It is a driver from a Chinese Manufacturer used in a Bluetooth speaker.
I have equalized it, for better extension in the Low frequencies, and I measured excursion close to +/- 6 mm, which is 100% above from the Xmax the manufacturer gives.
I don't see any failure problem for a couple of weeks now, but what will happen after a year or more of use?
This is the main question. If someone has any experience on this issue.
I have equalized it, for better extension in the Low frequencies, and I measured excursion close to +/- 6 mm, which is 100% above from the Xmax the manufacturer gives.
I don't see any failure problem for a couple of weeks now, but what will happen after a year or more of use?
This is the main question. If someone has any experience on this issue.
It will depend on the spider and surround construction, whether it will tolerate long term excessive excursion. Usually, with a smaller driver, the mechanical non-linearities will show up well before the actual limit is reached. Sometimes a very short VC former is used which can move too far out of the VC gap, potentially getting stuck in the outward position, like some older B&W woofers suffered from.
Ha. My guess is that in the competitive world of battery powered DSP/amplifier bluetooth speakers they push it to absolute x-limit, and then the compressor kicks to prevent clearly audible driver distress/ distortion.
But they don’t expect the Bluetooth speaker to last much behind the life of the battery. Which is about 1000 charges ~ 5 years. And they don’t expect you to be able to change the battery.
If you expect your speaker to last decades like a passive speaker, then that’s a different matter.
Now do you have spares?
Or can get another?
Perhaps you can do a case study - what happens if I send subsonic tones to my speaker to reach x-limit on regular basis?
(Probably nothing).
What happens when I exceed x-limit by 20%
50%?
100%
If you limiter works as intended and speaker is unable to exceed x-limit; then you will fine (probably)
Suck it and see!
Advancing audio one 4” drive unit at a time.
But they don’t expect the Bluetooth speaker to last much behind the life of the battery. Which is about 1000 charges ~ 5 years. And they don’t expect you to be able to change the battery.
If you expect your speaker to last decades like a passive speaker, then that’s a different matter.
Now do you have spares?
Or can get another?
Perhaps you can do a case study - what happens if I send subsonic tones to my speaker to reach x-limit on regular basis?
(Probably nothing).
What happens when I exceed x-limit by 20%
50%?
100%
If you limiter works as intended and speaker is unable to exceed x-limit; then you will fine (probably)
Suck it and see!
Advancing audio one 4” drive unit at a time.
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I thought all of these. But one or two pieces are not enough to have some safe results.
Yes, the limiter will protect the driver, but the question here is what excursion limit to use. Equal to Xmax or greater?
Any personal experience about this issue to share ?
Yes, the limiter will protect the driver, but the question here is what excursion limit to use. Equal to Xmax or greater?
Any personal experience about this issue to share ?
Depends on what your goal is. To prevent the driver from guaranteed mechanical damage (voice coil hitting the pole piece or jumping out of the gap and stuck etc), use protection that doesn't allow the driver to reach xmech, which is the maximum mechanical excursion of the driver before damage.
But if you want to stay within a certain amount of distortion value, measure the driver and use protection that prevents the driver to exceed that level of distortion. Unfortunately, the mathematical xmax doesn't show what level of distortion is produced by the driver.
But if you want to stay within a certain amount of distortion value, measure the driver and use protection that prevents the driver to exceed that level of distortion. Unfortunately, the mathematical xmax doesn't show what level of distortion is produced by the driver.
If the surround or spider is not fully extended each stroke (making a "pup-pup" type noise) and the former does not strike the back plate (making a clacking noise), the driver should last a long time.
Prior to having HP filters on crossovers set near Fb, I ran hundreds of speakers reaching peaks around double the Xmax value for ten years or more.
That said, a voltage setting used to limit excursion may eventually need to be reduced as the suspension softens over time.
trying to justify driving a bluetooth speaker
to distortion with EQ
like asking how long cheap 1/2 ton ball joints last
on dirt roads.
they work fine for a few weeks, months, years
all in all they break quicker.
rather self explanatory, and generalized
nobodys done extensive research on small 15 watt bluetooth speakers
aside from, they have no bass and distort easy.
to distortion with EQ
like asking how long cheap 1/2 ton ball joints last
on dirt roads.
they work fine for a few weeks, months, years
all in all they break quicker.
rather self explanatory, and generalized
nobodys done extensive research on small 15 watt bluetooth speakers
aside from, they have no bass and distort easy.
Your driver (and / or the amp) will likely fail, mechanically, thermally - or both. Your distortion comes because you are throwing signal (power) at a component that has reached its limit. Who knows what happens to the resistance at this point? The output isn't any 'louder' because the driver is doing all it can do.
Cautionary tale: In my youth I had a VW Golf GTi. I removed the rev-limiter from the distributor. It went like stink for a couple of months until the engine blew up.
