I had Seth Cothron at @studio38designs make them. He did all the woodwork, and a lot of it was done with a CNC. I don't know granular details.
Thanks for sharing and tagging me, Perry. My live edge dipoles build is moving along. I’ll share some pics once I get a little further.
Tech note on the Bitches Brew dipoles - someone watched the Parts Express walk-around video super carefully and saw some components not in the published schematic. I'm publishing the full schematic here. The parts you see in green are the added components.
They are 100% optional, as they are wired in parallel with the drivers, and not in the signal path. But I added them because they flatten the impedance curve.
On the tweeter section, the 7mH inductor and 10 ohm resistor create a flat impedance at low frequencies, compensating for the 80uF capacitor in series with the tweeter (which was necessary to protect it from turn-on transients and accidents). This R-L network is a "low frequency zobel." On the woofer section is a traditional high frequency R-C zobel.
Without the zobel my solid state amp (Adcom) makes a tiny little squeak as the power supply drains, after you turn it off. The zobel on the tweeter section causes the amp to not make any strange noises when you power it down.
This is a reminder that our amps, no matter how good, are NOT just perfect constant voltage ideal sources. They are real world devices with feedback loops, and they do not behave in reality they way we like to think of them.
The impedance compensation also means that cables and other variables interfere with the speakers less.
No matter how good your amp is, it always performs better when it sees an easy resistive load.
A lot of people who have asked me about these high efficiency designs like tube amps. These tweaks make a big difference with tubes because tubes have high output impedance and are very far from "ideal constant voltage sources."
Below: Impedance of the woofer section with the RC zobel network included. As you can see the Bitches Brew is not a difficult load, with 6 ohms average and 4 ohms minimum at 60Hz:
Below: Impedance of tweeter section with RL network included:
They are 100% optional, as they are wired in parallel with the drivers, and not in the signal path. But I added them because they flatten the impedance curve.
On the tweeter section, the 7mH inductor and 10 ohm resistor create a flat impedance at low frequencies, compensating for the 80uF capacitor in series with the tweeter (which was necessary to protect it from turn-on transients and accidents). This R-L network is a "low frequency zobel." On the woofer section is a traditional high frequency R-C zobel.
Without the zobel my solid state amp (Adcom) makes a tiny little squeak as the power supply drains, after you turn it off. The zobel on the tweeter section causes the amp to not make any strange noises when you power it down.
This is a reminder that our amps, no matter how good, are NOT just perfect constant voltage ideal sources. They are real world devices with feedback loops, and they do not behave in reality they way we like to think of them.
The impedance compensation also means that cables and other variables interfere with the speakers less.
No matter how good your amp is, it always performs better when it sees an easy resistive load.
A lot of people who have asked me about these high efficiency designs like tube amps. These tweaks make a big difference with tubes because tubes have high output impedance and are very far from "ideal constant voltage sources."
Below: Impedance of the woofer section with the RC zobel network included. As you can see the Bitches Brew is not a difficult load, with 6 ohms average and 4 ohms minimum at 60Hz:
Below: Impedance of tweeter section with RL network included:
Perry,
I´m veerrry impressed from you open baffle speaker constructions!
I´m looking for a "end game" speaker system for my living room which is arround 16x36x9ft (5x11x2,8m)
The bitches brew and also the live-edge dipoles are promising.
The Radian coax seems to be very sexy...
Which system shall I choose?
The size of the speakers does not play such a big role. WAF is more important
For good suggestions I would be very grateful!
I´m veerrry impressed from you open baffle speaker constructions!
I´m looking for a "end game" speaker system for my living room which is arround 16x36x9ft (5x11x2,8m)
The bitches brew and also the live-edge dipoles are promising.
The Radian coax seems to be very sexy...
Which system shall I choose?
The size of the speakers does not play such a big role. WAF is more important
For good suggestions I would be very grateful!
