Just read this entire thread. Awesome stuff. Very cool overall look. I can imagine its not for everyone, but I absolutely love it.
Have you had any updates in the last few weeks? Listening impression, modifications, etc?
I'm looking to make an attempt at my first OB build and your build intrigues me very much.
Have you had any updates in the last few weeks? Listening impression, modifications, etc?
I'm looking to make an attempt at my first OB build and your build intrigues me very much.
Thanks very much for your comments - yeah as I have said I'm not sold on the looks myself 
But the sound is something else.
Honestly I haven't posted much as at the moment I have just stopped tweaking and am now listening to music.
They are without doubt the most enjoyable things I have heard.
Usually I can't stop tweaking, measuring and 'improving' my builds so this is new to me.
But the sound is something else.
Honestly I haven't posted much as at the moment I have just stopped tweaking and am now listening to music.
They are without doubt the most enjoyable things I have heard.
Usually I can't stop tweaking, measuring and 'improving' my builds so this is new to me.
Frankly, I love the look. There isn't much out there that compares.
The woodworker in me imagines them sitting in a frame of walnut or white oak with a proper white/black paint accents. Definitely reminds me of some uber expensive speakers with new age looks that make you second guess life when you realize how expensive they are.
I have been studying your photos trying to see how you managed to actually suspend the drivers. The woofers at the bottom, are they suspended by eyebolts and rope? The goal is to suspend it by the magnet? And it looks like you just used some threaded spacers to attach the woofers together.
Did you build a mounting ring in the rear of mid woofer, and used eyebolts on the rear with string? How did you manage to angle the woofer up slightly?
The simplicity of the design makes it very attractive to me
The woodworker in me imagines them sitting in a frame of walnut or white oak with a proper white/black paint accents. Definitely reminds me of some uber expensive speakers with new age looks that make you second guess life when you realize how expensive they are.
I have been studying your photos trying to see how you managed to actually suspend the drivers. The woofers at the bottom, are they suspended by eyebolts and rope? The goal is to suspend it by the magnet? And it looks like you just used some threaded spacers to attach the woofers together.
Did you build a mounting ring in the rear of mid woofer, and used eyebolts on the rear with string? How did you manage to angle the woofer up slightly?
The simplicity of the design makes it very attractive to me
You are correct on nearly everything!
Wooden ring on back of the woofer so I could choose my mounting points. Eyelets and black paracord to suspend.
The woofer naturally wants to hang at an angle due to the centre of gravity. So paracord and more eyelets to actually pull it a little more vertical were used.
The subs are as you say. Chosen hanging point is the balance point - base of the magnets as they are so heavy!
I was thinking about going wooden or painted. And I may well change the cosmetics. This was such a quick and prototype build that I literally just chose black to minimise the appearance of size (they ain't small!).
But at the moment I just can't stop listening to them!! So cosmetics will wait!
Wooden ring on back of the woofer so I could choose my mounting points. Eyelets and black paracord to suspend.
The woofer naturally wants to hang at an angle due to the centre of gravity. So paracord and more eyelets to actually pull it a little more vertical were used.
The subs are as you say. Chosen hanging point is the balance point - base of the magnets as they are so heavy!
I was thinking about going wooden or painted. And I may well change the cosmetics. This was such a quick and prototype build that I literally just chose black to minimise the appearance of size (they ain't small!).
But at the moment I just can't stop listening to them!! So cosmetics will wait!
It's possible to hang drivers by more than two points and still have them swing freely. The amplitude of the swinging is very low (e.g. 1mm or less) and so hanging a driver is more to decouple its vibrational motion from the rest of the structure than anything.
If a driver is relatively lightweight, e.g. has a neo motor, then you can still use the two point hanging approach. When the magnet is ferrite and large, as you correctly mentioned the balance point moves back to about the top plate area, and the weight often becomes substantial. In this case, hanging by two points on the mounting flange (e.g. two of the mounting holes) and another point at the back of the magnet can work better. The rear point will carry most of the weight.
I just bought a roll of black vinyl coated heavy gauge welded wire fencing for this purpose. The wire will essentially be transparent to audio but is stiff enough to be used for mechanical support (e.g. the "frame"). As long as the wire is in a convex shape, fabric can be stretched over it and it will stay tight. This means that the wire can also serve as a grille, to hide all of the unconventional stuff going on inside.
I have a buddy who is a master with fiberglass and carbon fiber.
I'm sure he would come up with something interesting, something a bit more organic than pipes and fittings.
But, as much as the contraption looks like a Dalek with it's covers off, I'm strangely ok with what you did, BM, and I think you can keep them like that until the day you finally stop listening and get off the couch.
