Sounds great for little $....
You probably want to consider segmenting the drivers into vertical sets of two side by side drivers per baffle section (vertical or horizontal) to keep the baffle dimensions from getting too far out of square. You don't want to have different resonant points for depth Vs width set up in your 1/4 wave resonant lines. That's why round drivers with square baffles just big enough to fit the drivers are used and why not making the lines any deeper is advised.
I think this will be a very interesting project. The drivers are very compact, inexpensive and with multiple sets you can build up a large Sd. Your power handling should be excellent as should efficiency. As you said you can use a tallish sub cabinet as the base for a dipole mid/top unit.
You do want to try to keep your options open so here is a link for a 12 inch driver ($47.28 CND) with good perameters for a dipole sub which is very inexpensive and has lots of xmax. Cutting lots multiple holes in a baffle for 6x9 units has to be considered. Regards Moray James.
http://www.mach5audio.com/product_info.php?products_id=41&osCsid=df22114511d5b9b07ea425a028ed2259
You probably want to consider segmenting the drivers into vertical sets of two side by side drivers per baffle section (vertical or horizontal) to keep the baffle dimensions from getting too far out of square. You don't want to have different resonant points for depth Vs width set up in your 1/4 wave resonant lines. That's why round drivers with square baffles just big enough to fit the drivers are used and why not making the lines any deeper is advised.
I think this will be a very interesting project. The drivers are very compact, inexpensive and with multiple sets you can build up a large Sd. Your power handling should be excellent as should efficiency. As you said you can use a tallish sub cabinet as the base for a dipole mid/top unit.
You do want to try to keep your options open so here is a link for a 12 inch driver ($47.28 CND) with good perameters for a dipole sub which is very inexpensive and has lots of xmax. Cutting lots multiple holes in a baffle for 6x9 units has to be considered. Regards Moray James.
http://www.mach5audio.com/product_info.php?products_id=41&osCsid=df22114511d5b9b07ea425a028ed2259
Moray,
1/4 wave resonances come into play with depth. Other parallel dimensions can result in standing wave type resonances, which are 1/2 wavelength. I do plan a triangle divider between each vertical driver pair and to splay the drivers baffles at a slight angle resulting in each each cavity being only 6" deep by 9" tall with no parallel surfaces. The backside will have damping, which is required for U alignments. Plus I'll err on the side of larger pathways in the rear, and use stuffing to balance the airmass load and achieve the tuning I want at no sonic detriment. Believe me when I say that I take into consideration far more variables than the commerial ripoles used as an example.
Be careful not to follow dipole purists too closely, especially when it comes to bass. A good example is dipole use as subs. How many of them warn about dipole bass being room limited in extension? Have you built a Linkwitz W-baffle woofer? I didn't even use high excursion woofers and panel vibrations are a real problem. Fire a high excursion driver into an even narrower cavity, and it becomes a problem which must be considered. I think an awful lot of people have been lulled to sleep by what OB's do better than boxes. As a result, a lot of the basic construction requirements of boxed speakers are overlooked with almost all OB's, but for the most part the needs still exist.
BTW, as I've been typing this I had just 1 pair of the 6x9's in a shallow U baffle that I rigged as bottom end fill for a set of horns playing reggae and some other bass heavy music in the background. I've definitely decided to go with the 6 woofers per side compact alignment. That should be plenty for most listening, and I have 2 pairs of higher excursion pro type 15's to use in a high performance OB speaker pair that I have planned (100db at 30hz outside).
I have a digital camera now, and will start a big construction effort of a number of final form cabs along with test cabs, so expect lots of pics very soon, plus measurements shortly after.
1/4 wave resonances come into play with depth. Other parallel dimensions can result in standing wave type resonances, which are 1/2 wavelength. I do plan a triangle divider between each vertical driver pair and to splay the drivers baffles at a slight angle resulting in each each cavity being only 6" deep by 9" tall with no parallel surfaces. The backside will have damping, which is required for U alignments. Plus I'll err on the side of larger pathways in the rear, and use stuffing to balance the airmass load and achieve the tuning I want at no sonic detriment. Believe me when I say that I take into consideration far more variables than the commerial ripoles used as an example.
Be careful not to follow dipole purists too closely, especially when it comes to bass. A good example is dipole use as subs. How many of them warn about dipole bass being room limited in extension? Have you built a Linkwitz W-baffle woofer? I didn't even use high excursion woofers and panel vibrations are a real problem. Fire a high excursion driver into an even narrower cavity, and it becomes a problem which must be considered. I think an awful lot of people have been lulled to sleep by what OB's do better than boxes. As a result, a lot of the basic construction requirements of boxed speakers are overlooked with almost all OB's, but for the most part the needs still exist.
