User error, repair needed, or crummy cab?

[Noose]

So I picked up a monstrous peavy 1820 for 100 bucks on CL. The cabinet appears to be in fine shape. Sounds good at low levels. So I played a gig with it to give her a test run and it sounded like pure poo.

I know this is not a great amp head, but I am using a behringer 450 watt bass head. I know, not the best amp head in the world but its all I have right now. It works and it seems to have enough power (I think).

Anyway, If I turned up loud enough to match up with the drummer, the speakers buzzed. Im not sure if the buzz was coming from the 18 or the 10s. Either way, sounded like poo. I was using the full range input, so if im not mistaken, I was using both the 18 and the 2 10s.

It seems to me that an cab this freakin huge should have no problem competing with drums that are not miced. I know its only rated for 400 watts max. Seems like I should be fine with a 450 watt head as long as I'm not cranking up the gain and volume. (sp?)

Where do i start? I took the front grill of before I bought it and looked at the speaker cones. Alll looked fine. I made sure all the screws holding the speakers in place were tight. Used two different speaker cables, both did the same thing.

Any suggestions? Is it something Im doing wrong? Is it likely to be a mechanical/wiring problem? Is it just a crummy cab? I know its not the best in the world, but peavey is known for being cheap and solid from what I understand. This thing sounds terrible. I had a behringer 115 that sounded better than this thing. Please help.

[punkrocko]

Sounds like one of the drivers is bad. The 1820 has separate bi-amp inputs for the 18, and 10’s. Plug straight into the 18 first to see if you can recreate the buzzing. If not, go into the tens. When you determine what driver is bad, get it fixed.

[bassbrad]

There are several things to check, some of which you already have so the passive crossover may be old and having problems passing signal in that case a replacement would be in order.
Another thing to remember is with any biamp system you need a certain distance for the sound to come together, if you are too close it will sound very off.

[Noose]

Originally Posted by punkrocko

Sounds like one of the drivers is bad. The 1820 has separate bi-amp inputs for the 18, and 10’s. Plug straight into the 18 first to see if you can recreate the buzzing. If not, go into the tens. When you determine what driver is bad, get it fixed.

Well, I did what you said and it seems that i am getting buzzing from the tens and the 18. It only happens when I turn up to "gig volume". When I play at lower, practice levels I dont get the buzzing. When I say gig volume, Im talking low gig volume. Just loud enough to mix with a drummer.

Is there something I can visibly see to determine if a driver is bad? I am fairly inexperienced with this stuff.

[Noose]

Originally Posted by bassbrad

There are several things to check, some of which you already have so the passive crossover may be old and having problems passing signal in that case a replacement would be in order.
Another thing to remember is with any biamp system you need a certain distance for the sound to come together, if you are too close it will sound very off.

I have read on other posts that the crossover in these cabs tend to have problems. I will investigate that. There are a few other threads I bet I could find info for this.

When you refer to "biamping" what exatcly is required to do that? My amp head has two inputs in the back, but I dont think it actually has 2 power amps built in. Could I get away with running two speaker cables from the back of my head, one to the tens input and one to the 18 input on the cab? Would I need some sort of external crossover for this? I'm confused about biamping.

[Bassmec]

Originally Posted by Noose

Well, I did what you said and it seems that i am getting buzzing from the tens and the 18. It only happens when I turn up to "gig volume". When I play at lower, practice levels I dont get the buzzing. When I say gig volume, Im talking low gig volume. Just loud enough to mix with a drummer.

Is there something I can visibly see to determine if a driver is bad? I am fairly inexperienced with this stuff.

Well you might be able to feel for it by evenly moving the cones
in and out and feeling if the voice coil binds in the voice coil gap anywhere.
Other than that you are taking the drivers out and carefully running a sine wave sweep through each individually.
or carefully test with signal of any sort, with the driver out of the cabinet be careful not to over excurt the unloaded cone.

[Bassdirty]

Is it definately the speakers?

I'm just wonderin if maybe its a "rattle".Are those aluminum strips up n down the sides on the front?
Maybe its those.

Just a different angle..

[Noose]

Originally Posted by Bassdirty

Is it definately the speakers?

I'm just wonderin if maybe its a "rattle".Are those aluminum strips up n down the sides on the front?
Maybe its those.

Just a different angle..

Hmm Never considered that. Basically that front grill is cloth except for the metal frame. I bet I could find out by taking the grill off and seeing If I get the buzzing. I will try it tonight. Its a long shot, but definately worth trying.

[Noose]

Originally Posted by Bassmec

Well you might be able to feel for it by evenly moving the cones
in and out and feeling if the voice coil binds in the voice coil gap anywhere.
Other than that you are taking the drivers out and carefully running a sine wave sweep through each individually.
or carefully test with signal of any sort, with the driver out of the cabinet be careful not to over excurt the unloaded cone.

Is it safe to turn my volume up to the point that i was getting the buzzing with the speakers out of the cab?

I should also mention, the buzzing seemed to only happen on the lower notes. When I played stuff in the higher registers, it was producing a fairly clean tone. Dont know if this changes anything or not.