• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Balanced turntable outputs - thoughts?

ConradH said:
There's a bit thread on this over at diyaudio. Opinions vary. Self thinks there's no reason to do it. It isn't really balanced unless the coils have center taps that can be grounded, and none do. I don't know if the loading resistors accomplish the same function. OTOH, some people seem to get benefits. Never tried it.
Click to expand...
I don't quite understand that. Microphones are balanced without having a center taps to ground. Or are you distinguishing between balanced and floating? Floating sources can be balanced but I agree that there's probably not a lot of advantage with short cables.
 
This is all very interesting. I have a friend who is a cable engineer (former IBM engineer) that was talking about going full balanced with his phono set-up recently. I was thinking he just meant from Phono pre-amp to the line stage, but now I get what he was talking about! Now I'm intrigued by this whole concept. Since the Phono Box RS is somewhat affordable, has anybody here used one of these running balanced out of the turntable? If so, what are your impressions of that set-up?
 
afora377 said:
I'm reposting this from elsewhere as these fora were recommended highly. So...

I have a fully balanced setup in my home system. I'm now thinking about adding a turntable to it (been thinking for many years now) - I'm ready now but the tts I looked at within my budget ($1000) are terminated with RCAs. Why the theory behind balanced connectors would not apply to the phono stage? Also, are there any turntables with factory balanced output without requiring me to re-solder wiring? Thanks!
Click to expand...

XLR outputs on a turntable is be the best way to go but you will need either a SUT or Phone preamp with XLR inputs. You will be glad you did!
 
JP, will you please go into detail about how your turntable has balanced outs. I want to do what you have done because of the fully balanced tubed preamp showing up soon.
Thanks
 
rothwellaudio said:
I don't quite understand that. Microphones are balanced without having a center taps to ground. Or are you distinguishing between balanced and floating? Floating sources can be balanced but I agree that there's probably not a lot of advantage with short cables.
Click to expand...

Yes, balanced and floating are two different conditions. To me, a balanced source implies that equal and opposite signals will always be presented. That's the only way to get the full benefits of a balanced connection. A floating phono cartridge doesn't do that, but you still may get some benefit if the loading is symmetrical. Last I read, Self, who I respect greatly, doesn't see any reason to do it. Another good source of grounding and interference info in the engineering world is Ott, who has several books on the topics. In one of them he diagrams all different single ended and differential connections and gives the noise rejection of each. That might give some illumination. I've always wondered why nobody runs an extra power wire up the arm and puts a micro circuit up there to buffer the signals, which could then have a true differential output if desired.
 
yonder: There's not that much magic to that - in fact it would already work ok with the stock cabling in many cases, provided that consequently follows the separate grounds scheme (i.e. one conductor each for left & right signal plus as well as for left & right signal minus (or ground in case of regular, unbalanced amplification) plus one conductor for chassis, tonearm and headshell ground together on a separate ground wire). But optimised cable and connector types for balanced use would of course be preferable. Only remaining problem in some cases (foremost in combination with MM & MI carts): Cart may have a conductive body/mounting frame, and that will often be additionally grounded to one of the two signal ground pins, which however in our case would be signal minuses instead - so this ground connection would obviously ideally have to be removed, so that the generator shell and mounting frame are only connected via headshell ground. Alternatively one would have to revert to isolated cart mounting, but with the disadvantage that the generator shell and mounting frame wouldn't really be grounded anymore. Balanced MM & MI setups appear to be pretty rare anyway, though...

A friend of mine also runs one balanced setup with one of his modded Lencos and an Omtec Antares Vsomething, which uses some odd sort of MiniDIN-like connectors for the balanced MC inputs. On my suggestion he uses that with a pair of very small RG196A/U coax cables per channel.

Greetings from Munich!

Manfred / lini
 
Or, put another way, cartridge typically has:
  • L+
  • L-
  • R+
  • R-
To make a differential connection, afaik, you need to bring out (for example) L+ to pin 2 and L- to pin 3 of the XLR connector.

  • L+ > left channel XLR pin 2
  • L- > left channel XLR pin 3
Repeat for right channel.
 
rothwellaudio said:
Yes, it is more immune to common mode noise. However, in practice the benefits might be doubtful because of the cable lengths involved (usually just 1 metre) and because turntables tend to be afflicted with non-common-mode noise where balanced cables won't help.
Click to expand...

As it has been already pointed, you only connect the adapter (pickup) to the amp, and the adapter is inherently isolated unless one chooses to connect one pin of each channel to the Chassis. Otherwise by its nature it is a balanced output, just connect it to balance pair, shield it if so desired (always good) and there you have it.
As for the insignificant length of 1m.....having restored many tube radios I've seen much smaller distances resulting in hum. Thing is you do not necessarily deal with low frequencies which, truthfully, indeed would have little influence on anything this length, but you could have high frequencies modulated with low ferequencies, and those will get picked up and then detected, much like in a radio detector, and then amplified and sounded.

Again, may or may not be significant.