BTW, as I've been typing this I had just 1 pair of the 6x9's in a shallow U baffle that I rigged as bottom end fill for a set of horns playing reggae and some other bass heavy music in the background. I've definitely decided to go with the 6 woofers per side compact alignment. That should be plenty for most listening, and I have 2 pairs of higher excursion pro type 15's to use in a high performance OB speaker pair that I have planned (100db at 30hz outside).
I have a digital camera now, and will start a big construction effort of a number of final form cabs along with test cabs, so expect lots of pics very soon, plus measurements shortly after.
Help me see...
JohninCR: sorry my braain has frozen on this one. Are you building dual ripole style or U frame? If you can do a sketch or send a pic when you build it will help a lot.
The 6x9 driver was where I started with this thing thinking about saving a lot of money if the right driver could be found. Had thought about looking for a bunch of discounted units as the car bus is all about whats new and the volume huge. Still thinkthat it is a good idea but there is more work to be done with all the cut outs mounting and wiring.
6x9 units (or cheap 8's) could be built into a dual ripole structure which could be vertically extended into a floor to ceiling tower. The foot print of which would be very small yet house a lot of driver surface area. Easy to intigrate a pair of these into a room as they occupie such a small area but pack a wack of Sd. The determining factor would be the driver cost. Given the huge potential for Sd in this type of design hi xmax would not be an issue so lots of drivers to choose from. You could expect about the same piston area of about 4.5 15 inch units per collum. Not bad and lots of power handling. Something to think about. Regards Moray James.
JohninCR: sorry my braain has frozen on this one. Are you building dual ripole style or U frame? If you can do a sketch or send a pic when you build it will help a lot.
The 6x9 driver was where I started with this thing thinking about saving a lot of money if the right driver could be found. Had thought about looking for a bunch of discounted units as the car bus is all about whats new and the volume huge. Still thinkthat it is a good idea but there is more work to be done with all the cut outs mounting and wiring.
6x9 units (or cheap 8's) could be built into a dual ripole structure which could be vertically extended into a floor to ceiling tower. The foot print of which would be very small yet house a lot of driver surface area. Easy to intigrate a pair of these into a room as they occupie such a small area but pack a wack of Sd. The determining factor would be the driver cost. Given the huge potential for Sd in this type of design hi xmax would not be an issue so lots of drivers to choose from. You could expect about the same piston area of about 4.5 15 inch units per collum. Not bad and lots of power handling. Something to think about. Regards Moray James.
W-baffle with a U extension added in back. I will use the ripole approach to lower Fs and reduce size. That's why I posted to this thread. Yes multiple holes are a pain, and wiring less so, but for performance requires multiple drivers even if you use larger ones. The reduced size and much shallower cavities are a tremendous advantage.
Also, with OB bass, the primary concern is Xmax. Sd and Xmax are the 2 specs of critical importance as long as you stay away from the typical high Le big subwoofer drivers (another item of little concern using smaller drivers).
After hearing how good just a pair sounds, a column of 8 per side has a ton of potential, and I'm considering that too due to my narrow room.
Here's a top view of the baffle, not to scale and I may have to go with less splay to get the ripole effect, but I need to try a test manifold first. The blue panels are the driver mounting baffles.
Also, with OB bass, the primary concern is Xmax. Sd and Xmax are the 2 specs of critical importance as long as you stay away from the typical high Le big subwoofer drivers (another item of little concern using smaller drivers).
After hearing how good just a pair sounds, a column of 8 per side has a ton of potential, and I'm considering that too due to my narrow room.
Here's a top view of the baffle, not to scale and I may have to go with less splay to get the ripole effect, but I need to try a test manifold first. The blue panels are the driver mounting baffles.
An externally hosted image should be here but it was not working when we last tested it.
John,
I like that concept. The little bit of splay will make the driver faces visible. Done up in a nice, contrasting baffle material, it should be attractive. If built stacked, will create quite a decent line. Another advantage would be that you could actually build the enclosure, well braced. and then mount the drivers (a standard ripole requires that the drivers be "built into" the enclosure as there is no clearance in the design for slipping the magnet structures/baskets into the cutouts, let alone getting a tool in there to screw them down).
Anyway, a simple yet elegant design which is spawning ideas. Thanks. Oh, and I'm so happy you have a digicam now. Can't wait to see pics of your construction.
Kensai
I like that concept. The little bit of splay will make the driver faces visible. Done up in a nice, contrasting baffle material, it should be attractive. If built stacked, will create quite a decent line. Another advantage would be that you could actually build the enclosure, well braced. and then mount the drivers (a standard ripole requires that the drivers be "built into" the enclosure as there is no clearance in the design for slipping the magnet structures/baskets into the cutouts, let alone getting a tool in there to screw them down).
