I didn’t consider sound Coming from the rear as an issue in as much as sound would come from the rear of any ob speaker.
Technicality in this area is certainly not a strong point of mine.
Are you saying the performance would be worse if the driver was mounted at the focal point facing out from the convex side?
Technicality in this area is certainly not a strong point of mine.
Are you saying the performance would be worse if the driver was mounted at the focal point facing out from the convex side?
This is the first question to ask with OB speakers. They are used by the technical types because they can produce dipole radiation. They are sometimes tried by people who haven't met a box speaker they like the sound of.
In the end, a speaker without a back gives spaciousness as it radiates around the room. Ask yourself if you'd like the idea of an omnidirectional speaker.
My own 2 cents yes baffle shape matters but driver matters as much too, somehow different drivers of the same
size will sound different on the same baffle some better some worse so if your already am set on 1 particular driver,
than it pays to experiment more with baffle shape, width etc to get the best out of it. Needless to say room acoustics
is paramount for good OB performance.
size will sound different on the same baffle some better some worse so if your already am set on 1 particular driver,
than it pays to experiment more with baffle shape, width etc to get the best out of it. Needless to say room acoustics
is paramount for good OB performance.
Thanks for the explanation AllenB.
In my case it will be the trial and hopefully not much error approach. I realise ob’s are very polarising in this community.
Retirement gives me the luxury of exercising my arthritic hands and who knows the end result may be appealing both aesthetically and sonically.
Incidentally I am very happy with my A/B power amp and Gale 401’s at the moment, but in the not too distant future I will be downsizing to a smaller more efficient setup with class d powered stand mounts.
The ob’s if reasonable will be for the garage.
In my case it will be the trial and hopefully not much error approach. I realise ob’s are very polarising in this community.
Retirement gives me the luxury of exercising my arthritic hands and who knows the end result may be appealing both aesthetically and sonically.
Incidentally I am very happy with my A/B power amp and Gale 401’s at the moment, but in the not too distant future I will be downsizing to a smaller more efficient setup with class d powered stand mounts.
The ob’s if reasonable will be for the garage.
Yes, ob shape matters. Offcoure, because the shape affects cancelation. Worst shape is circular ob with speaker positioned in the middle. Center of the speaker has equal distance to the edge of the baffle, resulting in big dips in fr response, since cancelation is equeal all over.
Ob has figure eight pattern, not omnidirectional, like incorrectly stated above.
Side cancellation of figure eight pattern is one of the main benefits. First arriving signal is cleaner, with less side wall reflections, since dipole does not throw sound sideways.
Signal going back is no problem, since it has to bounce many times till it reaches the listener. It never interferres with first arriving signal. Floor and side wall reflection arriving too close to main sinal, milliseconds, are detrimental. Back signal arrives tens of milliseconds later is not detrimental, recognized by brain as separate, can add spaciousness.
Thats why people like quads, magnapans, and other electrostat&planar speakers.
Ob has figure eight pattern, not omnidirectional, like incorrectly stated above.
Side cancellation of figure eight pattern is one of the main benefits. First arriving signal is cleaner, with less side wall reflections, since dipole does not throw sound sideways.
Signal going back is no problem, since it has to bounce many times till it reaches the listener. It never interferres with first arriving signal. Floor and side wall reflection arriving too close to main sinal, milliseconds, are detrimental. Back signal arrives tens of milliseconds later is not detrimental, recognized by brain as separate, can add spaciousness.
Thats why people like quads, magnapans, and other electrostat&planar speakers.
Thanks adason, very much appreciate the info. Looks like it may be better offsetting the driver. I recall seeing in another thread a “formula “ for an ideal placement on the baffle (looks approximately 1/3rd from top edge) I am determined to use the sat dish for interest sake and will only get one chance with the position.
Being a circular baffle with the driver offset I wonder if rotating/tilting the baffle would change the sound characteristics.
Being a circular baffle with the driver offset I wonder if rotating/tilting the baffle would change the sound characteristics.
Hi, pardon, I'll add some details to your post since context is everything, and not all readers have that in mind. Coffee break philosophy stuff 
So, good advice only if you run the transducer beyond diffraction in which case, well, irregular shape would help to distribute the edge distance, but it is not optimal to run dipole driver so high in the first place. Better would be to limit the bandwidth below diffraction, in which case it doesn't matter too much anymore. As disclaimer, I haven't built dipole system, but see this stuff from simulations and from acoustics perspective, and the same "problem" is with any speakers. Baffle size and shape matters in system context, it's part of how the whole system is designed, relative to how many ways etc.
First floor reflection is in such low angle there isn't too much attenuation towards it, perhaps -6dB if it's 3m listening distance and transducer at ear height about 1m from floor. Less, if the transducer is closer to floor. One could tilt the system back to increase attenuation towards floor, but it would increase sound toward ceiling so just another trade-off. Line-array would be best if early vertical reflections need to be reduced.
Ten milliseconds is 3m (10ft) of distance in addition to what the listening distance is, which might be achievable on some small rooms for some 2nd or 3rd order early reflections, which are not the problem usually, but the earliest ones. Tens of milliseconds means big room, or purpose built reflection free zone studio control room kind of stuff. Speakers and listener several meters away from any boundary.
What's the problem, it's the "dipole null", alias edge diffraction related interference, which depends on size of the baffle basically. The bigger the baffle (regardless of transducer size) the lower in frequency this happens, it'll make the dip some where when wavelength is similar in size to the baffle. Usable bandwidth of a dipole transducer is below this regardless, so all big baffle does is it shifts the usable bandwidth of the transducer down, reducing system SPL capability ( limited by bandwidth and xmax of the driver ). So, baffle can be basically any size and shape, as long as good design practice is used, use the clean bandwidth of the transducer. Basically, best would be naked transducer without any baffle at all because it shifts edge diffraction issue as high in frequency as possible, shifting the usable bandwidth up which results most SPL capability. One can abstract naked driver to be circular baffle, transducer in the center.