For that large size of room, if you want bass all the way down to 20Hz, then only the Bitches Brew will deliver that.
For 20Hz bass in that size room the Birch Dipoles will need a subwoofer.
If you are happy with bass down to 35-40Hz then you can roll off the bass below 35Hz using the DSP, and the Birch Dipoles will be powerful enough for most people.
For 20Hz bass in that size room the Birch Dipoles will need a subwoofer.
If you are happy with bass down to 35-40Hz then you can roll off the bass below 35Hz using the DSP, and the Birch Dipoles will be powerful enough for most people.
Radian 5208 8" coax vs B&C 15CXN88 15" coax:
They sound somewhat similar if properly EQ'd with your DSP.
The B&C is 4-5dB more efficient, handles 3X more power, and on an open baffle easily goes down to 100Hz.
The Radian should be crossed over at 150Hz-200Hz on Open Baffle. The Birch Dipoles have a baffle that is 20" wide.
If you use a narrow baffle (8"-12" wide) with the Radian, you will need to cross over at 250-300Hz.
In my setup I replaced the Radian Aluminum tweeter diaphragm with Beryllium and it sounds extremely good. Slightly better than the B&C. With Radian aluminum diaphragm, I would say the B&C sounds slightly better.
A beryllium diaphragm is not available for the B&C. I would also love a Textreme diaphragm but I have not seen any coaxials where that is available so far.
Both of these drivers have more than enough dynamic range for any "sane" home music setup, even for a large room like yours. But like I said with an 18-20" wide baffle the Radians will only go down to about 150-200.
They sound somewhat similar if properly EQ'd with your DSP.
The B&C is 4-5dB more efficient, handles 3X more power, and on an open baffle easily goes down to 100Hz.
The Radian should be crossed over at 150Hz-200Hz on Open Baffle. The Birch Dipoles have a baffle that is 20" wide.
If you use a narrow baffle (8"-12" wide) with the Radian, you will need to cross over at 250-300Hz.
In my setup I replaced the Radian Aluminum tweeter diaphragm with Beryllium and it sounds extremely good. Slightly better than the B&C. With Radian aluminum diaphragm, I would say the B&C sounds slightly better.
A beryllium diaphragm is not available for the B&C. I would also love a Textreme diaphragm but I have not seen any coaxials where that is available so far.
Both of these drivers have more than enough dynamic range for any "sane" home music setup, even for a large room like yours. But like I said with an 18-20" wide baffle the Radians will only go down to about 150-200.
@perrymarshall thank you for publishing your designs. I really enjoyed reading your Bitches Brew paper back when you published it, then I read all of your previous papers. I was thinking I might try to make a pair. I’ve been a dipole fan for a while and ran Linkwitz’ Orions for a long time. Siegfried was local to me so I was able to listen and talk about speakers on several occasions.
Then I just checked your site and saw your new design and found your corner on this forum.
The papers and this new design got me thinking about bass tradeoffs.
In short, I’m curious what you think about the the importance of having dipole bass below 100hz, vs a jointly optimized bass array of 2-4 subwoofers, as advocated by Floyd Tool and Earl Geddes?
For example, the top section for Bitches Brew is amazing in that it can control directivity down to ~110hz all on its own. The top section alone competes well with some very expensive active system that can show a polar plot with directivity control that low.
Since the 110hz crossover to the woofers is so low, once could easily just crossover to a normal separate subwoofer. There are pros and cons, but you do gain some flexibility in position the subwoofer in an optimal location for maximum gain and room mode optimization for a (single) listening position.
I’d personally rather the dipole bass than a separate single sub.
But since this is an active design using a MiniDSP, we can easily create a bass optimized cluster of 2-4 subwoofers acting as one subwoofer. With REW, we can take measurements from every listening position * every subwoofer, then use a tool like MSO to run an joint optimization algorithm to EQ and phase adjust each sub individually, such that we get the smoothest summed bass response for every listening position on the room. The subs act like active bass traps for each other. And we can also optimize the “splice” such that the crossover of each speaker to the optimized subwoofer array does not cause any phase cancellations either. A MiniDSP Flex 2x8 would be perfect for this, with the 2-way tops and 2-4 subwoofers all going thru the same unit.
