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Source for Balanced-to-Unbalanced Cables? Effects Pedals, Units & Accessories
Old 1 week ago
  #1
Gear Maniac
 
Lady Gaia's Avatar
 

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Source for Balanced-to-Unbalanced Cables?

I'm finally getting around to upgrading my rather outdated studio setup, and that means bridging the worlds of older and modern gear. All I/O in the audio interface (a MotU 828es) is balanced, while much of the outboard gear I'd like to hang onto relies on unbalanced connections.

It all works with unbalanced cables. Audio coming from outboard gear with an unbalanced cable is, electrically speaking, the right thing to do. Going the other way is more problematic. It means I'm shorting the ring and sleeve of the balanced outputs together which is not exactly optimal since the output isn't cross-coupled. Indeed, the MotU user manual provides perfectly reasonable guidance noting exactly this situation:
Quarter-inch analog outputs are not cross-coupled. Therefore, when connecting them to an unbalanced input, use a TRS plug with the ring disconnected. Not floating the negative terminal will short it to the sleeve ground and cause distortion.
Clear and unambiguous, but where does one actually get such a cable? For all the zillions of different cables you can order online, I can't actually seem to find one that matches the description. Sure, I can order TRS plugs and do surgery on existing unbalanced cables but this seems like a recognizable need that could be better served by someone who doesn't dig out a soldering iron once a decade.

Insights, anyone?
Old 1 week ago
  #2
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If you don't want to make them yourself, Redco quotes around $10 for custom, 3-foot TRS to TS cables. (Amphenol nickel-nickel connectors and Redco mini mic cable). There is a place for special instructions where you can specify how you want it wired. There is a large variety of connectors and wire options. The Amphenol and Redco was just one example (and what I use).

Redco Audio - Audio/Video Supplies and Accessories, Custom Cables and Panels, and more

Redco Audio - Audio/Video Supplies and Accessories, Custom Cables and Panels, and more

A good reference for different wiring options is: Sound System Interconnection
Old 1 week ago
  #3
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Thread Starter
Quote:
Originally Posted by Richard Crowley View Post
If you don't want to make them yourself, Redco quotes around $10 for custom, 3-foot TRS to TS cables.
Thank you! That’s exactly the kind of recommendation I was looking for. On first glance it looks like there’s no way to choose a TRS end for a 2-conductor cable, but I understand why they want to catch that as a mistake normally. I’m sure I can work with them to get what I want.

Quote:
A good reference for different wiring options is: Sound System Interconnection
Indeed! I’ve had their PDF handy for reference as I started exploring my options.
Old 1 week ago
  #4
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Quote:
Originally Posted by Lady Gaia View Post
On first glance it looks like there’s no way to choose a TRS end for a 2-conductor cable, but I understand why they want to catch that as a mistake normally. I’m sure I can work with them to get what I want.
It is probably better to use 2-conductor shielded ("mic-cable") even for a cable with unbalanced TS at one end. Better to "float" the shield at the TS end and use the two inner conductors to connect to T and S at the TS end, and to T and S also at the TRS end. And also the shield to Sleeve at the TRS end.
Old 1 week ago
  #5
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That’s a perfectly reasonable suggestion, and sounds like the right way to go (much better than the dubious suggestions I’ve seen about tying the TS ground to the TRS ring to avoid the 3dB signal loss implied by losing the ground/cold differential - deliberately tying a signal to ground strikes me as asking for trouble!)
Old 1 week ago
  #6
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Quote:
Originally Posted by Lady Gaia View Post
That’s a perfectly reasonable suggestion, and sounds like the right way to go (much better than the dubious suggestions I’ve seen about tying the TS ground to the TRS ring to avoid the 3dB signal loss implied by losing the ground/cold differential - deliberately tying a signal to ground strikes me as asking for trouble!)
Huh? "tying the TS ground to the TRS ring" is EXACTLY shorting the ring (- side) to ground. Precisely what they recommended against. Analyze any advice (even from me! ) before following it.
Old 1 week ago
  #7
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Quote:
Originally Posted by Richard Crowley View Post
Huh?
Hah! I may have been a little too brief in my last response, because I think (hope?) we're in complete agreement.

