shields.
Sorry, but they are single ended.
Removing the GND is removing the shield, and you really don't want that if you are worried about switch mode psu noise, which is hf and definitely needs shields.
@SemperFi I don't pretend to know enough to argue this (if I did know then I wouldn't have had to ask the question in the first place!), but the Internet in general tends to disagree with you here (including companies like Pro-Ject and other threads on this very forum). I believe that you are describing how a MM cartridge is wired.
My background is mostly pro audio, but a balanced DI just needs the Up and Down signal from either end of the step-down transformer and then a totally independent ground. I believe an MC is the same here (one side of an MM is balanced, the other isn't as you described), I just don't know how to wire one side single-ended nor if the ground is actually necessary.
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My background is mostly pro audio, but a balanced DI just needs the Up and Down signal from either end of the step-down transformer and then a totally independent ground. I believe an MC is the same here (one side of an MM is balanced, the other isn't as you described), I just don't know how to wire one side single-ended nor if the ground is actually necessary.
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Can't remember the source for this file, but I think it covers it. (Possibly https://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=7&t=753&start=34). Well worth exploring both for some MMs and MC
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Can't remember the source for this file, but I think it covers it. (Possibly https://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=7&t=753&start=34). Well worth exploring both for some MMs and MC
I did that diagram and produce both MC and MM balanced input flat preamps. https://ka-electronics.com/shop/index.php?route=product/category&path=66
Here's a comparison of an MM cart terminated balanced and unbalanced. https://proaudiodesignforum.com/forum/php/viewtopic.php?p=10312&hilit=balanced#p10312
The unbalanced blue trace between 1-10 kHz shows a "hump" in noise where the cart is highly inductive.
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BTW every MM cart I have be it AT, Shure or Stanton can have the shell grounding clip that's attached to one of the "-" terminals removed. It's press-fit between the plastic terminal frame and the metal case. A fine point scribe or sewing needle can be used to lift it off the terminal. Its designed to be removed and they can also be reinstalled. This has to be done or one channel will not work properly.
Balanced operation requires shielded twisted pair. I've never had much luck using single conductor coaxial-shielded leads though I've been made aware that some RCA-terminated leads are actually STP and terminated in an RCA which will likely be wired balanced all the way from the cart up to the RCA. Most people, myself included, have been reluctant to cut them and simply wire a new harness to the arm base.
Modifying as an example an SL-1200 for balanced is super-simple. I did my ADC arm and posted it on LatheTrolls. https://www.lathetrolls.com/viewtopic.php?f=9&t=5876
Balanced operation requires shielded twisted pair. I've never had much luck using single conductor coaxial-shielded leads though I've been made aware that some RCA-terminated leads are actually STP and terminated in an RCA which will likely be wired balanced all the way from the cart up to the RCA. Most people, myself included, have been reluctant to cut them and simply wire a new harness to the arm base.
Modifying as an example an SL-1200 for balanced is super-simple. I did my ADC arm and posted it on LatheTrolls. https://www.lathetrolls.com/viewtopic.php?f=9&t=5876
I did that diagram and produce both MC and MM balanced input flat preamps. https://ka-electronics.com/shop/index.php?route=product/category&path=66
Here's a comparison of an MM cart terminated balanced and unbalanced. https://proaudiodesignforum.com/forum/php/viewtopic.php?p=10312&hilit=balanced#p10312
The unbalanced blue trace between 1-10 kHz shows a "hump" in noise where the cart is highly inductive.
Hi, thanks for making the illustration - (I kept a local copy for reference, forgot the source). I'm familiar with your phono transfer system, "the Wayne", as it's called by my friends
. Really attractive, have to say.I recently aquired my first differential input balanced phono stage, and for me it's easy to detect a big audible, improvement regarding noise and gain. I've measured it, but didn't make data sets for comparisons (yet, at least).
I've made some experiences with MMs and grounding: there are variations in design and material choice for carts, headshells and tonearms. Some are conductive, and some are not. Audio Technica MM carts uses both plastic and metal mounting brackets, which makes a difference, depending on headshell/tonearm grounding scheme. For me, metal mountingbrackets requires the "shield clip" to be removed, if a conductive/grounded headshell/tonearm is used to avoid GND loop (e.g. AT120Ea vs AT150Mlx).
I have some carts which may have GND/shield connected internally, and those I haven't tested yet.
It would be great to see these measurements! A hunch that I have is that you should see common mode noise being rejected and CMRR improvement as seen in @mediatechnology 's spectrum chart. (This "hunch" is based on some papers, standards, and presentations at AES by Bill Whitlock and the fact that the aforementioned "balanced flat input" preamps use the
THAT 1240 chip which is based on his "InGenius" IC transformer-less common-mode balanced impedance design). Important when using balanced to pay attention to the interconnects and shielding of the cables too.