Two singles, one in each enclosure. I'm building two as downfiring subs. There is a 10 inch version, but I know of no home builds of the 10.
They are a car sub. Based on other builds and measured specs, I'd say it doesn't matter in this particular case.
They are a car sub. Based on other builds and measured specs, I'd say it doesn't matter in this particular case.
Front-firing? Not always
Not a ridiculous question at all... they can also be side firing, but you'll need a box for this. It's a modified "u-frame" type of design, with the drivers mounted on the sides of the U, instead of front-firing.
You would mount the woofers on each side of the box, and leave the back of the box open. An additional benefit of this is that the back to back mounting will significantly reduce parasitically transmitted cabinet vibrations. You can even mechanically couple the woofers which helps a lot.
You could make the box as small as 16" tall and 16" to 18" deep and about 12" to 14" wide. (Bigger can also work). Plan to put some stuffing in the interior as this will reduce the slight horn-load from the box (it models mostly like a short-wall horn, with a peak in the response around 300 to 400 Hz, the stuffing will reduce the size of that peak, and also extend the bass response a bit).
There's a brilliant analysis of this, truly great work, at DIY-dipole-1
With the two Eminence Alpha 15a you'll get fairly high efficiency even after EQ'ing. If I recall the ML's aren't very high efficiency, so perhaps you would want to the Alpha 15a substitute with these to get more extended bass:
GRS 15PF-8 from Parts Express (#292-415)
Hey, look! now it's even less expensive $$....
How's that for a good deal, free advice and a cost savings too!
This approach should work really well with your 'stats, due to a high degree of similarity in the radiation patterns.
Please note: A good sealed or ported box can also work well as the radiation pattern will go from omni in the low bass, to cardioid through the crossing region to classic di-pole figure 8 for the 'stats from mid-bass on up... BUT... the interaction with the room is generally much, much better with the OB or u-frame, and the results are clearly audible.
If you implement the above with the phase correct crossover approach I mentioned previously I predict a kick-ess system.
And again, seriously, consider modding that DCX2496. Those Martin Logans really deserve better than the standard Behringer analog section.
Keep us posted!
Not a ridiculous question at all... they can also be side firing, but you'll need a box for this. It's a modified "u-frame" type of design, with the drivers mounted on the sides of the U, instead of front-firing.
You would mount the woofers on each side of the box, and leave the back of the box open. An additional benefit of this is that the back to back mounting will significantly reduce parasitically transmitted cabinet vibrations. You can even mechanically couple the woofers which helps a lot.
You could make the box as small as 16" tall and 16" to 18" deep and about 12" to 14" wide. (Bigger can also work). Plan to put some stuffing in the interior as this will reduce the slight horn-load from the box (it models mostly like a short-wall horn, with a peak in the response around 300 to 400 Hz, the stuffing will reduce the size of that peak, and also extend the bass response a bit).
There's a brilliant analysis of this, truly great work, at DIY-dipole-1
With the two Eminence Alpha 15a you'll get fairly high efficiency even after EQ'ing. If I recall the ML's aren't very high efficiency, so perhaps you would want to the Alpha 15a substitute with these to get more extended bass:
GRS 15PF-8 from Parts Express (#292-415)
Hey, look! now it's even less expensive $$....
How's that for a good deal, free advice and a cost savings too!
This approach should work really well with your 'stats, due to a high degree of similarity in the radiation patterns.
Please note: A good sealed or ported box can also work well as the radiation pattern will go from omni in the low bass, to cardioid through the crossing region to classic di-pole figure 8 for the 'stats from mid-bass on up... BUT... the interaction with the room is generally much, much better with the OB or u-frame, and the results are clearly audible.
If you implement the above with the phase correct crossover approach I mentioned previously I predict a kick-ess system.
And again, seriously, consider modding that DCX2496. Those Martin Logans really deserve better than the standard Behringer analog section.
Keep us posted!
Thank you Jack,
OK, but any advice on a downfiring open baffle? I know it sounds crazy...
And why 2 per speaker? It would increase the already high SPL by 6db, to be paired with the CLS in the mid 80's...Would a single in each channel not work correctly?
