Last-Hope-Patchbay-Thread

[snafu]

OK guys, you're my last hope!

I know, this is way off of Tascam related issues, but I know that here are some pros that might be able to help me out.

Currently I am trying to set up my Tascam DM 3200 to a patchbay (3 actually) - Neutrik NPPA-TT, so I got TT-conectors.

My first question is a mere general one:
do I hook up everything balanced? Or better: should I?

Second:
I got a wallbox with a 1/4" TS connector - you can't connect them balanced (it's a mono connector). So IF I should have to set up everything balanced, would it mean, I'd have to get a stereo 1/4" connector instead (kinda balanced mono)?

Third: I have an old Behringer power amp ha4400. The inputs to each headphone channel are 1/4" stereo connectors. I got a multicore cable from the ha to my patchbay, where at the moment it is going to be set up unbalanced stereo (meaning: ONE slot on the patchbay passing a stereo signal). Problem is: let's say I want to inject my output signal from my DM analog card, which is also routed to the patchbay, to one of the headphone channels. First thing is: the signal from the analog card is mono, so if I plug it into the input to the headphone amp, I will get most likely the same signal on both ears, or maybe just one side of the signal.
So, what is the pro solution here?

Thank you very much, and I apologize for being so far off to any TAscam related topic!

Greetings
snafu

 

[Phil Tipping]

Hi snafu, well if there's no other takers, you're welcome to my 'amateur' ramblings fwiw...

Normally if your cable runs are fairly short and your environment is not electrically noisy (motors, dimmers etc), unbalanced should be ok, and a lot cheaper!... but...

I started out this way and although I was amazed by how long a cable you could get away with, there were a few devices which had hum issues which I was unable to eliminate. I'm not a pro but have high standards, and to me, hum is inexcusable. Hiss is usually from the gear itself, but if you crank up the gain and hear hum, then this is down to poor wiring imho. DI boxes may have solved my problems, but it would have meant buying a lot - some devices were stereo, and it would mean additional boxes lying around... and more power adapters!

There were also problems trying to standardise signal levels as unbalanced gear tends to use the lower -10dBV levels, so if you have a device which only accepts balanced +4dBu levels, it can be difficult to drive, and vice versa. Eventually I bit the bullet and went with balanced and +4 where possible... and all problems went away. From what I've read, high signal levels are a good thing, and balanced wiring gives a degree of reliability in that if one of the signals fails, the other will act as a backup, albeit 6dB lower.

The patchbays are balanced, as are the mixer and multi-track recorder so these use TRS-to-TRS cables.
External balanced gear uses TRS-TRS or TRS-XLR depending on how the device handles +4 vs -10 levels. Some devices use switches for this so I use TRS if possible to make the cable more useful if/when the studio is re-organised!

External unbalanced gear uses TS-to-TRS or RCA/phono-to-TRS cables. I still use balanced wire as I buy it in bulk, so the cold wire is soldered to the screen at the unbalanced end.

I found researching the 'right' way for unbalanced-to-balanced and vice-versa a bit of a nightmare and seemed to need too many specialist cables, so decided to keep it simple and use the above for all unbalanced inputs and outputs. It may not be technically correct but I've had no problems. With this setup, the TS or RCA plug is easy to identify and this always goes to the device, and the TRS plug goes to the patchbay.

The ha4400 has separate left & right inputs and a switch for mono, so there's no problem connecting its inputs to the patchbay and just patching your mono output to one of the inputs.

If you really want to connect a stereo heaphone plug to your patchbay though, you're correct in that you'll get odd results. The stereo left & right signals appear on the Tip and Ring of the TRS plug, so if you connect this to an unbalanced TS socket, one side will be shorted out. If you connect it to a balanced TRS socket, the Tip & Ring will be the hot & cold balanced signals.

The effect on splitting these across left & right sides of headphones depends on how the device generates the balanced output. One arrangement would give a signal on one side only, the other would give out-of-phase signals, either of which can sound very odd! So if you really need to have a stereo feed, use a custom cable to split the left & right sides of a TRS plug (for stereo devices) to 2 separate TS plugs (for the patchbay).

As you'll no doubt find out, patchbays are great once they're wired up, but they do use lots more cable and plugs!

 

[snafu]

Hey Phil,

thank you so much for your reply. After having read your post, and thinking of my situation over and over again, I came to the point where I thought: no need for compromises - let's get balanced all the way!