In any case, do an experiment, and if you cannot hear any difference, whether because there is nothing to hear or because you in particular cannot hear it, it is not then worth for you to waste your time on it; if you could tell the difference, then yes - do the balanced connection.

I have it unbalanced (SE) from the turntable to my C22 - it is DEAD quiet the way it is.
 
ConradH said:
Yes, balanced and floating are two different conditions. To me, a balanced source implies that equal and opposite signals will always be presented. That's the only way to get the full benefits of a balanced connection. A floating phono cartridge doesn't do that, but you still may get some benefit if the loading is symmetrical. Last I read, Self, who I respect greatly, doesn't see any reason to do it.
Click to expand...
Balanced doesn't have to be floating, but floating is always balanced - at least unless you unbalance it by connecting one side to ground. Just like a dynamic microphone, a pickup cartridge's two output pins (per channel) could be connected to the two differential inputs of a balanced pre-amp - no need for any centre tap or any connection to ground or 0V. There will always be a equal and opposite signals presented to the balanced inputs by the opposite ends of the moving coil transducer. How could there not be?
Yes, I have a lot of respect for Douglas Self - he knows his stuff.
 
Morzh said:
As it has been already pointed, you only connect the adapter (pickup) to the amp, and the adapter is inherently isolated unless one chooses to connect one pin of each channel to the Chassis. Otherwise by its nature it is a balanced output, just connect it to balance pair, shield it if so desired (always good) and there you have it.
Click to expand...
I'm not sure if that comment was aimed at me or not - I can't see how it answers anything I said. Yes, of course the cartridge could be wired as a balanced source. I didn't dispute that.
Morzh said:
As for the insignificant length of 1m.....having restored many tube radios I've seen much smaller distances resulting in hum. Thing is you do not necessarily deal with low frequencies which, truthfully, indeed would have little influence on anything this length, but you could have high frequencies modulated with low ferequencies, and those will get picked up and then detected, much like in a radio detector, and then amplified and sounded.
Click to expand...
A metre interconnect can be made hum free without resorting to a balanced line. As you say, your system is unbalanced from turntable to pre-amp and is hum free.
 
Thanks for the thorough explanations Lini and Whoaru. My tonearm uses a 5 pin din connecter and figure I could get an extra to give it a try.
 
yonder said:
JP, will you please go into detail about how your turntable has balanced outs. I want to do what you have done because of the fully balanced tubed preamp showing up soon.
Thanks
Click to expand...

Pretty much as @lini said. I'm not worried about the wiring in my arms; the ground is separate to the arm tube so the cartridge coils can float, if the cartridge allows that. Not wanting to modify the connections at the arm base, I use Mogami balanced cable with + connected the center pin of the RCA and - connected to the "shield" of the RCA. I then break-out the cable shields through the connector boot to the ground/earth connection to the arm.

IMG_1058.jpg
 
JP said:
I've always found this topic amusing, in that the cartridge interface is generally the only interface in home audio where differential is truly beneficial, and yet it's the least likely place to find one.

I run all mine balanced; the common mode rejection affords me a good ~12dB less noise over SE.

**EDIT - I should add, that's with only 6" of cable from the arm to the gain stage.
Click to expand...

JP, what equipment are you using to measure noise? Tu
 
I record ~30 seconds on my DA-3000 with the arm in the rest and compare with your favorite software. I'm not measuring absolute noise as we know the theoretical max for a cartridge is around -70dB, rather I'm measuring balanced vs SE. In my case 60Hz dominates with a 180Hz component.
 
JP said:
Pretty much as @lini said. I'm not worried about the wiring in my arms; the ground is separate to the arm tube so the cartridge coils can float, if the cartridge allows that. Not wanting to modify the connections at the arm base, I use Mogami balanced cable with + connected the center pin of the RCA and - connected to the "shield" of the RCA. I then break-out the cable shields through the connector boot to the ground/earth connection to the arm.

View attachment 878397
Click to expand...

JP, this is excellent, would you recommend a trustworthy youtube video on how to rewire this myself?
Many thanks!
 
Also with Rega Planar 3 and Elys 3 can anybody confirm if that's wireable to balanced in principle? If i get a nod I might be ready to go and talk to our local retailer.
Thank you guys for all your thoughts!
 
JP, thanks for the very useful insight and will be putting all this to good use very soon.
Afora377, the preamp I'm most interested in is the BAT vk52se because everything is balanced. This all got started when I tried my rtr directly into my amp, bypassing the matchbox into an rca only preamp. Believe it when I say all clouds were cleared. This is a great topic with excellent information.
 
yonder said:
JP, thanks for the very useful insight and will be putting all this to good use very soon.
Afora377, the preamp I'm most interested in is the BAT vk52se because everything is balanced. This all got started when I tried my rtr directly into my amp, bypassing the matchbox into an rca only preamp. Believe it when I say all clouds were cleared. This is a great topic with excellent information.
Click to expand...


It is interesting you mention BAT as there were talking points from Victor in the link I provided earlier, that seemed to say balanced TT connection isn't a big deal. Victor is a BAT bigwig.
 
You must log in or register to reply here.
Back
Top Bottom