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Old 15th January 2012, 07:09 PM   #1
trevmar is offline trevmar  United States
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Default Tiny ground-effect omnidirectional biamped system

How small can you make a set of HiFi speakers?
A few months ago I realized that I was going to be traveling a lot over the next few years, and I started to explore how tiny I could design a HiFi system without losing fidelity. My goal was to produce a set of small speakers, with a tiny matching amp, that could travel in a suitcase with me, my laptop, and my FLAC collection. What I developed is the 8" high black speaker you can see in the photo. It uses the magnificent Peerless Tymphany 83093 widerange driver.

However, in all but the smallest rooms, the 2" widerange needed a little more deep bass, so I added a woofer, using the SEAS driver from my Linkwitz Pluto (the white tube) to boost output power below 200Hz. Suddenly I found I had not only a portable system, but a top-notch set of HiFi speakers capable (IMO) of holding their own in any 'average living living room'.

The amplifier modules are described over at the Class-D forum:
Class-D Output Filter Designs, SURE TDA7498 as example

Photo below. You can find the detailed stuff at my website:
Trevor Marshall - Ground Effect Omnidirectional HiFi Loudspeakers
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Last edited by trevmar; 16th January 2012 at 11:58 AM. Reason: clarification
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Old 16th January 2012, 03:12 AM   #2
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looks nice, you could make it even better with such silverconed Peerless, and damp the tubes outer wall with dynamat or something like that
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Last edited by DYNABLASTERTUNERS; 16th January 2012 at 03:15 AM.
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Old 16th January 2012, 03:19 AM   #3
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Neato !
If you could find a wider range for the woofer tube,
(negating the tweeter tube)
It would be even more elegant
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Old 16th January 2012, 12:01 PM   #4
trevmar is offline trevmar  United States
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Quote:
Originally Posted by hitsware View Post
Neato ! If you could find a wider range for the woofer tube, (negating the tweeter tube) It would be even more elegant
It's not really a tweeter'. The crossover is at 200Hz. The tiny speaker covers 200Hz-20KHz. All the woofer tube really does is increase the amount of air which can be pushed around at low frequencies. The smaller speaker tube does have an extended bass (down really low) on its own, it just can't push around a lot of air
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Old 19th January 2012, 06:19 AM   #5
Davey is offline Davey  United States
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Trevor,

Do you normally set those up on the floor, or possibly a large desktop as "computer" speakers?

Nice project.

Cheers,

Dave.
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Old 19th January 2012, 02:41 PM   #6
trevmar is offline trevmar  United States
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Dave, the speakers must be placed on the ground, so that they can use the ground-effect to radiate bass more effectively. They make good computer speakers, as they love complex 'computer-room' environments..
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Old 19th January 2012, 03:31 PM   #7
sreten is offline sreten  United Kingdom
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Hi,

An idea is to make the suitcase the additional subwoofer enclusure for portability.

rgds, sreten.
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Old 19th January 2012, 03:37 PM   #8
trevmar is offline trevmar  United States
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True, but I rejected that because of resonace (most suitcases are more resonant than PVC piping), and because I figured out an (IMO) much better way to produce an omnidirectional sound field
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Old 5th November 2012, 01:51 AM   #9
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Hi Trevor,
very interesting design.
The Peerless FR on the response graph is omni only upto 4Khz. So does the the smaller tube also need to be kept at ground level.

BTW, any reason you preferred to use the Peerless FR instead of the Aurasound NSW2 used in the Pluto
Did you also experiment with the idea that perhaps bipole FRs could also possibly give near omnipolar radiation
Thanks.
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Old 5th November 2012, 03:02 AM   #10
Bare is offline Bare  Canada
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Quote:
Originally Posted by trevmar View Post
How small can you make a set of HiFi speakers?
Erm.. isn't that exactly Why? God gave us Headphones and some pretty damned good ones at that.
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