15" 15 inch replacement driver speaker

eisenbug · #1 06-13-2010, 03:52 PM

Here's what I want to know: How does a EV EVX 155 get blown out in a tube combo with a max of 100 watts and a sealed 2.25 cuft box? These things are rated at 600 watts plus. Obviously, I'm pissed, but what I really want to know is should I get it re-coned, or should I put in something else? I got enough mids and highs from the EV, even though I don't know why. Sealed box? Bright signal? I don't care. It worked, until it stopped working. Now what?

RickenBoogie · #2 06-13-2010, 04:50 PM

Any speaker can be blown by any amp. It's all a matter of how the eq and gain stage were set. Even a 100 watt amp can produce more than enough signal to fry a speaker rated at 600 watts. The speakers rating is it's thermal limit, not the actual maximum wattage it'll take, and the amps rated power is what it can deliver constantly, not what it's capable of in short bursts.

craig.p · #3 06-13-2010, 05:33 PM

There's also the possibility the amp malfunctioned (or was malfunctioning over time) and sent (or had been sending) a bunch of nasty junk to the speaker that you couldn't hear. Much less likely than what RB said, but still possible.

Only you will know whether the speaker was abused by you or not. You have to pay attention to sound AND cone movement. Was it exhibiting signs of distress in either area?

billfitzmaurice · #4 06-13-2010, 05:35 PM

Quote:

Originally Posted by eisenbug

a sealed 2.25 cuft box?

The EVX isn't suited to a small sealed cab. For that matter it's not all that well suited to a small vented box either, in which it rolls off severely below 200Hz. So chances are you overpowered it trying to get some low end out of it. And as RickenBoogie said a decent 100w amp can generate a lot more than that when pushed hard.

eisenbug · #5 06-13-2010, 09:42 PM

So what is suited to a small sealed cab?

billfitzmaurice · #6 06-14-2010, 06:54 AM

Quote:

Originally Posted by eisenbug

So what is suited to a small sealed cab?

A driver with a low Vas, less than 200 liters, and a low EBP, less than 75. Few exist. Most low EBP drivers also have high Vas, which results in boomy response in small cabs. The Eminence Beta 15 and Delta 15 are probably as good as any. EV drivers have very high EBP, so they're the last drivers one would want to use in a small sealed box.

4-stringB · #7 06-14-2010, 07:22 AM

Just to add to what the other guys said, an overdriven distorted output from a small amp contains a lot of DC current.(Sine wave vs square wave) This can heat up the voice coil like a stove element..cheers

BassIan · #8 06-14-2010, 08:05 AM

Quote:

Originally Posted by 4-stringB

Just to add to what the other guys said, an overdriven distorted output from a small amp contains a lot of DC current.(Sine wave vs square wave) This can heat up the voice coil like a stove element..cheers

This is absolutely incorrect and should not be perpetuated.

A square wave is an AC signal just like a sine wave, but it contains a significant number of high frequency components in multiples of the fundamental frequency. Do a bit of reading on Fourier Series Analysis. There is no DC in a wave.

What is true, however, is that a square wave with the same peak-to-peak voltage of a sine wave carries two times as much power when dissipated across the same load (speaker). In other words, at the same voltage, it has twice the heating ability. This is theoretical, since we don't ever see true square wave output from an amplifier.

Voice coils get hot anyway, and fail either by getting TOO hot, or by mechanically contacting part of the surrounding structure due to overexcursion or misalignment. Nothing else.

uglyrumor · #9 06-14-2010, 08:36 AM

And a contributing factor could be that the speaker itself was defective. Sometimes that may not manifest until pushed.

jtc_hunter · #10 06-14-2010, 09:09 AM

If you are looking for a 4 ohm replacement , go to here and under scratch and dent ,scroll down to 15" Eminence.

http://www.avatarspeakers.com/ $68+$12 shipping

eisenbug · #11 06-14-2010, 10:16 AM

Thanks, everyone for all your help. No, it wasn't defective. I got 5 good years out of it and it was used hard everyday. I just never thought that 2 KT88s on 433v would wear it out. So, clearly, if I repair it, it will wear out again. Oh well, it sounded so good. Bill, thanks for your technical advice. I'm preparing a comparison sheet, and you're right, the drivers with the lowest EPB require more volume than I have. When it comes to compromise, which is the more critical number? At what point does the law of diminishing returns apply?

