Help! Signal deterioration with two patch bays?

[Beedster]

Folks, I'm trying to rationalise my recording setup at present, I'm using a temporary 'studio' that is I suspect not entirely free of damp so have installed my UAD and SSL devices in a portable (if rather large) rack unit that I move between house and studio, the added bonus of which is that I can work on editing/production in the house also. I have an 8-channel patch bay on the front allowing easy access to the inputs on the back of the UAD. The problem is that having already been faced with a sea of XLR cables in a relatively small case, I now need to access two channels of an 8-output DB25 output meaning even more cables and as far as I can tell 6 'spare' XLRs in the box running out of the back of the DB25. There seem to be two options, firstly take the DB25 apart and disconnect/remove the spare XLR cables (which even if it's easy to do in terms of the mechanics might be risky in terms of identifying which pins connects to which channel), or install a second and larger patch bay on the back that would significantly tidy things up, and which strikes me as the preferable option. This would mean that mic inputs into the UAD would pass through two patch bays and a total of 6 XLRs before getting to the preamps. 

 

Now I'm guessing the above is as clear as mud, but thoughts welcome, I'll try and take some photos that might simplify stuff a little, but the main question relates to the wisdom of passing audio through multiple plugs/cables/patch bays. I've a good idea who'll likely be responding with their expertise and experience so thanks in advance  👍 

[WinterMute]

If your balanced cables are in good order (XLR), it shouldn't matter, but it's not a great idea passing signal though multiple connections, as each one is a point of failure and can induce problems, you may also unbalance the signal with a poorly or wrongly soldered cable, which will leave you open to EM interference.

 

That said, mic signals get passed through multiple patch bay connections in your standard TT or Bantam patch-bay as a matter of course in most studios, with no ill effects, but the patchbays and patch cables are all balanced and checked.

 

I'd try to keep it down to as few cables as possible, even if that means a bit of creative rewiring on the fly.

[Beedster]

Thanks @WinterMute, much appreciated, it's only just occurred to me that the most obvious way of reducing cable problems is to un the front patch-bay to the DB25 input on the UAD rather than to the separate XLR ins, is tyere any reason why this is not a good idea (would I expect better quality with XLR for example)? 

[WinterMute]

18 minutes ago, Beedster said:

Thanks @WinterMute, much appreciated, it's only just occurred to me that the most obvious way of reducing cable problems is to un the front patch-bay to the DB25 input on the UAD rather than to the separate XLR ins, is tyere any reason why this is not a good idea (would I expect better quality with XLR for example)? 

 

XLR balanced connections won't make the sound any better, unless you've been using properly poor cables before, but they do eliminate hum and EM interference. They also allow signals to pass over longer distances as the impedance doesn't factor as much.

 

I'd need to look at your system to decide what might be the best way of approaching the problem, it's not an academic exercise...

[Beedster]

Thanks @WinterMute, I found the DB25 schematic for the O/P on my UAD so I assume this is also balanced? 

 

[Beedster]

I've been using XLRs so long that to use anything else just feels odd  

[BigRedX]

That's 8 balanced lines.

 

Clue is in the labelling Hot/Ground/Cold which would equate to pins 2/1/3 respectively on an XLR connector.

 

Just check the channel numbers carefully on the D connector as the channels appear to be arranged in triangular groups of 3 (channel 1 is pins 24, 25, and 12 etc.) rather than sequentially.

[Beedster]

13 minutes ago, BigRedX said:

That's 8 balanced lines.

 

Clue is in the labelling Hot/Ground/Cold which would equate to pins 2/1/3 respectively on an XLR connector.

 

Just check the channel numbers carefully on the D connector as the channels appear to be arranged in triangular groups of 3 (channel 1 is pins 24, 25, and 12 etc.) rather than sequentially.

 

Thanks @BigRedX, thought so, seems that using DB25s for both in and out might save me a bit of cable mess, keeping an 8 x XLR input patchbay on he front of the rack unit and a 8 x XLR output on the back

 

I get your point re the channels, that could have tripped me up 👍

[Dad3353]

Those 'triangular' grouping is to reduce crosstalk. A well-manufactured DB25 would be a better connector than a slew of XLR's, generally, but less flexible, as the channels are hard-wired, whereas XLR's can be swapped around. 

[Beedster]

4 minutes ago, Dad3353 said:

Those 'triangular' grouping is to reduce crosstalk. A well-manufactured DB25 would be a better connector than a slew of XLR's, generally, but less flexible, as the channels are hard-wired, whereas XLR's can be swapped around. 

 

Thanks @Dad3353, just checking I'm not missing anything in assuming that by taking the DB25 I/Ps from a female XLR patch-bay and send the DB25 O/Ps to a male equivalent gets around the flexibility problem?  

[Beedster]

9 minutes ago, Dad3353 said:

Those 'triangular' grouping is to reduce crosstalk. A well-manufactured DB25 would be a better connector than a slew of XLR's, generally, but less flexible, as the channels are hard-wired, whereas XLR's can be swapped around. 

 

BTW, @Dad3353I hesitate to ask having just looked at some prices, but what do you consider constitutes a well manufactured DB25? 

[Dad3353]

2 minutes ago, Beedster said:

 

Thanks @Dad3353, just checking I'm not missing anything in assuming that by taking the DB25 I/Ps from a female XLR patch-bay and send the DB25 O/Ps to a male equivalent gets around the flexibility problem?  

 

That wasn't my point, really. If I have a multi-pair with loose XLR's, I can plug any one into any channel. If I have a multi-pair with DB25's (or any other multi-pin connector...), the channel affectation is fixed. No big deal in a stable, permanent installation, but could be an issue with patching 'live', on stage. In your case, it's not a problem, so ignore.

 

1 minute ago, Beedster said:

 

BTW, @Dad3353I hesitate to ask having just looked at some prices, but what do you consider constitutes a well manufactured DB25? 

 

By 'manufacture', I mean the quality of the connector itself, but more importantly the quality of the cable and its sheathing, and the soldering or crimping. I wouldn't recommend a 'budget' connector, especially if it's to be manipulated often, but quality for audio use is a more delicate matter than for, for instance, a connector in an automobile or computer hook-up. Non-corroding pins, for instance, so that good audio contact is maintained for decades. Look up 'NorComp', for example. I'd not go down the 'AliBaba' route.

[BigRedX]

The problem I have with D-style connectors is that most of them are designed for computing use where they will be attached once and probably never touched again until one of the devices they are connecting fails. Musical equipment that does not live permanently in the studio requires something robust enough to survive being plugged and unplugged maybe several times a week for months in a row. Most computer type connectors do not fall into this category.

[Beedster]

Thanks for the above guys, I think the reality is that if I go the D-style route they'll go in and stay in, I'll always have the option of using the XLRs as the DB25/XLRs are switchable. Not fixed in this as a solution yet but it's looking the best compromise all around at present 👍

[WinterMute]

I have DB25 on my UAD2 A16, once they're set up they don't get moved much, which is where patch bays come in handy, and yes they're fully balanced as the others have noted.

 

VDC make excellent D-sub looms to any specification, I'v had VDC looms in my room for years and often spec them in audio designs, they are not cheap but they are 99.9% perfect at manufacture and they last.

[Beedster]

12 hours ago, WinterMute said:

I have DB25 on my UAD2 A16, once they're set up they don't get moved much, which is where patch bays come in handy, and yes they're fully balanced as the others have noted.

 

VDC make excellent D-sub looms to any specification, I'v had VDC looms in my room for years and often spec them in audio designs, they are not cheap but they are 99.9% perfect at manufacture and they last.

 

Many thanks @WinterMute 👍