Cable Lengths for Star-quad cable

[cnyk]

At what distance should I be concerned about audio quality being compromised when running star-quad cable? (canare is what I was going to buy at markertek)...

I'm a home studio guy who is moving into doing some deejaying..
Anyway, as I map out a system, I'm wondering which cables will be best. My first inkling was to make some canare (L-4E6S) star-quad balanced xlr cables to run to active speakers (mackie thumps)... But after some googling, I'm concerned they may not be a good fit for longer runs. I'm sure I'll be in the situation where someday I have to run 75-100' of cable for some reason...

My concern is DJ lights electrical cords, and powered spkr elec. cords crossing my cables path... Am I being overly cautious? I can't help it, I don't want to be deejaying somebody's important event and have a sudden hum to battle with. ALSO, aside from spkrs.. Should I use star-quad for going from my mixer to my other outboard stuff... driverack etc. since I'll be using a cordless mic.. should I be concerned about interference with it?

Also, I see there are 2 kinds of star quad cables, ones that are specifically referred to as "speaker" cables here... and others that are referred to as "mic" cables here... Does it matter?

Anyway, any info is very much appreciated. Thanks!

[frans]

Speaker cables: not shielded. Microphone cables: shielded. In an environment where you get small signals from A to B, go for shielded cable. Do you have experience in soldering? It's easy, but still does need some routine or you f___ it up. If in doubt, let a friend solder them.
100 feet of cable isn't a problem with line levels and, under the right circumstances, even mic level. Make sure your output signal is balanced and the input is balanced. In some cases where you got it all right and there's still hum an isolation transformer like an ART dti
http://www.artproaudio.com/products....&cat=13&id=106
will save you, it's cheap, versatile, acts as an adapter and the lot. Highly recommended.

I have a few Canare starquad, they are not bad at all. This cable suits your needs, but be aware that there are a million reasons why hum and all kinds of noise still can creep into your system, that topic is too huge to cover here.

That could give you a few hints:
Electricity and ground loops prevention for a new studio, I need some advices please!

[John Willett]

I always use BBC spec. tight helical wrap star-quad cable that I get from Canford Audio.


Image is a clickable link to the cable spec.

[frans]

Another vote for Canford if you're from the UK or Europe. I bought all my starquad from them, a whole roll.

[Corran]

I'm not sure about the line-level stuff, but I routinely run over 100' of Starquad cables through lights and rafters for the local orchestra for my main mics with not a bit of interference.

[rumleymusic]

Since mic cable is balanced it can run for 1000+ feet before cable capacitance becomes a problem. Using mic cable for passive speakers is not a good idea because there is no way to properly ground the circuit, and what you are left with is very thin, poorly insulated speaker cable.

Speaker cable is not balanced. There is always a possibility it will pick up noise on long runs, but usually has a much thicker gauge and heavier insulation to compensate. In most circumstances 100 feet is not a problem, you just have to be careful the cable does not run right next to devices with heavy magnetic interference like power transformers.

[Audiop]

Daniel,

balanced or not has really no influence over the lowpass function. It's voltage, source impedance and capacitance as usual.

Speaker cables can actually be considerd balanced when a bridged output amp is used. There's no reference to ground in that case.




/Peter

[cnyk]

Thanks for all the replies!
Audiop/Peter is kind of on to what I'm concerned about.. My worry is that if I have to run a star-quad cable at lengths exceeding 75'-100' or more.. Will I begin to audibly lose my high frequencies due to the capacitance of the cable.

I'm sort of passing on what I've read in other places & articles.. And not really educated on the subject as you can tell... But I've read that it is an issue to keep in mind.. But also see many folks (as with Corran above) who tun at these lengths without issue... I suppose I could be over-thinking it.. But thats what I do!

[John Willett]

Originally Posted by cnyk

My worry is that if I have to run a star-quad cable at lengths exceeding 75'-100' or more.. Will I begin to audibly lose my high frequencies due to the capacitance of the cable.

I have had no problem with 70m+ (that's almost 250 ft).

[rumleymusic]

balanced or not has really no influence over the lowpass function.

I know, I phrased my sentence wrong, sorry. I only meant to imply that balanced cable can be driven that distance if needed in almost any audio application.

My worry is that if I have to run a star-quad cable at lengths exceeding 75'-100' or more.. Will I begin to audibly lose my high frequencies due to the capacitance of the cable.

At any audio wavelength, that will not be an issue.

[panatrope]

Originally Posted by cnyk

My worry is that if I have to run a star-quad cable at lengths exceeding 75'-100' or more.. Will I begin to audibly lose my high frequencies due to the capacitance of the cable.

High frequency loss depends first of all on the impedance of the output of the device you are driving it with. For a low impedance (let's say less than 100 ohms, which takes in most mixer outputs these days) then using standard mic cable parameters loss at 20kHz will be a fraction of a dB for a run of 100m. However, at impedances higher than 200 ohm (which is a value that a lot of mics seem to offer), then you may start to see more than a dB loss at 20 kHz. If you have to use a device like an attenuator in front of youractive speaker, fit it at the speaker end of the cable.

Quad cable (correctly wired) will offer additional rejection of interference compared to pair cable, and the Canare shield is also very good, in my experience.

