Mythbusting

Re: Mythbusting

Mark DeArman said:
Totally agree, just don't bother getting into an argument with him. :o~:-o~:eek:
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It's hard to get into an argument about objective science, without one person (or both) being misinformed. It's pointless to argue about things that can not be proved objectively.

That's why i never argue with people about what they say they hear, while i will often dispute unfounded theories about why they think they hear what they do.

JR
 
Re: Mythbusting

Mark DeArman said:
Well the number of lies (manipulations of the data) told by manufactures in this industry over the years is enough to drive someone batty. Oh well, that there looks like an 800W speaker, we better stick a 1000W sticker on it cause that's 100W more than the JBL.
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Since I spent years dealing with such information for a major manufacturer, i don't share your low opinion of all such marketing media as lies or blatant manipulation. While marketers are not beyond feeding customers with the kind of specs that they think are important even if they aren't (like damping factor). In many cases the specs are not normalized for easy comparison so customers must understand the science to interpret, or perhaps the data is incomplete.

If you ask a speaker engineer from a speaker company they will tell you that they are the only company publishing honest specs and everybody else is exaggerating. The reality is less exciting with customer guilty of poor understanding and being responsive to the wrong kind of data. If customers reward a certain kind of spec by buying them, they will get more of the same.

Thus successful snake oil purveyors will lead to more snake oil purveyors as long as they don't break the letter of the law. Fraud remains illegal.

JR
 
Re: Mythbusting

John Roberts said:
i don't share your low opinion of all such marketing media as lies or blatant manipulation
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I'm not so sure it is blatant deception as much as, well that guy did it so we better do it also, or we are going to lose sales.
Don't get me wrong, I'm not that jaded. In fact the numbers are WAY more believable now for a lot of reasons. Testing has improved, adoption of standards is more universal, materials have improved, and etc. Many companies will supply the data also.

BUT, there are still plenty of OEM speakers I see floating around which say 600W AES, which there is NO WAY will pass the test. Maybe they have a Zmin of 0.01 ohms or something :-).
 
Re: Mythbusting

John Roberts said:
The reality is less exciting with customer guilty of poor understanding and being responsive to the wrong kind of data. If customers reward a certain kind of spec by buying them, they will get more of the same.
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Well this also may have been the biggest problem. Especially, regarding sensitivity numbers, I can invest massive amounts of resources into getting an extra 2 or 3dB from a speaker design. Only to have the customer say, "Gosh, it's only 2dB louder. Thats nuthin."

Well luckily the customers are getting way smarter as a whole also.
 
Re: Mythbusting

Silas Pradetto said:
As far as I know, speakers can only be blown two ways: too much heat (average power), or mechanical failure (peak power).
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Mechanical failure isn't necessarily due to peak power. With the right resonant frequency, it's possible to cause damage below rated power with some drivers.

Failure that is power rated is simply due to heat. A speaker coil can take a higher current for short periods as long as it has time to cool off. As long as the driver doesn't have mechanical problems at that high power, you'll survive.

Personally, I like to spend a little more on speakers so that I never have to run them beyond the point where average power is needed. If I'm ever running where I'm concerned that speaker failure is going to happen, I didn't bring enough rig to the gig. I've only seen a clip light on one of my amps once this year, at an install in a bar. Gear was updated the very next day.
 
Re: Mythbusting

Re: concerns about amplifier clipping sending high frequency energy to woofers

Sending HF to woofers isn't generally an issue, not least because the power content in extra HF generated by clipping is small and because the driver is inductive so its impedance rises linearly with frequency and power transferred falls linearly with frequency.

Example: Apply 100W 100Hz sine wave to a hypothetical woofer. It sees 100W at 100Hz. Now apply a 100Hz square wave with the same 100W power content instead. If it were non-inductive, the driver would see 81W at 100Hz, 9W at 300Hz, and around 10W at 500Hz and above (falling off rapidly with frequency). Because of its inductance, it actually sees 81W at 100Hz, around 7W at 300Hz, and under 5W from 500Hz and up.

Also, clipping a sine wave introduces energy at higher frequencies only, but clipping a signal that contains more than one frequency (like music) introduces energy at both higher and lower frequencies. That's one reason why, in a system with an active crossover, it's a good idea to retain a passive high-pass filter on the high frequency driver.

Re: over-excursion failure

This is related to average power and frequency, not peak power. All else being equal, halving the frequency without changing power quadruples the excursion.

Re: linked article

I haven't read it thoroughly but it seems generally on the mark. (There are things I'd take issue with, however, like sections 5 and 10.)

Nick
 
Re: Mythbusting

John Roberts said:
Thus successful snake oil purveyors will lead to more snake oil purveyors as long as they don't break the letter of the law. Fraud remains illegal.

JR
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Fraud is not illegal in China... Neither is lying or exporting toxic waste in your packaging to other countries while poisoning the groundwater that poor people in your manufacturing towns drink.

Funny how most loudspeakers are now manufactured in China, yet we are debating why they fail. I will posit that the reason they fail now more than they used to is due to some form of fraud, since fraud is rampant (and funded by the Chinese government) in China and many speakers are now made there, it is illogical to assume that any speaker made in PROC does not include some form of fraudulence during its manufacturing cycle. This would explain the higher than average user experience of failure without any user habits changing.
 
Re: Mythbusting

Mass market drivers have been made offshore for decades, with the occasional exceptions made here. While China was not that big in early offshore speaker manufacturing, I suspect they have a large share now. It wasn't always economic to ship the cabinets, so pretty common to make the boxes here and load the drivers from wherever into them. These days for high volume products I suspect they are completely assembled offshore.

JR

[edit= Last time I was in Hong Kong several years ago, visiting a small product development office, they had a bunch of high end hifi speakers they were working on for a British brand.. IIRC the western brand was owned by the Chinese parent company. /edit]
 
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Re: Mythbusting

Zomax, at one time, was casting speaker baskets for a couple of well-known professional transducer makers. The coning and magnetizing was done in the brand's factory.
 
Re: Mythbusting

I have been inside multiple US factories who made selected drivers (Bozak and Peavey). But in both cases they purchased low end mass market drivers for their lower cost offerings. My point is that the vast majority, by several measures, are not made here. If there was some broad sweeping quality issue it would have reared it's ugly head decades ago. I think CTS was one of the last large scale domestic speaker manufacturers.

JR
 
Re: Mythbusting

But I was talking about high quality, professional grade drivers like JBL, RCF, B&C, etc. Are there any top end pro-grade drivers made in China?
 
Re: Mythbusting

Chuck Simon said:
But I was talking about high quality, professional grade drivers like JBL, RCF, B&C, etc. Are there any top end pro-grade drivers made in China?
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Maybe some of those? While low volume SKUs are not that attractive to build at a distance. Even then, I suspect some components for those are sourced from China.

On a related note, the house just passed legislation making it easier to open new rare earth mines here, but it still has to get through the senate and signed, not likely in the current political environment.

JR
 
Re: Mythbusting

John Roberts said:
On a related note, the house just passed legislation making it easier to open new rare earth mines here, but it still has to get through the senate and signed, not likely in the current political environment.
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I'm not holding my breath... I just don't see how it would be cost competitive anyhow. Maybe 20 years down the road if China improves safety in both the processing and mining.
 
Re: Mythbusting

So the conclusion? It is not waveforms, lack of power or excessive power that destroys speakers, but chinese components??? :twisted:
 
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