OK, but any advice on a downfiring open baffle? I know it sounds crazy...
And why 2 per speaker? It would increase the already high SPL by 6db, to be paired with the CLS in the mid 80's...Would a single in each channel not work correctly?
Downfiring OB?
A down-firing OB? Hmmm.....the woofer would have to be enclosed in a U-frame, otherwise you'de be listening at 90 deg off the woofer axis where the bass cancellation is greatest... not so good IMO!
As for the efficiency disparities... for OB or u-frame you need a LOT of extra efficiency to start with because the bass is rolling off a whole lot more than a sealed or vented...
Due to this roll-off, with a smallish baffle the "effective low-bass efficiency" of the Alpha15a prior to EQ'ing is actually going to be fairly low, on the order of what you get with the ML's.
so you either have to EQ the bass way up or you have to EQ the mid-bass and mids way down to get flat response. With a small baffle, figure on "losing" about 12 to 15 dB from the nominal efficiency.
A BIG baffle will give you lots more low bass efficiency, but at the cost of using a lot of visual real estate and cluttering up the sound-stage. I'm not a fan of "big" OB.
However, due to the low efficiency of the 'stats, yes you could still get away with a single Eminence 15a in a small OB and get very good results.
BUT if you went with the GSR's you would almost certainly need to use doubles because they are much less efficient. The payoff with 2 GSR's side-mounted in a u-frame is that the bass will extend further down, with less EQ, to about 30Hz vs 40 Hz and at less cost.
And I like double drivers for other reasons: more headroom. The excursion on these is limited, so the double woof version gives you lots more SPL capability, and much lower distortion.
If I were you and really wanted to keep it simple: Qty 1 Eminence Alpha 15a per side in small OB, maybe 20"x 24"... but this will require using it in front firing mode, at 90 deg off axis it's full cancellation in the bass. I'm using that in my new entry level kits and it's really, really good.
If you want to make it narrower, make a U-frame with side-firing woofers with GSR's side-mounted one per lateral side. (that's 2 GSR's per u-frame). 16" tall, 18" deep by 12" or so wide is going to be about the minimum, but that's still a smallish box.
Both could sound really great with your 'stats. Keep us in the loop!
A down-firing OB? Hmmm.....the woofer would have to be enclosed in a U-frame, otherwise you'de be listening at 90 deg off the woofer axis where the bass cancellation is greatest... not so good IMO!
As for the efficiency disparities... for OB or u-frame you need a LOT of extra efficiency to start with because the bass is rolling off a whole lot more than a sealed or vented...
Due to this roll-off, with a smallish baffle the "effective low-bass efficiency" of the Alpha15a prior to EQ'ing is actually going to be fairly low, on the order of what you get with the ML's.
so you either have to EQ the bass way up or you have to EQ the mid-bass and mids way down to get flat response. With a small baffle, figure on "losing" about 12 to 15 dB from the nominal efficiency.
A BIG baffle will give you lots more low bass efficiency, but at the cost of using a lot of visual real estate and cluttering up the sound-stage. I'm not a fan of "big" OB.
However, due to the low efficiency of the 'stats, yes you could still get away with a single Eminence 15a in a small OB and get very good results.
BUT if you went with the GSR's you would almost certainly need to use doubles because they are much less efficient. The payoff with 2 GSR's side-mounted in a u-frame is that the bass will extend further down, with less EQ, to about 30Hz vs 40 Hz and at less cost.
And I like double drivers for other reasons: more headroom. The excursion on these is limited, so the double woof version gives you lots more SPL capability, and much lower distortion.
If I were you and really wanted to keep it simple: Qty 1 Eminence Alpha 15a per side in small OB, maybe 20"x 24"... but this will require using it in front firing mode, at 90 deg off axis it's full cancellation in the bass. I'm using that in my new entry level kits and it's really, really good.
If you want to make it narrower, make a U-frame with side-firing woofers with GSR's side-mounted one per lateral side. (that's 2 GSR's per u-frame). 16" tall, 18" deep by 12" or so wide is going to be about the minimum, but that's still a smallish box.