[cnyk]

Thanks. I'm going to pick up a dbx drive rack PA, I believe its output impedednce is 120ohm... And the cable would run directly to active speakers. sounds like I'll be ok.. ?

[Manfrensengensen]

It's done all the time for live sound. 100' balanced snake 16 channels from stage to mixer. Mixer outs to drive rack balanced in drive rack outs 100' back down snake to stage to amps or powered speakers. Don't worry....... Standard mic cable or quad mic cable is fine. TRS to XLR...fine. It's all balanced.

[Bubbagump]

Originally Posted by cnyk

Thanks. I'm going to pick up a dbx drive rack PA, I believe its output impedednce is 120ohm... And the cable would run directly to active speakers. sounds like I'll be ok.. ?

Let's put it this way, your speakers are going to be much more of a limiting factor than 1000' of StarQuad ever will be. You're worrying about putting 92 octane into a Pinto here... yeah, its not rocket fuel... but c'mon.

[grindx]

If you are using this in a situation where your cable will take any kind of abuse, stay away from the Canford. Is has a spiral shield which is nice for flexibility, but can become open (gap) if kinked.

[0VU]

Originally Posted by grindx

If you are using this in a situation where your cable will take any kind of abuse, stay away from the Canford. Is has a spiral shield which is nice for flexibility, but can become open (gap) if kinked.

I can't say I've had any problems with that. (Running about 1000m of Canford SQ6.5 in various lengths, some for about 20/25 years.) But I do make sure that people know how to handle and coil them properly.

The longest runs I've done in starquad have been about 700-750m, truck to stagebox, with maybe another 150m from box to mic. This used either BBC standard 7 quad/26pin MIL-spec multicore or some custom made 18 quad belonging to a friend then Canford SQ6.5/Connectronics Starquad head leads. There was a noticable improvement when we started putting remote mic amps on the system!


For better flexibility and screening than Canford, Connectronics Starquad is very good - double lap screen but it's a bit thicker, a lot heavier and a lot more expensive. It has a thicker, softer outer covering than most and stays nice and flexible across a good temperature range but the covering can nick/slice more easily than the harder covering on the Canford cables.

Mogami Neglex 2534 is a nice robust cable but rather inflexible when warm and sets pretty hard when cold. I find the same problem with the few Canare mic cables I have (though their quad multicores are not bad). I've gota couple of lengths of some Belden cable or other that's extremely tough (and very expensive over here) but it too is not particularly flexible. Van Damme do a reasonably priced quad with a braided screen that's a little thinner overall than most but I find it develops kinks quite easily, even with careful handling. It's ok in places where it doesn't have to be messed about a lot.

My favourite at the moment is probably Gotham's GAC4/1 starquad cable. It's excellent quality, extremely flexible, fairly thin (5.4mm) and so far seems at least as tough as the Canford/Belden/Mogami cables but, again, it's not cheap.

I think for best handling, flexibility and screening, the Gotham and Connectronics (both double screened) are top of my list, followed as a good quality, good value cable by the Canford. I don't really like the braided screen cables as, though they seem to be the toughest, they're harder (slower) to coil and handle which doesn't sound too important but when you have a lot of cable to pack up after a show and a stage/hall manager looking at his watch, it counts.


In starquad multicore, of the ones I've tried, Canford's SQJ is very flexible but much thicker than equivalents from Bryant or Canare and a little expensive. Their 'Economy' version (?SQE maybe) is cheaper and thinner but much less flexible - more like Bryant/Canare. The little sample I have of Gotham multi quad looks to be a good cable but is rather uincomfortably priced over here - makes Canare look like the 'value' option! Probably the toughest starquad multis I have are the old brown BBC 7 quads, the 'hevy duty' versions of which are getting on for the same thickness for 7 way as my 24 way VDC black series multis and weigh about the same. They're about the least flexible cables I've seen, apart from wire armoured underground mains cable(!) but do at least seem to be indestructible. I don't have much of this but for out-door runs in tough locations it's hard to beat. On anything less arduous, the horrible stiffness, weight, and low channel count mean that it usually stays in the store!

[Plush]

Quality cable can be run very far.

You've received good advice here.

Just as an exercise, please consult the online data sheets for the star-quad manufacturers. You'll find that the 3 dB down point at 20KHz. will only be reached after passing well over 2000 feet of cable.

Audio frequencies are robust when quality cable is used.

Here Gotham or Mogami cable is always used.

[hbphotoav]

The main problem with audio feeds/sends running with lighting or AC cables is older dimmer packs, on the same electrical circuit ground... which is why most productions require at least two discrete 100-200A services in any venue... one for audio/video; one for lights. Modern DMX dimmers and newer LED instruments (no external dimmers at all) should lessen the chances of buzz/hum even further. Keep long parallel runs to a minimum (run your audio down the opposite wall, for example) and try to cross AC at 90 degrees.

Most important... get to the gig early... find the venue's breaker box and be sure it's accessible during the gig... know your circuit needs (i.e., how many 7A powered boxes at full howl does it take to trip the breaker on one 20A circuit?) and get there early. Did I already say that? You never can have "too much time" to shoot possible trouble.

Cheers.

HB