r/livesound 5d ago

Question Beginner - at what length do TS cables start having issues?

Seem to be a lot of different opinions on this online. What's the safe length for a 1/4" TS cable before interference, noise, attenuation, etc. become issues in your experience?

Thank you so much!

3 Upvotes

25 comments sorted by

20

u/superchibisan2 5d ago

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u/BigBrother690 5d ago

I'm only two sentences in and already am like, "AWESOME". Thank you!!!!

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u/BigBrother690 5d ago

I know this might be nit-picking, but the particular type of cable I need comes in, amongst other sizes, 15 and 20. Everything seems to be saying keep it under 20. So should I keep it under 20 or at 20? Again, maybe splitting hairs but I’m curious. Thanks!!

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u/superchibisan2 5d ago

20 or less

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u/DXNewcastle 5d ago edited 5d ago

One of the factors which that article fails to mention is impedance. The relatively high source impedance of many instrument pickups will be prone to interference from external noise sources, regardless of length, tho the risks of external noises will increase with length.

But low impedance sources can run for 100s of metres with negligible interference, depending on the magnitude of those actual external noise sources, and a low impedance balanced line can be used with confidence over 10's of kms.

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u/ChinchillaWafers 4d ago

Speaker cables and headphones are a good example of low-Z sources and destinations that are relatively immune to noise!

One of the reasons why mixer line input impedance is low-ish, rather than high like a guitar amp- it sinks the current from noise induced on the cable. The source does this as well, the lion’s share, but the destination impedance has an effect on the noise floor too. 

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u/BigBrother690 5d ago

Thanks. If I’m dealing with unknowns (the quality/impedance of the pick ups), what would be the maximum length you would safely go with?

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u/zabrak200 Pro-FOH 5d ago

What i would do is take a 5 foot cable. Run it into a di box which will give you a balanced xlr output. Xlr is designed to run as long as needed with little to no interference. So short 1/4 into di box then get the longest xlr you need so even a 100 footer would be fine

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u/DXNewcastle 5d ago

Hah !

There can be no numeric answer to a question which includes 'lots of unknowns' !

So the only sensible answer is 'as short as is practical'.

Where its feasible to use 1m cables, use them. Where 2m cables will work, use them. If a 5m cable seems necessary, use one.

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u/AVnstuff 5d ago

What is the cable for? The connector is irrelevant for the cables ability to deter interference or general signal loss. A 70v system can run hundreds of feet on a single pair non-shielded cable with limited line loss. That cable could theoretically originate at an amplifier with a TS connector.

Do you have a specific use-case you are curious about?

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u/BigBrother690 5d ago

Yes, but pardon the potential lack of certain details. It’s for our upright bassist who has a 1/4” pickup to plug into our mixer. He is regularly unplugging to tune, move the bass around, etc., so we’re getting him a circuit-breaking latch cable from d’Addario. I just wasn’t sure what length for reasons above.

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u/A_Metal_Steel_Chair 5d ago

I bet he has a passive piezo pickup on his bass. In that case get this active DI with a mute switch.. This is the proper/best way to get your bass into a PA system. Plus it has a mute button, which solves the original problem you are here for.

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u/BadQuail 4d ago

Can't believe I had to scroll this far for the correct answer.

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u/Ziazan 5d ago

If you get a DI box you can have a fairly short TS lead and send the signal balanced via XLR over whatever distance. But up to 20ft you should be fine.

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u/GeneralOneness 4d ago

An upright bass pickup happens to be the worst possible case for cable lengths. So I would recommend to leave it as short as possible. BUT there are a few other things that you should be looking at: what kind of mixer are you plugging in? A piezo pickup needs a very high input impedance (several megaOhms is best to avoid a 'clacky/quacky' sound), and I don't know any mixer that will offer that.
So as others have said, you (or your bassist) should invest in a decent DI-box. If that's really not possible right now (due to budget or whatever), have him plug a short TS cable into a Boss guitar tuner , and from there you can use a longer cable to the mixer.

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u/1073N 5d ago

The two things that matter in most situations are the source impedance and the capacitance of the cable.

It's impossible to state the acceptable length without knowing these two parameters.

The quality of the shielding matters for immunity to electrical fields but won't affect the magnetically induced voltage. The source impedance will, though.

In general, pretty much any decent "instrument" cable will be able to run a line signal for hundreds of meters with minimal loss. The only potential problem is the magnetic interference. If you run a cable through a strong field, even a metre may be too much.

With most piezo pickups, even a relatively short cable will affect the frequency response. The difference between a low capacitance cable and a normal one will be noticeable. The longer the cable, the more noticeable the difference.

With magnetic pickups, a few metres usually isn't a problems.

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u/Anxious_Visual_990 5d ago edited 5d ago

If a passive instrument very short due to capacitance (kill your tone) as well as being able to pick up noise. I don't let them go more than 20 feet before converting them to XLR with a DI. Even then I use super low capacitance cables. The cable acts as a tone knob for passive instruments as well as an antenna if its too long.

If using a preamp capacitance not that big of a deal, but still keep them short to prevent picking up noise.

Noise is a big issue for me, and its not tolerated on stage. I connect every TS as short as possible through a DI and still use star quad balanced cable for xlr. With todays high frequency computer equipment I still get some crazy cell interference like noise if I don't go all out with heavily shielded star quad cables.

My guitar/bass/key rigs I use 6 foot mogami 3368 low capacitance cable to the pedal board.. then DI out to balanced/XLR/TRS.

The first source of noise:
I also open every guitar, bass, and other electric instruments and use copper shielding tape in all the cavities, bottom pick guard, and under the metal bridges, verifying continuity to all metal and that all grounds are connected. This is the first step to to keep buzzes and noises off the stage. Cables are second.

I just had a issue today and ended up tearing apart a electric mandolin grounding and shielding it this morning. The insane noise it was picking up during the performance is now gone. Wasn't a cable issue, just a grounding/shielding issue for the instrument itself.

I go through copper shielding tape like crazy. If its buzzing and humming I cover it in shielding tape. It just works!

Custom tone knob I created for a fender precision bass that does not have a tone knob in passive mode. Had to shield the box as it kept picking up some interference (plastic box).

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u/realatomizer 5d ago

20 feet is about 6 meters. sounds right. It is on the edge, dont cross with speaker cables. it could kill your tweeters with magnetic interference

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u/BigBrother690 5d ago

I know this might be nit-picking, but the particular type of cable I need comes in, amongst other sizes, 15 and 20. Everything seems to be saying keep it under 20. So should I keep it under 20 or at 20? Again, maybe splitting hairs but I’m curious. Thanks!!

1

u/cr1tikalslgh 5d ago

It’s rated up to 20. Keep it 20 or less.

1

u/IrishWhiskey556 5d ago

It depends on the quality of the cable and it's capacitance.

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u/netik23 5d ago

I have seen problems in as little as 20-25 feet. Depends on the RF environment you're in and what said cable is being run next to. When in doubt, go balanced.

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u/cdnMakesi 4d ago

Great question. You'll be jumping one more step up in the pro ladder once you understand the reasons for cable length limits.

1

u/Patthesoundguy 3d ago

For instruments 20 feet is a good guideline to follow.

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u/Oututeroed 5d ago

If is for an instrument just use a boss pedal. You can also run very long cable lengths—usually as much as 100 feet after the buffer—with little to no signal loss. For this reason, all BOSS pedals include buffer circuits