In my own experience with my Linkwitz Orions, I was never able to a good bass response in my last room owing to room modes I could never tame. I had some big suck outs below Schroeder frequency. Both my listening position and speaker placement in the room had limited flexibility.
When I eventually introduced a bass array (acting as a single, jointly optimized subwoofer), I was able to get a perfect bass response in all listening positions. In that room, I’m running 3 sealed dual opposed 12” subwoofers. Because the room dictates bass response below Schroeder, one really needs multiple subwoofers jointly optimized to deal with every mode. Floyde Toole is not a fan of dipole bass because it’s difficult to optimize.
So I’m curious what you think about “giving up” dipole bass. I love the sound of dipole bass, but i’ve run into problems in some rooms. With multiple subwoofers, there are some other advantages, such as placement flexibility. For example, the dipole tops can be a few feet into the listening room away from the rear wall, but the subwoofers can be along the rear wall or corners, both eliminating SBIR and adding a ton of gain and headroom in the sub range. And there would be no bad seats for bass, similar to no bad seats for the directivity controlled tops. The complexity of full dipole vs having the bass array is debatable, but I personally think it’s pretty easy to take the measurements and run the software to set up the bass array. Some might be more comfortable building a 3 way the introducing separate subwoofers.
I’m starting to noodle on these things because I’m looking to build speakers for both my living room, and home theater room in my new house. I’m thinking maybe a beautiful dipole for the former and something like a MEH/Unity/Synergy horn design for the latter.
Then I just checked your site and saw your new design and found your corner on this forum.
The papers and this new design got me thinking about bass tradeoffs.
In short, I’m curious what you think about the the importance of having dipole bass below 100hz, vs a jointly optimized bass array of 2-4 subwoofers, as advocated by Floyd Tool and Earl Geddes?
For example, the top section for Bitches Brew is amazing in that it can control directivity down to ~110hz all on its own. The top section alone competes well with some very expensive active system that can show a polar plot with directivity control that low.
Since the 110hz crossover to the woofers is so low, once could easily just crossover to a normal separate subwoofer. There are pros and cons, but you do gain some flexibility in position the subwoofer in an optimal location for maximum gain and room mode optimization for a (single) listening position.
I’d personally rather the dipole bass than a separate single sub.
But since this is an active design using a MiniDSP, we can easily create a bass optimized cluster of 2-4 subwoofers acting as one subwoofer. With REW, we can take measurements from every listening position * every subwoofer, then use a tool like MSO to run an joint optimization algorithm to EQ and phase adjust each sub individually, such that we get the smoothest summed bass response for every listening position on the room. The subs act like active bass traps for each other. And we can also optimize the “splice” such that the crossover of each speaker to the optimized subwoofer array does not cause any phase cancellations either. A MiniDSP Flex 2x8 would be perfect for this, with the 2-way tops and 2-4 subwoofers all going thru the same unit.
In my own experience with my Linkwitz Orions, I was never able to a good bass response in my last room owing to room modes I could never tame. I had some big suck outs below Schroeder frequency. Both my listening position and speaker placement in the room had limited flexibility.
When I eventually introduced a bass array (acting as a single, jointly optimized subwoofer), I was able to get a perfect bass response in all listening positions. In that room, I’m running 3 sealed dual opposed 12” subwoofers. Because the room dictates bass response below Schroeder, one really needs multiple subwoofers jointly optimized to deal with every mode. Floyde Toole is not a fan of dipole bass because it’s difficult to optimize.
