Balanced to unbalanced question (X-post to Analog)

Blue Jinn

Blue Jinn

Rider of the ARPocalypse
So, I have a Creamware TDAT 16 with TRS balanced I/O which are ring hot of all things. The owners manual says if you use unbalanced make sure your TS connectors only go in "One Position" so you don't short the (+) hot to ground. This would imply that you can use just (+) hot and ground and ignore the (-) cold. I'm not able to adequately insert TS connectors so the "tip" is only on the "ring." Most of the rest of my gear is semi-pro with RCA connectors, so I want to fashion my own TRS to RCA and of course cheaply and easily as possible. I can get a couple of cheap TRS to TRS snakes cut in the middle and just wire the ring to the RCA tip and the ground to the RCA ground. I don't have those on hand, I'm assuming the cable is shielded. But I've seen it recommended that you short (-) to ground. I've also seen guidance to ground the shield at the balanced out and connect (-) to ground/shield at the balanced out but not at the unbalanced in. Looking for recommendations here. My hunch is, it'll be fine to to just leave the (-) cold unattached if it's not already connected to the shield at what will become the TRS side.


Thoughts?
 
In a proper balanced system, it makes no difference at all to connect either of the conductors to ground. The only practical difference is the polarity - so doing it randomly can create that horrible hollow phasey sound where two mics fight to cancel out. Or worse, stereo synths and keyboards. Convention is that you short the ring to sleeve - which also allows the half-inserted thing to sometimes work. If you push an unbalanced jack into a patchbay, the tip is fine, and the jack shorts the ring to sleeve, unbalancing it. So the short the ring system is more likely to work. The half-insert only works if everything is wired in a way to allow it. The result is usually silence, or worse - horrible hums.
 
It depends...if the unit has 'proper' differential outputs, i.e. both tip and ring are driven then you can just ignore the "ring hot" situation and treat the outputs as regular 'tip hot'. This will I am guessing, not preserve 'absolute polarity' with the inputs but I cannot see that being a problem?

Whichever contact you treat as hot do not ground the other one since this means the drive IC will see a very low Z and will clip and that will surely break through. The only time you have to ground the cold side is if they are using floating transformer out puts. But I very much doubt they use differential amps because plugging in a TS plug would short the ring to ground. It is I suspect an 'impedance balanced' output and there is no signal on the tip. Still a daft way to build the thing though IMHO!

To get to RCA plugs I would buy a rake of TRS-TRS cables of twice the length you need. Chop in half and fit RCAs as required. Ring to centre, shield to body and use some heat shrink sleeving to tidy things up and add some strain relief.

Dave.
 
ecc83 said:
To get to RCA plugs I would buy a rake of TRS-TRS cables of twice the length you need. Chop in half and fit RCAs as required. Ring to centre, shield to body and use some heat shrink sleeving to tidy things up and add some strain relief.

Dave.
Click to expand...
Thanks. That’s what I initially thought to do and I’ve a couple of 5m TRS snakes in my Thomann basket.
 
BTW, you can get 'large body' RCA plugs pretty cheaply on Zon and using a 'Dymo' printer label them up..."ch 1 rec" and "ch 1 play" e.g. Saves a lot of hassle and bad language if you have to re jig the setup!

Dave.
 
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