Metropoulos Forum

I'm not sure how to ask this and could be a stupid question (I know 'cause I'm asking it. )

On the input end, I assume there are mili-volts going into the amp, but what is coming out of the power section, running through the cable driving the speakers ?
Does it become like a line cable where there's signal loss (???)... There'd be heat build up, I'd reckon.
How many feet is max for a 16Ω cab ?
I was curious after yngwie308 posted that he wanted to run cables from his heads to another room.

So, would it be kind-a-like a 100 watt power amp from the P.A. board to the speakers (stage).
Would that be pretty much be the same from another view ?

Depends how loud your amp is running hence what AC voltage it's putting out and your speaker load.

You can work it out approximately using the equations Volts = Amps* Resistance and Watts = Volts * Amps.

If your amp is putting out say 20 volts AC at the speaker jack into a 4 ohm load then outout wattage is 20 squared divided by 4, or 100 watts. Divide that by your 20 volts and that's 5 amps of current.

40 volts AC into 16 ohms is also 100 watts, but only 2.5 amps this time.

I use 13 amp mains cable for speakers, and never notice any heat build up. Good housekeeping like keeping cable runs as short as practical and not coiling them up in use wouldn't go amiss though.

As tommie has said: long cable runs will produce a greater voltage drop, thus increasing the current proportionally.

This is why thicker cable is generally used for speaker connection; for the current load it is supposed to take, and also to produce less voltage drop over a distance compared to thinner gauge cable.

How long a cable you can use before you start hearing losses or produce heat? You would have to work that out yourself by using calculators/equations online. You basically need to find out a cables current carrying capabilities (ccc)/electrical resistance, length of run, and load current. Then you can determine the volt drop, and use that against ohms law again to see how much the current draw has increased.

Noted !
I really appreciate you guys answering my post. Thanks for that. I didn't know how to approach explaining it.
Great to know that there's a way to teach yourself how to do that, if needed. (I get formula's Nerdy in that way...)

You guys rock !

~Jimmie

enough to shock the shit out of you......

rockgod212 wrote:enough to shock the shit out of you......

That comment cracked me up!

Generally, in the hi-fi world (I know, I know... ) it is considered that excess line level cable is only noticeable per foot, whereas excess speaker cable is noticeable per inch.

Well, my ears sure as hell aren't that sensitive, even when tweaking my no.1 system, but I do notice differences (though I struggle noticing interconnect length differences, but then decent stuff is too expensive to build longer than you need anyway ).

Given the differences I can very clearly hear when using longer guitar leads than necessary (same type and jacks) I have a tendency to keep speaker leads to an absolute minimum with barely any slack.

Considering that milliamperes can kill a person based upon their health condition, skin condition (moisture/dryness/cuts) etc., then amperes would surely kill. Just don't go sticking your tongue to the cabinet end of the cable to test to see if it has a charge. LOL

I seem to remember putting the multimeter on my speaker cable from my 50w when it was set to 9 on the volume. Pretty sure it said it put out 36 volts. That's the output equivalent of 90 plus watts at that volume level, though. I should probably do this again with both the 50 and 100w and report back....right after I build these four speakers that got ordered while I was doing some shipping.

Scumback Speakers wrote:I seem to remember putting the multimeter on my speaker cable from my 50w when it was set to 9 on the volume. Pretty sure it said it put out 36 volts. That's the output equivalent of 90 plus watts at that volume level, though. I should probably do this again with both the 50 and 100w and report back....right after I build these four speakers that got ordered while I was doing some shipping.

Lefty Lou wrote:That's great Jim, actual real world data for the logbooks.

Lefty Lou wrote:Considering that milliamperes can kill a person based upon their health condition, skin condition (moisture/dryness/cuts) etc., then amperes would surely kill. Just don't go sticking your tongue to the cabinet end of the cable to test to see if it has a charge. LOL

Yes amperes can kill, but not at speaker levels. There will not be enough voltage to conduct through normal dry skin.
Tongue is a bad idea though.

demonufo wrote:

Lefty Lou wrote:Considering that milliamperes can kill a person based upon their health condition, skin condition (moisture/dryness/cuts) etc., then amperes would surely kill. Just don't go sticking your tongue to the cabinet end of the cable to test to see if it has a charge. LOL

Yes amperes can kill, but not at speaker levels. There will not be enough voltage to conduct through normal dry skin.
Tongue is a bad idea though.

Because the voltage is not consistent yes. Maybe on the the cheeks, as in "Tongue and Cheeks" LOL (a play on words).

Depending on current draw, I was always taught that anything over 75V was dangerous for the human body. Anything below you may notice, but with no harmful effects other than a little shock/sensation.

Current draw is the important thing here!

40 mA range and sometimes less, dependent upon the shock recipients health.

So potentially dangerous. Hopefully no-one will feel the need to touch those wires when the amp is on and playing !