Quote:
"tying the TS ground to the TRS ring" is EXACTLY shorting the ring (- side) to ground. Precisely what they recommended against. Analyze any advice (even from me! ) before following it.
I was citing this configuration as an example of bad advice I've seen elsewhere, not as something you recommended. I'm usually pretty good at working through things from first principles and reading background as necessary to understand a concept.

Here's the configuration I believe you suggest, which matches my understanding of the generally agreed upon approach as adapted to a three-conductor shielded cable:
  • Tip of TRS --(red wire)-> Tip of TS
  • Ring of TRS floating
  • Sleeve of TRS --(white wire)-> Sleeve of TS
  • Shield tied to sleeve on TRS end only
Old 1 week ago
  #8
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Perfect. You got it!

Remember to MARK that connector/cable because it won't work in most other balanced TRS inputs OR outputs.

Last edited by Richard Crowley; 1 week ago at 05:33 PM..
Old 1 week ago
  #9
Gear Maniac
 
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Absolutely. I was hoping to use a different cable color, but I didn’t see color options for any of the cable stock I was interested in. Some kind of collar ring near the TRS end to indicate its unique purpose should do the trick. Thanks again for pointing me at Redco and offering your thoughts in general.
Old 1 week ago
  #10
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I use white shrink wrap around the connectors so I can write on with indelible markers. high visibility and also easy to cut off and replace. if that's any help to anyone.
Old 1 week ago
  #11
Gear Maniac
 

For permanent markings it's also possible to use something like Brother EZ Tape thermotransfer labels and cover them with transparent heat shrink tubing (preferably a good quality like for example Raychem/Tyco RNF-3000).

There are also printers for shrink tube but it's more expensive.

There are many different systems to mark cables; I wanted to post the link of a French company with interesting products as example of a wide range of cable marking systems used in the industry but their website is such a mess that I give up, I simply want a basic PDF catalog link, not some flash animated flip catalogs nor other annoyances like required registration or so).
Elastic marking sleves I've no experience with and they require special tools (sort of 3-prong pliers) to install them.
Old 1 week ago
  #12
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Several 2-conductor, shielded cables are available from Redco in colors other than black or gray.
It seems reasonable to assume that if you select one of those cables, you can specify which color you want.

Canare L-2B2AT | Redco Audio available in black or gray
Gepco XB201M | Redco Audio available in 5 colors
Lake AVB221A Single Pair 22awg Install Cable | Redco Audio available in 8 colors *
Mogami W2549 | Redco Audio available in 5 colors
Mogami W2944 | Redco Audio available in 10 colors
https://www.redco.com/Mogami-W3031.html available in black or white
https://www.redco.com/Redco-LO-Z1-Mi...al-Shield.html available in 4 colors

* Note that "install cable" is typically pretty stiff and is designed for more fixed applications inside racks, behind gear, etc..

I used the Redco Mic-Line cable recently to make several dozen XLR and XLR/TRS patch cables. It is nice stuff.
Old 1 week ago
  #13
Gear Maniac
 
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Thread Starter
Quote:
Originally Posted by Richard Crowley View Post
Several 2-conductor, shielded cables are available from Redco in colors other than black or gray.
The custom cable configuration tool doesn't expose color options, but it can't hurt to try. After measuring a few of my existing patch cables both for length and diameter I've taken the plunge with the LO-Z1 cable stock. For any who might find this thread in future, the specific configuration can be recalled with this link and these instructions:
Use the red LO-Z1 cable if possible.
Must be wired as follows:
* TRS end - TIP to red, SLEEVE to both blue and shield, RING floating (no connection)
* TS end - TIP to red, SLEEVE to blue only
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