I am blowing speakers every two weeks...

[billfitzmaurice]

If ONE end is toasted, DC is suspected, that or a manufacturing defect..

The rear of the coil (magnet end) may be more effectively cooled than the front of the coil (cone end) because of the polepiece, so often the front of the coil will be burned while the rear is not. Some drivers address this by extending the polepiece, one example being the Eminence Kilomax, which not only extends the polepiece but adds a heatsink to it in front of the dustcap.

 

[Jerrold Tiers]

Yes, as mentioned....

As the Xmax goes up, generally the coil gets longer, longer than the top plate thickness (overhung). If so, the ends are not so effectively heatsunk. Then the ends will toast quicker, especially the end nearer the cone, where the center pole does not extend.

Obviously an extended pole piece helps, although two sided heat removal is likely a bit over twice as good, due to the insulating qualities of many coil former materials, such as Kapton, or the necessary insulation between coil and aluminum former. However, one end toast and the other end apparently unaffected is strong evidence for an offset position, for which DC is one good reason.

A relatively small actual dissipation is created by an amount of DC that will offset the coil considerably. A 4 ohm speaker with 2 amps DC flowing will probably dissipate only around 12 to 14 watts from DC, but may have the cone/coil offset a rather large distance.

For a speaker, a constant position offset of "only" 1/16 to 1/8 of an inch may be a lot. The 2A DC may, depending on the suspension, offset the cone/coil considerably more than that.

In normal AC use, the box and acoustic load controls the speaker movement against much larger currents/forces. But at DC, the box is out of the picture, acoustic loading is essentially non-existent, and the speaker responds as if there was NO box. The ONLY things affecting the limits of speaker movement at DC are the suspension and the interaction of coil current and magnet, due to BL product and geometry of magnet and coil (unless some mechanical obstacle is interposed, such as grille, or magnet backplate, etc).

 

[bgavin]

I'd be looking at bigger tires.

This is the solution.

You simply do not have enough drivers for the amount of noise you are trying to make.
Add more drivers.

 

[Single Coil]

OP here.

Your speakers should be able to handle that GK. You've been playing for years and you're not stupid. There is either a problem with your head (have it bench tested), your speaker cable is bad (replace it), or for some odd reason, every speaker you touch is a piece of crap.

I am inclined to agree with getting the GK bench tested. All I have to do now is find someone in the middle of nowhere do this for me.

I have already decided to get all new speaker cables (why not?)

I also found that only one of the drivers in my 4 x 10 is making fuzzy noises. Therefore, I am going to replace it with an identical driver and run only my Hartke head (being careful to keep the volume and EQ reasonable). If the problem comes up again, I'll know it's not my GK.

I will get the GK tested while I'm using my Hartke.

You simply do not have enough drivers for the amount of noise you are trying to make.
Add more drivers.

I have used a friend's 8x10 on several local gigs over the years and it never has a problem.

I bet you're thinking, "Why don't you buy an 8x10, Einstein?" Well, this is a stupid reason for a band that plays out regularly, but there's not enough room in the van.

Just thinking outside the box on this one...

Could there be an issue with transportation and storage of the cab in question? 20 miles down a pot-hole filled dirt road in the back of open pickup truck. In the pouring rain?

Just a thought.

A valid suggestion, but no, they are not transported as you described. Not even close. It's 20 miles down a pothole-filled road in a minivan. BTW, I'm not kidding. I really drive exactly 20 miles to practice.

I will also take apart one of the blown speakers to investigate the damage, but I'm a school teacher and school starts tomorrow; so I won't have a lot of time to play with these things.

You know, after this problem is solved and I replace all my drivers in my cabs, I am going to own two 2x12's, a 4x10, and two 1x12's; and they will all be functional!

Is that too many speaker cabs?

Thanks again, everyone.

 

[Bob Lee (QSC)]

This is the solution.

You simply do not have enough drivers for the amount of noise you are trying to make.
Add more drivers.

I agree.

-1 on needing a bigger amp, -1 on speaker cables, -1 on all this other extraneous stuff. You need more drivers so you don't have to push them as hard to get the sound levels you want.

 

[seamonkey]

Or more efficient cabinets. (i.e. www.billfitzmaurice.com )

 

[Bob Lee (QSC)]

Bob? Holy crap! I had no idea you hung out in these parts; I didn't know you got around beyond the LAB (Live Audio Board, for some of the other folks around here). Nice to see you!

