A bit of an unusual request, not strictly audio. I need to generate cymatic effects using a mechanical system (its complicated) for that i need to shake stuff at low frequency. the harder the better.
i know that low frequency "shakers" and actuators exist, but these generally dont produce long linear movements, or if they do, cost a fortune.
for the "experiment" stage at least id like to hack a subwoofer, removing the cone and most of the frame, leaving spider and dust cap and attaching the mechanism to that.
(it will be interesting to see what kind of mechanical attachment can be made to the voice coil that wont break under prolonged shaking with a load attached!)
- i have some dayton subs (in use) which have a heavy aluminium cone/dust cap. Those would probably be ideal since it would be easy to bond something solidly and the dust cap is robust (and presumably well attached) . however they are too spendy to hack apart, for something that may not work.
any suggestions most appreciated. ideally something available in Europe.
i know that low frequency "shakers" and actuators exist, but these generally dont produce long linear movements, or if they do, cost a fortune.
for the "experiment" stage at least id like to hack a subwoofer, removing the cone and most of the frame, leaving spider and dust cap and attaching the mechanism to that.
(it will be interesting to see what kind of mechanical attachment can be made to the voice coil that wont break under prolonged shaking with a load attached!)
- i have some dayton subs (in use) which have a heavy aluminium cone/dust cap. Those would probably be ideal since it would be easy to bond something solidly and the dust cap is robust (and presumably well attached) . however they are too spendy to hack apart, for something that may not work.
any suggestions most appreciated. ideally something available in Europe.
Look for cheap car subwoofers, they mostly have the xmax for long movements and can be found cheap. Those cheap brands are mostly local as the production is generic and rebranded to the sales outlets. I don't know what is availeble in the UK market.
Known brand drivers that can do that will always cost at least a few hundreds, as this is not cheap or easy to build right.
Known brand drivers that can do that will always cost at least a few hundreds, as this is not cheap or easy to build right.
Long throw can mean low efficiency, which wants more power and can thereby reduce robustness. So look for a reasonable voice coil.
I thought about using Linear Actuators, even making some if no suitable ones exist.
I got some trampoline springs to suspend my couch, leaving it free to move.
Not sure if this project will get finished, I see many obstacles to overcome.
I got some trampoline springs to suspend my couch, leaving it free to move.
Not sure if this project will get finished, I see many obstacles to overcome.
those look very chunky (the site blocked me but I've looked on Google) however I'd not define the ones I've seen as "dirt cheap" in fact they cost at least 2-3x what the aluminium cone Dayton's cost, and those have a similar xmax (11mm on a 10 inch driver as opposed to 13mm on the 12 inch skar I saw)
What signal do you intend to drive them with?
If it's a bespoke system, could you look at electric motor and linkage to linear piston, driven by DC input?
If it's a bespoke system, could you look at electric motor and linkage to linear piston, driven by DC input?
id like the system to react to an audio signal, so varying amplitude would be important.. i did consider the "piston and cam" idea.
its currently at the "vague concept" stage, but for option A) i would either be vibrating a dish of gallium with a laser reflected off it to produce cymatic patterns on the ceiling, or the same concept with a transparent dish and water or similar, with the laser refracting through.
This probably does not require a particularly powerful driver.
option B) is the driver would move a linkage (increasing amplitude) before vibrating a long and fairly thick "string" of some kind visibly recreating the waveform. Whether a mechanical linkage is necessary or not is open to experimentation. this string would be of a fluorescent colour and illuminated by UV... the key thing here is to have sufficient maximum amplitude (minimum 30 cm or so on a string/wire several metres long) all of the similar " experiments" ive seen feature an amplitude of maybe 5 cm in the waveform.
its currently at the "vague concept" stage, but for option A) i would either be vibrating a dish of gallium with a laser reflected off it to produce cymatic patterns on the ceiling, or the same concept with a transparent dish and water or similar, with the laser refracting through.
This probably does not require a particularly powerful driver.
option B) is the driver would move a linkage (increasing amplitude) before vibrating a long and fairly thick "string" of some kind visibly recreating the waveform. Whether a mechanical linkage is necessary or not is open to experimentation. this string would be of a fluorescent colour and illuminated by UV... the key thing here is to have sufficient maximum amplitude (minimum 30 cm or so on a string/wire several metres long) all of the similar " experiments" ive seen feature an amplitude of maybe 5 cm in the waveform.
There are many of us out there doing cymatics in water using small speakers. I started out with a 2 inch woofer with a 35mm film can lid glued to the cone.
Peerless by Tymphany TA6F00 or TC6FD00 are great for this purpose. Around $15.00 US from Parts Express, I'm sure you can find vendors in the UK as well.
Water in the plastic film can lid, and illuminated with a cheap LED ring light.
