Cable choice again?

[kenwstr]

I am almost afraid to ask this but here goes.

The back story is a church PA system, I swapped out the old slightly shorter 18 AWG FB cables for 7.5 m 14 AWG cable. The improvement was very dramatic in clarity and I have a little extra flexibility on stage. However this was something of an experiment so I only got the minimum length of cheap cable to run 1 pair on FOH & and another on FB (4 in total) cable happened to be Studio Acoustic as that was easily sourced locally.

Now for an outdoor setup, I want to add another 2 enclosures on FOH, 2 in a parallel on each channel at 4 ohm but I need more cable. I could just get more of the same but I am aware that some folk like to just run 10 AWG on everything regardless and as I use 12 AWG at home for a 4 m run, I'm thinking, well why not go for 10 AWG for the 7.5 m FOH leads. By the traditional PA standards, this is gross overkill but that same 5% of load standard has proved inadequate so I'm considering going from 14 to 10. Is that ridiculous? If I do this, I don't have a whole lot of options, experience or advice to draw on so I'd be buying something unfamiliar to me. I have suitable connectors for 10 AWG and I'd rewire the enclosures internally to maximize any possible benefit. The available non exotic choices are:

Space 10 AWG 259/0.16 strands
Ugly 10 AWG 672/0.1 strands

Studio Acoustic don't do 10 AWG, 12 is available but hard to find and 14 is 196/.012 strands

Jaycar Jumbo is around 12-13 AWG 259/0.12 strands.

Someone commented that more strands are better so I'm favoring the Ugly cable I'd have to byt a 50 m roll at $178 to make 3 pairs of 7.5m cables.

So is anyone familiar enough to comment on any of these cables?
Anyone have an opinion as to which is more likely to sound best?

Regards,
Ken

 

[tyhjaarpa]

For such a short runs 10-14 awg won't make a difference. I would go for cheapest OFC option you can find between those awg ranges. More strands makes the cable more flexible and easier to work with but thats about it.

 

[Rickster71]

I am almost afraid to ask this but here goes.

The back story is a church PA system, I swapped out the old slightly shorter 18 AWG FB cables

When I saw PA system and 18 AWG. Is this a 70-volt system?

 

[ManBarra]

Yeah don't go too crazy. Anything 10-14 AWG is good.

 

[kenwstr]

When I saw PA system and 18 AWG. Is this a 70-volt system?

I am not sure what you mean by 70 volt in relation to speaker cable though power can be translated to volts RMS. The FOH speakers are rated to 200 W continuous, the amp is limited to a bit over 200 W into 8 ohms or 400 w into 4 ohms. The latter being the case with 2 parallel speakers per channel. Power supply and phantom power seem to me irrelevent to speaker cable so I doubt these to be your question.

The thing that got me questioning speaker cable guage is that 18 AWG should have been sufficient under the 5% of load standard but it is very obviously not an adequate standard as changing to 14 is like night and day. So this logically leads to the question just how far can guage be pushed before it doesn't make a difference. I am very skeptical of certain claims about cables so tend to only consider comments based in real engineering or blind testing. I found a small sample blind test article in the home HiFi context that suggested every listener agreed there were improvements up to 12 AWG but opinions differed at guages heavier than this. So, beyound that point personal preference came into play. So my thinking is that the old 5% of load standard may not reflect the point between real improvement and personal preference. It seems to me, such a point would be the best standard to work too and may be worth reviewing.

Ken

 

[MrBoat]

I am not sure what you mean by 70 volt in relation to speaker cable though power can be translated to volts RMS. The FOH speakers are rated to 200 W continuous, the amp is limited to a bit over 200 W into 8 ohms or 400 w into 4 ohms. The latter being the case with 2 parallel speakers per channel. Power supply and phantom power seem to me irrelevent to speaker cable so I doubt these to be your question.

The thing that got me questioning speaker cable guage is that 18 AWG should have been sufficient under the 5% of load standard but it is very obviously not an adequate standard as changing to 14 is like night and day. So this logically leads to the question just how far can guage be pushed before it doesn't make a difference. I am very skeptical of certain claims about cables so tend to only consider comments based in real engineering or blind testing. I found a small sample blind test article in the home HiFi context that suggested every listener agreed there were improvements up to 12 AWG but opinions differed at guages heavier than this. So, beyound that point personal preference came into play. So my thinking is that the old 5% of load standard may not reflect the point between real improvement and personal preference. It seems to me, such a point would be the best standard to work too and may be worth reviewing.

Ken

I have some experience with wiring and seemingly profound results with switching out wires. Mine comes from the marine industry. I have switched out smaller gauges for larger but for different reasons. Mostly redundancy with the connections and actual wire movement, or perhaps I wanted to add a significan length for a service loop because it's near impossible to get to it to service.

On the surface, the jump up in size would seem to have been an improvement, when in fact, it was because I had new, 'clean' and solid connections again, perhaps even better than the initial install. So just for the heck of it, I try the thinner wires again but again, clean, or even new and now there is suddenly no discernible difference. Happens a LOT with ground wires in my industry but the idea is the same.

I have speaker wire here that is 30+ years old, that is tarnished completely throughout, even though the insulation has not been breached.

