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Author Topic: THHN  (Read 3696 times)

Roger Talkov

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Re: THHN
« Reply #10 on: December 05, 2016, 03:07:54 pm »

Think of it this way.

If cross talk in speaker wires in conduit was an issue, would it not be MORE of an issue in multi core speaker cable?  Where the conductors are forced to be very close to each other?

I have never heard of anybody complaining about crosstalk in a NL8 or socopex speaker cable.

Agreed.  Makes perfect sense to me.
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Kevin Graf

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Re: THHN
« Reply #11 on: December 06, 2016, 08:58:37 am »

Twisting a speaker wire pair has two advantages:
a] Reduces the self-inductance of the pair. High self-inductance on a long run can reduce treble response.
b] In rare cases, it can inhibit the speaker pair from acting as a interference antenna.
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Ivan Beaver

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Re: THHN
« Reply #12 on: December 06, 2016, 12:39:09 pm »

Twisting a speaker wire pair has two advantages:
a] Reduces the self-inductance of the pair. High self-inductance on a long run can reduce treble response.
b] In rare cases, it can inhibit the speaker pair from acting as a interference antenna.
But the longer length will add capacitance-which will also reduce the HF.

I am not sure how much each would add or reduce to affect the overall response.

Of course it will greatly depend on a lot of factors, the twist ratio, the impedance of the load, the length of the run, the size of the insulation of the wire, the ga of the wire and so forth.

There is no "easy simple" answer, unless you know all of the details involved.  And even then you have to do some calculations in order to get a usable answer.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Rob Spence

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Re: THHN
« Reply #13 on: December 06, 2016, 12:54:33 pm »

At least with a loose twist, everyone will know they are paired and even electricians should know a twisted red/black isn't power.


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Kevin Graf

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Re: THHN
« Reply #14 on: December 06, 2016, 02:58:57 pm »

But the longer length will add capacitance-which will also reduce the HF.
In a loudspeaker system, the added capacitance will be trivial with regards to high frequency response.
But the added capacitance might make some legacy and boutique amplifiers unhappy.
Heck, running speaker cables in metal conduits or near metal beams can make some modern amplifiers unhappy.
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Hal Bissinger/COMSYSTEC

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Re: THHN
« Reply #15 on: December 06, 2016, 08:28:21 pm »

But the longer length will add capacitance-which will also reduce the HF.

I am not sure how much each would add or reduce to affect the overall response.

Of course it will greatly depend on a lot of factors, the twist ratio, the impedance of the load, the length of the run, the size of the insulation of the wire, the ga of the wire and so forth.

There is no "easy simple" answer, unless you know all of the details involved.  And even then you have to do some calculations in order to get a usable answer.

How much shunt capacitance would make a noticeable difference in the HF response of an 8 ohm speaker? Now, I don't know what the capacitance per foot of a twisted pair of #10 THHN is but consider that the capacitance for a twisted pair of 24 ga outside plant telephone cable is .076 mfd per mile.

The only time I found twisting to be beneficial in speaker wiring was when I had to run individual runs to several 70 volt speakers that were tapped at 1/8 watt. Each speaker was individually switched back at the source and without twisted pairs, when a speaker switch was open there was still discernible sound from the speaker. Individual twisting took care of that together with a switch that would short the pair when open and off.

But like I said, I like to twist because it's easier to pull and identify, not because it needs to be twisted.

-Hal
« Last Edit: December 06, 2016, 08:31:33 pm by Hal Bissinger/COMSYSTEC »
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Ivan Beaver

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Re: THHN
« Reply #16 on: December 06, 2016, 09:12:52 pm »

How much shunt capacitance would make a noticeable difference in the HF response of an 8 ohm speaker? Now, I don't know what the capacitance per foot of a twisted pair of #10 THHN is but consider that the capacitance for a twisted pair of 24 ga outside plant telephone cable is .076 mfd per mile.


Notice that I said it would affect the HF.

I DID NOT say how much or at what freq----------------

As with many other things, it is real easy to get "hung up" on things that don't make a difference in the intended performance range of the device.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Hal Bissinger/COMSYSTEC

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Re: THHN
« Reply #17 on: December 07, 2016, 01:01:24 am »

Notice that I said it would affect the HF.

I DID NOT say how much or at what freq----------------


And neither did I. My question was rhetorical.

-Hal
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Ivan Beaver

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Re: THHN
« Reply #18 on: December 07, 2016, 07:35:27 am »

And neither did I. My question was rhetorical.

-Hal
Agreed

As with many things, it is easy to make a statement, and it may be true, but DOES IT MATTER?

For example.  I can go to the local lake and pee in it.

Then I could claim that I made the lake level rise because I peed into it.

While that is true, it does not make any REALIZABLE difference in the actual outcome.

But there are lots of products that love to make useless claims-and they are not lying-but they are not making a useful statement.

The end result is "does it matter", "can you easily hear the difference" etc

This is not saying it is meaningless, but a lot of "statements" lead people on paths that don't make a difference, while they completely ignore the ones that DO make a difference.

All to often people like to get hung up on the little things.

As the saying goes, "Choking on a gnat while swallowing a camel".
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Hayden J. Nebus

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Re: THHN
« Reply #19 on: December 07, 2016, 12:12:51 pm »

Here's crosstalk across a roughly 25' run of parallel, untwisted, tight bundled #10 THHN. In the neighborhood of -30dB, it is audble in the high end.

This cable run, 36 amp channels for a 3 channel mains system, exits the rack bundled, and runs together across a tray for about 20 ft before breaking into individual runs of EMT per hang (L,R,C) .

Blue trace is one box driven in the R hang, on ax, in the nearfield. In the purple trace the mic hasn't moved, but L side is now driven.

   
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