Weird electric question about solid bare wire

[zbang]

The NEC current ratings are based on heat dissipation and the insulation (fire safety), so forget about all of those for this application. The things to look at are resistive and minor inductive losses (ignoring any "skin effect").

Work from the current back through the resistance to voltage loss and decide what's an acceptable level. Example, 10g wire is about 1.1 ohm/1k-ft, so a 50 amp current will give about a 2.4v drop (probably way too high). Maybe 4g will do the job, you'll have to run the numbers. And if this is not an "audiophile" application, things are a lot easier.

 

[drcampbell]

... I will be laser cutting acrylic channels and brackets. ...

If you mount them off the surface with metal brackets and free air on all sides, you can use "small" bare conductors and let them operate at obscenely high temperatures. Copper melts at about 1360 Kelvin, so you can be unconcerned about copper conductors at temperatures up to about 680 K. (be mindful of your terminations; solder certainly can't perform at that temperature)

 

[ggunn]

There are a few full bridge on the market now that can be run as 2 half bridge amps but are internally strapped to a full bridge so you get a full push pull from the amp

I'm not sure what the difference is but with the amps I am familiar with one side is polarity flipped with the - conductors connected in the amp, and the speaker cable is connected to the two + outputs.

 

[ggunn]

This will be roughly a 167 db spl demo vehicle playing music for extended periods of time.

167dB? Ye gods! I don't want to be anywhere near it.

 

[RayM77]

The NEC current ratings are based on heat dissipation and the insulation (fire safety), so forget about all of those for this application. The things to look at are resistive and minor inductive losses (ignoring any "skin effect").

Work from the current back through the resistance to voltage loss and decide what's an acceptable level. Example, 10g wire is about 1.1 ohm/1k-ft, so a 50 amp current will give about a 2.4v drop (probably way too high). Maybe 4g will do the job, you'll have to run the numbers. And if this is not an "audiophile" application, things are a lot easier.

Yeah not really a audiophile application for the subs and the longest wire will be about 12’ so I wouldn’t think the loss would be very low.

 

[RayM77]

If you mount them off the surface with metal brackets and free air on all sides, you can use "small" bare conductors and let them operate at obscenely high temperatures. Copper melts at about 1360 Kelvin, so you can be unconcerned about copper conductors at temperatures up to about 680 K. (be mindful of your terminations; solder certainly can't perform at that temperature)

I was looking at doing the acrylic as it would look nice and don’t really want the thing to be a electric heater lol

 

[RayM77]

I'm not sure what the difference is but with the amps I am familiar with one side is polarity flipped with the - conductors connected in the amp, and the speaker cable is connected to the two + outputs.

Very similar but we do it on the outside of the amplifier so gives us other options for wiring

 

[RayM77]

167dB? Ye gods! I don't want to be anywhere near it.

lol you don’t hear the music we beat it into your organs

 

[winnie]

Just confirming: 20Hz to 60Hz (intestinal evacuation subwoofer) and not 20kHz?

IMHO for this application you really shouldn't be thinking 'wire' but rather 'bus bar'. Even if you are using a round bus bar

You say the maximum room available for your conductors is 0.4", but you need 2 conductors for your speakers. Would any pair of conductors that fits in a 0.4"x0.8" cross section work? For example two 1/8 x 3/4 copper bars?

I bet you could do some pretty exposed bus work using nickel plated copper bus bars...

Bus bar ampacity:

Copper Alloy C11000 Bus Bar Ampacity Chart

Ampacity table for bus bars having an emissivity of 0.4. Observed on samples exposed for 60 days in an industrial environment.

stormpowercomponents.com

-Jonathan

 

[drcampbell]

I ... don’t really want the thing to be a electric heater lol

If you're pushing 10kW into each speaker, you've already crossed that bridge. The hook up wires -- even if they're "undersized" will contribute a fraction of that.

 

[Elect117]

Bare copper will allow noise on audio lines. It is ill advised to not have a insulator on the wire.

 

[zbang]

That makes approximately zero sense, especially at the power levels the OP is talking about. (I mean it hardly makes sense even for small signals.)

