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Omnidirectional designs?
Omnidirectional designs?
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Old 18th September 2021, 05:32 AM   #1
talaerts is offline talaerts  Belgium
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Default Omnidirectional designs?

I saw these old cabinets posted in a discussion group on Facebook, apparently originally these used an upward firing 12” fullrange speaker.
Curious if anyone tried to diy similar designs? Do they work well?

IMG_2322.jpg
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Old 18th September 2021, 07:20 AM   #2
Avondalenaim is offline Avondalenaim
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I have seen that design somewhere before but can't remember the page. What reminds me is the fact it looks like a trash can.Looks cool to me.i have a special interest in omni's.

I think that the driver requires a rising top end (quite a few FR's do) and the shape of the diffuser / reflector is very important. That one uses a cone which are said to be better than spheres but the ultimate is an exponential cone like Duevel uses higher up it's range.

In my experience omni's can be excellent if done right but I have never heard one done with a FR. Seems to be the ideal solution imo apart from the beaming top end and successfully redistributing it.

Last edited by Avondalenaim; 18th September 2021 at 07:22 AM.
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Old 18th September 2021, 08:19 AM   #3
cracked case is offline cracked case  England
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If you look for " a cheap omni ( aperiodic/weight on magnet )" on ( currently on page 2 of the full range section ) you'll see my effort in that direction.
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Old 18th September 2021, 08:43 AM   #4
Jazz Man is offline Jazz Man  Wales
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You can experiment with an omni-like effect by placing a shallow boxed speaker on it's back on the floor. Many of the designs similar to the one you posted have little radiation upwards, so not really omni.
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Old 18th September 2021, 11:25 AM   #5
johnmath is offline johnmath  Australia
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I built some 'omnis' in the 1970s based on a design published in Electronics Australia magazine. If I recall correctly it was a bass reflex design of about 60 litres with a Philips 10" paper collinear cone bass driver and a Philips 1" dome tweeter, coaxially mounted. Like the picture in the OP the two drivers faced upwards into an exponential director/diffusor, in this case made from cardboard sides and filled with polyurethane foam, which I had the fun of mixing and watching it foam up to fill and solidify the director. I was able to find a manufacturer who sold me a litre or so of the two components to make the urethan foam, which I took home in a couple of Coke bottles.

The speakers were essentially omnidirectional in the horizontal plane, which made background music very tolerant of listening position. They weren't so good for critical listening, unfortunately, because ultimately omnidirectional loudspeakers sound unnatural in real rooms. There will be reflections of sibilance from all walls, for example; this is quite contrary to real acoustic performances where the sibilance from a trumpet or vocal only goes in one direction, and that's usually towards the listener, not away.

Last edited by johnmath; 18th September 2021 at 11:38 AM.
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Old 20th September 2021, 11:47 AM   #6
cracked case is offline cracked case  England
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IMG_20210920_111258.jpg
With the omnis that I'm currently using I have them as far from the rear wall as I ( at least my ears ) am from the speakers, also the speakers have slightly reduced treble, so I don't have any problems with reflections. Also my listening room is rather cluttered ( a bit of an understatement ). If I did have problems I'd stick so foam absorbers on the speakers ( as illustrated in the above diagram ) to turn them into " half omnis ", or perhaps more precisely half radials - I'd consider them omnidirectional in the bass, hemispherical in the upper midrange, and radial in the highs.
I find my current omnis to be closer to " live " than any other speaker that I've heard, however I think that's down to the construction ( 4.5 KG of iron bolted to the magnet and a light weight double wall upper chamber ) resulting in a very uncoloured sound, with almost all sound coming from the driver cone rather than some from the cone and some from enclosure vibrations.
Perhaps I should have a go at copying the Band and Olufsen acoustic lens, but I prefer the sound to be coming directly from the driver, rather than deflected.
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Old 18th October 2021, 12:30 PM   #7
roj48 is offline roj48  United Kingdom
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Those are mine - Expert Acoustic Columns (formerly EMG). Currently using Kef B200s and Peerless tweeters + x-over at 4KHz. Very nice indeed - but I am very much in the market for general purpose 12" drivers (not sub woofer types).
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Old 20th October 2021, 02:02 AM   #8
Bigun is offline Bigun  Canada
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Omnidirectional designs?
Hey Cracked Case, how do your speakers perform if using only one, playing mono?

I’m a single speaker mono kind of guy and have been contemplating a half-omni / radial as a better option of my big boffle speaker. I’m not an anti-stereo loonie or anything, In my living room I just don’t want to be ‘fighting’ the room with my set up or listening pisition and mono keeps life simple.
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Last edited by Bigun; 20th October 2021 at 02:04 AM.
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Old 20th October 2021, 12:23 PM   #9
roj48 is offline roj48  United Kingdom
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Default Decca Corner Horn

This design from 1949 is excellent for mono (I have 2 - good for stereo too). Driver fires into the corner, producing a nice wide soundstage. Peaky around 80Hz and serious joinery skills required !!

http://p10hifi.net/forum/RWest-Build...orner-Horn.pdf
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Old 20th October 2021, 03:59 PM   #10
Bigun is offline Bigun  Canada
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Omnidirectional designs?
cool approach!

For my mono interests though, I don't want to be restricted to corner placement.
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