I really like the coherency, pin-point imaging of my 4" full range speakers. They seem to do a lot of things right and I enjoy listening. Then came the day when I wondered why the DJ's voice wasnt crisply in the center, that's mono after all. So I connected up a pink noise generator and found I'm listening to a null... at my seated position on a sofa, with the speakers setup normally (far field)
Sweep my head right and left about +/- 12 inches and the pink noise sounds like the old phase shifter effect used in that old "sky-pilot" song. I had wondered why the image always seemed left shifted... to the point I thought I must have a bad right ear. I was sitting about 6" to the left of the center-vise position...
This is just ridiculous! I'm certain it has all been worked out, only I cant find anything except other people commenting "Yeah, I dont like it (head-in-a-vise sweet spot) also".
The only thing that seems to take care of it is to position the speakers "nearfield" - yeah, so close it's totally impractical to place them there in the middle of the room - or move the sofa into the middle of the room...
What can be done to make the farfield listening distance work - with an improvement on the existing ultra narrow sweet spot? A round horn? No solution possible to the farfield problem when using this type of speaker? Any advice would be appreciated. Thanks!
Sweep my head right and left about +/- 12 inches and the pink noise sounds like the old phase shifter effect used in that old "sky-pilot" song. I had wondered why the image always seemed left shifted... to the point I thought I must have a bad right ear. I was sitting about 6" to the left of the center-vise position...
This is just ridiculous! I'm certain it has all been worked out, only I cant find anything except other people commenting "Yeah, I dont like it (head-in-a-vise sweet spot) also".
The only thing that seems to take care of it is to position the speakers "nearfield" - yeah, so close it's totally impractical to place them there in the middle of the room - or move the sofa into the middle of the room...
What can be done to make the farfield listening distance work - with an improvement on the existing ultra narrow sweet spot? A round horn? No solution possible to the farfield problem when using this type of speaker? Any advice would be appreciated. Thanks!
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Yes, the FE103en. They came with these Akai "desktop" TLs. I listened to them for a while, thought they sounded great so I thought about my own cabinet for them. I built a pair out of 8" cement tubes, filled with ~25 lbs of sand, suspended within which is a long conical chamber for the back of the speaker. So the FE103 basket is set into an 8" round baffle of 3/4 ply, centered. There's some stuffing in the conical section and the end is open, mainly because I havent put the end caps with the speaker connectors on yet.
These I have set horizontally, about ear height, and I can rotate them about the vertical axis, point them at me like cannons if I wish. Everything is fast, I assume because the speaker now has 25 lb of dead weight to push against. Being an avid multiway for the past 45 years, I didnt even know what a little speaker like this could do sonically, until a couple of months ago.
I'm going to presume that the smaller the speakers, the space comprising the nearfield is projected closer to the source. The larger speakers have a more extended nearfield, more easily engulfing a normal sized (versus desk size) listening space. Maybe I spent $100 to learn these two things.
Well, I have these 4" speakers, I really like 'em, but I want to use them in a normal listening space, where I'm out of the near field. I'm imagining SPL peaks and troughs in 3D, where I'm sitting in a trough of some kind, being outside the nearfield. Listening to pink noise, if I move my head a few inches to the left, some center panned bandwidth gets louder in that ear. Same thing if I do that with the right. These frequencies are suppressed when I'm laser centered effecting whatever's recorded in monaural. It makes a person speaking - who should appear dead center in a crisp image - have no discernible image at all. While at the same time, the stereo instruments sound fantastic stage wise.
I've tried different toe-ins and it still does it wherever I set that, without being absurd. I'm wondering if there's something I can build that would reduce this annoying effect? I.E. Make this little speaker "appear" to be bigger acoustically, so I can sit closer to the nearfield and hear the mono material again. I spose that would be a horn, wouldnt it? Or a larger speaker system. Thanks!
These I have set horizontally, about ear height, and I can rotate them about the vertical axis, point them at me like cannons if I wish. Everything is fast, I assume because the speaker now has 25 lb of dead weight to push against. Being an avid multiway for the past 45 years, I didnt even know what a little speaker like this could do sonically, until a couple of months ago.
I'm going to presume that the smaller the speakers, the space comprising the nearfield is projected closer to the source. The larger speakers have a more extended nearfield, more easily engulfing a normal sized (versus desk size) listening space. Maybe I spent $100 to learn these two things.
Well, I have these 4" speakers, I really like 'em, but I want to use them in a normal listening space, where I'm out of the near field. I'm imagining SPL peaks and troughs in 3D, where I'm sitting in a trough of some kind, being outside the nearfield. Listening to pink noise, if I move my head a few inches to the left, some center panned bandwidth gets louder in that ear. Same thing if I do that with the right. These frequencies are suppressed when I'm laser centered effecting whatever's recorded in monaural. It makes a person speaking - who should appear dead center in a crisp image - have no discernible image at all. While at the same time, the stereo instruments sound fantastic stage wise.
I've tried different toe-ins and it still does it wherever I set that, without being absurd. I'm wondering if there's something I can build that would reduce this annoying effect? I.E. Make this little speaker "appear" to be bigger acoustically, so I can sit closer to the nearfield and hear the mono material again. I spose that would be a horn, wouldnt it? Or a larger speaker system. Thanks!