And I will defer my somewhat improper statement earlier to Bob...he is one of the smartest I've ever seen on amp design and function.

-Mark "Flounder"

Hi Mark,

Yes … have you ever noticed how many live sound guys are also bass players? (I think it has something to do with wanting good sound without being in the spotlight.)

I'm fortunate to have worked with a bunch of smart amp designers here at QSC, and previously at Crest. Without them, I'd actually know very little about power amps.

 

[Daniel Elliott]

If the GK head goes DC the output would shut off and the blue light by the power switch would turn red. It's designed to do that. I still believe that your problem is electrical of some kind either from one of the heads or the wall outlet that you're plugged into.

I think you should have both heads looked at. You are welcome to contact me about the GK head.

 

[Freddels]

You need to get off the lecture circuit.

 

[bigfatbass]

Ya know what's funny about this thread? It took 9 posts before anyone even asked what the ratings were.



All this went by before anyone bothered to ask what the gear could handle:

__________________


A few things:

1) The absolute level of the master volume on an amp has very little to do with how much power and volume the amp is producing. Depending on the strength of the signal, and also the taper design of the master volume control, one amp might be pushed to distortion at a 9 o'clock setting, where another design might not even start to pump until it gets 'past noon'.

2) As has been posted a zillion times, 'underpowering' is not a cause of speakers blowing up.

Something is strange here. If you are hearing speakers 'fart' out, and keep playing at that volume, then you could be in for trouble. However, if you are running your rig appropriately (i.e., so the speakers are not distorting), then something else is going on.

The EE's will chime in... you might have something wrong with the amp... like DC (if I have that term correct) somehow pumping into the speakers.
__________________


Bassist Heal Thyself
You have blown five speakers in two years with two different heads.

The problem might be the guy holding the bass
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Quote:
Originally Posted by PSPookie View Post
You have blown five speakers in two years with two different heads.

The problem might be the guy holding the bass

I think that is most likely the case Didn't see the 'two amp' thing in the original post. Per Alex comment... too loud with too much bass!
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Quote:
Originally Posted by Single Coil View Post
I run my GK (at practice) with the settings recommended in the manual.
Which are? I can see four recommended settings.

Quote:
Originally Posted by Single Coil View Post
The gigs I have played with it have been with my Hartke head; the pre-amps have been set to half, the volume was never past six.
So you could easily be at the amp's limits. Remember the position of gain (or volume) knobs does not directly affect power output as that also depends on the input signal.

Quote:
Originally Posted by Single Coil View Post
1. There is some distortion coming out of my GK head; if so, it is barely audible.
Distortion does not blow woofers, only too much power, especially in the lows, does that. Distortion can blow tweeters due to increased treble content.

Quote:
Originally Posted by Single Coil View Post
2. I used to run my GK head above half on the master volume, thereby underpowering the speakers, causing distortion to the speakers. On my latest (4 x 10), I ran the GK over half for one minute total, every other time I have used it (or the Hartke), it has been below half.
You misunderstand 'underpowering'. There is no such thing - only overpowering due to demanding more power from an amp than it can cleanly supply.

Incorrect cab positioning could be the problem. If you place your cabs at a distance from the wall that cancels out 100Hz (back wave is 180 degrees out of phase with front wave) and then boost 100Hz to compensate you'll use up all your amp power and speaker excursion to no avail.

Or you could be suffering from the disease known as rock guitarists.

Alex
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I wonder if one of your heads is putting out DC on the speaker output. Most amps are protected to prevent this but I'd say it could happen, that could damage the voice coils pretty quickly and it might not even make a sound...

 

[KJung]

Ya know what's funny about this thread? It took 9 posts before anyone even asked what the ratings were.

Actually, if you read all the very good responses, you will realize that the 'ratings' are the least important piece of the puzzle

Why would you think 'ratings' would have anything to do with this? You can easily blow up any combination of amp and speaker by 'user error'... regardless of the power of the head or the maximum 'suggested' power of the cab.

 

[fenderhutz]

Are you using the same surge protector and/or rack power supply? Could be going bad and causing a surge.

 

[Stumbo]

I have been playing in my current band for almost five years and this problem did not start until two years ago.

Probably some Chinese made parts that, while meeting specs for the engineering plans, magically get replaced during production with cheaper, marginal materials to increase the profit margin.

