Blown speakers ideas?

[valooz]

Hi All,

Hoping you can help me out on this, I'm out of ideas.

This isn't PA, but no reason this should any different.

I specced a bass amp rig for a friend of mine, that consists of a Yamaha PB-1 bass preamp, a DBX160A compressor inserted in the loop of the preamp, and the preamp feeding an Electrovoice Q1212 power amp.

The EV amp was then connected to 2 bass cabinets: 1 is a MesaBoogie 1x15 with a tweeter, the other is an Orange 4x10.

The PB-1 has two filtered outputs, one with an LPF and the other with an HPF. The idea was to use the LPF channel for the 15" cab, and the HPF for the 4*10, thus giving loads more headroom and efficiency from the system.

 

It worked fine and sounded great up until yesterday, when both cabs stopped working. The 15" cab stopped all together, only the tweeter works now. The Orange 4x10 got quieter and quieter and then popped and stayed really quiet.

 

The EV 1212 is rated at 750W per channel under 8Ohms and the cabs are 500W for the 15" and 600W for the 4x10, both under 8Ohms

 

Unfortunately I'm not on-site, everything is with the bass player about 1000 miles away, but I've sent him to check what he can. He's tried the 15" cab with a standard bass amp, and same result. I'm waiting to find out the status on the Orange 4x10.

 

My thoughts are that the filters have gone on the cabs. I can't imagine the drivers going, especially as he has told me that he hasn't hammered the pants off anything ever, on the contrary, and I completely believe him.

He's off to have a look, but in the meantime, I'd appreciate you input as to what the breakage could be, and mainly, what could possibly cause it?

 

The amp is brand new, so if it has a problem it needs to go back ASAP.

I can't imagine the Yamaha pre-amp being the problem, because he said up until the cabs stopped working, the rig sounded amazing.

And I don't think/hope the drivers haven't blown, they're good quality drivers, and again, no distortion whatsoever from them prior to breakage.

 

Any suggestions as to where to look would be appreciated!

 

Thanks folks!

[Brian]

My thoughts are that the filters have gone on the cabs.

 

What filters?

 

Without knowing what models the cabs are it's difficult to be certain but I'd be surprised if the Orange had any filters in it. The same with the Mesaboogie; it might have a HPF for the HF units but I suspect the LF might be driven full-range.

 

And are you sure about your power ratings for the cabs? Google 'Orange 4x10' and the most common hit is the PPC410 which is only 120W RMS.

[Mixermend]

Oh boy - the EV power amp is cable of producing 1800 watts per channel into 2 ohms - and with a compressor in the pre-amp FX loop, the 'average' power being sent to the speakers could be huge......

 

No more can be said until the speakers have been properly inspected, remember that speaker transducers are relatively inefficient, so probably 95% of the power from the amplifier has to be dissipated as heat in the speaker voice coils, which under these conditions will get very hot indeed.

 

My guess would be that the voice coils are jammed solidly in the magnetic gap.

 

If you believe in reincarnation - then you certainly don't want to come back as a bass speaker unit!

[laolu]

I such a case I would do the following: Check the cabs with another amp and the amp with another cab.

Since the 15" cab turned out to be belly up already, you're right: the crossover inside (what you called filters?) could be the problem. If it has a crossover. Otherwise it's the driver.

Then to the question what caused it? Mixermend has a valid point: overheating.

Oh yes, and let him connect a pair of good quality PA-speakers to the amp and play some classic guitar or solo piano music (no joke!) through them from CD. If that sounds clear and undistorted, the amp is probably OK.

 

Good luck

[TimmyP1955]

Feed both channels from the HPF, and set it to about 40Hz (no lower then 35!), so you don't feed stuff into the cabinets that they have no change of reproducing. This is what will give you maximum efficiency and output from the system.

[paulears]

I suspect we're all going to suggest the speakers - BUT - they rarely die without pleading first. If the scenario is that he overdrove (is that a proper word?) them - then when the first failed, he probably turned up even louder and did the same to the other. I must admit I've never heard one die by getting gradually quieter, but it's perfectly possible if they were well made, and over specified, so it was friction from expansion, rather than the usual melted winding.

 

Modern amps are really good at short circuit and overdriving protection. It does strongly suggest a few things:

1. The bass player is deaf

2. The bass player is 100% responsible

3. He's not telling the entire story.

 

It does indicate to me that he was playing at really mega volume though

[dbuckley]

Thing is, given sound levels are logarithmic, there isn't that much of an audible difference in level between 200w and 2,000w. Especially when we are talking about bass, which can almost never be too loud, and never "sounds" loud.

 

Back in my gigging days there was a local 3 piece band with a loud guitarist with a AC30, and the bassist had a pair of 4x12s and a pair of 2x15s driven with a setup very similar to the setup described above. A very nice, very pretty rig. The amplifier in the rack was a 2u Yamaha, a couple of hundred watts a side. It was run just under clipping, and was almost a level match to the AC30.

 

I could easily see that having a rig like that with a lot more power available would be turned up just a bit more.

[valooz]

Yes sorry, Crossovers, it was late when I wrote that post.

The Orange is an OBC410, which is rated at 600W/8Ohms

The PPC410 is a guitar cab.

Hard to get any info on the Xovers online anywhere.

 

 

 

My thoughts are that the filters have gone on the cabs.

 

What filters?

 

Without knowing what models the cabs are it's difficult to be certain but I'd be surprised if the Orange had any filters in it. The same with the Mesaboogie; it might have a HPF for the HF units but I suspect the LF might be driven full-range.

 

And are you sure about your power ratings for the cabs? Google 'Orange 4x10' and the most common hit is the PPC410 which is only 120W RMS.

 

In most cases I would agree, however, I know the guy, and he is really really pro about his gear.

We've gone through all the details about the given night that everything dropped dead, and no signs of anything before it broke...

 

I suspect we're all going to suggest the speakers - BUT - they rarely die without pleading first. If the scenario is that he overdrove (is that a proper word?) them - then when the first failed, he probably turned up even louder and did the same to the other. I must admit I've never heard one die by getting gradually quieter, but it's perfectly possible if they were well made, and over specified, so it was friction from expansion, rather than the usual melted winding.

 

Modern amps are really good at short circuit and overdriving protection. It does strongly suggest a few things:

1. The bass player is deaf

2. The bass player is 100% responsible

3. He's not telling the entire story.

 

It does indicate to me that he was playing at really mega volume though