So I’m curious what you think about “giving up” dipole bass. I love the sound of dipole bass, but i’ve run into problems in some rooms. With multiple subwoofers, there are some other advantages, such as placement flexibility. For example, the dipole tops can be a few feet into the listening room away from the rear wall, but the subwoofers can be along the rear wall or corners, both eliminating SBIR and adding a ton of gain and headroom in the sub range. And there would be no bad seats for bass, similar to no bad seats for the directivity controlled tops. The complexity of full dipole vs having the bass array is debatable, but I personally think it’s pretty easy to take the measurements and run the software to set up the bass array. Some might be more comfortable building a 3 way the introducing separate subwoofers.
I’m starting to noodle on these things because I’m looking to build speakers for both my living room, and home theater room in my new house. I’m thinking maybe a beautiful dipole for the former and something like a MEH/Unity/Synergy horn design for the latter.
@Yourmando great question. I'm not any sort of "dogmatist" about how one should approach this. My "heretical" Flanagangsters being proof of this. It's not what you do, it's how elegantly you do it.
One of the objectives of the Flanagangsters and the Bitches Brew was a relatively simple elegant design. Obviously one can throw as many parts and dollars and complexity as one can muster, but that gets unwieldy. I like both of these designs because they have relatively few components and almost resemble 2 1/2 ways instead of 3 ways; and since the Bitches Brews are also coax, it's almost as though there's no crossover. Very seamless.
As soon as you get into separate subs, you're in new territory with all new advantages and disadvantages.
Advantages: All of the room and bass response strategies you just named. I have not designed a multi-sub distributed system like you describe but I have no doubt you are right, and my good friend Tom Perazella who has written a lot of articles in AX and who has been a judge at Midwest Audiofest raves about how well this works.
So yes you can absolutely build a multi-sub system and integrate it with dipole mid-bass and it will surely sound great.
Disadvantages: Integrating the sub with the satellites. Phase alignment issues; physical position issues; room modes; crossover slopes; "speed" issues (for various reasons, the timbre between sub and sat often don't seem to match). Notice that I used 6dB electrical slopes in the woofer<>midrange xover of both of these designs, for precisely this reason.
So it would be very easy to solve all of your room mode bass problems and still feel like the subs and satellites don't seamlessly blend together.
My first Open Baffle project was the Faital Italian Dipoles using the excellent Faital 12HX230 coaxial driver https://s3.amazonaws.com/psma-website-assets/Faital_Coax_Dipoles_Plans.pdf
They do OK down to 40Hz then drop like a rock requiring a steep high pass 40Hz filter. They can play reasonably loud down to 40 Hz in that configuration. But if you push them they sound strained.
I used MiniDSP to cross them over to a pair of acoustic suspension Dayton Titanic 12" subs with 19mm xmax. Subs were placed in the corners of the room. Xover frequency 70Hz. Subs EQ'd flat down to 15Hz, with some notch filters to deal with room modes. Time adjusted so impulses line up.
Those 12" coax dipoles, crossed at 70Hz to those two 12" sealed subs, sounded FANTASTIC. In particular drums and toms had huge dynamic range and aliveness. The 97dB sensitivity really makes a difference. They sounded so effortless because they were relieved of the burden of low bass. With some recordings, they would punch you in the face and the chest at the same time. My friends were super impressed :^>
The crossover was pretty good but not seamless. I don't think most people would notice - but I could distinctly hear the difference between the dipole bass above 70 and the monopole bass below. It just had a different character.
Tom Perazella told me I should try the multi-sub config you mentioned; he said the culprit was not the monopole <> dipole issue. He suggested that, contrary to popular belief, corners among the worst places to put a sub.
I have never had a chance to test it out, and moving 4 subs all around in that room isn't realistic either.
A lot of subs that measure well still sound like well-articulated, low distortion thumps and just don't sound that musical. I don't know the exact reason but I have some hunches:
-Maybe it's that magical thing that makes high efficiency speakers sound better than low efficiency speakers. All things being equal, the lower the efficiency, the more dead and less lively a speaker sounds. There's a LOT of subs with 75-85dB efficiency and they can play loud with tons of power but there's something missing.