OldogNewTrick · #12 06-14-2010, 10:27 AM

check out the Eminence Basslite C2515. Reasonable EBP of 75.3 and VAS of 270 will give a decent result. Much better than both Beta15 and Delta15 IMO.

eisenbug · #13 06-14-2010, 11:02 AM

I saw that. The VAS of 270 concerns me. I don't like that boomy sound. I found that a B&C neo, the 15HPL76W, has VAS of 156 but an EPB of 86. What will I be giving away to drop the VAS under the 200 line Bill gave me? Has anybody used B&C speakers in bass cabinets? On the other end of the weight spectrum, Eminence has the Definimax 4015LF with VAS 115 and EPB of only 78, better numbers, but possibly too dull.

billfitzmaurice · #14 06-14-2010, 12:07 PM

Quote:

Originally Posted by eisenbug

I'm preparing a comparison sheet, and you're right, the drivers with the lowest EPB require more volume than I have. When it comes to compromise, which is the more critical number? At what point does the law of diminishing returns apply?

Download WinISD Alpha Pro, take some time to learn how to use it. It's not difficult and makes choosing drivers as far as low frequency results go very easy. Driver data sheet SPL charts will fill in the rest. As far as getting opinions on drivers go you'll get as many opinions as you do replies, with most subjectively based. SPL and displacement limited power charts are completely objective.

4-stringB · #15 06-28-2010, 10:07 AM

Quote:

Originally Posted by BassIan

This is absolutely incorrect and should not be perpetuated.

A square wave is an AC signal just like a sine wave, but it contains a significant number of high frequency components in multiples of the fundamental frequency. Do a bit of reading on Fourier Series Analysis. There is no DC in a wave.

What is true, however, is that a square wave with the same peak-to-peak voltage of a sine wave carries two times as much power when dissipated across the same load (speaker). In other words, at the same voltage, it has twice the heating ability. This is theoretical, since we don't ever see true square wave output from an amplifier.

Voice coils get hot anyway, and fail either by getting TOO hot, or by mechanically contacting part of the surrounding structure due to overexcursion or misalignment. Nothing else.

Yo man, not doubting you or nothin', but what is the type signal at the peaks. I was taught by Uncle Sam that a square wave is pure DC at those peaks. However, I agree there is no DC in a wave, but at those peaks, it's not a wave...(I'm gonna go look up this Fourier crap)..Keep those cards and letters coming..it's OK to disagree, but a little respect goes a long way..Cheers...PS (after several hours of research and consulting with an electronic engineer) I found that, strictly speaking, you are correct about the numerous harmonics at the peak of a square wave, however, in the real world, considering the frequency response of most bass speakers and the numerous competing harmonics, the speaker will perceive the signal as DC and fry itself. I stand by my earlier statement.

rpsands · #16 06-28-2010, 10:36 AM

Cut the tube head out of the combo, get a real cabinet.

billfitzmaurice · #17 06-28-2010, 12:20 PM

Quote:

Originally Posted by 4-stringB

in the real world, considering the frequency response of most bass speakers and the numerous competing harmonics, the speaker will perceive the signal as DC and fry itself. I stand by my earlier statement.

You can stand anywhere you wish, but your assessment is 100% totally incorrect. A woofer doesn't perceive a clipped signal any differently than a clean signal, and due to the rising impedance of a woofer with frequency the bulk of the harmonics created by clipping are low-pass filtered out of the signal anyway.

mulchor · #18 06-28-2010, 01:04 PM

Quote:

Originally Posted by 4-stringB

Yo man, not doubting you or nothin', but what is the type signal at the peaks. I was taught by Uncle Sam that a square wave is pure DC at those peaks. However, I agree there is no DC in a wave, but at those peaks, it's not a wave...(I'm gonna go look up this Fourier crap)..

Perhaps what your uncle was trying to say is that a square wave has non-zero energy at every harmonic approaching infinity. ?

That Fourier crap is truly old-school

edit Obligatory on-topic:
Not necessarily that anything wrong was done to cause the speaker to fail. Mechanical things fail. Electrical things fail.

anonymous02282011 · #19 06-28-2010, 01:10 PM

I use EVX 155s in a TL box which is 3.2 cubic feet and hit em with a lot of wattage. I've never had an issue. The OP is using a 2.25 cu ft box.

My question for the experts is: would cabinet size make such a difference in speaker wear, excluding all other factors?