First blown bass speaker

[JACKSON JS1XM]

This sounds like you're just stringing a bunch of tech terms together, without actually saying anything.

Asking questions to determine why the speaker came apart ? When an original post doesn't explain what factors might have caused or contributed. Take blowing a fuse in an amp, it might be the fuse was defective, degraded or something else in the amp didn't regulate the electricity. Are we trying to solve a mystery here, solve a problem or just standing around and looking at a blown speaker, scratching our heads, no clues as to what happened ?

 

[Old Garage-Bander]

Unsafe impedance mismatch Parallel vs Series ? Tube vs solid state amp head power section ? And it could be something inside the amp chassis circuit that might've failed to auto detect the correct impedance load ?

Asking questions to determine why the speaker came apart ? When an original post doesn't explain what factors might have caused or contributed. Take blowing a fuse in an amp, it might be the fuse was defective, degraded or something else in the amp didn't regulate the electricity. Are we trying to solve a mystery here, solve a problem or just standing around and looking at a blown speaker, scratching our heads, no clues as to what happened ?

I'm all for asking questions. But I also believe the first questions to ask should relate to the information you think is missing in the original post. Let me ask a few of my own then.

"Unsafe impedance mismatch Parallel vs Series..."
Is there a SAFE impedance mismatch?
How does an impedance mismatch, safe or otherwise contribute to speaker damage?
How does parallel vs series configurations contribute to speaker damage?

"Tube vs Solid State amp head power section..."
How is it that one amplifier topology is more prone to causing speaker damage than another?

"Something inside the amp chassis circuit that might've failed to auto detect the correct impedance load."

First, I will point out some redundancies.
Impedance IS the load. You don't need to say it twice.
Amp chassis circuit. A chassis is the metal box that contains the circuitry of the amp. You could just say "the amp" without including the other non-essential wording. "Amp circuit" is also redundant. This kind of writing leads to confusion, especially for non- technical people. Also, this is often how non-technical people refer to things. By throwing a lot of unnecessary words into the description.
"What is this impedance "auto detect" that you speak of? Tubes amps have some form of manual means to allow for different loads; either by using a specific jack, or by using a switch. Solid state amps specify a minimum impedance to use. Anything higher than minimum is OK, though usually at the expense of reduced output. But there is no "auto detect system that I am aware of.

"Something else in the amp didn't regulate the electricity. "The only "regulation of "electricity" is what goes on in the various power supply circuits. Sure a voltage regulator may not be functioning properly, but that in itself doesn't damage speakers. You need to connect the dots and explain how this might happen, so those less knowledgeable can learn from you.

It is all of these examples of heavy uses of catch-phrases that caught my attention.

Your -blowing fuse in an amp- example has no bearing on the questions at hand. I know it was just intended as an analog. But that's about as far off of an analogy as one could get. If you used the example of how a bias supply cap might be defective from the start, or simply degrade over time, you'd at least only be a couple of degrees of separation from the speaker, rather than about as far away from the speaker as you can get, electrically.

Again, it seems you were just stringing a lot of words together. But doing so without explaining how they might relate too the OP's questions, just makes it seem more a stream of consciousness exercise than a technical analysis.

My final questions to you...

Are we trying to solve a mystery here, solve a problem?
Or are we just standing around looking at a blown speaker, scratching our heads, no clues as to what happened?
If your answer is the latter, then everything you posted makes sense. My concern in all of this is that your postings end up being quoted elsewhere by someone with much less electronics knowledge than you. This is how these myths come into being, and once they are out in the "wild", it's tough to rein them back in.

So if you intent was to stand around and scratch your head, I apologize for busting your chops.

12" Neo speaker. I respect the brand, so I am not going to call them out.

Was using a pair of 12"s, with a higher wattage rating than my Ampeg classic 15" cabs. I would not say I was pushing them too hard. About 1/4 of the volume from a 500 watt head.

One of the 12's now distorts. Are Neo 12" speakers more prone to issues, when used as bass speakers? I am wondering if it's worth ordering a factory replacement, or just going with the old school heavy magnet.

This sounds like you're just stringing a bunch of tech terms together, without actually saying anything.