-Bass reflex speakers tuned around 20-30Hz have a lot of group delay and you can absolutely hear it. The thump arrives at a later date than the slap.
-Open Baffles sound more like "open windows." I realize they are still inefficient at 20-30Hz; and they have a lot of distortion at those low frequencies; but when EQ'd they do not have the group delay, and they just sound more natural to my ear. They don't sound thumpy even if you EQ them down to 20.
I would be very interested to see what the Bitches Brews sound like if you just sealed off the 2 lower woofers and used them in acoustic suspension mode instead of dipole. I suspect they'd sound great. They'd obviously play a whole lot louder below 35Hz than they do now. I think you could get away with crossing the 15" mid as low as 75Hz.
Might be even better to seal off only the bottom woofer and put a high pass on the middle woofer at 50Hz. Of course you wouldn't get the room placement flexibility but the crossover integration would be easier.
Tradeoffs, tradeoffs.
My hunch is you might get the best of all worlds if you set your crossover point at 40-50Hz and tried the distributed sub strategy you advocate. You also wouldn't need a full size Bitches Brew to do that. You could get away with a 2/3rds bitches brew (subtract the bottom woofer, make the cabinet 17" shorter, because it only needs one SB 15OB350), and the single 15's would easily handle 50Hz+ in dipole mode.
One of the objectives of the Flanagangsters and the Bitches Brew was a relatively simple elegant design. Obviously one can throw as many parts and dollars and complexity as one can muster, but that gets unwieldy. I like both of these designs because they have relatively few components and almost resemble 2 1/2 ways instead of 3 ways; and since the Bitches Brews are also coax, it's almost as though there's no crossover. Very seamless.
As soon as you get into separate subs, you're in new territory with all new advantages and disadvantages.
Advantages: All of the room and bass response strategies you just named. I have not designed a multi-sub distributed system like you describe but I have no doubt you are right, and my good friend Tom Perazella who has written a lot of articles in AX and who has been a judge at Midwest Audiofest raves about how well this works.
So yes you can absolutely build a multi-sub system and integrate it with dipole mid-bass and it will surely sound great.
Disadvantages: Integrating the sub with the satellites. Phase alignment issues; physical position issues; room modes; crossover slopes; "speed" issues (for various reasons, the timbre between sub and sat often don't seem to match). Notice that I used 6dB electrical slopes in the woofer<>midrange xover of both of these designs, for precisely this reason.
So it would be very easy to solve all of your room mode bass problems and still feel like the subs and satellites don't seamlessly blend together.
My first Open Baffle project was the Faital Italian Dipoles using the excellent Faital 12HX230 coaxial driver https://s3.amazonaws.com/psma-website-assets/Faital_Coax_Dipoles_Plans.pdf
They do OK down to 40Hz then drop like a rock requiring a steep high pass 40Hz filter. They can play reasonably loud down to 40 Hz in that configuration. But if you push them they sound strained.
I used MiniDSP to cross them over to a pair of acoustic suspension Dayton Titanic 12" subs with 19mm xmax. Subs were placed in the corners of the room. Xover frequency 70Hz. Subs EQ'd flat down to 15Hz, with some notch filters to deal with room modes. Time adjusted so impulses line up.
Those 12" coax dipoles, crossed at 70Hz to those two 12" sealed subs, sounded FANTASTIC. In particular drums and toms had huge dynamic range and aliveness. The 97dB sensitivity really makes a difference. They sounded so effortless because they were relieved of the burden of low bass. With some recordings, they would punch you in the face and the chest at the same time. My friends were super impressed :^>
The crossover was pretty good but not seamless. I don't think most people would notice - but I could distinctly hear the difference between the dipole bass above 70 and the monopole bass below. It just had a different character.
