Help with terminology

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Mongoo

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In my quest to find the best quality cable I have realized that there is still alot of terminology that I only know the very basics of.

So I'll just tell you what I think I know and any info you want to throw in to help me understand it and it's use/range/what to use to do this and that with it/etc. Oh, and if there is a good site on explaining most of this, by all means leave that too. Thanks

RFI - No Idea

EMI - ????Electro magnetic interferance???? how is this controled?

Ohm - I know its got something to do with electricity buy I hear 100ohm this and 400ohms that. What is the range of ohms for general equiment? When is it a good/bad thing?

Impeadance - I've heard High and low and thats about it.

Capacity - Something to do with wires. Again I don't know whats good and bad here.

Decibles - If I'm not mistaken this is volume? But I always see like +04db or -06db etc. what is 0db? is db the change in volume but not the actuall volume?

What is High end roll off? I heard quad cables over 12feet have high end roll off. This seems to be a bad thing. But I thought quad cables where the best for noise? If you don't get quad cables what is the second best?

Thanks again for all your help on clearing these up for me.

Mongoo
 
RFI:

http://www.radioing.com/eengineer/rfi.html

EMI: Electromechanical induction. Magnetic fields from high-voltage circuits can induce signal into audio and data circuits just by their proximity if they are strong enough. This is translated as noise. Always keep power supply cords at least 2 inches away from audio cables in they are running parallel, and cross at 90-degree angles to keep this noise to a minimum.

Ohm is the standard unit of measurement for resistance of a conductor, or of a non-conductor.

Impedence is the sum of resistance and other factors on a circuit, including inductance and capacitance. An example of an inductive load would would be a flourescent light running off a standard electroMAGNETIC ballast, which is just another way of saying transformer. A capacitive load could be a metal halide light, or a tube amplifier.

Capacity is generally the amount of current a conductor will carry before it starts interfering with the insulation of the conductor. As in causing the insulation to break down. On both insulated and bare conductors, the rated capacity is what is considered safe by engineering standards (usually in terms of ampacity) before the conductor will overheat and melt.

Decibel. Unit of measure, and there are a lot of definitions of Decibel, determined by whether it's being used to define an audio signal, or a sound source, or a few other things as well.

In measuring sound levels, Decibels are a logarithmic function. A gain of 3 dB is equal to DOUBLING the volume of a given source or frequency.

http://www.cs.berkeley.edu/~randy/Courses/CS294.S96/dB.html

This page has more definitions for dB, and explains how dB's work in measuring audio signals:

http://et.nmsu.edu/~etti/fall96/communications/db/db.html

The +4dB and -10dB are GENERALLY used to differentiate between pro-level gear and "consumer" or "prosumer" gear. The high-end stuff is GENERALLY gonna input or output a +4db signal.

I haven't heard of "high end roll off" with regard to quad cables used in a low-impedence format.

OTOH, high-impedence signals, like electric guitars, work best with shorter cable runs due to the nature of pickups. You can easily run a low-Z mic cable 100 feet without significant loss of signal. try that with a guitar and it's a very different story.
 
re

So are you saying that all mics are low impedance and all guitars are high impedance?

What type of cord would you use for guitar and bass cables? I'm in the market for some. Price doesn't concern me as much as quality. Whats the longest I should get if I'm don't what the quality to fade?

What type of mogami cable would be the best for guitar? I can buy that in bulk. If I didn't go with Mogami would you recammend, Monster, blue, canare, or a different brand?

So are quad cables the best for microphones? You don't think I will have a problem making my mic cables 20-25 feet long?

Thanks for all of the links.

Mongoo
 
I hope these added links helped....

BTW. There is a member of HR.COM that has his own BBS. I'm sure that some of your cabling questions could be answered there.
 
Thanks for all the links spin. I'll be sure to check them out.

Mongoo
 
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