So, good advice only if you run the transducer beyond diffraction in which case, well, irregular shape would help to distribute the edge distance, but it is not optimal to run dipole driver so high in the first place. Better would be to limit the bandwidth below diffraction, in which case it doesn't matter too much anymore. As disclaimer, I haven't built dipole system, but see this stuff from simulations and from acoustics perspective, and the same "problem" is with any speakers. Baffle size and shape matters in system context, it's part of how the whole system is designed, relative to how many ways etc.
This is true when the system is positioned carefully, it's not automatic just having a dipole. Backwave, first specular reflection from front and close side wall would have similar ~6ms delay (positioned roughly >1m from these walls), like with any speaker positioned at the same location. Difference is the reflections might be attenuated if toe-in is optimized, side nulls pointed toward the earliest specular reflections of front and side wall. Due to having same delay these would interfere similarly as any other speaker, except being attenuated the interference is far reduced in amplitude as long as nulls are utilized to attenuate them.
First floor reflection is in such low angle there isn't too much attenuation towards it, perhaps -6dB if it's 3m listening distance and transducer at ear height about 1m from floor. Less, if the transducer is closer to floor. One could tilt the system back to increase attenuation towards floor, but it would increase sound toward ceiling so just another trade-off. Line-array would be best if early vertical reflections need to be reduced.
Ten milliseconds is 3m (10ft) of distance in addition to what the listening distance is, which might be achievable on some small rooms for some 2nd or 3rd order early reflections, which are not the problem usually, but the earliest ones. Tens of milliseconds means big room, or purpose built reflection free zone studio control room kind of stuff. Speakers and listener several meters away from any boundary.
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https://www.diyaudio.com/community/threads/lii-audio-f12.385377/
https://www.linkwitzlab.com/H-U woofer2.htm
Open baffle means you loose spl on low frequencies - a lot. Seems like LiiAudio 12" doesn't have huge Xmax that would be needed for equalization...
Other than planar baffle means that frequency response and dispersion will be different on front- and backside. With AKABAK one could make a simulation, but I wouldn't bother.
If you have a 12" driver or can purchase such, easiest is just to make it and give a go. My guess is that it will sound awful.
https://www.linkwitzlab.com/H-U woofer2.htm
Open baffle means you loose spl on low frequencies - a lot. Seems like LiiAudio 12" doesn't have huge Xmax that would be needed for equalization...
Other than planar baffle means that frequency response and dispersion will be different on front- and backside. With AKABAK one could make a simulation, but I wouldn't bother.
If you have a 12" driver or can purchase such, easiest is just to make it and give a go. My guess is that it will sound awful.
Perhaps by luck! and what is right depends on positioning for example. It might be family living room with certain positioning, which then must be taken into account with the design, and so on.
Everything doesn't have to be perfect in order to be good and enjoyable, first speakers can likely deliver just fine! But, if you want to take next step, then more and more things need to be considered and taken into account, there is no single magic bullet that would fix everything, sound is combination of all things simultaneously. Because human and the environment is in the evaluation loop as well, it would likely take at least two sets of speakers to reach some kind of an ideal: first set for initial prototype to learn listening skill and craft with, while the second build likely fixes most obvious issues (one is able to detect). And here is the trap of context, advice from other people in other room and constraints, might be good for you in your context, or exactly the worst advice, which you don't know until enough understanding and listening skill, awareness that context matters, how stuff relates into your context.
I would think it is as likely that one learns more things with the second prototype, which likely makes third set better than the previous two, and so on anyway, making prototypes, listening, having fun, reasoning, studying, everything would develop things further which I've reduced to generalized form: the playback system is as good as your listening skill
and what is right depends on positioning for example. It might be family living room with certain positioning, which then must be taken into account with the design, and so on. Everything doesn't have to be perfect in order to be good and enjoyable, first speakers can likely deliver just fine! But, if you want to take next step, then more and more things need to be considered and taken into account, there is no single magic bullet that would fix everything, sound is combination of all things simultaneously. Because human and the environment is in the evaluation loop as well, it would likely take at least two sets of speakers to reach some kind of an ideal: first set for initial prototype to learn listening skill and craft with, while the second build likely fixes most obvious issues (one is able to detect). And here is the trap of context, advice from other people in other room and constraints, might be good for you in your context, or exactly the worst advice, which you don't know until enough understanding and listening skill, awareness that context matters, how stuff relates into your context.
I would think it is as likely that one learns more things with the second prototype, which likely makes third set better than the previous two, and so on
anyway, making prototypes, listening, having fun, reasoning, studying, everything would develop things further which I've reduced to generalized form: the playback system is as good as your listening skill
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I have a friend who is a retired Army artillery officer. His hearing is pretty bad. So what we did was design a set of loudspeakers with a 6db rise in output from 800hz as the frequency goes up. Of course they sound forward and bright to most people but they are great for him.
Hi
I think it matters, I am listening to this, with cheap midrange woofers and a Neo 8S, the low part is handeld by 2 disubs and I am impressed....soundstage is really better than the square ob I had before.
Cheers, Tom.
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I love the philosophy. Those speakers would not sound normal except to people with hearing loss in the upper registers. This is different than the bass maniacs who love a lot of 50hz boom. That isn’t normal, it’s a preference. This man couldn’t hear normal sounding music without an abnormal set of speakers. To him normal was indistinct and dull. He needs the music presented to him with enhanced upper mids and highs, otherwise it sounds abnormal to him.