Tom Perazella told me I should try the multi-sub config you mentioned; he said the culprit was not the monopole <> dipole issue. He suggested that, contrary to popular belief, corners among the worst places to put a sub.
I have never had a chance to test it out, and moving 4 subs all around in that room isn't realistic either.
A lot of subs that measure well still sound like well-articulated, low distortion thumps and just don't sound that musical. I don't know the exact reason but I have some hunches:
-Maybe it's that magical thing that makes high efficiency speakers sound better than low efficiency speakers. All things being equal, the lower the efficiency, the more dead and less lively a speaker sounds. There's a LOT of subs with 75-85dB efficiency and they can play loud with tons of power but there's something missing.
-Bass reflex speakers tuned around 20-30Hz have a lot of group delay and you can absolutely hear it. The thump arrives at a later date than the slap.
-Open Baffles sound more like "open windows." I realize they are still inefficient at 20-30Hz; and they have a lot of distortion at those low frequencies; but when EQ'd they do not have the group delay, and they just sound more natural to my ear. They don't sound thumpy even if you EQ them down to 20.
I would be very interested to see what the Bitches Brews sound like if you just sealed off the 2 lower woofers and used them in acoustic suspension mode instead of dipole. I suspect they'd sound great. They'd obviously play a whole lot louder below 35Hz than they do now. I think you could get away with crossing the 15" mid as low as 75Hz.
Might be even better to seal off only the bottom woofer and put a high pass on the middle woofer at 50Hz. Of course you wouldn't get the room placement flexibility but the crossover integration would be easier.
Tradeoffs, tradeoffs.
My hunch is you might get the best of all worlds if you set your crossover point at 40-50Hz and tried the distributed sub strategy you advocate. You also wouldn't need a full size Bitches Brew to do that. You could get away with a 2/3rds bitches brew (subtract the bottom woofer, make the cabinet 17" shorter, because it only needs one SB 15OB350), and the single 15's would easily handle 50Hz+ in dipole mode.
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Indeed, these are relatively simple and elegant designs. Simpler and better looking than others I have put together, oh and better directivity control too. And more dynamic...
It’s true that this is a common problem with sub/satellite integration. But this is also easily solved with a tool like MSO. I mentioned above that it has the ability to “optimize the splice” between sub and sats. So you can use it to both create the optimized pool of subs with the right eq, delay, and phase adjustments, as well as to optimize the phase between sub and sat. MSO generates all-pass filters that can be applied in the crossover region to each speaker so that it is in phase with the subwoofer in order to get a smooth sub/sat blend.
This type of process is done by theater room calibrators every day. It’s a bit different skill set than speaker design, but it’s pretty automated with a tool like MSO. We’re more in the realm of room optimization at low bass frequencies, so this added complexity makes sense. (With a receiver with Dirac Live Bass Control, it is fully automated, but you’d need to use a receiver with this feature.) A speaker builder using a MiniDSP can do the same exact thing in the same unit as the active crossovers, as long as there are enough outputs as with the MiniDSP Flex 2x8.
Awesome!
Give multi-sub a try!
About corner placement, I’ve seen a few arguments. The most famous paper(s) on multi-sub placement are by Todd Welti, who found that the mid-points on walls, 1/4 & 3/4 position on walls, and corners were some of the best placement options. The corners were the 2nd or 3rd best option of the above, but by a small margin, according to the room models. Actually, the “best“ placement is 4 subs all away from the walls at 1/4 and 3/4 positions—so near every corner but 1/4 length away from both the side and rear walls (and maybe even floor/ceiling). This kills the most length and width axial room modes because they are placed in them. But that’s impractical because the subs are so far in the room.
Then you have the practitioner perspective—home theater builders and calibrators that do multi-sub optimization every day. Basically, real rooms don’t follow models so well so the room modes usually show up in different places than predicted, due to not having perfectly rigid and dense surfaces, etc.
Anthonly Grimani, who has designed many high end CEDIA awarded theaters, has a rule of thumb: just use 4 subs and always place the subwoofers in the corners. He has found that the huge additional gain you get with corner placement outweighs the slight benefit of finding a more optimal woofer placement. He finds it unnecessary to either use locations that model better, or to hunt and measure for optimal locations, because the additional headroom you gain with corner placement gives you more room for optimizations, plus the extra gain is also usable, like doubling the number of subwoofers for free. Once you get up to 4 subwoofers, you pretty much never fail to get a perfectly optimized result, regardless of placement (assuming they are all separated), so then it’s a matter of what gives you the most bass/headroom. Placement matters hugely with 1 sub. With 2 subs, you could optimize many rooms in multiple positions with great placement. With 3 and 4 subs, you get diminishing returns and also placement isn’t a big issue anymore except for more gain. Anthony has several room acoustics talks on YouTube, including some specifically on multi-sub bass management .
I think I agree with all of that. For subs, I typically like sealed + high efficiency for those reasons.
I do love how dipoles sound like “open windows,” and I also love the sound of dipole bass. If I didn’t have issues below Schroeder frequency in that particular room, I might not have gone down the multiple subwoofer path. Not only do dipoles lack that boxy sound, but you also get the late reflections coming from the rear that are unique to dipole.
Your design alternatives with 1 or 2 woofers are interesting. I would worry again about getting an even enough bass response, because down there, the room is in control. Let‘s say I built a full Bitches Brew, then found that I have room mode issues again, requiring multi-subs.
I guess the approach would be to build a prototype first.
- Get a MiniDSP Flex 2x8 so I have extra outputs if needed (only $100 more than the 2x8).
- Then, build a prototype Bitches Brew top with the 15” coaxial and rear horn tweeter.
- Run the Brew tops full range in a 20” wide test baffle, just for measurement purposes. I’d not be able to run them loud, but I should be able to get usable measurement sweeps.
- if I can get even bass across the entire listing area, the proceed to build the full Bitches Brew with beautiful slabs.
- if I have seat to seat consistency issues, then built a nice Brew Top on a nice slab without wings, then use an optimized 2-4 sub array and optimize the splice as well.
- if the seat to seat consistency issues are only down very low, then consider a variation such as you described above…and still use multiple subs for the problematic range.
It seems like the 2 simplest options are 1) full Bitches Brew, which also looks the best and 2) 2-way Bitches Brew wing-less top with multiple subs if there are bass consistency issues.
Thanks for the stimulating discussion and food for thought.
A friend told that his friend has noticed that it much easier to be forgiven than to get a permit.--- W have to be tuned for AF
@Yourmando
1) I have another theory about my Faital dipoles and 12" Dayton Subs sounding very good but not blending perfectly:
My room is a small library 12 feet x 14 feet with 9 foot ceiling, with bookshelves and three doors. It has very limited placement options for a sub.
My 12" Dayton subs are in a 1 cubic foot box. Fb is 48Hz and they need a LOT of EQ to go flat to 15Hz. If you have a 300 watt amp it all looks perfect on paper and it certainly does shake the house. (By the way I also added accelerometers and motional feedback circuits to my 12" Titanic subs, which cut distortion by 10dB or more.)
But small speakers EQ'd for deep bass always sound "boxy". Doesn't seem to matter what you do. It's true with ported speakers too. I love DSP, I wrote an article for AudioXpress called "The DSP Assisted Reflex" because you can do some super cool stuff by bending the rules all over the place.
But the damaging admission I have to make is that a small low efficiency speaker can be pretty darn impressive, but it still sounds a little boxy and constrained and small and inefficient no matter how much lipstick you apply with EQ.
So... it could just be that getting 20Hz bass out of a 28 liter 12" sub is gonna sound boxy no matter what you do with your crossovers. Maybe that's why the low bass sounded 2-dimensional. Maybe the problem is not the room or the monopole output or the crossover or the room placement. Maybe if I used 100 liter / 4 cubic foot subs with my Faital Dipoles, it would blend perfectly.
(I'm sure a 3X bigger room would help too...)
The Bitches Brew dipoles are the size of a small refrigerator. I'm sure that helps them not sound boxy :^>
You and everyone else.... does this jive with your experience???
2) I have not tried the MSO tools or MiniDSP Flex 2x8. I anticipate one frustration with the Flex 2x8 though, which is that while the 2x4HD has 2K of FIR DSP for each of its 4 channels, the Flex 2x8 only has 2K of FIR DSP for the 2 stereo channels for the entire unit; and no FIR taps for the individual 8 channels.
Being a bit of a control freak, I would MUCH rather have FIR for individual channels, than to have to use the optional DIRAC plugins to achieve linear phase.
Maybe I'm being nitpicky, but I am an engineer after all! But this speaks to all the issues we're discussing here. Because in order to attain the kind of crossover control at low frequencies that you and I are speaking about, we would need not just 2K taps on each of the 8 channels, you'd need more like 8 or 16K of taps for each channel. 2K of taps is only enough to do EQ above 150Hz or so.
The best you can do with Flex 2x8 is to build parametric, shelf and standard butterworth or LR filters, play with delay, and then fix everything with Dirac when we're done.
Am I correct about this?
1) I have another theory about my Faital dipoles and 12" Dayton Subs sounding very good but not blending perfectly:
My room is a small library 12 feet x 14 feet with 9 foot ceiling, with bookshelves and three doors. It has very limited placement options for a sub.
My 12" Dayton subs are in a 1 cubic foot box. Fb is 48Hz and they need a LOT of EQ to go flat to 15Hz. If you have a 300 watt amp it all looks perfect on paper and it certainly does shake the house. (By the way I also added accelerometers and motional feedback circuits to my 12" Titanic subs, which cut distortion by 10dB or more.)
But small speakers EQ'd for deep bass always sound "boxy". Doesn't seem to matter what you do. It's true with ported speakers too. I love DSP, I wrote an article for AudioXpress called "The DSP Assisted Reflex" because you can do some super cool stuff by bending the rules all over the place.
But the damaging admission I have to make is that a small low efficiency speaker can be pretty darn impressive, but it still sounds a little boxy and constrained and small and inefficient no matter how much lipstick you apply with EQ.
So... it could just be that getting 20Hz bass out of a 28 liter 12" sub is gonna sound boxy no matter what you do with your crossovers. Maybe that's why the low bass sounded 2-dimensional. Maybe the problem is not the room or the monopole output or the crossover or the room placement. Maybe if I used 100 liter / 4 cubic foot subs with my Faital Dipoles, it would blend perfectly.
(I'm sure a 3X bigger room would help too...)
The Bitches Brew dipoles are the size of a small refrigerator. I'm sure that helps them not sound boxy :^>
You and everyone else.... does this jive with your experience???
2) I have not tried the MSO tools or MiniDSP Flex 2x8. I anticipate one frustration with the Flex 2x8 though, which is that while the 2x4HD has 2K of FIR DSP for each of its 4 channels, the Flex 2x8 only has 2K of FIR DSP for the 2 stereo channels for the entire unit; and no FIR taps for the individual 8 channels.
Being a bit of a control freak, I would MUCH rather have FIR for individual channels, than to have to use the optional DIRAC plugins to achieve linear phase.
Maybe I'm being nitpicky, but I am an engineer after all! But this speaks to all the issues we're discussing here. Because in order to attain the kind of crossover control at low frequencies that you and I are speaking about, we would need not just 2K taps on each of the 8 channels, you'd need more like 8 or 16K of taps for each channel. 2K of taps is only enough to do EQ above 150Hz or so.
The best you can do with Flex 2x8 is to build parametric, shelf and standard butterworth or LR filters, play with delay, and then fix everything with Dirac when we're done.
Am I correct about this?
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