 

[RayM77]

Just confirming: 20Hz to 60Hz (intestinal evacuation subwoofer) and not 20kHz?

IMHO for this application you really shouldn't be thinking 'wire' but rather 'bus bar'. Even if you are using a round bus bar

You say the maximum room available for your conductors is 0.4", but you need 2 conductors for your speakers. Would any pair of conductors that fits in a 0.4"x0.8" cross section work? For example two 1/8 x 3/4 copper bars?

I bet you could do some pretty exposed bus work using nickel plated copper bus bars...

Bus bar ampacity:

Copper Alloy C11000 Bus Bar Ampacity Chart

Ampacity table for bus bars having an emissivity of 0.4. Observed on samples exposed for 60 days in an industrial environment.

stormpowercomponents.com

-Jonathan

So each conductor needs to run through a .4” diameter hole, but for the beauty part I was thinking polished clear coated copper so it stay nice looking.

 

[RayM77]

Just confirming: 20Hz to 60Hz (intestinal evacuation subwoofer) and not 20kHz?

IMHO for this application you really shouldn't be thinking 'wire' but rather 'bus bar'. Even if you are using a round bus bar

You say the maximum room available for your conductors is 0.4", but you need 2 conductors for your speakers. Would any pair of conductors that fits in a 0.4"x0.8" cross section work? For example two 1/8 x 3/4 copper bars?

I bet you could do some pretty exposed bus work using nickel plated copper bus bars...

Bus bar ampacity:

Copper Alloy C11000 Bus Bar Ampacity Chart

Ampacity table for bus bars having an emissivity of 0.4. Observed on samples exposed for 60 days in an industrial environment.

stormpowercomponents.com

-Jonathan

But yes the box is tuned 21hz rear chamber and 42hz front chamber.

 

[RayM77]

If you're pushing 10kW into each speaker, you've already crossed that bridge. The hook up wires -- even if they're "undersized" will contribute a fraction of that.

Yeah and I under thermodynamics and the conservation of energy.

 

[Speedskater]

3 hours of 150 Amp continuous current thru 4AWG copper will destroy PVC/Nylon insulation (that's 105°C). Bare wire will run cooler.
But music is nowhere near continuous current. But it will still be hot.

 

[LarryFine]

I had a decent stereo in my first mini-van, a Dodge Caravan, many years ago.

An in-dash CD/radio fed a 4-way active cross-over that fed:
A 2x35w amp running ribbon tweeters on top of the dash next to the OEM speaker openings,
A 2x40w amp running 5" mid-ranges in the OEM openings,
A 2x55w amp running a pair of 6.5" mid-woofers in the front doors,
And a 1x125w amp running a 12" sub-woofer in a large tuned-port box in the back of the van.

It had an excellent front sound-stage image.


But my best system is now my home theater.

 

[RayM77]

3 hours of 150 Amp continuous current thru 4AWG copper will destroy PVC/Nylon insulation (that's 105°C). Bare wire will run cooler.
But music is nowhere near continuous current. But it will still be hot.

And this is the exact reason I asked that question on here is I have no idea how hot it could get, I do know the air moving around the wire will help as it will be a lot of air, thank you

 

[RayM77]

I had a decent stereo in my first mini-van, a Dodge Caravan, many years ago.

An in-dash CD/radio fed a 4-way active cross-over that fed:
A 2x35w amp running ribbon tweeters on top of the dash next to the OEM speaker openings,
A 2x40w amp running 5" mid-ranges in the OEM openings,
A 2x55w amp running a pair of 6.5" mid-woofers in the front doors,
And a 1x125w amp running a 12" sub-woofer in a large tuned-port box in the back of the van.

It had an excellent front sound-stage image.


But my best system is now my home theater.

Yeah right now we have door panels for 6 10” drivers and 4 compression drivers each. We are building this as a ground and pound system

 

[GoldDigger]

Neutral in speaker wires?

Some speaker circuits are unbalanced with one terminal grounded (neutral). Others, typically for higher power. are balanced, with the center tap grounded but not run to the speakers. So in this particular case, a neutral running to the speaker is unlikely.