Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

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Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by Synthemophone »

Un/Balanced... Does it actually matter...?
...When connecting synths to audio interfaces which will take either signal, and have gain controls.
...And vice-versa into synths, which all have input level controls, to make use of their FX.

I've recently bought a MOTU 24ai interface (clearly to tempt myself into buying hardware instruments for years to come), and so I'll be needing three DB25 D-Sub to 8x TS or TRS jacked cables.
I would automatically have gone with balanced looms, in case future synths have balanced outputs. I'm not sure it necessarily matters.
I suppose my concern is whether it could actually cause problems.

Until recently I've had 8 synths connected to MOTU 828es and 828x interfaces, via TS jacked cables, and can't say I've heard a whisper of noise, or had any loop problems. Only one of those synths has balanced outs, although a TS cable would have been used. And none of the cables has been, or needs to be, more than 3m, most of them less.
The only digital noise I've ever heard with past gear, was when synths were also connected directly to PCs via USB. I now have a MOTU MIDI Express XT interface for all hardware instruments, which I hope won't induce issues.
To be honest, I've collected all this gear (Damn you eBay!) over several years and not yet configured it all to be available simultaneously, which really is the point of what I'm trying to do.

So, all the MOTUS accept balanced/unbalanced connections and obviously have level controls on all inputs and outputs.
I've contemplated that the inputs on three synths (Fantom XR, Juno-G, Argon8x) could press the outputs of my 828es into service as effects sends, utilising the internal routing grid of these interfaces, passing synths through each other, if desired, to share effects, and all these instruments have input level controls.
And finally I've just treated myself to a Roland TR8S, to start to fill the new interface channels, which likewise has an audio input for synthetic incestuousness, and this device apparently has TRS outputs. So that could be one 8-channel balanced cable no-brainer.

I'm assuming level issues simply don't really exist, due to all the input/output controls.

I understand the polarity reversing cleverness of balanced cables. But I suspect I've proven to myself that interference hasn't been induced that way.
Unbalanced has been OK, but I've not had everything connected simultaneously.
I'm not trying to avoid balanced, quite the reverse.
But could TRS actually introduce any problems I haven't considered?
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Re: Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by James Perrett »

I'd go for a balanced loom into a TRS patchbay. You can then choose the most appropriate cable from your synth to the patchbay. The balanced DB25 to TRS looms from CPC are so cheap (and work well in my experience) that it makes no sense to go for anything else.

https://cpc.farnell.com/pro-signal/psg0 ... dp/AV14524

Like you, I don't normally have a problem with unbalanced cables but I make sure that I have a sensible grounding scheme.
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Re: Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by The Elf »

The benefits of balanced connections are cumulative. I'd make balanced connections throughout and only resort to an unbalanced cable for specific devices, if necessary.
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Re: Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by Arpangel »

I’d go unbalanced, in a typical home studio cable lengths aren’t a concern.
The reasons I’m saying this are, there will be no sonic gain from going balanced, if you do get a synth with balanced outputs, you don’t need to use them, and "in my experience" I’ve had things that actually won’t work at all if you insert a balanced lead, the Novation A-Station for one, and if you’re inserting pedals into the scene, balanced leads can cause all sorts of non-working scenarios.
Keyboards etc in a home studio, no need for balancing, IMO, not worth bothering yourself with.
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Re: Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by ef37a »

The only real draw back to a fully balanced setup is the possibility of getting a reversed signal polarity but it is easy and cheap enough to make up one 'OOP' test cable and get the system checked out, once done no need to touch it again.

On the other hand there is definitely a potential problem with plugging a TS jack plug into a TRS balanced output. You will short the 'cold' ring output to ground and that will cause that amplifier to constantly clip with the chance of that clipping breaking into the 'hot' input. Very unlikely is the possibility of 'blowing' the OP chip but that is unlikely with any but the oldest kit.

These days many 'balanced' outputs are 'impedance' balanced so a polarity flip will just give zero signal.

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Re: Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by Hugh Robjohns »

Synthemophone wrote: Mon Dec 06, 2021 10:28 pmI suppose my concern is whether it could actually cause problems.

You can potentially get problems either way. The greatest risk with unbalanced connections is that of ground-loops and the associated unwanted noises, or of shorting the cold-side of balanced outputs to ground and getting 'breakthrough distortions'.

On the other hand, using balanced connections with some (mostly vintage) keyboards may result in a lack of signal or unwanted interference pickup where the cold-side is left floating.

There is no 'one format fits all' solution. You need to understand how each device is designed to be used and then wire it accordingly.

James' idea of using balanced looms to a balanced patch bay, and then individual application-specific cables between the patch bay and each device is the most elegant and technically cleanest solution. This is the route I have taken also.

The alternative is to just blanket bomb with either balanced or unbalanced cables, and hope it all works adequately... replacing any problematic connections afterwards, which is the approach Elf and Arpangel suggest.

Until recently I've had 8 synths connected to MOTU 828es and 828x interfaces, via TS jacked cables, and can't say I've heard a whisper of noise, or had any loop problems.

Fabulous. Stick with that then.

I'm assuming level issues simply don't really exist, due to all the input/output controls.

Instruments tend to all work over a relatively narrow nominal operating level, so I wouldn't expect there to be a major problem there.

But could TRS actually introduce any problems I haven't considered?

Yes, but it's unlikely to be an issue with electronically balanced inputs:

https://www.soundonsound.com/sound-advi ... ot-others
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Re: Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by Synthemophone »

Thank you all so much for your replies and helpful input and info!
Sorry for the long delay in coming back to you.
So busy.
Thank god I've taken Christmas off to play with my new toys! Wish it was next week already.
Merry Christmas all...
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Re: Un/Balanced Un/Bothered? ....D-Sub to TS/TRS

Post by ef37a »

The Elf wrote: Mon Dec 06, 2021 10:59 pm The benefits of balanced connections are cumulative. I'd make balanced connections throughout and only resort to an unbalanced cable for specific devices, if necessary.

I agree. I am assuming all the interface inputs are balanced? Those outputs that are not can be made so with transformers. Not that expensive in the whole scheme of things?

I am a bit worried mind? Lots of synths, lots of wires. Questions...Hope we do not have an embryonic Arpangel waiting in the wings here!

Omicron, Brexit, let down with son's prezzie...I can't stands n'more!

Dave.
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