 

[agedhorse]

As you know, I worked at EV for many years. EV was already working with General Motors, who was one of the discoverers of Nd-Fe-B magnets when they first developed it. EV did a lot of research into that material for audio applications and was the first audio company to introduce speakers and microphones using neodymium. In our research (at the time - back in the mid-late 80s), Nd was powerful and fast, but it didn't have the "push" at the extremes of Xmax that ferrite had (again - at the time) of ferrite magnets. I didn't participate in this research, but the people who did it were quite expert and very serious.

The geometry of the pole piece and return plate can greatly affect the shape ("focus") of the magnetic field at the ends of the gap. This is independent yet indirectly related to the magnet because of the difference in the shape and location of the magnetic material.

For a ceramic magnet, it's so weak that for enough motor strength it needs to surround the pole piece and be sandwiched between the return plate and the top plate that the pole piece is attached to. A Neo magnet is usually strong enough that it can be made into a slug that is part of the pole piece itself so it's easier to focus. The edges of the field, the fringe field, determines the amount of control and distortion (amount and type) as the VC moved towards Xmax.

There has been much debate and discovery of the pros and cons of the different focused field parameters. While one may be more forgiving under some conditions, it can be less so under others. In general, I have found that most modern Neo motors to be fairly similar in focus to their ceramic brethren. It's how the process evolved.

 

[StereoPlayer]

I love speaker threads!

 

[StereoPlayer]

I love speaker threads!

Yes, there are quite a number of members that know a lot more than me about speakers.
I just plain love speakers. Always have.

 

[Old Garage-Bander]

I love speaker threads!

Me too!

When I was working as a solder jockey in broadcasting, I was most fascinated with antennas.
I'd get calls from listeners, saying I couldn't receive your station very well so I spent a bunch of money on a big antenna and it didn't help. (Sounds similar to things we hear on TB, yes?)
Once I explained why a bigger antenna wasn't the solution, and advised them what to try that cost little or no money, we usually got good results. (It was public radio, so a few even ponied up as a way of saying thanks.)

There can be a lot of similarities between antennas and speakers. I guess that's why the Amps and Cabs forum is my favorite here.

 

[S-Bigbottom]

Are we trying to solve a mystery here, solve a problem?
Or are we just standing around looking at a blown speaker, scratching our heads, no clues as to what happened?

This is what we are doing.

 

[S-Bigbottom]

Once I explained why a bigger antenna wasn't the solution, and advised them what to try that cost little or no money, we usually got good results.

How do I get more with less?
It is foil wrap the antenna, ain't it?

Got that on my rabbit ears, gets me channel 12 , and not without it.

 

[mlowe]

Please explain how you came to this conclusion. Or is it just something you heard or read somewhere?

When an amplifier clips (severe clipping) it's sending DC to the voice coil of the driver. The voice coil will heat very fast and fail. Even with a lot less power than the AC rated power handling this is catastrophic to a voice coil. Speakers are AC devices. By under powering a speaker and driving it into clipping you have a high risk of damaging speakers. This is why amplifiers often have clip indicators or even clip protection circuits.

 

[mlowe]

I wish this myth would die, what you posted here is just so wrong.



How’s does that work?

I'm not understanding how you see this as a myth? It can be demonstrated any number of times. There is thresholds of course. Running 5W DC into 1200W driver may only become a heater at best but when the ratings are closer you can certainly kill a 300wRMS driver with 75v DC and some current pretty quickly. I could be misunderstanding your point of course.

 

[mlowe]

Please explain how you came to this conclusion. Or is it just something you heard or read somewhere?

Watch a voice coil winding mimic a fuse.

 

[swarfrat]

Watts is watts. Thermal damage to the voice coil is pretty much just watts. Which not coincidentally is the same units as BTU/hr.
But we're talking about over excursion here.
What clipping can do is kill tweeters which are sized by expected spectral content for the woofer. It's wasteful to have a 400w tweeter for a 400w woofer. Spectral content aside they're usually more efficient too. And clipping changes the spectral content.

Clipping doesn't cause over excursion by itself. Otherwise we could never listen to distorted guitar at low volumes without blowing speakers.

And btw the guy you're arguing with knows the deep magic from before the dawn of time.

 

[mlowe]

See Dumb question about wattage..... Very entertaining. Short version: the amp designers and electronics engineers in that thread basically say underpowering is a myth. Several other "but-I've-seen-it-happen!" posters persisted in arguing otherwise until the mods had to kill the thread.

Quote from Bob Lee of QSC Audio, in post 81 in that thread:

Clipping is not DC and does not make the loudspeaker cone stop moving.

At frequencies above resonance a waveform portion that is a constant voltage, as in the flat-topped peaks of a clipped signal does not make the cone stop, but is instead a constant accelerative force--even if just for a couple of milliseconds.

Typically more than 90% of the power into a loudspeaker is wasted as heat instead of converted into acoustical energy. The danger in power amp clipping is excess power: the amp will then put out more power than its rating would suggest, and the average power even in between the clipped peaks can be pushed extremely high.

The last bold point makes perfect sense. The issue is the way it's described out of context in many posts. You could have an amp and driver of a given type spec clip all day and no damage but with another set have magic smoke. This issue is also common in UPS protection I work with by day. Quasi wave AC generators are cheap but they burn everything you plug into them. That time in DC changes the math.

 

[agedhorse]

Clipping has NOTHING to do with DC, it’s still an AC waveform.

clipping is the most common circuitry in distortion pedals, they are used all the time and with just a little bit of common sense do not damage speakers.

 

[mlowe]

How does this work exactly?

DC delivers more average power/time. An amplifier with the less RMS rating in the right scenario could be delivering more power than one that is more powerful operating with a clean AC signal. Then we have the all the thermal factors like coil material, the former, magnet and basket material that can mitigate this.

 

[Old Garage-Bander]

When an amplifier clips (severe clipping) it's sending DC to the voice coil of the driver. The voice coil will heat very fast and fail. Even with a lot less power than the AC rated power handling this is catastrophic to a voice coil. Speakers are AC devices. By under powering a speaker and driving it into clipping you have a high risk of damaging speakers. This is why amplifiers often have clip indicators or even clip protection circuits.

The only thing that causes a speaker that is previously in good working order, to fail is exceeding it's electrical and or mechanical limits. I can send it a sine wave, square waves, severely clipped music or just straight up DC all day long. As long as I don't exceed the speaker's design limits it will be OK.
People think it's the clipped signal that killed their speaker because it died when they were clipping it. The truth is that they also happened to be exceeding electrical or mechanical limits, or both, while clipping.
THE SHAPE OF THE SIGNAL IS NOT WHAT HARMS SPEAKERS.

Under powering a speaker, by definition means not exceeding the speaker's limits.

You are well within your rights to believe otherwise, but when you spread misinformation to others, you are perpetuating the myth. If you want the truth you can either believe the design engineers, one of which (not me) has already weighed in on this being a myth. Or you can do all the work yourself to understand what is really happening.

Correlation is not causation.

 

[Old Garage-Bander]

How do I get more with less?
It is foil wrap the antenna, ain't it?

Got that on my rabbit ears, gets me channel 12 , and not without it.

The foil changes the directivity of the rabbit ears. You got lucky and it just happen to be in direction that worked for the station of interest.

Would you care to know how many reception issues I fixed for people by telling them to remove the regular antenna and use a paper clip instead?

 

[Old Garage-Bander]

This is what we are doing.

Uh huh!

 

[swarfrat]

I killed one of those 50w 4 ohm Aura Pro shakers once... actually smoked it. Bad combination of math and "can't hear how loud it is". After I found my math errors I realized that I had potentially 700w available. And it was feeling awesome right up until it smoked.

 

[Old Garage-Bander]

Watts is watts. Thermal damage to the voice coil is pretty much just watts. Which not coincidentally is the same units as BTU/hr.
But we're talking about over excursion here.
What clipping can do is kill tweeters which are sized by expected spectral content for the woofer. It's wasteful to have a 400w tweeter for a 400w woofer. Spectral content aside they're usually more efficient too. And clipping changes the spectral content.

Clipping doesn't cause over excursion by itself. Otherwise we could never listen to distorted guitar at low volumes without blowing speakers.

And btw the guy you're arguing with knows the deep magic from before the dawn of time.

You of course refer to Mr. @agedhorse.
Any arguments I am involved in are done simply as a mere fledgling, disciple of the truth about speakers.
Wanted that to be clear.