The speaker is used without an enclosure, and no baffle, so you can get lots of cone extension with very little power input.
A little amp of 1 watt is plenty powerful to bounce the water right out of the cup.
And the published frequency range of the speaker is irrelevant, since you aren't making audible sound, just cone motion.
They work very nicely at 1 Hz and up!
Attached is one of the first glyphs I made back in 2007.
Happy experimenting!
Peerless by Tymphany TA6F00 or TC6FD00 are great for this purpose. Around $15.00 US from Parts Express, I'm sure you can find vendors in the UK as well.
Water in the plastic film can lid, and illuminated with a cheap LED ring light.
The speaker is used without an enclosure, and no baffle, so you can get lots of cone extension with very little power input.
A little amp of 1 watt is plenty powerful to bounce the water right out of the cup.
And the published frequency range of the speaker is irrelevant, since you aren't making audible sound, just cone motion.
They work very nicely at 1 Hz and up!
Attached is one of the first glyphs I made back in 2007.
Happy experimenting!
Attachments
Attachments
Nah, you definitely do not need that much grunt, a big cone does not help. We once built an array of speakers from one inch to 12 inches, so you could try them all in turn.
2 inches was the sweet spot. Smaller and you couldn't get enough cone extension to wiggle the water properly. More than that and the rig would just throw the water at the operator!
2 inches was the sweet spot. Smaller and you couldn't get enough cone extension to wiggle the water properly. More than that and the rig would just throw the water at the operator!
Uh, that reminds me this product
https://www.powersoft.com/en/products/transducers/m-force-technologies/
Eliminating most of the cone of a long excursion driver might cut MMS in half or less.
Using this 12" with 34mm Xmax as an example:
64 mm peak to peak excursion could be achieved with no lever.
Cutting 50% of the 330grams mms would leave around 165 grams available for a lever assembly with no more moving weight than it would normally shift.
A lever made from a structural aluminum like 6061 150cm x10cm x3mm would weigh ~122 grams.
The lever weight could be reduced considerably cutting circle or triangular holes and still have plenty of strength to wave a string.
With only a 5/1 lever, 30cm (300mm) peak to peak should be achievable.
Router bearings fastened to the lever arm and voice coil "truss" axle/pushrods could handle subwoofer speed and power long term.
The relatively lightweight M-Force neodymium magnets move past the very heavy (high powered) coils, a good idea when pushing very large heavy cones with a considerable air-load relatively short distances.
I think for this application, a standard moving coil with lever would give a better cost/amplitude ratio.
Art
wow great reply 🙂 yes i imagined that removing the cone would compensate at least partially for the load a lever would represent. youve already gone further than me and done some calculations!
i just need to get my head round the type of "string" i need. the "school lab experiments" ive seen use a horizontal string, that goes over a pulley and hangs down with a weight on the other end. other options include elastic or tensioned steel wire, or even a long strip of spring steel.. wouldnt even need supporting from above! etc..
my end-goal is a vertical representation of the music waveform in light, several metres high. . (glowing string) (i know i'm not going to get a nice audio spectrum with the highs at the top and the lows at the bottom.. but something dynamic and pretty should be achievable.
i need to do lots of experiments with different materials/tensions etc.. i understand that im gonna get much larger excursions at multiples of the resonant frequency of the string.. but im hoping i can get something that gives a decent, large waveform at all (low) frequencies.
if the driver is powerful enough there is no reason it has to be a single string. could be a rod moving linearly with many vertical strings attached. even with different lengths to have different resonant frequencies. lots to play with. just need the actuator to start.
i just need to get my head round the type of "string" i need. the "school lab experiments" ive seen use a horizontal string, that goes over a pulley and hangs down with a weight on the other end. other options include elastic or tensioned steel wire, or even a long strip of spring steel.. wouldnt even need supporting from above! etc..
my end-goal is a vertical representation of the music waveform in light, several metres high. . (glowing string) (i know i'm not going to get a nice audio spectrum with the highs at the top and the lows at the bottom.. but something dynamic and pretty should be achievable.
i need to do lots of experiments with different materials/tensions etc.. i understand that im gonna get much larger excursions at multiples of the resonant frequency of the string.. but im hoping i can get something that gives a decent, large waveform at all (low) frequencies.
if the driver is powerful enough there is no reason it has to be a single string. could be a rod moving linearly with many vertical strings attached. even with different lengths to have different resonant frequencies. lots to play with. just need the actuator to start.
as you all may have noticed this is really 2 projects. (of many actually) i need multiple proposals for my potential client who wants cool stuff and will pay (i hope) if he likes any of the ideas.
I googled harmonic oscillator and was rudely surprised with a suspicious Adam’s Apple 😝