Which cable to use for balanced stereo signal?

[Richtrohr]

Hi there,

 

I'm planning on adding a figure 8 mic to my blimp for stereo recording. It looks like the accepted standard is to run both 3-pin XLRs from the mics inside the blimp into a single 5-pin XLR fixed to the shock mount base. There even is a corresponding pinout in AES14, so that part is sorted.

 

Which type of cable should I use for the run between the 5-pin XLR at the pole top and the recorder inputs?

 

Of course the optimum would be a multicore with separately shielded twisted pairs but I imagine that being a bit cumbersome for field use. Also, 2-pair multicore is not that common, they usually start with 4 pairs. Every commercial solution I saw appears to be using some rather thin cable - but which one?

 

Are they just using star quad with each orthogonal pair connected to a separate mic? I'm sure this would work OK under most circumstances but my occupational signal integrity OCD kicks in just thinking about it.  

 

So, which cable do the manufacturers use, which one do you use?

 

Thanks.

[The Documentary Sound Guy]

Most of the commercial cables I've seen seem to use regular Starquad.  I've built stereo cables with Canare L-4E5C and also generic 4-conductor (I believe some kind of Denko cable ... it had silver insulation, and was stiff and slippery compared to L-4E5C).

I also built a cable using Canare L-4E3-2P, which is 2ch Starquad.  This was very thick but surprisingly flexible.  Getting it to fit in a regular XLR headshell was tough ... I recall having to modify it a bit.

I tested cross-talk with all three cables, and none seemed to perform better than any of the others.  All three had cross-talk in the -80 to -90dB range if I recall, though I'm going from memory right now.  All were 25' lengths (which is as long as I need for my boom).  I'm sure differences would show up at longer cable lengths, but for my purposes, it didn't seem to matter too much.

[Derek H]

Surprising that the dual starquad didn’t have much advantage against re-puposed single channel starquad. Though 80-90dB would be pretty insignificant in practice I would think. 
 

I wonder if it has more to do with the shared ground inside the 5-pin somehow? 

[The Documentary Sound Guy]

Yes, it was pretty insignificant.  I had no issues in day-to-day use.  I have no satisfactory explanation.  I wish I could do more testing, but my stereo kit was stolen last year, so I don't have the cables any more.

I would imagine there would be more significant differences on longer cable runs.

[Richtrohr]

Thanks for your replies.

 

Canare L-4E3-2P appears to be the optimum solution from a signal integrity perspective but for some reason Canare products are a little hard to come by in Germany. Also at 82 g/m it's exactly twice as heavy as Cordial CMK 422 which is the other option I had considered. That one is basically two balanced mic cables with a common outer PVC jacket. Then again I'll need only about 3 m so that shouldn't be a practical issue.

 

I think I'll try CMK 422 first since it's cheap and readily available over here. Looks like the PVC jacket can be split so I might even get arround using a 5-to-3 XLR splitter on the recorder end by terminating in two low-profile XLR3. For the XLR5 side I'll probably just use a Neutrik BXX-14 so that the strain relief is fully functional which is something you kinda lose when just drilling the regular cap.

 

If the CMK 422 is too cumbersome to handle, I'll try to order some L-4E3-2P from Belgium. If it comes to this I would be surprised if I won't build a third cable from some Mogami 2893 and take all three of them to the lab. So if you don't hear back from me I either never made it to a stereo setup at all or the CMK 422 just worked.

[Derek H]

Try Sommer cable they must have something that would suit you. 

[The Documentary Sound Guy]

Yup, I found Canare L-4E3-2P very hard to source.  I don't think it gets used much.  I think the Cordial will be a pain to work with on a boom pole because of its shape; if you only need a 3m run, I think you have lots of options.  I think I'd try in the Mogami first if I were in your shoes.

[Richtrohr]

15 hours ago, Derek H said:

Try Sommer cable they must have something that would suit you. 

 

Indeed, they do: Multipair SC-Quantum QMC, a balanced multicore as well as Multipair SC-Pegasus CMCK, a starquad multicore. The balanced one is readily available and the starquad appears to be a rarity. Since the "SC-Quantum QMC" is supposed to be flexible and fit for stage use, I'll give it a try. Thanks for the recommendation!

 

Sommer Cables was off my radar because of their lack of serious data sheets, inconsistency of specs across sources and absolutely ridiculous marketing copy in their product descriptions. But since their multicore seems to fit my application I'll give them a chance this time.

 

15 hours ago, The Documentary Sound Guy said:

Yup, I found Canare L-4E3-2P very hard to source.  I don't think it gets used much.  I think the Cordial will be a pain to work with on a boom pole because of its shape; if you only need a 3m run, I think you have lots of options.  I think I'd try in the Mogami first if I were in your shoes.

 

I'm with you on the handling of Cordial CMK 422. Gladly I found a round and supposedly flexible 2-channel multicore that's as easy to come by as the Cordial twin cable, see above.

[Sebi]

Another Sommer Cable but it's actually not primarily intended for stereo use: Square 4-Core MK II Highflex

I ordered some of it to try it out and built a 5m stereo-cable for my MS boom setup. It's quite flexible and only a little more stiff than my usual XLR cables. Sounds fine to me but didn't do any further testing besides using it regularly.

[Richtrohr]

On 5/4/2024 at 10:44 AM, Richtrohr said:

Since the "SC-Quantum QMC" is supposed to be flexible and fit for stage use, I'll give it a try

I like it, it’s a real multicore, flexible and the Neutrik BXX-14 strain relief is a nice fit.

[Richtrohr]

Finished! It folds nicely into my MixPro bag.

 

I got the multicore strain relief sorted but now I need a nice solution to hold the excess cable loop on the bag. Suggestions?

[henrimic]

 The Cable Ties from Porta Brace are great to attach the loop of cable to the bag .

[Richtrohr]

On 5/11/2024 at 8:55 PM, henrimic said:

 The Cable Ties from Porta Brace are great to attach the loop of cable to the bag .

 

Thanks for the tip! As usual, those were hard to come by and I found some cheap ones on Amazon.de that actually don't look too bad. Time will tell, I guess. Looks like they're not selling on Amazon.com for some reason but I'm sure you can find the same product under some other made-up brand name over there. Edit: I think I found the original product on AliExpress here.

 

Edited 16 hours ago by Richtrohr
Added another source for the straps.