Anyone familiar with aura bass shakers?

[jneutron]

I am using 4 of them on a plate to perform sweep vibration tests for a superconducting magnet. I'll shake the thing, the physicists will measure cryostat and magnet response.

My question: the units are rated 25 watts apiece, and are spec'd from 20 hz to 100 hz.

Anyone have experience with these things? When I test the array by vibrating a 7 ton granite block, I notice that at the shakers' resonance freq, about 45 hz, we can hear harmonics. I assume that I'm hitting and exceeding Xmax for the devices, and that non linearity is giving the harmonics.

Is the power rating based on xmax at resonance? or is it a dissipation thing?

I've wired them in series, for 16 ohm total..that way, the physicist guys can't easily pop them with my amp..a qsc rmx 1450..

Any info would be welcomed..thanks.

Cheers, John

[jneutron]

Pic of the magnet setup. The shaker set is on the magnet stand, the cryostat is the beige vacuum vessel, and the magnet is that thing inside all the insulation.

Cheers, John

[markp]

They make a 50 watt version too. Try it if you are exceding the limits of the one you have.

[JonPike]

You might try calling Parts Express and see if anyone knows the deeper details.. They bought 'em all out as Aura stopped making them, as I understand.

I think there were 3-4 models even larger than these.. though I don't know if PE has any of them. They do have the next one up.

A suggestion... you could be to attach them in a different axis.. or up on the tube.. you might get more vibration per watt if they had an "easier" angle of effect on your device under test..

[markp]

I think its a dissipation thing. The heavier units have heatsink fins on them.

[JonPike]

Hmmm... check if there's still info on Aura's website. I seem to recall the bigger ones (maybe not the 50W one) being physically much larger as well as having more "lb force", or however they rated them, per watt output.

[zuki]

i know only the lower power to be capable of 5 hz.

the higher power ones are not as full range

if that helps any

[navin]

how heavy is the load you are shaking. what is the freq. range and max amplitude you desire. a heavy load will damp much of the vibration. what is application. do you need to shake at a particular freq. or freq range.

the aura machie is more apt for supplementing low freq audio signals. i have used them for that purpose with limited success.

for your application i would suggest something more industrial.

if you are in the US try www.eriez.com (http://www.eriez.com/pages/catalog/c...spx?ItemID=324) or http://www.clevelandvibrator.com/vms.htm

if you are looking for something with a variable freq. range there are many cos. making such electromagnetic vibrators out there. like http://www.vibra-schultheis.com/eng/eng_an_03.asp

u can also get a unbalance motor such as one in the link below and use a freq. controller.
http://www.emagindia.com/unbalvi.htm or a simpler less refined but more rugged device http://www.emagindia.com/vibrator.htm

DISCALIMER: I WORK FOR ELEKTROMAG (emagindia.com) however i dont feel it appropriate to push our prodcuts on a forums such as this. i just used the last 2 links as a reference guide. BTW 20 odd years ago i wrote a small basic primer doc on vibration it can be referenced at http://www.emagindia.com/appli.htm

[cowanrg]

there is also something called a buttshaker. they are quite a bit more powerful and quite a bit more expensive. do a search on the web, you will find what you need.

[jneutron]

I forgot to include some app info.

The end result of all this will be a "final focus" quadrupole superconducting magnet, to be used for beam focussing for the next generation linear collider, a 30 or so mile long machine.

This quad is actually a lens to bring the beam vertical size down to 3 microns. Since two beams are aimed at each other, if they are misaligned by 3 microns, which is what will happen if one "lens" moves up 3 microns, the beams will pass by each other, with no collisions..which is the whole purpose of the shootin match..

Earth vibration levels, depending on the location, can exceed that number by orders of magnitude. Also, liquid helium going through the pipes to cool the magnet can also vibrate it at those levels.

I used the Aura's as a quick and dirty method to allow the physicists the ability to see a known frequency on their geophones. I also chose them, as it will be possible to use them in negative feedback mode, to actively reduce vibration..we are not very far along the learning curve there..

The final app will be at 4.5 Kelvin, and several tesla (the focus magnet will be within a 2 or so tesla detector field, so the aura's are definitely not applicable for the final machine..the iron in them will saturate, and they will distort the detector solenoid field uniformity. The final app will probably use piezo's with some reaction masses, capable of all three axis'.

Right now, I'm vibrating a seven ton granite table, and the magnet in the pic, which is I think about 5000 lbs..

Cheers, John