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Why does the gauge of speaker wire matter?
mkop
post Oct 11 2003, 04:12
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I've read some things discussing speaker wiring such as speaker reviews and their is always something like "the included cables are ok but you'll probably want to go and get something thicker." My question is why do I want some huge python of a cable? And what principles are used to decide what size is big enough?
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Pio2001
post Oct 11 2003, 13:53
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Speaker cable blind tests :

Placebo at work : http://www.nytimes.com/library/tech/99/12/...les/23down.html
ABX tests (negative) : http://www.pcavtech.com/ABX/abx_wire.htm

Skin effect evaluation :
http://www.hydrogenaudio.org/forums/index....50&#entry135877

Frequency response of speaker cables, theory :

Gauge : a 2.5 mm2 cable (big lamp cord) should stand 3000 W IIRC. If you don't pump up more than 3000W from your ampli (this might cut off your electric supply anyway) it's OK.

The resistance of the cable interacts with the impedance of the speaker.
Say that the speaker impedance varies between 4 and 8 Ohm according to the frequency, the ampli output is 0.08 Ohm, and the cable 10 meters and 0.75 mm2 (cheap speaker cable).
Resistance of the two wires of the cable (20 meters) :
0.0178/0.75*20=0.47 Ohm.
Voltage difference at 4 and 8 Ohm :
At 4 Ohm :
V4=E*4/(4+0.08+0.47)=0.936 E
V8=E*8/(8+0.08+0.47)=0.879 E

With V4 volage on the speaker at 4 Ohm, V8 at 8 Ohm, E being the Thevenin Voltage of the ampli.

The attenuation is
20log(0.936/0.879)=0.54 dB

Ths might or might not be audible according to the width of the frequency range affected.

If we suppose that the speaker impedance can fall to 1 Ohm at a given frequency, as suggested by -, then we get 3 dB of loss at this frequency, that should be audible. But I wonder under which condition an 8 Ohm speaker can fall to 1 Ohm.

Since these data are near the threshold of audibility, and thicker cable not much expensive, it's better to stay on the safe side and use a thicker cable.

Frequency response of speaker cables, measurments :
http://www.hydrogenaudio.org/forums/index....50&#entry135916
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Posts in this topic
- mkop   Why does the gauge of speaker wire matter?   Oct 11 2003, 04:12
- - boojum   If you are driving speakers which require much pow...   Oct 11 2003, 04:29
- - TwoJ   I think I have never seen such bending of physical...   Oct 11 2003, 04:38
- - ScorLibran   [reaching back 15 years to my electrical engineeri...   Oct 11 2003, 06:12
- - TwoJ   Right concept but wrong application, sorry ScorLib...   Oct 11 2003, 06:37
- - ScorLibran   QUOTE (TwoJ @ Oct 11 2003, 01:37 AM)Right con...   Oct 11 2003, 06:43
- - AgentMil   QUOTE (ScorLibran @ Oct 11 2003, 01:43 PM)QUO...   Oct 11 2003, 08:02
- - _Shorty   the longer the cable of X gauge is, the higher its...   Oct 11 2003, 08:24
- - JeanLuc   There are three major parameters that influence el...   Oct 11 2003, 10:29
- - boojum   Reading the posts of my learned engineering collea...   Oct 11 2003, 11:18
- - fewtch   Baah... I think I want to try $15,000 speaker...   Oct 11 2003, 12:56
- - Pio2001   Speaker cable blind tests : Placebo at work : htt...   Oct 11 2003, 13:53
- - AgentMil   QUOTE (fewtch @ Oct 11 2003, 07:56 PM)Baah......   Oct 11 2003, 14:06
- - TwoJ   What I think most "real" audiophiles wil...   Oct 11 2003, 16:03
- - JeanLuc   QUOTE (Pio2001 @ Oct 11 2003, 12:53 PM)But I ...   Oct 11 2003, 17:05
- - _Shorty   http://www.hydrogenaudio.org/forums/index.php?show...   Oct 11 2003, 18:30
- - sshd   There sure is some interesting information about e...   Oct 12 2003, 00:05
- - adamjk   Pio2001, I'm rather observer, but you're t...   Oct 12 2003, 01:14
- - NeoRenegade   QUOTE (ScorLibran @ Oct 11 2003, 12:12 AM)[re...   Oct 12 2003, 06:03
- - TwoJ   QUOTE However, I noted an interesting thing - ever...   Oct 12 2003, 06:16
- - lucpes   QUOTE (Pio2001 @ Oct 11 2003, 12:53 PM)Say th...   Oct 30 2003, 14:43
- - Dex4now   QUOTE (fewtch @ Oct 11 2003, 03:56 AM)Baah......   Oct 30 2003, 15:07
- - lucpes   Nice I always wondered why the lights in my house...   Oct 30 2003, 15:27
- - fewtch   QUOTE (lucpes @ Oct 30 2003, 07:27 AM)Nice I...   Oct 30 2003, 16:09
- - lucpes   No, conventional drivers but dipole (open baffle) ...   Oct 30 2003, 16:46
- - Pio2001   QUOTE (lucpes @ Oct 30 2003, 02:43 PM)impedan...   Oct 30 2003, 20:07
- - lucpes   QUOTE (Pio2001 @ Oct 30 2003, 07:07 PM)QUOTE ...   Oct 30 2003, 21:50
- - Pio2001   Before starting, how do we know that this is the a...   Oct 31 2003, 00:01
- - lucpes   ABX result of 2xCAT5 cables per polarity (4x8 wire...   Oct 31 2003, 14:00
- - lucpes   QUOTE (Pio2001 @ Oct 30 2003, 11:01 PM)Before...   Oct 31 2003, 15:30
- - Continuum   QUOTE (lucpes @ Oct 31 2003, 03:00 PM)Should ...   Oct 31 2003, 18:32
- - Pio2001   Thank you very much for sharing your results, Lucp...   Oct 31 2003, 20:08
- - lucpes   The offset did not influence the test: ABC HR con...   Oct 31 2003, 20:42
- - ff123   QUOTE (lucpes @ Oct 31 2003, 11:42 AM)The off...   Oct 31 2003, 21:11
- - Continuum   I didn't think that you were hearing the offse...   Oct 31 2003, 21:33
- - lucpes   QUOTE (Continuum @ Oct 31 2003, 08:33 PM)I di...   Oct 31 2003, 21:37
- - Pio2001   So it is quite a big gauge after all. 24 AWG is 0....   Oct 31 2003, 22:50
- - _Shorty   unless it has protection for those situations, man...   Nov 1 2003, 01:54
- - Mike Giacomelli   QUOTE - Although it should be the case - I can tel...   Nov 1 2003, 04:49
- - KikeG   High freq. attenuation of CAT5 cable is quite prob...   Nov 1 2003, 19:31
- - lucpes   QUOTE (Pio2001 @ Oct 31 2003, 09:50 PM)So it ...   Nov 1 2003, 22:04
- - sshd   What type of cat5 cable was used in this test? I...   Nov 2 2003, 00:43
- - lucpes   El cheapo CAT5 solid core type used in the test. ...   Nov 2 2003, 01:24
- - sshd   QUOTE (lucpes @ Nov 1 2003, 10:04 PM)Until th...   Nov 4 2003, 00:24
- - Pio2001   QUOTE (sshd @ Nov 4 2003, 12:24 AM)3. Does th...   Nov 4 2003, 00:37
- - lucpes   QUOTE (sshd @ Nov 3 2003, 11:24 PM)It seems y...   Nov 17 2003, 15:05
- - Pio2001   Sorry to hear about this. Either there was a short...   Nov 17 2003, 23:36
- - lucpes   Phew, I fixed it... turned out that the potentiome...   Nov 18 2003, 13:59


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