Hello to you all!
I'm considering doing dipole and am concidering how to design the best midrange ( ~ 400 to 2200 in my case ) possible without breaking the bank too much
My first possible choice is to simply do a standard open baffle with M15CH002, nothing fancy here.
The second is to use the 6nd430 which according to distortion measures by zaph should run circles around the M15CH when used as midrange. The 6nd430 however doesn't have that nice open magnet structure and I want as close to identical front and rear dispersion so I've thought about two possible configurations:
The rightmost is the standard open baffle, the leftmost however is what I wish your opinion on: would there be any sound quality compromises in doing this closed box set up compared to the open baffled version?
I will use EQ so I don't care about exact response unless it can't be EQed away, but about what will get me the best sound quality.
And if anyone wonders why, to hide the magnet and unify dispersion is only half of the truth... the other half is that the box would be half as tall
I'm considering doing dipole and am concidering how to design the best midrange ( ~ 400 to 2200 in my case ) possible without breaking the bank too much
My first possible choice is to simply do a standard open baffle with M15CH002, nothing fancy here.
The second is to use the 6nd430 which according to distortion measures by zaph should run circles around the M15CH when used as midrange. The 6nd430 however doesn't have that nice open magnet structure and I want as close to identical front and rear dispersion so I've thought about two possible configurations:
The rightmost is the standard open baffle, the leftmost however is what I wish your opinion on: would there be any sound quality compromises in doing this closed box set up compared to the open baffled version?
I will use EQ so I don't care about exact response unless it can't be EQed away, but about what will get me the best sound quality.
And if anyone wonders why, to hide the magnet and unify dispersion is only half of the truth... the other half is that the box would be half as tall
Attachments
Have you considered also an 'only frame' speaker suspension ?
So you don't have to deal with a baffle at all .
But..only in case you fear of vibrational effects from/to other parts of the system.
I would surely build the boxed dipole ... for my taste it's a little too expensive !
At least , you know what you get when passing from to monopole to bi-pole the dipole listening . I do prefer classic monopole , as no extra EQ is involved thus playing with passive EQ requires less circuitry .
But...I remember my experiment with boxed dipole like the sketch on the left ( way cheaper than m15 ....) produced a nice attack from the drums !
So you don't have to deal with a baffle at all .
But..only in case you fear of vibrational effects from/to other parts of the system.
I would surely build the boxed dipole ... for my taste
it's a little too expensive !At least , you know what you get when passing from to monopole to bi-pole the dipole listening . I do prefer classic monopole , as no extra EQ is involved thus playing with passive EQ requires less circuitry .
But...I remember my experiment with boxed dipole like the sketch on the left ( way cheaper than m15 ....) produced a nice attack from the drums !
The left option will have lower efficiency as it is functionally one driver.
I tried a bit with MTM on open baffle; the diffraction at the back side when mounting the drivers both "front firing" is nothing to worry about. At least I could not hear something "wrong". Sound from the back of a dipole is reflected anyway. You could easily try the right version both ways and check with your ears.
I tried a bit with MTM on open baffle; the diffraction at the back side when mounting the drivers both "front firing" is nothing to worry about. At least I could not hear something "wrong". Sound from the back of a dipole is reflected anyway. You could easily try the right version both ways and check with your ears.
No , if the drivers are wired appropiately
well ,maybe some offset between the centers might be taken into account ...
Sreten, the first option has the drivers out of phase (as well as physically reversed).
Peter, good point about the efficiency but they are connected isobarically. What would you think about using some pvc between them but retaining the box as a baffle?
OllBoll, there are numerous reasons I might be reluctant to cross too high. Anyway, your box is interesting because you could round the sides to reduce diffraction, eg: cut some pvc pipe in half which will fit front to back corners of each side of the box.
Peter, good point about the efficiency but they are connected isobarically. What would you think about using some pvc between them but retaining the box as a baffle?
OllBoll, there are numerous reasons I might be reluctant to cross too high. Anyway, your box is interesting because you could round the sides to reduce diffraction, eg: cut some pvc pipe in half which will fit front to back corners of each side of the box.
