It is currently Fri Mar 29, 2024 3:53 am


Speaker Wire

Speakers, amplifiers, headphones, multi-channel audio, reverb units, mixers, wiring, ...
  • Author
  • Message
Offline

brooke.benfield

Member

  • Posts: 183
  • Joined: Fri Apr 10, 2009 10:38 am
  • Location: Oregon City

Speaker Wire

PostFri Mar 09, 2012 3:52 pm

Hi Folks;

If any of you have ever wondered what sort of wire to use in your HW speaker system then I'd like to recommend you read the information found in this link:

http://www.roger-russell.com/wire/wire.htm#thetruth

I stumbled on this page while seeking an answer for the large HW installation that will be going into the church I play for.

There's a table part way down the page that lists the maximum distance a given wire gauge (AWG) can be run. The concept is to keep the resistance of the wires to no more than 5% of the Nominal Resistance of the speaker. The author states that there's no audible difference between simple zip cord or lamp cord and fancy expensive audiophile speaker wires so long both wire types are of sufficient gauge to fall within the 5% rule.

Our HW instrument will most likely have around 70 audio channels. All of the speaker wires (up to 30ft. or 40ft. in length) will have to be routed through a fairly small aperture, so I am wondering if cross-talk and stray interferences are a big enough problem to require shielding?

Does a shielded wire cause the amplifiers to see a more capacitive load?

I remember a couple of posts here that stated twisted-pair (cancels capacitance) and equal length on all channels (minimizes voicing) are both desirable characteristics for speaker wires. Any comments, additional wisdom?

Thanks.
Brooke Benfield
Organist, Gethsemane Lutheran Church
Portland OR
Offline
User avatar

engrssc

Member

  • Posts: 7283
  • Joined: Mon Aug 22, 2005 10:12 pm
  • Location: Roscoe, IL, USA

Re: Speaker Wire

PostFri Mar 09, 2012 9:02 pm

Belden and some others make multi paired cables of various gauges that are bundled in a single jacket. Makes for easier installation especially in tight spots, conduits,etc. I haven't run into crosstalk problems with speaker cables running near other speaker cables. Twisted pairs are good.

I did run into what I would categorize as a weird situation many years ago, where there was an unexplained distortion occurring on an installation where many speaker cables (and these were carrying substantially high audio levels) were run together. The length was at least 100 feet or more. There were some unused pairs in the bundle. Long story short, when we grounded the unused pairs, (at the amplifier end) the distortion was gone. To prove the "theory" we ungrounded them, the distortion returned. Someone higher learned than myself might be able to explain that, maybe?

Assuming the power amplifiers are separated from the speakers by the distance(s) you mention. Crosstalk mainly occurs when low level (as in amplifier input signal) audio cable runs near a cable carrying high(er) level signals for any distance. Good technique says you can cross a low level (signal) cable over a high level (signal) if they are separated (some) or don't run parallel. As in crossing over at 90 degrees. If possible, keep them separated, a good rule. High level also means power (110VAC) cables/runs. Easy to pick up 60 Hz (hum) from these.

Regarding input signals, unbalanced (single conductor shielded) cables are more prone to all sorts of audio issues (junk) as compared to balanced (two conductors - shielded of course). In some installations, we find the shield being connected only at one end works better. The two inner conductors are carrying the signal (referred to as balanced).

Amplifier input cables should always be shielded (if possible). I say if possible because I have many times taken an audio signal (isolated usually with capacitors and a transformer) from a telephone line which isn't shielded and sometimes isn't twisted at least not very much.

From my experience of many years installing many sound systems huge and small.

Rgds,
Ed
Offline
User avatar

schantzplayer

Member

  • Posts: 485
  • Joined: Tue Jun 22, 2010 4:50 pm
  • Location: Mifflinville, PA USA

Re: Speaker Wire

PostFri Mar 09, 2012 9:29 pm

Telephone lines are twisted balanced pairs and therefore don't need a shield (usually). Grounding the spare wires made them acts a shield and eliminated a ground loop.
Offline
User avatar

John Murdoch

Member

  • Posts: 358
  • Joined: Fri Mar 18, 2011 8:06 pm
  • Location: Wind Gap, Pennsylvania

Re: Speaker Wire

PostFri Mar 09, 2012 10:50 pm

Brooke,

You might talk to Tom Mody at Church Audio Supply:

http://www.churchaudiosupply.com/

I have not done business with him, but only because I'm worrying about the audio components of my church project first. (My church is a lot smaller than your church.) But his business is church audio--specifically wiring and cabling--and he has an impressive list of customers.

In one of his articles on his web site he makes much the same point as the article you refer to: voltage drop is a function of wire size and distance, not the brand name of the cable. CAS offers pre-bundled cables in a wide range of varieties--specifically for church audio applications where a lot of wires need to fit into a small space.

The web site emphasizes--repeatedly--that they want you to call. I'd give him a call.

If you do, let us know what you think--and how your project turns out.
Offline

brooke.benfield

Member

  • Posts: 183
  • Joined: Fri Apr 10, 2009 10:38 am
  • Location: Oregon City

Re: Speaker Wire

PostMon Mar 12, 2012 10:36 am

>Crosstalk mainly occurs when low level (as in amplifier input signal) audio cable runs near a cable carrying high(er) level signals for any distance.

I had thought this would be the case. We are planning on using balanced TRS connections between the audio interface and amplilfiers.

>In some installations, we find the shield being connected only at one end works better. The two inner conductors are carrying the signal (referred to as balanced).

We will definitely keep that in mind.

>You might talk to Tom Mody at Church Audio Supply

We will check him out.

Engrssc, Schantzplayer, John, I thank you for your responses.
Brooke Benfield
Organist, Gethsemane Lutheran Church
Portland OR

Return to Amplification

Who is online

Users browsing this forum: No registered users and 2 guests