Ive used the hell out of stethoscopes, accels, velometers and even listening to screwdrivers on your cranium but, Ive never seen a laser vibrometre, I just looked it up, very cool.
Really you would just need to find a Cell phone " Toolbox"
which monitors and graphs cell phone sensors.
Basically almost all android or Iphone devices or pads have
Accelerometers built in.
Lay your phone on the speaker.
Run a sweep.
Use cell phone app to waterfall plot
the accelerometer.
If your screen has a rotate function.
Then your phone has a accelerometer to sense
the phones position.
And there is likely hundreds of Apps to graph
the phones sensors.
You can measure gravity, or make a step counter.
or play marble games too.
But in this case you can measure panel resonance
as well.
which monitors and graphs cell phone sensors.
Basically almost all android or Iphone devices or pads have
Accelerometers built in.
Lay your phone on the speaker.
Run a sweep.
Use cell phone app to waterfall plot
the accelerometer.
If your screen has a rotate function.
Then your phone has a accelerometer to sense
the phones position.
And there is likely hundreds of Apps to graph
the phones sensors.
You can measure gravity, or make a step counter.
or play marble games too.
But in this case you can measure panel resonance
as well.
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While I await the results of the vibration measurements, I also repeat my advice to make close range (2cm max), full spectrum measurements of both bass drivers. Use no gating, at least not shorter than about 50ms and apply long enough FFT samples for low frequencies (lower FFT sample rates like 48 or even 24 kHz pay off here). Derive the spectral decay plot (preferably the burst decay, it 'reads' more easily) and see if resonances in the drivers and/or those ín the enclosure should bother you.
Hi Tone
This from horn master Kolbrek is about the best you can do with home equipment https://kolbrek.hornspeakersystems.info/index.php/tubes/vibration-measurements. See also in the site how he optimizes his bass horn on vibrations https://kolbrek.hornspeakersystems.info/index.php/blag/40-belts-and-braces-pt-1
Best
Jean-Louis
This from horn master Kolbrek is about the best you can do with home equipment https://kolbrek.hornspeakersystems.info/index.php/tubes/vibration-measurements. See also in the site how he optimizes his bass horn on vibrations https://kolbrek.hornspeakersystems.info/index.php/blag/40-belts-and-braces-pt-1
Best
Jean-Louis
You'll notice I said effective braces. Or maybe you won't. What you linked isn't permanent and might not even be good enough to test with. You're the one that wanted to be scientific.
This is a dead end. Sensors in mobile phones aren’t that sensitive and how to connect the sensor to the enclosure?
are you always this hospitable to newcomers?
people usually offer tea and cookies.
lol
I'm a bit confused on what it is you're measuring tone? . Is it enclosure resonances or panel vibrations?
I want to measure the box and see if I can improve upon it.
don’t know if that makes sense
it’s ‘ detective ‘ work
don’t know if that makes sense
it’s ‘ detective ‘ work
OK ... but what are you measuring or assessing? Enclosure resonances and panel vibrations aren't the same thing.
How will you know if the box has been improved? For example, you seem to be trying to add braces to "stiffen" and change the resonant structure but how is this related to any unwanted audible sounds you may hear? For example, consider how small a tweeter is and how small it's deflection needs to be at high frequency in order to be as loud as a large woofer deflecting a large amount at low frequency. What does that mean when it comes to "stiffening" your cabinet in order to raise resonant frequencies?
Yes it is detective work and detectives should be guided by facts rather than the opinions of those that lack a thorough understanding of the relevant physics. Facts (i.e. competent measurements or competent simulations) are thin on the ground when it comes to sound radiated by cabinets but there are a few if you take the time to look. They don't support the widely held opinion that bracing the hell out of everything will make a cabinet quieter.
The lack of competent measurements and simulations by DIYers is curious and almost certain to change in the near future. The only DIYer I am aware of that started to measure a cabinet in a competent manner didn't show any results. Whether he gave up or tripped up I am not sure. Not sure quite what hardware you are looking to get but you may be in a position to have a go if interested.
"resonance
noun
UK /ˈrez.ən.əns/ US /ˈrez.ən.əns/
resonance noun (SOUND)
[ U ]
the quality of being loud and clear
[ C or U ] PHYSICS specialized
the production of a sound as a result of vibration (= shaking) of another object:" From the Cambridge dictionary.
I won't get drawn into a a discussion as to whether they are the same thing, (as some sources also say that it's a sound reflection that causes a vibration) who cares? But it seems to me that the questioner is trying to quantify the level to which final sound output of the speaker system is different from that initiated by the signal from the amp alone, and if and where cabinet modifications could be made to lessen those extrainious sound outputs.
Anyway, I've also asked myself this same question and as a result of help here have just ordered myself a £5 contact microphone 🙂 I will see what happens if I measure the output using a soundwave sweep into a scope. I also wonder if I might use a multimeter with a peak hold function, and replay the sweep multiple times whilst measuring at different places on the cabinet. £5 will not bankrupt me either way.
PS, I also belatedly saw that it's possible to get five for about £18 🙁
you know Andy. That’s a really relevant observation.
i admittedly don’t know.
i will use whatever scientific quantitative results I get and use my ears and form an observation.
i will definitely tell all here how it went.
if you look at another thread of mine it states how I completely failed to stuff a cabinet properly or improve upon it.
no qualms
i am also a musician so my ears are pretty good.
yeah that’s not quantitative but it’s what it’s worth
e.g. last night I put flanges on my woofers because they didn’t have any
i didn’t like the change in sound. So I took the flanges off.
didn’t do any measurements because it was quite clear to me.
it would be cool if I did do some kind of measurements to show what the flange did.
anyway I think you get the idea
i will conduct my experiments and see what the outcome is
and I will definitely post the results. No matter what they may be
cheers
After adjusting for age and other factors that could influence hearing, the research team led by Dr. Wolfgang Ahrens found that, compared to the general population, professional musicians had a 3.51 times higher risk of NIHL (noise induced hearing loss) and were 57% more likely to contract tinnitus.
I am also a (lousy) musician, used to be a very good sound engineer with excellent hearing.
Now, at age 65, I wish my hearing was as good as the general population like in the above graph 😉
If you hear a difference in putting in a "cabinet stretcher" as you depicted in post #1, good for you!
Of course, those cabinet resonances won't be in the hearing range most affected by presbycusis or NHIL, so I won't give up hope you will👍
That said, if you've spent much time in front of those Marshall amps you liked to modify, I'd suggest you will need more of a change than you are looking at in your "tweeter upgrade" thread..
Cheers,
Art
ha this is true.
however I always really took care of my hearing
luckily for me I had an audiogram recently and can still near to 16.5khz on my left ear and 16khz on the right