Flaming Amps! A Lesson Learned

[Bob Lee (QSC)]

Originally Posted by Sarah5string

Ok.. being thick here but what's the difference between a instrument cable and a speaker cable?

Loudspeaker cable is a two-conductor pair of some substantial size, similar to lamp cord. In fact, lamp cord makes fine speaker cable.

Instrument cable is a very different beast. It also has two conductors, but one (the shield) encircles the other, in order to help shunt electrostatic noise to ground. The conductor gauge or cross-sectional area is much smaller than with a loudspeaker cable.

[black_labb]

ive been meaning to get some decent cables for speakers for a while, but after reading this i walked down to the electronics store nearby on my break between classes to get some speaker cable and inputs. ill solder them up tonight.

i had short cables before that i made cith some coax (before realising that shielding wasnt nessesary), but the proper cable should be a much better match.

[TheGrizz]

So I color coded all of my cables at practice today. No more mix ups We have a big show tomorrow, and I don't want another amp scare. Thanks for the advice guys!

[Parabolic Box]

Originally Posted by barbarbass

Err, I've used an instrument cable from head to cab for about fifteen years now. Is this going to happen to me some day?

Well, that, or you've been using speaker cable from bass to amp for about fifteen years.

[Munjibunga]

Originally Posted by Chebass88

Sarah,

Fundamentally there is NO difference. Both are cables that transport an electrical signal from one location to another.

The difference lies in the power-handling capabilities of the cables. Speaker cable is heavier, and is meant to transport more power (voltage * current) necessary to activate & move the speaker (lots of air to vibrate!). The signal from your instrument, however, is very weak in comparison.

Conversely, you would not want to use a speaker cable for your instrument, as the resistance is too high, and you may not get the best results.

Hope this helps!

imp

P.S. Perhaps you could label the chords & their location - it could help your singer help set up the PA systems much quicker & save you some headache! It could be REALLY SIMPLE - orange sticker on speakon jack goes to orange jack on speaker. etc. etc.

I'd say there are significant fundamental differences. Aside from the heavier gauge of speaker cables, the physical configuration of the conductors is very different.

Instrument cables are typically coaxial, meaning they have a single central conductor and a woven or spiral shield around it. The conductors are separated by an insulator that may introduce some cross-conductor capacitance into the cable. The thin gauge (usually 20- or 22-gauge) of the central conductor makes it unsuitable for the heavy current loads drawn by a speaker cabinet.

Speaker cables, on the other hand, don't really require any shielding and, as Bob Lee said, regular old zip cord like the stuff hooked to your lamps is fine. The introduction of noise is less critical in speaker cables because the ratio of the noise to the voltage from the amp is minimal.

[georgestrings]

Bob and Munji have it correct - no surprise there...




- georgestrings

[Chebass88]

Munji et al.,

Thanks for the correction - my limited knowledge of electrical signal processing shows when I post remarks like I did.

Thanks!

imp

[TheDarkReaver]

if you had so much time to kill why did you not set up earlier?