OT Need help with PA system

Ok. So today my band was practicing, and i noticed that one of my speakers was alot quieter than the other one. I have them bridged, so this really shouldn’t happen. I tried changing speaker cables with no luck, which means the problem is definitely with the speakers and not the amp or cables or anywhere else in the chain.

Its wierd though, because it isn’t distorting or cutting out or anything, its just really quiet. Any ideas? Thanks.

PA you say? I assume it’s at least two way. That could be a problem with the built-in crossover, or even something as simple as corossion in one or more of the internal connectors. The fact that is isn’t cutting in and out and is simply quieter points to there being some extra resistance in the signal path somehow — inside the speaker cabinet, based on what you told us.

Phoo’s got it.

The only thing to add is that sometimes the positioning of the speakers can alter the apparent loudness of them, but that is generally no more than about 3 to 6 dBs or so in the LF, and I 'spect you’ve checked that anyway.

So as Phoo said, check your wiring/crossover (assuming that is, you’ve already checked for tribbles nesting in the cabinet). :)

yeah, i checked the phase and made sure it wasn’t just an apparent loudness thing.

I’m gonna have my electronics guru friend check it out. He suspects something in the crossover.

The more I think about it the more I think it could very well be the crossover itself. Those usually have resisters, coils and capacitors, but could be as simple as a single cap before the tweeter. If something came loose or shorted it could throw the whole thing out of whack.

Describe quieter? Could it be that it’s nothing more than the tweeter being out?

EDIT: We crossed in posting by a minute. :) Sounds like you have it covered pretty well.

It’s not just the tweeter being it. I am hearing sound from both the tweeter and the woofer

Can you just wire the woofer in directly (using a test lead…) and bypass the crossover? That will tell you in a hurry.

well, i’m at school now, (i was back over thanksgiving break), but once i come back for christmas break, we will check that out.

It could also be that you overdrove one speaker and started to fry the coils. Hopefully not, because that means replacing the driver. It’s unlikely that would happen in the same amount to both woofer and tweeter, so you could try sending high and low test tones (well above and well below the cutoff frequency) and see whether the volume difference affects both drivers. Note that this test doesn’t rule out the crossover.

It shouldn’t be too difficult to swap the crossovers and see if the problem follows it. Hopefully your guru can debug the crossover with less effort than that.

Ok, update on my stupid speakers. Upon closer, calmer inspection (as in not in a violent fit of rage), it appears I have blown just the woofer in one speaker. This sucks, but it could be worse. I’ve had everything blow before.

But anyway, this taught me an important lesson. I would have saved alot of money had I just bought a compressor/limiter right away.

And on that subject, who has advice on a good, inexpensive compressor/limiter for live use? The 2 main criteria are, it has to work (not behringer gear) and it has to be 2 or 4 channel, and hopefully not sound like crap.

Not cheap, but dbx is great gear. Look for used.

Yeah what Bubba said… on the new but inexspensive side, the Alesis 3630 is a good unit $99. There is an easy to do after-market mod/kit that supposedly really improves performance for recording purposes. For PA use though, I’d get one or two as needed and go. If money was no object… dbx DriveRack is THE ticket from what I hear. Alesis 3630 Link at the Fiend


Quote (Diogenes @ Dec. 22 2005,11:02)
Yeah what Bubba said... on the new but inexspensive side, the Alesis 3630 is a good unit $99. There is an easy to do after-market mod/kit that supposedly really improves performance for recording

Ditto on the Alesis 3630 - I've had one for about nine years, used to use it in my bass rig.

What is this mod/kit that you speak of?!?

Hit the TapeOp site as the mod was in one of their issues a few months back.

Here is a link

Yep. Thazzit! Thanks Bubba.


Quote (Bubbagump @ Dec. 22 2005,13:26)
Hit the TapeOp site as the mod was in one of their issues a few months back.

Here is a link

Wow... That kit is $115, which is $16 more than what the 3630 sells for right now!

Was there any reviews on what this sounds like?


I goofed. The mod in TapeOp involved cutting a few wires to remove the limiter circuit from the compressor. From what I can gather it was only published in their magazine (I think Jan/Feb 2005). I’ll see if I can dig up the article once I get back in the country. If you get TapeOp (AND YOU SHOULD!) it was the same issue that Carol Kaye was in.

So for using this badboy live (the alesis). If I want to use both the compressor and the limiter (the compressor to bring the apparent volume up, and the limiter just to make sure my stuff doesn’t blow again), would I need to use both channels to do that for 1 input?

No Steve. The unit is two channels of comp and limiting. The mod Bubba is talking about in TapeOp was about clipping a couple jumpers to take the limiter out of the circuit for guys who wanted the comp with no limiter for recording purposes. Now an enterprising sorta guy WOULD mount a mini-toggle switch on the unit INSTEAD of just clipping the jumper(s)…


PS For PA use though, I’d just plug 'er in and go.