I see, I also made a mistake there: my 1/4" connectors have three pins, so they are balanced mono! I can't remember how often I mixed that up. Guess, I was surprised to find out that all stereo 1/4" Jacks are not balanced stereo - it's more like balanced mono or unbalanced stereo. So all the headphones we have and love are unbalanced stereo. Yes, I was surprised!

So, my conclusion now is that all my signals should be balanced - where not possible, I'll just hardwire them to I/Os and completely bypass the patchbay. I have only one example for this, since everything else is going to accept balanced signals:
- the four RCA I/Os on the rear of my DM3200! (Studio outputs and 2Trk In)

Well, I could send them over the patchbay, but there would be a risk for misspatching that could - in the worst case - damage equipment. (Imagine plugging in a phantom powered signal into the RCA circuit...)
So, I think, it's best to have those not on the patchbay, or indicate them in a very (very!) foolproof way, so that there is no chance you might ever send unexceptable signals into that patch.

Your post helped me a great deal in getting things straight, and re-thinking about my situation. (In fact it helped me identifying my mistake mentioned above).

Thank you, Phil, have great week

best regards
snafu

 

[Phil Tipping]

No problem snafu but note it's only one person's experience. Hopefully some real pros will chip in so you can get a more balanced view - no pun intended
Yes, TRS plugs are very ambiguous - headphone stereo is effectively 2 unbalanced monos.
If you have a mixer with insert jacks, you'll usually find these also use TRS sockets where the Tip & Ring are the unbalanced send & return for the channel, so there's another variation. The tip & ring are normally shorted inside the socket, so if you want to tap off individual channels to feed a multi-track recorder, there's an old-school trick of inserting a plug half-way so you get the signal without breaking the flow. This always sounded a bit hit & miss to me, so if you ever need to do this, I recommend making a set of patch leads with TRS at one end with the Tip & Ring shorted together, and a TS at the other for the recorder. I used this with my dp32sd for recording individual channels from a mixer/PA system at a concert. Much more freedom being able to mix everything later independent of the PA mix.

Re. phantom power, you're right to be concerned. I don't use mics on my patchbay as a lot of the gear has switches to select the XLR mic input vs the 1/4" jack line input, so I normally leave mic cables plugged directly into their pre-amps, and connect their line inputs & outputs to the patchbay. I also use patchbays for MIDI, but these are on separate panels to avoid accidental cross-patching, and also to keep some distance between the analogue and digital signals. I recently bought a modular synth so have now installed yet another panel for handling CV signals... so be prepared for expansion!... and as you say, keep everything organised to be as foolproof as possible.

 

[Arjan P]

Hi @snafu, (Ehm, disclaimer: really not here to qualify for the 'real pro' title..)
I use two Neutrik NYS-SPP-L1 patch bays with the DM3200, so nearly the same setup I guess. I patch almost everything except MIC inputs. They are hardwired to physical locations around the studio, and since the DM is a big patch bay anyway, I'll just patch them to whichever channel I want. This mostly because I don't want to patch with phantom power and certainly not with jack plugs. I do use another patch bay (Fostex 3013; unbalanced) for all channel inserts. This is where I connect compressors going into the channels. Then the Neutriks are used for all channel line inputs, Aux Send and Returns, Studio Out, Stereo Out, 2-track in, you name it, and also to patch my HA4700 headphone amp to studio locations. All is balanced, except where the DM is not.

I'll just hardwire them to I/Os and completely bypass the patchbay. I have only one example for this, since everything else is going to accept balanced signals: - the four RCA I/Os on the rear of my DM3200! (Studio outputs and 2Trk In)

The point is that although the DM connections are unbalanced, you can still patch with balanced cables, as long as you connect the other side of the patch bay correctly. So use only Tip and Sleeve at the back of the Neutrik (I see yours has push terminals, so you'll have to figure out which is which, but in any case use Hot and Ground) and you can't go wrong.

And for stereo headphone signals - I only patch the outputs of the headphone amp to locations and the input can be either Studio Out (normally patched) or Aux 1 & 2 (patchable). The headphone patching itself therefor takes place at another set of channels so there should be no confusion there.. I'll attach a picture of my patch excel sheet, hopefully it's a bit readable, I had to downsize to 900 (colors correspond with my multisnake cable colors):