[Elecraft] Nearfield monitors
Jim Brown
jim at audiosystemsgroup.com
Thu Oct 28 19:35:42 EDT 2010
On 10/28/2010 2:21 PM, Don Wilhelm wrote:
> Yes, it is all about Ohm's law, but there *are* some advantages to the
> "exotic" cables 1) they are usually made with large diameter wires,
> satisfying the Ohm's law requirement even with higher power amplifiers;
> and 2) they are quite flexible which makes running them in tight places
> easier, and they will stand more flexing before the wires break.
Sure. But those large diameter wires that are part of exotic cables also
come with a huge markup, justified only by the marketing gobledegook.
These mechanical issues are their only advantage, but sometimes that's
important. Good engineers view them as simply another alternative,
taking their cost into account. There are, for example, some very wide
flat two-conductor cables, sort of like flex circuit packs, that are
built so that they can be run under carpet. They would NOT be good from
an RFI point of view though, because they're not twisted. :)
#12 stranded copper is $0.10/ft in 500 ft lengths at your friendly Home
Depot. Probably less than double that in 50 ft lengths. Even paired
house wire or flexible AC extension cords are a jacket is a good cheap
alternative. You can also reduce the resistance by putting the green
wire (ground) in parallel with one of the other conductors. Just be sure
to cut off the AC connectors -- some rather smoke could be released from
speakers or amplifiers if someone plugged that cable into a 120V outlet
by mistake. :)
Funny story, sort of. About 15 years ago, some fool bought a booth at
an AES convention to promote a product he called J-Conn or something
like that. The product was simply a set of adapters to convert from AC
plugs and sockets to speaker connectors. Throughout the convention,
many engineers descended upon their booth to tell them how stupid and
dangerous that was.
> Other than for those advantages, any piece of wire of a suitable size
> for the max power involved will do the job
The issue is NOT power, but rather damping factor. If the resistance is
high, the transient response of the loudspeaker can be degraded, so the
low end sounds sloppy.
73, Jim K9YC
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