 

[kenwstr]

Yes, I agree that corrosion affects performance. I make apoint of regularily cleaning all connections and contacts in the entire system. Deoxit all interconnects, plugs sockets, clean lube all pots, faders, trimmers and wire wound posts etc, anything that is not soldered gets a treatment. I try to do this every 2 years or so. Any cable ends that are too far get clipped and reconnected until low resistance is reestablished. Speaker cable is hard to test though as I don't have a suitable meter for the required scale range, hundredths of an ohm. I guess you could have a point there. Aside from the end connection, are you suggesting surface corrosion along the length may also be an issue?

Ken

 

[MrBoat]

Yes, I agree that corrosion affects performance. I make apoint of regularily cleaning all connections and contacts in the entire system. Deoxit all interconnects, plugs sockets, clean lube all pots, faders, trimmers and wire wound posts etc, anything that is not soldered gets a treatment. I try to do this every 2 years or so. Any cable ends that are too far get clipped and reconnected until low resistance is reestablished. Speaker cable is hard to test though as I don't have a suitable meter for the required scale range, hundredths of an ohm. I guess you could have a point there. Aside from the end connection, are you suggesting surface corrosion along the length may also be an issue?

Ken

Yes, surface and inter-strand corrosion, relaxed contacts over time. I have chased connections on 12v systems where it was less than a volt off. 11 volts acts like 12 volts everywhere else, but not to the ecm on an outboard engine and some other sensitive systems. Even acidic pollution in the air can result in a battery with regard to dissimilar metals, regardless of how noble the metals may be. Half of why they dope sensitive connections with lithium in corrosive environments. Coax the same, and likely worse outdoors if they don't use weather tight connections. The old wire I have here that's tarnished, almost feels like it has a waxy residue on it. It looks brown, but if you wipe it with a paper towel, it comes off green. If it's not shiny copper, it's fouled. The only saving grace may be a secure connection when the wire was new will buy time, but eventually there is bound to be some losses.

Even solder joints get tired over time which is why they may re-flow connections on older equipment, even though they still have a good mechanical bond.

 

[slipperybidness]

Yes, surface and inter-strand corrosion, relaxed contacts over time. I have chased connections on 12v systems where it was less than a volt off. 11 volts acts like 12 volts everywhere else, but not to the ecm on an outboard engine and some other sensitive systems. Even acidic pollution in the air can result in a battery with regard to dissimilar metals, regardless of how noble the metals may be. Half of why they dope sensitive connections with lithium in corrosive environments. Coax the same, and likely worse outdoors if they don't use weather tight connections. The old wire I have here that's tarnished, almost feels like it has a waxy residue on it. It looks brown, but if you wipe it with a paper towel, it comes off green. If it's not shiny copper, it's fouled. The only saving grace may be a secure connection when the wire was new will buy time, but eventually there is bound to be some losses.

Even solder joints get tired over time which is why they may re-flow connections on older equipment, even though they still have a good mechanical bond.

You don't even need acidic pollution to get "battery action" from 2 different metals. 2 metals in contact with each other will create a voltage, this is the entire basis behind Thermocouples.

Also, I really think that you may be mistaken for adding Lithium for corrosion resistance. Can you supply a source of this information?

The thing is, Lithium is a Coulumn 1A element on the periodic table, it only needs to lose 1 electron to have a full outer shell, that means it will share similar chemical properties as Na and K, and will readily be highly reactive with water, even atmospheric moisture. If you are really using Lithium, then is it an alloy or some post-treatment? If a post-treatment, then I'm curious if the lithium if used sacrificially (but seems like it should corrode very quickly) or if it's just a Lithium grease to allow the parts to come apart easier later.

 

[Speedskater]

A '70 Volt System' is a commercial or PA sound system. It allows many loudspeakers to be driven by one 70V power amplifier. Each loudspeaker has it's own transformer. The transformers have several taps that allow adjustment of the level of that speaker in respect to the others.

 

[Rickster71]

I am not sure what you mean by 70 volt

Ken

18 AWG is normally used a a 70-volt system.
If it doesn't say that at the amp, or the speakers don't have a multi-tap. Then it makes me wonder if someone didn't change the amps and speakers and didn't bother running new wire to accommodate the different equipment.

 

[Speedskater]

A RaneNote about 70V systems.

Constant-Voltage Audio Distribution Systems
Dennis Bohn, Rane Corporation

RaneNote 136 written 1997; last revised 3/07

• 25, 70.7 & 100 Volts
• U.S. Standards
• Just What is "Constant" Anyway?
• Voltage Variations -- Make Up Your Mind
• Calculating Losses -- Chasing Your Tail

http://www.rane.com/note136.html

 

[kenwstr]

18 AWG is normally used a a 70-volt system.
If it doesn't say that at the amp, or the speakers don't have a multi-tap. Then it makes me wonder if someone didn't change the amps and speakers and didn't bother running new wire to accommodate the different equipment.

I see, same principle as the AC power grid to counter loss over long distance.
No it isn't that type of system. Although there have been several amp configurations over the years, the speakers don't have transformers. The system was originally cobbled together under tight budget constraints and some components weren't even ballanced. Now we have full ballanced connectivity from stage to mixer, equaliser and FOH amp. The FB amp is still unbalanced though. It's essentially an analogue system with a couple of PCs attached to handle recorded music and projection. The latter is not implemented well but I am gradually improving things. I have been concentrating effort on the delivery from mixer to stage for now to ensure this is not limiting performance quality. The digital side of things will be the next project.

Ken