Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

ISO 30Hz Square wave reproduction.
ISO 30Hz Square wave reproduction.
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th February 2019, 02:24 PM   #1
sdhillon70 is offline sdhillon70
diyAudio Member
 
Join Date: Feb 2019
Default ISO 30Hz Square wave reproduction.

Hey everyone. I'm involved in a project where I need a 30Hz Square wave reproduced above 90db If using a speaker, I can't have any box or enclosure behind the speaker and I need it as small as possible. Anyone know where to start looking?

Thanks.

This is NOT for music so sound quality doesn't matter as long as the Hz and db requirements are met.
  Reply With Quote
Old 9th February 2019, 05:02 PM   #2
weltersys is offline weltersys  United States
diyAudio Member
 
weltersys's Avatar
 
Join Date: Jan 2008
Location: Florida
To accurately reproduce a 30 Hz square wave would require a driver with no mass, so start looking for nothing ;^).

Previous discussions here:
Can't Reproduce a Square Wave.

If sound quality, that is, accurate reproduction, does not matter, there are many sub woofer designs capable of 30 Hz 90 dB at one meter, you will have to be more specific in what your definition of "small" is, and what you mean by "I can't have any box or enclosure behind the speaker".
  Reply With Quote
Old 9th February 2019, 05:11 PM   #3
rayma is online now rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by sdhillon70 View Post
I need a 30Hz Square wave reproduced above 90db If using a speaker, I can't have
any box or enclosure behind the speaker and I need it as small as possible. .
There's no chance of a 30Hz square wave, you'd need flat response down to around 5Hz.
Maybe a 30Hz sine wave at high distortion. What is this for?

Last edited by rayma; 9th February 2019 at 05:13 PM.
  Reply With Quote
Old 9th February 2019, 05:20 PM   #4
sdhillon70 is offline sdhillon70
diyAudio Member
 
Join Date: Feb 2019
Default 30Hz Square

Currently we use a Function Generator sending a 30Hz Sq. Wave to a 1000w Amp then to a 10in Sub. The sub is not in an enclosure but does have a waveguide, (Nothing Behind it) and we want to find a speaker/driver (are these 2 terms interchangeable?) that can produce the same result but is smaller than 8in if possible. Not being big acoustic people we are not sure how small we can go to reproduce the wave. Life of the emitter is not important as long as we can get a few hours out of it. 1Kw is our maximum power we can send to the speaker. The application can be seen at forcesv.com, as well as visual examples of our current setup.
  Reply With Quote
Old 9th February 2019, 05:21 PM   #5
bentoronto is offline bentoronto  Canada
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
ISO 30Hz Square wave reproduction.
Quote:
Originally Posted by sdhillon70 View Post
This is NOT for music so sound quality doesn't matter as long as the Hz and db requirements are met.
Is it for human hearing or for some mechanical purpose? Airborne or mechanical? Clean?

What are you doing?

B.
__________________
HiFi aspirations since 1957. Currently working on motional feedback again... the final frontier in audio (also, see recent post with data on a 17-foot labyrinth sub)
  Reply With Quote
Old 9th February 2019, 05:22 PM   #6
sdhillon70 is offline sdhillon70
diyAudio Member
 
Join Date: Feb 2019
Fire Suppression
  Reply With Quote
Old 9th February 2019, 05:27 PM   #7
SubSoniks is offline SubSoniks  Wales
diyAudio Member
 
Join Date: Nov 2005
Location: Wales
I wouldn't have thought it is impossible to get something resembling a square wave 30Hz and up certainly not straight forward, with FIR filters the phase can be flattened out. The hard part would be getting it to work over usable distance and dispersion angle.
  Reply With Quote
Old 9th February 2019, 06:47 PM   #8
weltersys is offline weltersys  United States
diyAudio Member
 
weltersys's Avatar
 
Join Date: Jan 2008
Location: Florida
Quote:
Originally Posted by sdhillon70 View Post
1)The sub is not in an enclosure but does have a waveguide, (Nothing Behind it) and we want to find a speaker/driver (are these 2 terms interchangeable?) that can produce the same result but is smaller than 8in if possible.
2)Not being big acoustic people we are not sure how small we can go to reproduce the wave.
3)Life of the emitter is not important as long as we can get a few hours out of it. 1Kw is our maximum power we can send to the speaker. The application can be seen at forcesv.com, as well as visual examples of our current setup.
1)Your "waveguide" is rather more a vortex cannon. Speaker/driver/transducer are generally interchangeable terms. Your vortex generator relies on large and rapid air displacement. Reducing driver size (Sd) requires an increased linear travel to achieve the same displacement, which is measured in Xmax, one way travel. The drivers depicted on your website do not have particularly large Xmax, and use ceramic magnets- neodymium magnet structures would greatly cut the weight to strength ratio, but increase cost.
2)Unlike a loudspeaker, which is designed to reproduce a wide range of frequencies, your vortex generator appears to be producing a pulsed toroid of air. The pulse frequency may be 30 Hz, but the acoustical output at that frequency is not really applicable, the 30 Hz acoustical output is omnidirectional from the "waveguide" (cannon). The rotating taurus of air emmited is what is doing the "work" of maintaining directionality at a distance usable for "blowing out" fire.
To reduce device size, and increase stroke, a solenoid could directly drive a piston in the cylinder. A Geneva drive using rotary motors could also be used to drive a piston in a more "square wave" fashion.
3)1000 watts is going to limit your device to "toy" status, to be of useful fire-fighting use will require much more power to drive much larger air pulses further distances. Lightweight motors with 5-10 peak horsepower (4-10kW) are far less costly than pursuing standard acoustical transducers to achieve your desired effect- a directional pulsed air train.

I'd suggest filling your device with smoke from a fog machine, video tape the torroidal output, and view the results in slow motion to see what is actually making your device work ;^).

Cheers,
Art
Attached Images
File Type: png Vortex at 8 meters.png (437.5 KB, 205 views)

Last edited by weltersys; 9th February 2019 at 07:11 PM.
  Reply With Quote
Old 9th February 2019, 06:59 PM   #9
cbdb is offline cbdb  Canada
diyAudio Member
 
Join Date: Oct 2008
Location: Vancouver
So its impulses not square waves? Like putting out oil well fires with dynamite. The piston idea sounds right, but with a mechanism that changes the rotary motion of an electric motor into impulses.

Last edited by cbdb; 9th February 2019 at 07:05 PM.
  Reply With Quote
Old 9th February 2019, 07:33 PM   #10
SubSoniks is offline SubSoniks  Wales
diyAudio Member
 
Join Date: Nov 2005
Location: Wales
Need to start checking if anybody has replied before hitting the post button, ho hum. If pulses are what your after then possibly a 4th order bandpass tuned tube may work, tune for a very high gain at 30Hz and size the port so as to produce high velocity pulses, something like the motor system and dome from a Precision devices 24"?
  Reply With Quote

Reply


ISO 30Hz Square wave reproduction.Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Linn Lingo vs. Dr. Fuß or Square-Wave vs. Sine Wave Oscillator for Motor Control tiefbassuebertr Analogue Source 66 10th February 2019 09:02 PM
Listening Question: Would a high frequency square wave sound the same as a sine wave? jlny Everything Else 21 14th September 2018 05:46 PM
Sine wave - Square & Triangle wave generator using Transistors / OP-Amps lineup Solid State 20 9th October 2006 01:15 AM


New To Site? Need Help?

All times are GMT. The time now is 10:33 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki