Proper wiring of TRS return inserts from balanced TRS patchbay?

[Tonepad]

Guys,
I'm finally modding a TRS/TRS snake (Canare/Neutrik gold..ooohhh... spendy!) from my 500 module racks with a balanced patchbay to the return only of the DM4800 inserts. Been meaning to do this after years of using the half-jack return trick. I have a few inputs that don't make a great connection to the ring. Sooo would anyone care to weigh in on what the proper termination of the return TRS should be. Quite frankly just clippping the tip seems to do the job but when we half-jack we are actually using that tip to the ring return. The tip is usually the hot+...but the ring is usually the cold- from a TRS or XLR. I've seen some other confusing suggestions aroun the net that I should connect the hot+ to the ring and tie the cold- to ground. Does any of this really matter since we are not balanced to the DM Insert circuit anyway? Not trying to be lazy but the easy fix...clipping the hot+ tip seems to work.

THX

 

[Arjan P]

Ring and Sleeve are the return signal to the insert jacks. I don't know what you mean by "clipping the hot+ tip", but Tip is the Send part, so not used in your case. But, by inserting a jack fully, the tip contact opens the normal pass-through from inut stage to pre-amp. See this part from the block diagram:

 

[Tonepad]

I'll try to be clearer here:

1. I'm not sending to anything as a ie. external FX units etc. connected to my patchbay

2. I'm trying to return the output of my external Mic Pre/comp/etc. outboard units from my patchbay to the DM. I wish to avoid the traditional DM line in so as to avoid the extra amp/gain stage there and I've found a more true sound when bypassing this circuitry.

3. On this very Forum at least back on the original one it became an accepted hack to acheive a "return only" input scenario by half-jacking a TRS cable to the insert ring/return only. By this measure the tip or Hot+ is contacting the ring. If I clip this wire and fully insert the jack the ring contact is Cold- (I refered to it as Hot- in my OP...now corrected)

4. I may be wrong in assuming that since nothing is receiving the connected tip send at my patchbay it is a shunt. Indeed I've passed signal to the DM this way without any real issue, it just doesn't seem correct to send a signal that is not actually received by anything in my bay and indeed could be causing some type of loop (but not grounding) scenario.

5. My former Tascam tech guy who I ran into at NAMM suggested the clipped tip method but in the madness of a convention I didn't clarify if he was meaning to move the tip (Hot+) to the ring (and clip the ring Cold-)

6. I might just be overthinking this since either of the TRS connections (Hot+/Cold-) is carrying signal and are just differential to each other to acheive a balanced condition. It would just be nice to be double sure.

7. This seems to be a unique request since I'll be damned if Googling or searching here has come up with a definitive answer, which seems very odd to me.

THX

 

[Arjan P]

I'll try to clarify as well: Signal for the return input is using Ring and Sleeve, so coming from a balanced situation that would be Ring: Signal + (hot) and Sleeve: Signal - (cold). This is similar to half-jacking since in that case also you use Tip at the + of the return input and Ring at the (common) Ground of it. Biggest difference there being that the channel input stage stays intact and half jacking can be used to take signal from the input stage after trim.

Doing it your way (cutting, I understand, the hot wire) leaves you with Signal - and Ground, which may or may not give you grounding issues. Not to say those won't occur in above situation, but there you still have the option of connecting Ground and Signal - together.

 

[Tonepad]

Arjan thanks for pitching in here. I called the Tascam guys (I'm in LA and they've serviced my 4800) since this tip came from them. Brian there defered to Jim's opinion from my NAMM conversation and former Tascam contact as mentioned. We thought that snipping the tip/Hot+ would make sense, since it goes nowhere... so I went ahead with that but lo and behold now I have to halfjack at the patchbay out via the TRS snake to the DM insert return. Sounds great and easier to check any funky connection there but it proves my hunch that after one terminates the tip at the DM insert ... wire for pin 3 SHOULD go to the ring to keep the patchbay flowing correctly. I may have to do that or make some special rolled patch cables for that part of the bay. This is what I think you're saying as well. For now the half jack tweak has found a new location !!! Ha ain't it fun.