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Cables.

#42
Coolhandjjl said:
Yup, Do it right, do it once. No sense spreading misinformation. These forums are supposed to keep the level of quality at its highest.
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Would this mean I should better shut up in future?
There is at least one guy at this form who is by far more skilled all around audio and musical reinforxement technique, much better skilled then I will ever do.
IMO if to keep a forum at its highest quality possible would mean that only the very best qulified person should answer a question!
 
#43
ThisBass said:
Would this mean I should better shut up in future?
There is at least one guy at this form who is by far more skilled all around audio and musical reinforxement technique, much better skilled then I will ever do.
IMO if to keep a forum at its highest quality possible would mean that only the very best qulified person should answer a question!
Click to expand...

I've seen you discuss more that blindly post. Discussion is great in my opinion. I hope that translated properly in German.
 
#45
My take on cables is pretty straightforward. Buy decent but not esoteric mic cable in lots of colours - select it for toughness and flexibility and the ability to lay flat. Speaker cable needs to be matched for size, so that the length is not going to mean the cable resistance is an appreciable proportion of the total load - after all, 8 Ohm impedance speakers, but 8 Ohms of cable resistance means half the power is wasted warming up the cable. So for us in the UK, this means metric conductor sizes - for short runs of lower power, for monitors, for example - I'm happy with 1.5mm2 cable. For a couple of my Pas I'm using 4 core, 2.5mm2 cable (Bi-Amped), and I've also got a couple of VERY heavy 4mm2 cables for when the stacks have to be very far apart, or the cable has to go around the back of the stage area. On the notion of amps frying themselves, I don't worry because most are designed to work into virtual short circuits - 2Ohm operation, plus they can cope with a bit of extra capacitance - if you did use screened cable. Mic and instrument cable typical has quite small conductor cross section, so with a BIG PA, the current the cable handles could well melt the conductor - and this I have had happen. With amp design now coping with open and short circuit protection, I'd suggest any amp that died as a result of using a cable with a screen was pretty poorly designed. I did know a PA company who routinely used screened multicore (2.5mm2 cores) for their loudspeaker multis because they wanted maximum screening. I doubt it really did much, but it certainly never caused any frying. Many of these stories are just handed down knowledge. Physics says that certain things will happen when speaker cables are screened, but nobody ever quotes specs for how much capacitance 'normal' speaker cable has. It's certainly true that changing the capacitance of the cable does have an impact on amps that rely on feedback - and you can get a rounding of the leading edge of the waveform. Push it further, and this can lead to the oscillation mentioned - but only poorly designed amps have issues - hence why we don't hear about it very much.

Heavy cable for speakers, flexible and tough for mics and instruments. Most of my loudspeaker cables are actually mains cable, H05 or H07 type (UK spec). Tough and long lasting. Mic cable is 90% Canford Audio HST, most of it purple. I have some HST that is 20 years old, I'm sure, and some rubber flexible stuff of even older.

If people wish to use the crazy cable, fine - but I'm laughing inside.
 
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#46
paulears said:
My take on cables is pretty straightforward. Buy decent but not esoteric mic cable in lots of colours - select it for toughness and flexibility and the ability to lay flat. Speaker cable needs to be matched for size, so that the length is not going to mean the cable resistance is an appreciable proportion of the total load - after all, 8 Ohm impedance speakers, but 8 Ohms of cable resistance means half the power is wasted warming up the cable.
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Let's see... 10 gauge copper wire has a resistance of 1.24 ohms per 1000 feet (from Table 8 of the National Electric Code), so allowing for two way resistance, a 10 gauge speaker cable would have to be... <cipher, cipher> 3225.8 feet (~0.6 mile) long to add 8 ohms to the circuit.

Within reason you don't need to worry about matching the length of speaker cables.
 
#47
Indeed, and that is why I use2.5mm2 cable, which is about the same size, but if you use the other common size her, 1.5mm this is close to your AWG15 size, and 1000ft of that as a speaker cable would be near the same as the speaker.

I do appreciate that in real life lengths, the ratio between cable and speaker is much less, but wasted power is well, wasted. Some purpose designed speaker cable has even worse performance.
 
#50
paulears said:
Indeed, and that is why I use2.5mm2 cable, which is about the same size, but if you use the other common size her, 1.5mm this is close to your AWG15 size, and 1000ft of that as a speaker cable would be near the same as the speaker.

I do appreciate that in real life lengths, the ratio between cable and speaker is much less, but wasted power is well, wasted. Some purpose designed speaker cable has even worse performance.
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There is no AWG 15. AWG 16 (1.31 mm^2) is about 5 ohms per 1000'. As to the wasted power, the amount of power wasted in a 20' speaker cable is vanishingly small even if it is 16 gauge, not that I ever use wire that small. It's certainly far too little to worry about matching lengths of speaker cable.
 
#51
paulears said:
Indeed, and that is why I use2.5mm2 cable, which is about the same size, but if you use the other common size her, 1.5mm this is close to your AWG15 size, and 1000ft of that as a speaker cable would be near the same as the speaker.

I do appreciate that in real life lengths, the ratio between cable and speaker is much less, but wasted power is well, wasted. Some purpose designed speaker cable has even worse performance.
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Sometimes it is impressing to see what's inside of some pro PA cabs. Discussions about proper diameter of wire size seems to be like a kind of absurdism just this moment.

Oversized wire diameter may improve sound quality due to improved damping factor of the speaker. But I can't see a significant loss of power due to slightly "undersized" wire diameter
.
 
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#52
There certainly are intermediate wire gauge sizes, wire gauge is based on formula.

If you do the math, you will find that focusing on wire gauge (or cross-sectional area) is much more an excercise in marketing and sales than one in solid engineering. Also, some of the large gauge cable will NOT fit into the connector which makes a MUCH bigger problem in the bigger picture.

I come from the pro audio world, 12 & 13 gauge cable is pretty standard as is 14 gauge. Since in larger format systems the amps are (generally) close to the speakers, the losses are really small in context. For flown speakers, larger multi-core (Socapex) cables are used for the up & down, then broken out. Now, with many of the larger format powered speakers making headroads into large format PA, it's just feeder and signal that goes up.
 

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