Speaker Cable

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#51
traderbam said:
DSCk
This is competent cable and lies flat. It isn't cork coloured so you'd have to paint it. Maybe they do a transparent version.
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I bought some stuff just like that when I built my speakers. It was white but had silver printing on the side. It is quite nice to handle, very flexible, but more important I got it really cheap from Madisound. The printing on the side said "Sliver" instead of "Silver", so I assume the vendor dumped it.
 
#53
scottjoplin said:
The Wikipedia definition seems a little ambiguous
> Reading around it does seem to be largely a made up term for marketing purposes.
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Exactly.

It actually is a simple expression of "merit".

Of the *amplifier* in particular. So the load is whatever round number, not the actual impedance of any *speaker*.

But it gained prominence when late tube-amp designs met early "acoustic suspension" speakers. Speakers were now designed by L-C-R math, and lower R could be shown to be better. Naked triode driving "8 Ohms" might be 4 to 2 ohm source, total 12 to 10 Ohms. Taking the source down to 1 Ohms has a small effect, to 0.5 Ohms even less effect, BUT it was "natural" for high-NFB amps to go even lower. Especially a few years later when transistors got rid of the output transformer and eventually found high gain with low phase shift. DFs of "thousands" have been touted, even if no real meaning.
 
#54
Sorry, I meant down the coaxial tube of course! Just my attempt at humour! 🙁

Wouldn't the central conductor of a line level coax be a tad thin for loudspeaker use?

Guitarists often make the mistake of using a guitar lead as a speaker cable. At the high volumes involved, the cable can become intermittent and cause damage to a valve amp.
 
#55
Haha, don't worry I got it! 🙂 Some line level coax is pretty thick, then there's the Mogami speaker coax linked to earlier. I have a short length of quite nice clear sheathed coax I bought from Maplin years ago, I think it's made by Shark, quite flexible and about the right colour.

Now we've resolved the DF issues it's nice to get back to the really important qualities of speaker cables.....

This is it (I think) Shark Audio Coax Single Screened Single Core: Amazon.co.uk: Electronics
 
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#59
scottjoplin said:
The Wikipedia definition seems a little ambiguous, it talks about using only the resistive part of the impedance
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It is the resistive part of the impedance which does the damping, plus amp O/P plus cables etc. However, the amp maker does not know what your speaker resistance will be so he uses the nominal impedance instead.

Wikipedia says:
However, the damping factor at any particular frequency will vary, since driver voice coils are complex impedances whose values vary with frequency.
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I think this suggests that the person who wrote it has not thought hard enough. DF is a single number, a figure of merit. It only tells you something (and not very much) in the region of the bass resonance, because usually only this resonance has significant coupling between mechanical and electrical domains. DF is the ratio of the amp O/P resistance to the speaker resistance, but using nominal impedance as a convenient proxy. DF is not the ratio of amp O/P resistance to whatever impedance the speaker happens to have at some specified frequency, including bass resonance - that would be a function of the amp+speaker, and therefore meaningless as a figure of merit for an amp.

I see we have been banished to the Lounge. Not sure if we should be ashamed or proud of that; this thread is still somewhat about actual cables which someone wants to buy.
 
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