Bizarre speaker behavior. Any Ideas?

[Gmclachlan]

Originally Posted by subbasshz

dont listen to these geezers. well done on the bomb that went off in that little 10 incher

Ha! Yeah, not too many of those comments are sinking in with me. Our band is extremely loud, as in 2 SVT's-was-just-loud- enough-but-hard-to-carry-so-I-bought-a-1000-Watt-solid-state-head-and-2-1200-watt-cabinets loud. And custom molded earplugs.
The bottom line is the drummer is hard hitting monster and the guitar player uses 2 100 watt Marshalls. The volume requirements for this band are non-negotiable; I need to be heard. I bring both cabinets, that is (2400W power handling) when I can. Here's a live video if anyone's interested, ironically, the bass is kinda quiet.
http://www.youtube.com/watch?v=WByvdw_e6po
http://www.youtube.com/watch?v=3zfzU0j-BDg

Occasionally, I blow speakers. Having said that, the HPF is excellent advice, and I'm following it immediately. Much thanks to those who suggested it. No reason to ruin gear if it's avoidable.
It turns out one of the speaker looks to be bad. Everywhere I put it caused that pair to not respond to the battery. In retrospect, it was obvious, but I assumed new speakers wouldn't be the problem.

Thanks again everybody.

[Downunderwonder]

You guys have some sweet video making skillls on tap. How was the sound recorded? It's not like the bass is quiet when you got the solo into sections. Somebody made the mix light on bass on the recording or that was how it sounded? The guitar dominated sound is very common in metal. I wish it wasn't so.

From your "non negotiable" comment and the general gist of the vids it seems like your guitar player has a musical screw loose and wants to be dominating the mix instead of fronting it.

Shame as the band is tight. Very cool drummer, I bet he could bring heaps more dynamics to it if the guitar wasn't so full on so much of the time. There's one shot of him in the second vid playing with his fingers in a quiet bit, kid has skills.

My favourite quote: "without quiet, there is no loud", save the really loud for emphasis and dial back. A few times guitar goes to phaser the whole thing could have gone to a whisper for more effect. Instead of "FEEL MY ANGST, I"M STILL ANGRY!", "feel my angst!!!!!". Dynanic sound is the reason live music is still in business.

Bridged amp into fearful 1515/66 might work for you in that sort of environment.

[Gmclachlan]

We do have a few quieter sections, but the loud is LOUD. No regrets, it's fun as hell, just occasionally hard on the equipment.

[arai]

The high pass filter is a great idea. I would also consider a limiter.

Originally Posted by Downunderwonder

My favourite quote: "without quiet, there is no loud",

Great quote. I would really like to use that on a drummer and guitarist I know. Who is the quote from?

[Downunderwonder]

It's an aphorism, a quotable truth, I probably got it from BFM.

[mystic38]

to the OP

blowing cones when you have cabinets rated 2x the amp means you are sending those cabs square waves... ie transients beyond which the amp has headroom for.... you may want to invest in a much larger amp..2-3kW to give headroom, but in the meanwhile :
a limiter is an absolute must.. something with a soft response... and the good thing about a great limiter is that you never hear it unless you are trying to blow your speakers and even then it simply sounds like a compressor.

have you checked to see if you can physically move the cones of the new speakers?.. this is a decent test to feel for physical issues in the windings...

Originally Posted by arai

The high pass filter is a great idea. I would also consider a limiter.



Great quote. I would really like to use that on a drummer and guitarist I know. Who is the quote from?

[Mr. Foxen]

Originally Posted by mystic38

to the OP

blowing cones when you have cabinets rated 2x the amp means you are sending those cabs square waves... ie transients beyond which the amp has headroom for.... you may want to invest in a much larger amp..2-3kW to give headroom, but in the meanwhile :
a limiter is an absolute must.. something with a soft response... and the good thing about a great limiter is that you never hear it unless you are trying to blow your speakers and even then it simply sounds like a compressor.

have you checked to see if you can physically move the cones of the new speakers?.. this is a decent test to feel for physical issues in the windings...

Aargh, the square waves thing is a myth. Clipping amps blow tweeters. The broken speakers is excursion damage, not thermal damage, and the watt rating is thermal, thus totally irrelevant to the power it takes to make this sort of damage. Transients aren't square waves either.

