Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

coaxial cable for speaker output wiring within amplifier
coaxial cable for speaker output wiring within amplifier
coaxial cable for speaker output wiring within amplifier Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th August 2016, 11:40 PM   #1
HiFiNutNut is offline HiFiNutNut  Australia
diyAudio Member
 
Join Date: May 2004
Location: Sydney
Default coaxial cable for speaker output wiring within amplifier

Does anybody use coaxial cable for wiring speaker output on the amplifier circuit board to speaker terminals on the amplifier chassis?

I have some Belden 1694 that has 19AWG core and 12AWG shield, the resistance of which is low enough for 150mm length of wire between the amp board and speaker terminals.

General Description of the cable: 19 AWG stranded (7x27) bare copper conductor, gas-injected foam HDPE insulation, double tinned copper braid shield (95% coverage), PVC jacket.

I think using coaxial cable may reduce EMI due to the high current of speaker wire, or does it not?

Is the coaxial cable made of materials suitable for carrying high current?
  Reply With Quote
Old 28th August 2016, 12:52 AM   #2
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
At least in the realm of pro audio where I labor, I can;t see any reason to do this. Would the inch or two of wire to the jacks radiate more than the entire amp circuit connected to it?
  Reply With Quote
Old 28th August 2016, 02:19 AM   #3
HiFiNutNut is offline HiFiNutNut  Australia
diyAudio Member
 
Join Date: May 2004
Location: Sydney
I wrapped around the PSU wires near the amp board with clamp-on ferrite and it made the sound clearer! I love it.

I am not sure if it is the effect of the ferrite filtering the RF or the ferrite wrapping around the PSU wires helping to shield the EMI. I guess it may be the later so I think coaxial cable for speaker wires may help. I happen to have the PSU and speaker output wiring points on the PCB right in the middle of the PCB so radiation at those points could affect the sensitive signal level circuits.

I can't think of a case that coaxial cable will make it worse. The only concern is that I don't know if a coaxial cable is up to the job for high current use.

Last edited by HiFiNutNut; 28th August 2016 at 02:26 AM.
  Reply With Quote
Old 28th August 2016, 09:09 PM   #4
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
No need for coax in this position. If it is thick enough or short enough it will do no harm. Better to use twisted pair with nice thick cable.
  Reply With Quote
Old 30th August 2016, 11:38 AM   #5
AndrewT is offline AndrewT  Scotland
R.I.P.
 
Join Date: Jul 2004
Location: Scottish Borders
19awg may start to warm up slightly when asked to pass pass continuous high currents.
It's well insulated inside that foam dielectric. The foam may start to overheat and maybe melt?
The resistance of the 150mm of wire is actually quite low so will not interfere with the performance of the speakers.
A couple of metres to the speaker may be too high a resistance and adversely affect LF performance.
__________________
regards Andrew T.
  Reply With Quote
Old 30th August 2016, 10:57 PM   #6
HiFiNutNut is offline HiFiNutNut  Australia
diyAudio Member
 
Join Date: May 2004
Location: Sydney
Thanks, DF and Andrew.

I was using twisted pair for it as well as for the PSU wires. Wrapping around the PSU wires with a few clamp-on ferrite improved the sound by much, so it might be due to common mode RF noise on the PSU lines, instead of the EMI from the PSU line radiating into the circuit board.

If there is a risk of using coaxial cable then I have to abandon the idea.
  Reply With Quote
Old 30th August 2016, 11:11 PM   #7
HiFiNutNut is offline HiFiNutNut  Australia
diyAudio Member
 
Join Date: May 2004
Location: Sydney
Calculated based on the datasheet, 150mm length will have a resistance of 0.0042R at 20 degree temperature. Consider 5A constant current, the dissipation would be 5 x 5 x 0.0043 = 0.1W.

Will 0.1W melt the cable?

It is possible that the current will be less than 5A constant current for music. For 5A constant current and 6R speakers, the speaker power dissipation will be 160W. I guess that would be very loud.

If the averaged current going through speaker wires is 1A for music, then the power dissipated in the 150mm coaxial cable will be 0.0042W. If 2A current, dissipation will be 0.017W. That is possibly not going to melt the cable.

Last edited by HiFiNutNut; 30th August 2016 at 11:16 PM.
  Reply With Quote
Old 31st August 2016, 06:15 AM   #8
HiFiNutNut is offline HiFiNutNut  Australia
diyAudio Member
 
Join Date: May 2004
Location: Sydney
The real question is, how far the signal tracks need to be away from the high current carrying PSU and SPEAKER output tracks on the PCB without picking up noise?

And how far the SPEAKER output tracks need to be away from the PSU tracks without picking up noise?
  Reply With Quote
Old 31st August 2016, 09:48 AM   #9
KSTR is offline KSTR  Germany
diyAudio Member
 
KSTR's Avatar
 
Join Date: Jul 2007
Location: Central Berlin, Germany
The biggest issue with a foamed dielectric coax is soldering because the foam is not heat resistant, very easy to produce a short right away (good b/c you'll notice quickly), or one that may develop in future (bad).
  Reply With Quote
Old 31st August 2016, 11:19 AM   #10
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Quote:
Originally Posted by HiFiNutNut
The real question is, how far the signal tracks need to be away from the high current carrying PSU and SPEAKER output tracks on the PCB without picking up noise?

And how far the SPEAKER output tracks need to be away from the PSU tracks without picking up noise?
The further they are, the less they will pick up. As a rough guide, pick up will begin to tail off from the point where the distance between two circuit loops begins to exceed the size of those circuit loops. You need to be well beyond this point.
  Reply With Quote

Reply


coaxial cable for speaker output wiring within amplifierHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gotham interconnect cables, speaker cables and coaxial cable Musik007 Twin Audio 24 23rd August 2013 05:57 PM
help with single bi-wiring audioquest rocket 33 speaker cable nnck Parts 1 23rd December 2007 11:36 AM
microphone cable vs coaxial cable Leolabs Parts 4 31st August 2006 11:24 AM
RG59 Coaxial shielded cable for input wiring? John Biles Solid State 77 8th December 2005 10:29 PM
Focusing on wiring cable for gainclone!!!Share ur experience in wiring cable.... thomgun_lc Chip Amps 38 31st August 2005 03:46 PM


New To Site? Need Help?

All times are GMT. The time now is 11:47 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki