How to connect PA speakers?

[Eric***]

Hi everyone,

So at this weekly jam/band thing I've been going to recently, the guy has 2 huge PA speakers (EV FR15-2), but the horn on them doesn't work at all. As in not a peep. The woofers seem to work fine, but nothing at all from the horns.

It has two screw terminals (- and +) in the back of each speaker, and the owner right now has it going from the PA output to the speaker via an instrument cable. He took the 1/4" jack off of the speaker end and stripped the wires so that he could screw it in.

Is it possible that the lack of sound from the horn is from the way the speakers are attached? From what he says, there's no way they're blown. Any ideas on what to try? What is the right way to attach these speakers to the PA?

Any help would be appreciated. Thanks!

[deeaa*]

Check the innards---the horns maybe have a fuse, which could be a simple lightbulb that's burned. Or a normal fuse in the crossover circuit. Most likely culprit. Likely the horns are intact but the fuse's blown. If there's just one input it's a fullrange so the connection method doesn't affect anything. Had to do that several times with our old Peavey 2-ways.

[otaypanky***]

I could not say for sure connecting PA cabinets, but I know when connecting speakers to a guitar amplifier that using an instrument cable can do considerable damage to the amp. You must use a cable designed for connecting a speaker(s). I use speaker cables for my PA, not instrument cable.

[Eric***]

I could not say for sure connecting PA cabinets, but I know when connecting speakers to a guitar amplifier that using an instrument cable can do considerable damage to the amp. You must use a cable designed for connecting a speaker(s). I use speaker cables for my PA, not instrument cable.

Yeah, I thought of that, but figured I'd keep my question simple for the time being. Why is it that it can cause damage? I thought that speaker cable was just thicker than instrument cable to lower the resistance.

[Eric***]

Check the innards---the horns maybe have a fuse, which could be a simple lightbulb that's burned. Or a normal fuse in the crossover circuit. Most likely culprit. Likely the horns are intact but the fuse's blown.

Hmm, I'll check on that. We had the horn pulled out, but all I saw was a bunch (4?) of coils of copper wire that then connected to the sides of the speaker. I wasn't sure what to make of it. I guess we'll look for a fuse in there somewhere.

If there's just one input it's a fullrange so the connection method doesn't affect anything. Had to do that several times with our old Peavey 2-ways.

So with this, the cable he was using somehow had one wire for the center and two separate wires that I took to be the shielding, since it was instrument cable. Am I right in guessing that the center should be on one terminal and both of the outside/shielding wires on the other terminal? Would the center one be connected to the negative terminal.

I guess you did say it doesn't matter, but I'm just curious about this stuff.

[deeaa*]

I missed that - don't use instrument cable! Get regular electric cord rather, or anything with 2 plain/straight wires, no coaxial in any case!

There should be just + and - leads, nothing else.

[t_ross33]

Had to do that several times with our old Peavey 2-ways.

Likewise... When our drummer switched to his Roland electronic kit, the high frequencies from cymbal crashes would light that sucker up so bright you could see a kind of strobe effect through the ports on the front of the speaker. Looked cool, but only lasted a few moments before blowing the fuse altogether!!

My guess, Eric is a blown fuse. You might have to pull the horns and hook them up to a signal source directly to confirm that they aren't blown.

[Duffy]

Go to Lowes, no affln., and get some bulk speaker cable or lamp cord cable, both in the same area of big rolls of electrical wire. Speaker cable has a larger diameter copper wire and both are sold at Lowes. Go to Radio Shack and get some on quarter inch mono jacks for the Pa outputs if it doesn't have posts you can attach bare wire. Plug in the quarter inch jacks to the PA and connect the bare wires to the cabinets, keeping the plus and minus sides of the speaker wire straight so you connect the positive to the positive on the Pa outputs and the cabs, and similarly with the minus - this keeps the speaker cones moving together in and out in synchronization.

If you hook up the positive side of the speaker wire, usually marked with a white stripe or raised ribs to the positive side on the PA output but to the negative side on the cabinet; THEN correctly hook up the other cabinet wth plus to plus, minus to minus, the speakers on each cabinet will be moving in and out opposite to each other - meaning when one moves in the other moves out (the paper cone moves in and out pushing air) and this out of synchronization state of being causes the speakers to have an effect that actually somewhat "cancels" the overall perceived at our ears, sound overall. This same principle holds true for home stereos as well.

Make sure that your speaker wires are not just connected, but that the two wires are connected properly to the amp output and the speaker input, in that the wire with the stripe or rib is connected to the plus or minus on BOTH the amp and the speaker and this is done for both speakers.

Don't just randomly connect the wire ends to the terminals on the cab or solder them onto quarter inch plugs without making sure each of the wires goes to the same plus or minus terminal on each end.

It is definitely possible that there is a fuse broken to the horns. You can check to see if there is a signal going to the horns by using your multimeter set to DC voltage, with the PA turned on and the cabinets connected to the PA, and see if you have any voltage going thru the wires to the horn. Check this on the spade jacks or where the wires attach to the horn. See where the wires from the horn go: do they go directly to the main speakers, etc,? Follow these horn wires all the way and you will eventually find voltage and the place where the conducting of the voltage stops, at a fuse, breaker, or other object, even disconnected wires. Don't assume anything - trace the circuit until you find voltage.

What if you find voltage at the horns? Not likely, but don't assume anything and start at the beginning - the horn speaker wire terminals on the horns.

First check with you multimeter for voltage to the main speakers at the speaker spade connectors where the wires connect to the speaker. Whatever this voltage is should be the same voltage at the horns.

If you do not have voltage at the horns you can follow the wires back toward the main speakers and try to discover where you suddenly have power in the wires and examine why the power all the sudden stops in between. Is it a fuse or some loose connection or disconnected wire? Some people don't like the hiss that sometimes comes from tweeter horns and they disconnect the wires to them.

Sometimes inside the cabinet there will be a speaker "crossover" that tells the wire which frequencies to let pass thru to the horn. The crossover could be destroyed or disconnected or might even have an adjustment on it to tell the wire which frequencies to send over, or even an on off switch like the tweeters on some bass amps.

Being ElectroVoice, I think you said, I would think these would be VERY good PA cabinets and very possibly have advanced wiring schemes within them, including speaker protection, fuses, a crossover, possibly an adjustable crossover or on off switch to the horn or a way to disconnect the horns.

The horns may very well be disconnected purposely by some previous owner or something like that.

Trace the wires from the horn that are not getting voltage with the PA TURNED ON, and try to locate where you suddenly have voltage. In this simple following of the wire back toward the PA you will be able to locate where the voltage stops and see what the culprit is.

Hope this long comment is okay, but I learned the hard way, long ago, how to trace back electrical problems by trying to find where all the sudden there is voltage in the wires, and lo and behold that's right where the problem is and you can usually easily correct the problem.

Since both cabinets are doing the same thing, I would think that both have the exact same problem. Very possibly the horns are turned off or the wires to them are disconnected.

Hopefully there is not a blown horn that caused the owner to disconnect both horns, but with ElectroVoice I would think the horns will be VERY durable and last a lifetime because they are probably very well protected by a circuit inside the cabinet.

Hope his helps.

[Eric***]

This is what I found from a search online for the speaker circuit (a screen cap from the manual):



Since I'm not too good with circuit diagrams other than...uh...grounds, can someone help me find the fuse in this diagram?

[deeaa*]

I can't read diagrams much but I don't see one. If you can't see one when you open it up, there probably isn't one..they would hardly be hidden anywhere, at the most in a casing in the lead like in car stereos etc.

Check the tweeter with a weak/almost dead battery, like a used up 9V, is it completely silent? DO NOT use a fresh 9V it's too much.

Otherwise Duffy pretty much explained all there is to know and do :-)

[Eric***]

We tested the resistance across the horn and I think there was...none? Too much? I can't remember, but the owner (who is an electrician) said it was bad. So...my guess is that the horns are blown. His PA unit isn't the greatest either, so I think we're looking at other options for vocals for now.

Speaking of that, I just posted a different question on this in another thread. BUT...thanks to everyone for your help with this.