[JimmyM]

Originally Posted by Mr. Foxen

Aargh, the square waves thing is a myth. Clipping amps blow tweeters. The broken speakers is excursion damage, not thermal damage, and the watt rating is thermal, thus totally irrelevant to the power it takes to make this sort of damage. Transients aren't square waves either.

+1. OP is just plain too loud for his cab to take and that's all there is.

[mystic38]

aargh indeed,

you clearly did not read my post carefully enough ...

read : "transients beyond which the amp has headroom for"

that is what i wrote, and that is clipping, which is what i meant.. and clipping in a solid state amp produces odd harmonics of the fundamental to infinity...which is the definition of a square wave.. i was simply using a euphemism but should have realised i was not talking to other engineers.

The issue at hand has nothing to do with "too loud" its a lack of headroom in the amp causing output distortions...

options are:
1. a soft limiter in the fx loop. this will act as a compressor at extremes and that is his best solution...it is transparent until in use.
2. a hf filter in the fx loop.. (as already suggested) as using tones controls is inadequate as this is before the output stage of the preamp
3, a compressor, again post pre-amp, though this is likely to have audible artifacts at all levels.
4. a much larger amplifier.. it is MUCH less likely to kill speakers with too large an amp than too small due to clipping and the associated output distortion.

Originally Posted by Mr. Foxen

Aargh, the square waves thing is a myth. Clipping amps blow tweeters. The broken speakers is excursion damage, not thermal damage, and the watt rating is thermal, thus totally irrelevant to the power it takes to make this sort of damage. Transients aren't square waves either.

[B-string]

Not at all. Square waves have a sharp immediate rise to rail voltage, remain at rail voltage for a period of time then immediately reverse rail polarity.
Clipped sine waves ARE NOT square waves and audio amplifiers are not designed to reproduce square waves and will not produce "square waves" without being designed to.
Dumping massive amounts of amp power will produce a massive clean signal that will a gain cause catastrophic failure to drivers both mechanically and electrically.
Point #4 is completely wrong and has been proven wrong by more engineers and sound companies than can be counted without dedicating your life to the task.
If you want to test your assumption, speakers are basically a motor. They convert voltage (and current) to mechanical movement. So take any 120 VAC motor and double the voltage input, say 220 VAC here in the US and see how long this clean power at double the motors rating will last. Music IS AC.

[Bass_Pounder]

Originally Posted by B-string

Dumping massive amounts of amp power will produce a massive clean signal that will a gain cause catastrophic failure to drivers both mechanically and electrically.

Agree...........


The damaged speaker did not jump out of it's basket due to clipped signal - it was a pure case of overpowering.

Going to a larger amp will only make the same thing happen again, maybe even sooner.

[B-string]

Point of interest: Destructive "speaker" testing is done with "clean" sine waves to identify failure points. Power ratings are also done with "clean sine waves" so exceeding the power rating with "clean sine waves" gets you where? Blown drivers.
This is not unsupported myth this how things are.

[Mr. Foxen]

Originally Posted by mystic38

that is what i wrote, and that is clipping, which is what i meant.. and clipping in a solid state amp produces odd harmonics of the fundamental to infinity...which is the definition of a square wave.. i was simply using a euphemism but should have realised i was not talking to other engineers.

Those solid state amps with infinite bandwidth that are yet to be invented then.

I run my amps in clipping often, no speaker deaths.

[Monotheist]

Originally Posted by Gmclachlan

Ha! Yeah, not too many of those comments are sinking in with me. Our band is extremely loud, as in 2 SVT's-was-just-loud- enough-but-hard-to-carry-so-I-bought-a-1000-Watt-solid-state-head-and-2-1200-watt-cabinets loud. And custom molded earplugs.
The bottom line is the drummer is hard hitting monster and the guitar player uses 2 100 watt Marshalls. The volume requirements for this band are non-negotiable; I need to be heard. I bring both cabinets, that is (2400W power handling) when I can. Here's a live video if anyone's interested, ironically, the bass is kinda quiet.
http://www.youtube.com/watch?v=WByvdw_e6po
http://www.youtube.com/watch?v=3zfzU0j-BDg

Occasionally, I blow speakers. Having said that, the HPF is excellent advice, and I'm following it immediately. Much thanks to those who suggested it. No reason to ruin gear if it's avoidable.
It turns out one of the speaker looks to be bad. Everywhere I put it caused that pair to not respond to the battery. In retrospect, it was obvious, but I assumed new speakers wouldn't be the problem.