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Unless pinpoint size transducer it'll start beaming at frequency relative to the size. For larger sweet spot you'll need wider dispersion = smaller transducer. Use 1" or under diameter tweeter for highs, with wave guide, to get wider sweet spot 
Or a constant directivity horn. There are even more tricks like phase plugs, whizzer cones, Karlson aperture / tube, acoustic lenses and some other I don't know of that try to reduce beaming, but these come with their own set of compromises. Always a tradeoff... Anyway, here is a more recent try, try it out! Berstis Lens
edit: round baffle with the driver at center is the worst one can build diffraction wise, might have something to do with your perception. Check out this recent thread
How to tame your diffractions
Edit: attached diffraction simulation if the driver was offset from the center
Or a constant directivity horn. There are even more tricks like phase plugs, whizzer cones, Karlson aperture / tube, acoustic lenses and some other I don't know of that try to reduce beaming, but these come with their own set of compromises. Always a tradeoff... Anyway, here is a more recent try, try it out! Berstis Lensedit: round baffle with the driver at center is the worst one can build diffraction wise, might have something to do with your perception. Check out this recent thread
How to tame your diffractions
Edit: attached diffraction simulation if the driver was offset from the center
Attachments
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Something else to consider is that if the speakers are at a room odd harmonic such as near/at a wall and the sweet spot [Lp] is not at another one [1/5, 1/3, 2/5, etc.], it can cause some unpleasant response anomalies. Regardless, built many speakers using this driver and its Radio Shack rip-offs and always must be toe'd in to cross in front of the sweet spot with the distance a variable found empirically and a very few folks liking them pointing at their ears.
Another thing, with the system in mono and speakers straight ahead, stand exactly in the center between them facing the room and if they don't sound like it's coming from you [dead center mono], you'll need to correct this first or everything else will be off.
GM
Another thing, with the system in mono and speakers straight ahead, stand exactly in the center between them facing the room and if they don't sound like it's coming from you [dead center mono], you'll need to correct this first or everything else will be off.
GM
Directivity of a loudspeaker (single source) depends on it's diameter and frequency. This is modified by membrane profile, surround and baffle. A single unit is always suffering with either highs or lows. Multi-way spekers have other kind of issues or "problems". If you can give your little finger to the devil of evils - crossover network - you will get wider and smoother response and directivity (wider listening area), less harmonic and IMD distortion and higher spl capacity.
FUNDAMENTAL LIMITATIONS OF LOUDSPEAKER DIRECTIVITY
My sggestion for jjasniew is to try modern co-axial hifi speakers eg. from KEF or Elac, or even Tannoy! These share some virtues of full-rangers.
FUNDAMENTAL LIMITATIONS OF LOUDSPEAKER DIRECTIVITY
My sggestion for jjasniew is to try modern co-axial hifi speakers eg. from KEF or Elac, or even Tannoy! These share some virtues of full-rangers.
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tmuikku - Thanks for pointing that out; I was considering offsetting the driver on the 8" round baffle, but was anxious to get the thing together for a listen, so I just cut it centered. I figure I can enlarge that hole diameter and add a second baffle, fitted to the 93mm cutout of the speaker, over the top of the 1st one. That way I can make the second baffle board any shape I want, oval, rectangular, T shape, whatever. What if I simply padded it with 1/2" thick felt, like the old Spica TC50 had around Woof and tweet?
GM, I have yet to conduct the mono experiment you suggest. I'm interested in your cab experience with the FE103 driver, particularly if you found one relatively easy to build that worked well. Some of the designs I see have an internal wall so close to the back of the speaker, which in the nutzo design I've done, I try to do the opposite.
Juhazi, I have a pair of KEF Qs with modified crossovers (just a cap upgrade and sand filled lower chamber to give them some dead weight) and I've always liked the "UniQ" idea of making the tweeter time-aligned with the woofer. Since hearing the little Fostex however, I want to take all my other speakers and put them out on the curb with a FREE sign... So too bad I didnt catch these 20 years ago.
wesayso, Thanks for pointing out that thread - I've got some reading to do there.
I still have some general questions on speakers;
1. When I see pictures of someone with Altec Valencia's or VOTs in their normal sized living room - are they taking advantage of the correspondingly gigantic near-field space? Or are they just showing off?
2. Why are there so many...3" full range speakers? If this for wider dispersion as tmuikku was saying? I cant unwrap my thinking that if 4" speakers are for computer or mixing desktop use, then 3" must be for laptop or iPhone sound systems.
3. What's the technical definition of near field / far field? Is near field something like you're close enough to the speaker that you hear its sound before the room effects have their say? Far field is the speaker's sound, including all the room effects? Or is it something different. Thanks!
GM, I have yet to conduct the mono experiment you suggest. I'm interested in your cab experience with the FE103 driver, particularly if you found one relatively easy to build that worked well. Some of the designs I see have an internal wall so close to the back of the speaker, which in the nutzo design I've done, I try to do the opposite.
Juhazi, I have a pair of KEF Qs with modified crossovers (just a cap upgrade and sand filled lower chamber to give them some dead weight) and I've always liked the "UniQ" idea of making the tweeter time-aligned with the woofer. Since hearing the little Fostex however, I want to take all my other speakers and put them out on the curb with a FREE sign... So too bad I didnt catch these 20 years ago.
wesayso, Thanks for pointing out that thread - I've got some reading to do there.
I still have some general questions on speakers;
1. When I see pictures of someone with Altec Valencia's or VOTs in their normal sized living room - are they taking advantage of the correspondingly gigantic near-field space? Or are they just showing off?
2. Why are there so many...3" full range speakers? If this for wider dispersion as tmuikku was saying? I cant unwrap my thinking that if 4" speakers are for computer or mixing desktop use, then 3" must be for laptop or iPhone sound systems.
3. What's the technical definition of near field / far field? Is near field something like you're close enough to the speaker that you hear its sound before the room effects have their say? Far field is the speaker's sound, including all the room effects? Or is it something different. Thanks!
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