RIP
Cautionary tale: In my youth I had a VW Golf GTi. I removed the rev-limiter from the distributor. It went like stink for a couple of months until the engine blew up.
RIP
Plenty of Bluetooth speaker reviews complaining that the speaker starts to sound distorted or compressed if it is turn up too high.
What’s the alternative? Let them push themselves til they flap and drop?
Those smart engineers make those smart features in portable Bluetooth speakers with 4” twoofers, studio monitors, and PA speakers with 15” woofers and Golf GTI so that the public doesn’t destroy their product.
Fair trade I say.
What’s the alternative? Let them push themselves til they flap and drop?
Those smart engineers make those smart features in portable Bluetooth speakers with 4” twoofers, studio monitors, and PA speakers with 15” woofers and Golf GTI so that the public doesn’t destroy their product.
Fair trade I say.
It is simple with the current DSP chips to use equalization, compressors and limiters to avoid distortion above some voltage input limit.
Although it is very common to measure distortion close to 50% or even 100% for the frequency range between let's say 60 to 80 Hz for a Bluetooth speaker with a 4" driver, which usually is used as "subwoofer". Mainly this is done to gain greater sound pressure level.
My purpose was to ask for other's experience about the limits of these drivers due to excessive excursion.
Although it is very common to measure distortion close to 50% or even 100% for the frequency range between let's say 60 to 80 Hz for a Bluetooth speaker with a 4" driver, which usually is used as "subwoofer". Mainly this is done to gain greater sound pressure level.
My purpose was to ask for other's experience about the limits of these drivers due to excessive excursion.
As indicated, going beyond Xmax will cause damage. Compressors, limiters are distortion in themselves. Regardless, to produce bass you need to move the diaphragm to move air.
Small subwoofers have limited scope and offer diminishing returns. An increase in Xmax requires an increase in surround resulting in decreased sensitivity due the reduction of the diaphragm area. Subsequently you need more power for the same output.
If you look at the example: the drive is all surround and dustcap, there is very little diaphragm area.
Small subwoofers have limited scope and offer diminishing returns. An increase in Xmax requires an increase in surround resulting in decreased sensitivity due the reduction of the diaphragm area. Subsequently you need more power for the same output.
If you look at the example: the drive is all surround and dustcap, there is very little diaphragm area.
I think this is not valid to the type of speakers (Bluetooth etc) we are talking here.
Compressors at lower frequencies and limiters at the higher frequencies are widely used to protect the speaker.
Also to offer a somehow "bigger & louder" sound that they would not have without them.
Compressors at lower frequencies and limiters at the higher frequencies are widely used to protect the speaker.
Also to offer a somehow "bigger & louder" sound that they would not have without them.
We dont even know what speaker we are talking about.
and mechanical and electrical values were standardized
long time ago.
enter the driver in a model, apply voltage
once you hit xmax it is 10% distortion.
manufactures like laser measurements. makes
xmax look larger than the older accepted method.
based on the gap n coil height.
within reason the magnet only has so much control.
in a hifi community most are trying to be under
or around 3% distortion
if you wanna drive speakers way over 10% distortion
have fun, it has been done and done often.
over a lifetime, blasting a speaker past 10% distortion
will reduce its lifespan.
otherwise people use limiters and filters to reduce
distortion or damage.
speaker has a resonant frequency. anything below that
is pointless, and then add another 6 dB that goes by by
to full space
and mechanical and electrical values were standardized
long time ago.
enter the driver in a model, apply voltage
once you hit xmax it is 10% distortion.
manufactures like laser measurements. makes
xmax look larger than the older accepted method.
based on the gap n coil height.
within reason the magnet only has so much control.
in a hifi community most are trying to be under
or around 3% distortion
if you wanna drive speakers way over 10% distortion
have fun, it has been done and done often.
over a lifetime, blasting a speaker past 10% distortion
will reduce its lifespan.
otherwise people use limiters and filters to reduce
distortion or damage.
speaker has a resonant frequency. anything below that
is pointless, and then add another 6 dB that goes by by
to full space
In this kind of application (Bluetooth, portable, speakers), the distortion below 100 Hz, can reach easily even 100%, since the excursion of the driver is way above its Xmax.
My question was, if there is any experience from others, about the the lifespan of the driver in these cases.
My question was, if there is any experience from others, about the the lifespan of the driver in these cases.
Since all drive units differ in motor, cone & suspension design, unfortunately the only real answer to that is 'it depends on the driver'. You can't really generalise that far.
It seems to me that some posters are confusing Xmax with Xmech (and rarely provided Xdamage). Xmech is typically several times larger than Xmax, so setting the limiter for +-5 mm is safe. I would go with Weltersys advice: carefully drive the cone to the "pup-pup" excursion with infrasound, measure that excursion and set limiter to 20-25% lower.