Anyway, a simple yet elegant design which is spawning ideas. Thanks. Oh, and I'm so happy you have a digicam now. Can't wait to see pics of your construction.
Kensai
Kensai,
With push pull I'll have ugly baskets and magnets to hide, so I'll paint everything possible inside the manifold a flat black and put a grill on the front painted gloss black to hide everything nicely. Since I'm using cheap drivers, and I want to go as compact as possible, the drivers will probably have to be mounted at least before the side panels go on. The pair of 6x9's I have go surprisingly low, so I don't need the maximum ripole effect of lowering Fs. I don't listen to pipe organ music or trance type stuff, so solid output into the low 30's is fine for me, since HT gets a proper sub.
The end result will be something similar to those below, but with less odd angles to torture myself (that pair has no screws or fasteners and were a real pain to glue with pressure for a good joint). I'll go with only enough cavity on top to hide the magnet of whatever main driver I use.
With push pull I'll have ugly baskets and magnets to hide, so I'll paint everything possible inside the manifold a flat black and put a grill on the front painted gloss black to hide everything nicely. Since I'm using cheap drivers, and I want to go as compact as possible, the drivers will probably have to be mounted at least before the side panels go on. The pair of 6x9's I have go surprisingly low, so I don't need the maximum ripole effect of lowering Fs. I don't listen to pipe organ music or trance type stuff, so solid output into the low 30's is fine for me, since HT gets a proper sub.
The end result will be something similar to those below, but with less odd angles to torture myself (that pair has no screws or fasteners and were a real pain to glue with pressure for a good joint). I'll go with only enough cavity on top to hide the magnet of whatever main driver I use.
An externally hosted image should be here but it was not working when we last tested it.
Kensai said:
Thanks, I'm going to rip those manifolds out and put four 6x9's in instead. They sound great as is, but only capable of moderate volumes, so I don't use them much. Also, I wish I could have retained the light color of the front pictured. Clear varnish darkened them way too much as you can tell from the rear pic. I'm quite pleased with proportions of the cab, though. It took some tinkering during construction because nothing had a firm plan, just a mental pic of what I wanted. The wing angles and top cap were critical to achieve what I felt was well proportioned, and the only "looks over sonics" compromise was the diffraction effects of the top cap overlapping the front baffle.
When I upgrade the bass section, I'll probably have to add more air flow resistance on the back side to equally load both sides of the woofer cones. 2.5 years ago when I built them, I was getting some ripole behavior without understanding it because those little 6's play much deeper in the manifold alignment, even though they aren't very restricted in the pathway.
Paul Ebert said:
They began life as Adire HE8.1 kits based on the Eminence Beta8CX in the recommended BR. They were a little sterile for my tastes, but once I freed them of the confines of a box the sound came to life. They're low Q and definitely need bass augmentation, but I'll never forget the day I finished them and did a head-to-head with one in the box and one in my Flintstone OB. My 9yro daughter came and danced around while music played, and she asked "Daddy, why does one speaker sound so much better than the other?". Of course without the benefit of the stereo illusion, it's always a no contest comparing one OB to one box.
just thought I would mention...
That there are a couple of great posts by djk in the following thread on the last page which pertain to OB and dipole design.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1018239#post1018239
DJK is an experienced designer when it comes to speakers and his comments are well worth reading and of use here. The first and foremost driver consideration he says is "driver noise" after that the T/S numbers will depend upon your actual application.
Thanks to djk and lets hope there are further installments here. Regards Moray James.
That there are a couple of great posts by djk in the following thread on the last page which pertain to OB and dipole design.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1018239#post1018239
DJK is an experienced designer when it comes to speakers and his comments are well worth reading and of use here. The first and foremost driver consideration he says is "driver noise" after that the T/S numbers will depend upon your actual application.
Thanks to djk and lets hope there are further installments here. Regards Moray James.
Trade offs...
What are the associated trade offs when choosing the Qts of a subwoofer? If you choose a hi Qts driver the bass response will hump and there will be less need (or little) to EQ the system bass response. If you choose a lower Qts driver then the re will be more roll off and a need to EQ the system response.
Since hi Qts drivers have large powerful motors and lo Qts drivers have smaller motors then would it be fair to assume that a hi Qts driver would yield stronger more controlled (less distortion) bass response? I am under the impression that lo Qts drivers will maximum efficiency, minimum box size, and lowest cut-off point, if so does the reverse hold true for hi Qts drivers?