The square box in the drawing is of course symbolic, in practice I had planned to do a more rounded box of course
Though a pipe around the drivers might be even better for them internally.
Though the more I think about this the more I lean on not overcomplicating the project and instead using a single M15CH002 as the midrange, I won't have to handle the 6nd430 breakup either which simplifies my crossover
But about spacing, if the box sit ontop if a single OB woofer and then have the correct dime delay then wouldn't the spacing issue become a non-issue? Isn't the box approximable as a larger flat baffle with a single driver but with a time delay on said driver?
Would be fun to try but as I said a single M15CH002 might be the easiest. Wouldn't be that much cheaper though since I live in europe so can get 6nd430 fairly cheap, two is only 56 dollars more than a single M15CH002.
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The driver spacing, but also radiation through the basket have their limits. All part of the compromises you have to make before you build. I do think the larger rounding sounds promising. If I were going to go that way, I'd stuff the box and forget about trying to couple the drivers. I'd take the efficiency loss. Just my opinion.
But in fact one is enough for OB, have a look at my 'Blindstone': http://www.diyaudio.com/forums/multi-way/123512-ultimate-ob-gallery-47.html#post2433427 .
I cross active with DCX2496 at 277 Hz (from AE IB15) and at 2.07 kHz (to Neo3W) for the 6ND430.
/Erling
There's really no sonic advantage to the in box dipole as there's still enclosure artifacts working on the response and internal reflections passing back through the cones. Also as mentioned earlier, you're not going to get full dipole cancellation as the front and rear drivers cancellations will be limited to a narrower pass band. Get rid of the box idea. The 6nd40 shouldn't require too much coaxing to get to 200hz on an open baffle.
I know some guys experimented with the no baffle suspended driver arrangement. I can't imagine a non biased listener wouldn't be opposed to all of the diffraction at the edge of the driver frames.....ouch!
I know some guys experimented with the no baffle suspended driver arrangement. I can't imagine a non biased listener wouldn't be opposed to all of the diffraction at the edge of the driver frames.....ouch!
The purpose of the box wouldn't be to cross lower, but rather to avoid the not as nice rear dispersion of the driver since the magnet is so large. And in doing so it would also make front and rear dispersion perfectly symmetrical.
What I wondered was mostly about those internal reflections, are they merely theoretical or would they in practice cause measurable and hearable distortion?
That is an odd idea don't you think? Unless you are able to audition your speakers front and rear simultaneously
There is a relationship between frequency, bafflewidth and diffraction. Each driver in such an arrangement is Xovered, before diffraction becomes an issue.
In your dipole box there is no massive pressure change like in a closed box, not even a notable pressure at all. This makes a world of a difference - for the better.
Rudolf
That is an odd idea don't you think? Unless you are able to audition your speakers front and rear simultaneously
But isn't that exactly what you do with all the reflections from the room? I also want to build the speakers to be as omnidirectional as possible. I don't want to have a sweet spot for listening or even a direction but instead I just want to spread music in the room so I can enjoy it wherever I am.
My current speakers are omnis which is my reference, the natural sound of reflections is not to be underestimated
Symmetrical front and rear response would simplify crossover also. Then I only have to fiddle with response on one side, I can also ignore that off-axis response of the drivers drop earlier on the rear than the front and can therefore cross higher.
You always fiddle with reflections in a listening room no matter wether the speakers are monopole, dipole, bipole or truly omnidirectional.
When you prefer omnidirectional sound maybe bipole is better for you, but I think dipole speakers have better focus.
Dipole radiation patterns become more cardioid with rising frequency, and the combination of direct and reflected sound with dipoles (assuming proper location) results in a very fine diffuse sound field, which, to my ears at least, gives an illusion approaching sound of a live concert.
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The speakers only become cardioid with rising frequency if you build them that way, I wish to build a pair with the same off-axis response and dipole pattern and on all frequencies
Shame though that smaller tweeters aren't made that have perfect off-axis response all the way up to 15-20 khz
To compensate the current plan is to have a ring of four cone tweeters on each side of the baffle, kinda like my current speaker but doubled to become dipole.- Status
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