Both could sound really great with your 'stats. Keep us in the loop!
bjorno -> Cool!! Can you sim one up on the GRS 15" from Parts Express?
Jack -> Just purchased four of the GRS 15 per you recommendation for my little test. Still have to decide the final arrangement, but leaning to stacked / forward firing, but I still like the small-ish 16x18x12 "side firing U" arrangement you mentioned.
The Test: I want to see how it will hold up against a single Martin Logan Depth Sub.
Jack -> Just purchased four of the GRS 15 per you recommendation for my little test. Still have to decide the final arrangement, but leaning to stacked / forward firing, but I still like the small-ish 16x18x12 "side firing U" arrangement you mentioned.
The Test: I want to see how it will hold up against a single Martin Logan Depth Sub.
Great Sims!
Hey Bjorno, thanks for the pix, they really do help validate the dual 15" Eminence Alpha 15a example as having sufficient SPL capabilities for most users from 40 Hz up.
This moves the discussion into "OK, this definitely looks like something that can work well for SPL".
Now the Q is how will it sound in a room?
The Martin Logan Depth sub comparison should be a very interesting. I would predict the ML will play louder and certainly cleaner in the very low bass and thus add room ambience and reverberant cues. But when it comes to mid-bass impact and tonality, my bet is on the twin 15's OB, primarily due to the way it interacts with the room.
I predict they will sound way "faster" from 50Hz on up. This effect is predominantly because the OB is not exciting the vertical and lateral room modes nearly as much as the Depth will. What many think is a "slow and plodding" subwoofer is actually room resonances and hang-over.
John, if you have the option of using the twin 15's OB in conjunction with the ML Depth, that could be excellent indeed. Just run the OB's fully Eq'd down to 42 Hz and add in the Depth with it's low-pass somewhere in the 35 to 45 Hz range... this can be a truly great sub array as the Depth will add the room pressurization capabilities that the Eminence OB's would lack below 42Hz or so.
The GSR's will get you down a little lower, but even so, you'll find the room doesn't pressurize very well at the low-low frequencies.
I use a similar OB setup at home + a Velodyne servo-sub, and can tell you that when it's properly calibrated, it can sound astonishingly fast, tuneful and good.
Hey Bjorno, thanks for the pix, they really do help validate the dual 15" Eminence Alpha 15a example as having sufficient SPL capabilities for most users from 40 Hz up.
This moves the discussion into "OK, this definitely looks like something that can work well for SPL".
Now the Q is how will it sound in a room?
The Martin Logan Depth sub comparison should be a very interesting. I would predict the ML will play louder and certainly cleaner in the very low bass and thus add room ambience and reverberant cues. But when it comes to mid-bass impact and tonality, my bet is on the twin 15's OB, primarily due to the way it interacts with the room.
I predict they will sound way "faster" from 50Hz on up. This effect is predominantly because the OB is not exciting the vertical and lateral room modes nearly as much as the Depth will. What many think is a "slow and plodding" subwoofer is actually room resonances and hang-over.
John, if you have the option of using the twin 15's OB in conjunction with the ML Depth, that could be excellent indeed. Just run the OB's fully Eq'd down to 42 Hz and add in the Depth with it's low-pass somewhere in the 35 to 45 Hz range... this can be a truly great sub array as the Depth will add the room pressurization capabilities that the Eminence OB's would lack below 42Hz or so.
The GSR's will get you down a little lower, but even so, you'll find the room doesn't pressurize very well at the low-low frequencies.
I use a similar OB setup at home + a Velodyne servo-sub, and can tell you that when it's properly calibrated, it can sound astonishingly fast, tuneful and good.
U-Frame sims?
Bjorno, in the U-frame sims it looks like one of the drivers is facing forward into the measuring area, the other one backwards. The ones I've built and tested had the drivers mounted on the sides and firing laterally, with the box opening on the back, (open back, closed front, top, and bottom, box stuffed with about 0.25lbs/cu ft of hollow fiber poly-fill). They performed very well and required about 3dB less EQ than the sims you have there would seem to indicate.