I'm sure he would come up with something interesting, something a bit more organic than pipes and fittings.
But, as much as the contraption looks like a Dalek with it's covers off, I'm strangely ok with what you did, BM, and I think you can keep them like that until the day you finally stop listening and get off the couch.
I read this a couple times trying to envision in my head what you had it mind with the vinyl coated wire acting as a frame and I must admit, I'm drawing a blank.
My catch on Charlie's system is, that first you cut a eg. 5 ft piece of the fence web, then roll it without connecting the ends, then put a cloth sack around it as a hood. The tension of the web roll keeps the system cylindrical. Perhaps that could be made to work in cardioid shape as well. A bonus is that WAF can be involved in the process!
Synergy horns do that, up to 3-way (tweeter being single), but like bushmeister said, wavelength is the key and midrange dipole clamshell is not possible any more. Physical front-back symmetry will be a problem above 2-3kHz even with a single cone/coil dynamic driver
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I'm not really sure what all the excitement is about the dual "clamshell" woofer arrangement (see pics in post #9). This arrangement does not do any harm per se, but does not seem to achieve much of anything compared to a single nude driver.
The arrangement is similar to a isobarik (two drivers, used face-to-face) closed box subwoofer, and much of the purported advantages of that arrangement (e.g. lower distortion, etc.) have been debunked except for the reduction in the required box size, and that is a moot point in a dipole system. About the only change I can think of is that the acoustic center on both the front and rear sides is moved outwards by a few inches, away from the vertical mid-plane of the rest of the loudspeaker. But at crossover frequencies of a few hundred Hertz and below, this will not be significant in terms of phase or delay.
In terms of acoustical performance, bass, max SPL, etc I would not expect any difference compared to a single driver of the same type. The main difference is that it is twice as expensive because the driver count is doubled.
@bushmeister - can you comment on why you chose that arrangement and what you think are the pros and cons now that you have measured/listened? I apologize if I missed that in the thread up until now.
The arrangement is similar to a isobarik (two drivers, used face-to-face) closed box subwoofer, and much of the purported advantages of that arrangement (e.g. lower distortion, etc.) have been debunked except for the reduction in the required box size, and that is a moot point in a dipole system. About the only change I can think of is that the acoustic center on both the front and rear sides is moved outwards by a few inches, away from the vertical mid-plane of the rest of the loudspeaker. But at crossover frequencies of a few hundred Hertz and below, this will not be significant in terms of phase or delay.
In terms of acoustical performance, bass, max SPL, etc I would not expect any difference compared to a single driver of the same type. The main difference is that it is twice as expensive because the driver count is doubled.
@bushmeister - can you comment on why you chose that arrangement and what you think are the pros and cons now that you have measured/listened? I apologize if I missed that in the thread up until now.
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Hi Charlie,
Please see post 40.
To my surprise there was a 6dB difference on disconnecting one sub-woofer.
Each sub has it's own amp and so this was not an impedance error.
So appears to be 3dB from summing and 3dB from the second amp (and therefore twice the power).
To me it is just a space saving device - rather than having them side by side etc.
Hmmm, that doesn't sound right.
Since you are powering each driver with a separate channel, I would expect +3 dB from your arrangement - this is simply because you are applying twice the power. But there is NOT a doubling of radiating surface compared to a single driver. A single driver has the front and rear surfaces of the cone that radiate acoustic energy, and your dual-driver arrangement has two rear surfaces.
So I am not sure how you measured a 6dB difference when you removed one driver (you did remove one driver for the one driver measurement, right?). If you didn't remove one driver when remeasuring, that is probably the reason for the difference right there.
Since you are powering each driver with a separate channel, I would expect +3 dB from your arrangement - this is simply because you are applying twice the power. But there is NOT a doubling of radiating surface compared to a single driver. A single driver has the front and rear surfaces of the cone that radiate acoustic energy, and your dual-driver arrangement has two rear surfaces.
So I am not sure how you measured a 6dB difference when you removed one driver (you did remove one driver for the one driver measurement, right?). If you didn't remove one driver when remeasuring, that is probably the reason for the difference right there.
Ahh - I bet this is it Charlie! I didn't remove the driver - so I bet it is just because of the driver sitting there!
Thanks for that - I was surprised by the results too - so I bet this is it!
Does this mean you feel linkwitz is wrong with his mathematical modelling?:
Electro-acoustic models
Thanks for that - I was surprised by the results too - so I bet this is it!
Does this mean you feel linkwitz is wrong with his mathematical modelling?:
Electro-acoustic models
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