Thanks again everybody.

What an awesome band! Sick work my friend. Do you guys have an album out?

[B-string]

You knew "square wave" was going to come up huh. You know what is next?

[Gmclachlan]

Monotheist, we do have a self titled record on iTunes, CDbaby, etc..
I shouldn't be surprised that this thread has turned so contentious, but it is moderately entertaining. And although the original post had no question like, "Why am I blowing speakers?" certainly most of the posts address this issue, and I suppose I'm to blame by posting that photo. I guess I have chimed in with tangential comments on other thread if I felt I had something to add.
I'm pretty sure when the paper cone blows out of the surround and slams against the grill, it's caused by over excursion, most likely from low end. That isn't the only way speakers blow, i.e. transient reaction or voice coil thermal failure, but I think that is the cause in my case. I do check the level with no distortion frequently; the amp level isn't that high, a little more than halfway, but there is a lot in front of the amp. The clip LED never lights.
Again, thanks for the info....

[1958Bassman]

Originally Posted by mystic38

to the OP

blowing cones when you have cabinets rated 2x the amp means you are sending those cabs square waves... ie transients beyond which the amp has headroom for.... you may want to invest in a much larger amp..2-3kW to give headroom, but in the meanwhile :
a limiter is an absolute must.. something with a soft response... and the good thing about a great limiter is that you never hear it unless you are trying to blow your speakers and even then it simply sounds like a compressor.

have you checked to see if you can physically move the cones of the new speakers?.. this is a decent test to feel for physical issues in the windings...

More power, as in, more power without adding speakers? He's already pounding the snot out of his speakers. The best t hing would be to add power AND speakers. If he doesn't add power, he can just add speakers and he'll be much louder than he is now. As long as the impedance makes the amp happy, he'll be fine.

[1958Bassman]

Originally Posted by B-string

Not at all. Square waves have a sharp immediate rise to rail voltage, remain at rail voltage for a period of time then immediately reverse rail polarity.
Clipped sine waves ARE NOT square waves and audio amplifiers are not designed to reproduce square waves and will not produce "square waves" without being designed to.
Dumping massive amounts of amp power will produce a massive clean signal that will a gain cause catastrophic failure to drivers both mechanically and electrically.
Point #4 is completely wrong and has been proven wrong by more engineers and sound companies than can be counted without dedicating your life to the task.
If you want to test your assumption, speakers are basically a motor. They convert voltage (and current) to mechanical movement. So take any 120 VAC motor and double the voltage input, say 220 VAC here in the US and see how long this clean power at double the motors rating will last. Music IS AC.

As you know, true square wave is vertical rise and fall but if an amp doesn't have the slew rate to handle the short rise time, it rounds the corners and may add some tilt. For this reason, maybe it's time to just say "close enough for Rock N Roll". Technically, not correct but it gives some people an idea of what's happening to the waveform.

Personally, I think we should sticky some oscillograms of various signals- clean LF, HF and both with soft & hard clipping. Also, some complex waveforms with a description of what's happening, why and the effects as well as some spectrum analyzer shots of the harmonic content of clean vs high THD and IM distortions. Visual aids help a lot when the explanation isn't understood.

[JHAz]

I kinda like the limiter idea. That sure looks like initial transient throwing the cone to me. IIRC, the BassGearMag review of the TC 450(?) showed initial transient of 10 to 12 dB above the beginning of the tone. So 10 to almost 20 times more power in that 1/20 or less of a second than in what comes after. Turn that transient down with a hard limiter and maybe the speakers survive.

[12bass]

Originally Posted by Gmclachlan

... the amp level isn't that high, a little more than halfway, but there is a lot in front of the amp. The clip LED never lights.
Again, thanks for the info....

Knob position is not a valid indicator of how much power you're sending the speakers. Many amps hit maximum power before the volume knobs make it to the 12:00 on the dial. In other words, volume controls do not provide a linear representation of how much power your amp is putting out (i.e. half rotation = half power). Also, a bass with a hot preamp and/or boosted EQ can change the amp's power output significantly at a given volume setting.

One thing that we can know for sure is that your amp is putting out a lot more power than your speakers can handle, which is why they are suffering catastrophic failure. That means that they're getting far too much power, regardless of what the knobs might indicate. Thus, the question becomes how do you reduce that power level to a safer level while still being able to hear yourself in the mix?