I'm thinking the sim will correlate better if you rotate the array so the open back is aimed at the rear corner....
Thanks!
Bjorno, in the U-frame sims it looks like one of the drivers is facing forward into the measuring area, the other one backwards. The ones I've built and tested had the drivers mounted on the sides and firing laterally, with the box opening on the back, (open back, closed front, top, and bottom, box stuffed with about 0.25lbs/cu ft of hollow fiber poly-fill). They performed very well and required about 3dB less EQ than the sims you have there would seem to indicate.
I'm thinking the sim will correlate better if you rotate the array so the open back is aimed at the rear corner....
Thanks!
OK, I will start procuring the MDF for the U baffles - lateral-side firing... next dumb question, are these two back to back drivers hooked up in phase or out of phase (push-pull) for lateral fire?
How high off grade would you suggest? I like the 12" wide front, 18" deep, 16" high, but 16" high means under 1" off floor...is this correct?
How high off grade would you suggest? I like the 12" wide front, 18" deep, 16" high, but 16" high means under 1" off floor...is this correct?
They'll be connected in phase. If your sub amp can handle 4 ohms (likely it can), hook em up in parallel. You can also try in series, although I don't see what the point of presenting a 16 ohm load, given the amp you referenced. But if you were using a tube amp, then maybe 16 ohm would make sense.
As for woofer height from the ground, with an 8ft ceiling you might get smoother bass at 36" or 19" (1/3rd and 1/5th of the height respectively), but since this array will be mostly canceling at the vertical and lateral 90 deg off-axis (yes, even with the woofers opposite each other and side-firing), the vertical modes and lateral will not see much excitation... theoretically you could put them right at the ground level and not see much difference.
Are you planning to place the woofers under the ML's? Or side by side?
The Icepower amp I have can easily handle 4 ohms.
I would prefer to put them under the CLS, but may not be parallel - if the driver baffles were flared out, say 30 degrees, would that hurt?
Otherwise, a parallel "U" along the outside of the CLS would be do-able.
I would prefer to put them under the CLS, but may not be parallel - if the driver baffles were flared out, say 30 degrees, would that hurt?
Otherwise, a parallel "U" along the outside of the CLS would be do-able.
An Idea....
OK, got the speakers...that was quick. They are huge...I forgot how big 15" was (There is a joke in there somewhere...)
Anyway, I was looking at the IKEA Stand that I have my CLS's on. A Large, low, thick Pentagonal table, and I have been thinking of the following,mounting the drivers in the stand...just a thought...
OK, got the speakers...that was quick. They are huge...I forgot how big 15" was (There is a joke in there somewhere...)
Anyway, I was looking at the IKEA Stand that I have my CLS's on. A Large, low, thick Pentagonal table, and I have been thinking of the following,mounting the drivers in the stand...just a thought...
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Hi,
Sorry for answering late 😱
The open back is already aiming the room corner as should.
Submitting a new U-frame simulation using the GRS 15PF-8 drivers and a picture showing the consequence of OD (Offset driver) mounting using different MJK and HR programs.
b🙂
Attachments
Hey Bjorno, great work! These sims for the GSR 15 look pretty good. When used this way, drivers in parallel for 4 ohm load, if you add a reasonably sized series air-core inductor, for example 5mH with approximately 1 ohm DCR, the response will flatten out very nicely, and the system will need very little in the way of EQ in the bass.
It might be useful to use the inductor even when using the DCX with it, as with digital EQ's it is beneficial to reduce the amount of EQ where possible... there is less loss of resolution when you don't have to throw away 15 to 18dB just to get the levels matched...
I have a few 5mH and 9mH inductors (Iron core) that I can try...just gotta find some time to get out and buy the MDF...
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That doesn't look right...
Warning, Will Robinson, warning!
Looking at post #32, if I'm seeing the drawing right, what you are proposing will not work well at all. In your drawing it looks like you have the drivers mounted sideways without any enclosure at all. If that's the case, you're not going to get any bass at all!