I've found in other electronic items (electric tooth brush, rechargeable flashlights) that the chargers work for awhile then crap out. I've purchased from different manufacturers. The electric tooth brush's charger was replaced by batteries. I also bought a non-rechargeable battery powered flash light.

The same thing has happened in baby formula(The chinese did it to their own people), dog food(60 million cans recalled) and drugs(Chinese drug regulator sentenced to death). Who do you sue when these things happen?

I'm just sayin'...

 

[brivello]

To simplify the way I see it, A 200 watt amp over-driven into clipping doesn't put out 200 watt smooth sine waves into the speaker

A bass does not put out sine waves. Far from it.

 

[62bass]

Probably some Chinese made parts that, while meeting specs for the engineering plans, magically get replaced during production with cheaper, marginal materials to increase the profit margin.

I've found in other electronic items (electric tooth brush, rechargeable flashlights) that the chargers work for awhile then crap out. I've purchased from different manufacturers. The electric tooth brush's charger was replaced by batteries. I also bought a non-rechargeable battery powered flash light.

The same thing has happened in baby formula(The chinese did it to their own people), dog food(60 million cans recalled) and drugs(Chinese drug regulator sentenced to death). Who do you sue when these things happen?

I'm just sayin'...

I knew the Chinese would eventually get blamed.

 

[dannster]

I would have sent both amps in to get checked after the second cabinet blew up. Or bought a new amp. 5? really?
Amplifiers have a 3 prong plug for a reason. Regardless of weather that is the issue here you should stop using the 2 prong outlet. Maybe your amp was damaged because of this and is now borking your cabs. who knows? THE AMP REPAIRMAN THAT CHECKS OUT YOUR AMPS!

If you think you are pushing your amp harder than you should to acheive the volume and tone you are after than you probably are.

 

[bassplayer48]

I think its most likely just not enough speaker area, i recently blew (at least i think its blown havent had it checked) my EANL-210 cab its a 4 ohm cab and i was driving it with an Iamp 800 so putting in 800 watts (cab is rated at 500 watts) i used this setup with a country band with no problems.

Then i joined a louder rock n roll / blues band with 2 guitarists, and i knew i was pushing it harder anyway one night that distortion thing started ( i didn't hear any speaker fart) and now it sounds distored when you plug the cab in.

I needed a quick fix so i bought a used Mark Bass 410, i have the settings on the iamp exactly the same only the cab is 8 ohms so the iamp is only putting out 500 watts, (cab is rated at 800) and it works fine plenty of volume and crystal clear.

The guitarists i play with are only using 25 watt amps but with a fairly loud drummer it is bloody loud.

I think if you can run what ever head you are using so its not pushing too much and have enough speaker area so you can hear yourself this will fix your problems.

I don't believe that other variables like cables, power supply etc etc can really make that much difference.

If you think about if you are ruinning the exacy same number of watts into 1 cab then 2 the 2 cabs will always be louder, cos you have more speaker area.

 

[ashtray]

I'll add one thing here - which might not be worth much: I've been cautioned as to hw to properly transport speakers in a cabinet. I've been told to face the speakers downwards (magnet side up) to reduce potential damage from hitting a bump and having the speaker cones extend past their limits. Theory being that when you hit a pot hole, your tires go down, then hit the bottom and cause a solid "thunk" which is a downward pressure on anything that is floating in the cabin (ie your speaker cones, you, the cat, etc). If the magnet is under the speaker, this will amplify the problem - whereas if your magnet is over the speaker, it will help reduce the thunk.

That's what I've been told. That said, I would think less damage would happen if you transported the speakers upright, as they wouldn't have play to move up and down when you hit a bump.

But this all might be myths - don't really know. Just thought I would pass it along, as 20miles if you're transporting your cabs to and fro each time, could cause some damage I would think if being transport "improperly"....?

 

[Bob Lee (QSC)]

I've never heard of a cone-type loudspeaker actually suffering overexcursion damage by jostling while in transit, but I suppose it could be possible.

If it's a concern, you can protect the loudspeaker by inserting a shorting plug into the cabinet input jack. Short-circuiting the loudspeaker terminals will damp the cone motion. Just be sure to remove it before you hook up the amp to the loudspeaker!

 

[mfgl]

I wonder if someone else uses your cabinet when you are not around?

This was my first thought when i read you said it started when you got in your current band, and that it didnt happen to you before that. Maybe when your not there guitarist is playing thru your cab? Or something like that.