I am trying to decide between OB and Ripole sub bass for a high SPL 4 way OB.
Crossover will be either around 80hz to two 15" woofers or a little higher, 120-140 to a single 15" woofer.
I am looking at 18" drivers and the main problem with ripoles is cavity resonances at ¼ wavelength. For 18" that would be around 180hz.
What if I mounted the 18" drivers on baffles with 12" holes. That would reduce the chamber depth by 3". The chamber itself could flare out from 12" at 9" depth to 18" at the mouth creating a short horn of sorts.
1. Would it work?
2. Has this been done?
3. Can it be modeled?
This would be the ultimate OB bass foundation.... 4x18" in Ripole configuration up to 80Hz and 2x15" in concrete baffles up to 400hz.
For a stereo pair that would be 8x18" which would equal 2 ½ x the Fostex 31.5" woofer.
Crossover will be either around 80hz to two 15" woofers or a little higher, 120-140 to a single 15" woofer.
I am looking at 18" drivers and the main problem with ripoles is cavity resonances at ¼ wavelength. For 18" that would be around 180hz.
What if I mounted the 18" drivers on baffles with 12" holes. That would reduce the chamber depth by 3". The chamber itself could flare out from 12" at 9" depth to 18" at the mouth creating a short horn of sorts.
1. Would it work?
2. Has this been done?
3. Can it be modeled?
This would be the ultimate OB bass foundation.... 4x18" in Ripole configuration up to 80Hz and 2x15" in concrete baffles up to 400hz.
For a stereo pair that would be 8x18" which would equal 2 ½ x the Fostex 31.5" woofer.
......but with 6x the xmax of the Fostex the 8x18" have 15x the displacement of a single Fostex 31.5. this should keep excursion and distortion low.
Here is a sketch in case my earlier description is confusing.
The reduced depth of the chamber should push the resonance from 180 to 225 and the horn shape should also reduce/spread the resonance peak I guess.
The reduced depth of the chamber should push the resonance from 180 to 225 and the horn shape should also reduce/spread the resonance peak I guess.
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If you cross with a 4th order filter at 80Hz, then you don't need to care about a lambda/4 resonance at 180Hz. Your resonance will be < -30dB down. Make a ripole then, hands down, if
... if you like to clutter your listening environment with huge boxes. And if you don't bother the hilariously low efficiency of an open (dipole) sub. And if you endorse to fill your room with inctractable, nasty resonances (unless you like them). You will neither really impress girls with huge speakers, then. Only a bunch of macho-minded, hard-core barefoot boxters such in the picture will eventually take a brief notice and maybe even post a "like".
Honestly, I would search for other and better options to listen to very low bass. Your may e.g. make some smaller, behind-your-head woofers,and then delay them by DSP (CamillaDSP anyone?), with a much, much better overall result.
Sub bass? Yes please, but better go smallish and near-field!
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Interesting idea. Probably (?) also get a throat chamber resonance as well, but if filtered as above suggestion...
For bass bigger is really better. Dipole bass is inefficient but sounds super clean and never boomy. It doesn't excite room modes like boxes. I could never go back to boxed bass. I would rather have bookshelf speakers with dipole subs than open baffle speaker with box subs.
Another feature is that a dipole sub basically acts as two separate sound sources so you already get a similar effect as with distributed subs with only one sub! Since I plan for a Ripole on the bottom and top of each speaker I basically get 8 kind of distributed subs. Isn't that neat?
I get it that the WAF factor is low......but that is OK since I am divorced 😆
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Not sure if I get what you mean. Do you have a picture?
I like the Ripole because of the force cancellation. Without force cancellation you would need very thick and heavy baffles for high excursion 18" drivers!
Hadn't even thought about throat chamber resonance. Now I come to think of it, it also doesn't address the back chambers..... I clearly haven't thought it through properly.
Dunno. I'm not a ripole-person, but it seems HR can do them so you could export a basic HR model and add a TC into Akabak etc to play with it and see if it provokes some thinking or other.
I went down the route of SLOB/Ripole subwoofers using 4x 15" drivers each side.
Also trying to counter some of the nasty peaks generated from the slots, - curved backwall, all milled out of 104mm (stacked MDF).
It did take the top of the peak, but heavy filtering was still needed. As it was run active with DSP anyway that was not such a big problem.
The big issues, at least for me, was that the efficiency is very poor. It really only have a boost at the resonance, which you fight to get rid of.
While it worked excellently, for lowering the Fs of the system, (to 16Hz) that comes from the rise in Qts -> they were ringing like churchbell's
Okay, maybe not quite that bad - But, it was exactly as far away, from the low Q response, from the same units used in a std. winged open baffle as the Fs would indicate. Can't defy physics.
Electrical filters or not, mechanical resonators remain - and we do well to remeber that they can be triggered by other mechanical/acoustic sources.
If the higher Q suits the system you matches it to, this can be a gift for for finally achieving a nice blend in to other dipoles certainly including large planar membrane ones.
The next project (somewhat down the list unfortunately) will be OB's in z shape baffles, 21" long throw units. Adding a lift in the low end and otherwise keeping the Q low. I'm also done with sloppy bass 🤣
Or like Legacy Audio speaker 'Whisper'.
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Yes putting a simple hole IS working for Ripole. it needs to ne the same area of what should be put in normal Ripole.
There was an old thread (maybe in a french forum) that was talking about that. I can't find it.
But I recently saw that ABX guys tooked the same principal (here without the back Chamber). They did not a hole but a "circle" of same area. To reduce even more the volume they put a plastic cone that have more or less thé shape of thé speaker cône.
There was an old thread (maybe in a french forum) that was talking about that. I can't find it.
But I recently saw that ABX guys tooked the same principal (here without the back Chamber). They did not a hole but a "circle" of same area. To reduce even more the volume they put a plastic cone that have more or less thé shape of thé speaker cône.
Do these move in phase or out of phase? What are the benefits and drawbacks of this arrangement? I haven't seen it before but it looks interesting.
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My guess would be they are out of phase so you get 4 lobes in stead of two and in the crossover region less energy to the back wall. But they are almost baffleless so it will be very hard to go below 30hz and it definitely won't work without DSP and dedicated massive amplifiers.....
Long time ago I made a Ripole as an experiment from some very poor pro drivers. They did ring like church bells but I attributed it to the crap drivers at the time....
Maybe direct radiator is always best. I recently experimented with horns. Bought a whole box of different types of horns and finally concluded I just don't like the horn sound. When I measured all horns added tons of distortion to my very clean driver. Each horn had its own flavor.....some had high 2nd order distortion, others 3rd order but none of them were remotely clean. Compared to horns my ESS Heil barely has any distortion at all. Even playing very loud it doesn't exceed 1% THD and most of it is 2nd order.
To me the compression driver only sounds good naked, crossed higher with some felt baffle or short porous foam waveguide to minimize diffraction. Used that way it almost rivals the Heils but has a less smooth frequency response.
So maybe Ripole is a similar story....
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👍 I am also running Heils as part of the OB system. I have had great results in my non dipole systems with horns, but this has been dedicated and well documented Constant directivty designs. Wayne Parhams H290C, Altec MR94 and JBL's follow up on that the 2360A
I have had to realign several of the drivers to get the distortion sorted. (even out of box, seal unbroken on the cap) But then they really are low distortion - still not as low as the ESS's though.
I've not been on Be. yet, but Ti, Alu and Aquaplas coatings to counter some of the break up modes is of course part of the story. I still prefer them to any standard dome. Also for the wide coverage and ability to almost keep the entire voice range free of crossovers.