You want the drivers to be FRONT firing if on an open baffle, as they have a figure 8 response pattern with full cancellation at the sides. What you drew looks like an open baffle facing upward, with openings on both sides and front. Which means you are listening at near a full 90 degree off-axis, which means nearly total cancellation.
If you are facing the sides of the drivers you will get nothing in the way of bass unless either the front or the back are enclosed in a U-frame or a box. Open baffle is directional and you want to listen on-axis.
The U-frame variant also:
The reason you can get away with side-firing woofers on the U-frame is because the box is CLOSED on all sides save for the back, and the radiation pattern starts looking like a cardioid or figure 8 with a large lobe in front and a smaller lobe in back, and a cancellation to the sides. The U-frame is also directional, even the side-firing version. With the side-firing version, you'll be facing the closed front, with the opening to the back.
To make it clear, the front, top, bottom and sides of the side-firing U-frame box are all CLOSED save for the driver openings. Only the back is open.
The main reason to consider the side-firing U-frame vs front-firing is to get a narrower front aspect, for example if you want to mount a mini-monitor on top.
Since you want a short, wide base for the 'stats, just build a front-firing open baffle or U-frame box, with drivers side-by side. It'll be about 16" tall by 32" wide, make it as deep as you want and it'll still work very well.
Whoa!
Warning, Will Robinson, warning!
Looking at post #32, if I'm seeing the drawing right, what you are proposing will not work well at all. In your drawing it looks like you have the drivers mounted sideways without any enclosure at all. If that's the case, you're not going to get any bass at all!
You want the drivers to be FRONT firing if on an open baffle, as they have a figure 8 response pattern with full cancellation at the sides. What you drew looks like an open baffle facing upward, with openings on both sides and front. Which means you are listening at near a full 90 degree off-axis, which means nearly total cancellation.
If you are facing the sides of the drivers you will get nothing in the way of bass unless either the front or the back are enclosed in a U-frame or a box. Open baffle is directional and you want to listen on-axis.
The U-frame variant also:
The reason you can get away with side-firing woofers on the U-frame is because the box is CLOSED on all sides save for the back, and the radiation pattern starts looking like a cardioid or figure 8 with a large lobe in front and a smaller lobe in back, and a cancellation to the sides. The U-frame is also directional, even the side-firing version. With the side-firing version, you'll be facing the closed front, with the opening to the back.
To make it clear, the front, top, bottom and sides of the side-firing U-frame box are all CLOSED save for the driver openings. Only the back is open.
The main reason to consider the side-firing U-frame vs front-firing is to get a narrower front aspect, for example if you want to mount a mini-monitor on top.
Since you want a short, wide base for the 'stats, just build a front-firing open baffle or U-frame box, with drivers side-by side. It'll be about 16" tall by 32" wide, make it as deep as you want and it'll still work very well.
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Been playing around with the Depth. Nice. I don't care for deep, deep bass, but I do like tight, solid mid bass, something the Tympani IVa had in spades.. I should start building the 15" U frames or vertical, stacked, Front firing baffles soon - currently very busy at work.
As far as determining / tuning actual frequency response - I have an Audyssey mic, and another mic that came with my Pioneer SC-07 Home Theater Receiver. Any advice on a Laptop based program to use with these mics??
As far as determining / tuning actual frequency response - I have an Audyssey mic, and another mic that came with my Pioneer SC-07 Home Theater Receiver. Any advice on a Laptop based program to use with these mics??
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OK, work is somewhat back to normal - I should be able to put the Drivers in the baffle tonight - To make things simple, I have the arrangement as front firing / stacked. I can always cut the baffles to make the side firing later if I choose.
I downloaded the Behringer software, but I have no serial ports on my laptop, and no serial cables, so I ordered the USB/serial adapter - will be a few more days.
A 5mh coil in series with both drivers...will post back after trying it out.
I downloaded the Behringer software, but I have no serial ports on my laptop, and no serial cables, so I ordered the USB/serial adapter - will be a few more days.
A 5mh coil in series with both drivers...will post back after trying it out.
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