Regards Moray James.
What are the associated trade offs when choosing the Qts of a subwoofer? If you choose a hi Qts driver the bass response will hump and there will be less need (or little) to EQ the system bass response. If you choose a lower Qts driver then the re will be more roll off and a need to EQ the system response.
Since hi Qts drivers have large powerful motors and lo Qts drivers have smaller motors then would it be fair to assume that a hi Qts driver would yield stronger more controlled (less distortion) bass response? I am under the impression that lo Qts drivers will maximum efficiency, minimum box size, and lowest cut-off point, if so does the reverse hold true for hi Qts drivers?
Regards Moray James.
The trade off is a bigger box, but wait there is no box, so it's kind of free. Qts is the measure of a driver's ability to control it's cone at resonance. Big drivers with high Q can start to flop around in the lower frequencies, especially with amps that have a low dampening factor. That's why you see the big motors on high excursion sub drivers, along with smaller box requirements of lower Q.
That's one of the reasons you have to start with your performance goal using OB bass. With Linkwitz's SPLmax spreadsheet you can figure out exactly what you need to get to your goal. Then it's a matter of driver selection, but mid/high Q drivers with high excursion are rare, and EQ or lots of drivers end up required for high performance, because in the bottom octave it's only about how much air you can move.
That's one of the reasons you have to start with your performance goal using OB bass. With Linkwitz's SPLmax spreadsheet you can figure out exactly what you need to get to your goal. Then it's a matter of driver selection, but mid/high Q drivers with high excursion are rare, and EQ or lots of drivers end up required for high performance, because in the bottom octave it's only about how much air you can move.
It would seem then...
that the determining factor would be that of not exceeding xmax at your desired low frequency cut off. Somehow that seems too simple. A stronger better damped motor system must produce bass with less distortion. I feel like I am missing something important here. I think that in a dipole the trade offs will be different than if you wanted a reflex box. The dipole would be closer to the kind of driver specs that you would be looking for in a sealed box driver. Does anybody specify driver EBP for dipoles? I know that the standard rule for vented boxes is an EBP close to 100 and close to 50 for sealed cabinets (EBP = Fs/Qts).
If we look at accepted quality drivers in W framed dipoles like the Peerless SLS 10 we see an EBP of 65, the SLS 12 has an EBP of 59, the xls 12 a EBP of 90 and the xxls 12 an EBP of 47. So the acceptable range would seem to be 45- 90.
Obviously if you don't want to do any EQ then higher Qts drivers would be the way to go but if EQ is going to be employed then lower Qts drivers would be more desireable and also probably offer a wider selection of possible candidates.
Comments would be most welcome. Perhaps Rudolf or Calvin could address this. Thanks Moray James.
that the determining factor would be that of not exceeding xmax at your desired low frequency cut off. Somehow that seems too simple. A stronger better damped motor system must produce bass with less distortion. I feel like I am missing something important here. I think that in a dipole the trade offs will be different than if you wanted a reflex box. The dipole would be closer to the kind of driver specs that you would be looking for in a sealed box driver. Does anybody specify driver EBP for dipoles? I know that the standard rule for vented boxes is an EBP close to 100 and close to 50 for sealed cabinets (EBP = Fs/Qts).
If we look at accepted quality drivers in W framed dipoles like the Peerless SLS 10 we see an EBP of 65, the SLS 12 has an EBP of 59, the xls 12 a EBP of 90 and the xxls 12 an EBP of 47. So the acceptable range would seem to be 45- 90.
Obviously if you don't want to do any EQ then higher Qts drivers would be the way to go but if EQ is going to be employed then lower Qts drivers would be more desireable and also probably offer a wider selection of possible candidates.
Comments would be most welcome. Perhaps Rudolf or Calvin could address this. Thanks Moray James.
Moray,
Overdamping is not a requirement. Think about a driver like the B200 fullranger. Qts of .7 Fs in the 40's, but it plays great up past 10khz.
To me, if you want a perfect OB woofer for sub use, then look for a Qes of .7, Qms of 10, an Fs of 10hz, an Xmax of 20+mm, and an Xmech of 40mm, in small sizes with square or rectangular frames and cones that fill the frames for efficient stacking of your Sd in any configuration.
Overdamping is not a requirement. Think about a driver like the B200 fullranger. Qts of .7 Fs in the 40's, but it plays great up past 10khz.
To me, if you want a perfect OB woofer for sub use, then look for a Qes of .7, Qms of 10, an Fs of 10hz, an Xmax of 20+mm, and an Xmech of 40mm, in small sizes with square or rectangular frames and cones that fill the frames for efficient stacking of your Sd in any configuration.