I found merit in this thinking. Often I miss that *sheer* slam of Monopole Subwoofers.
So what's a good Dipole to Monopole xo frequency for the bass? I have tried from 120hz down to 80hz. At 120 hz the disconnect is noticable, and surprisingly good enough at 80hz. Any lower I'm afraid to put too much strain on the dipole woofers (Seas W22).
According to JohnK's resource below 80hz also seem to have passed the boundary effect of monopoles.
www.musicanddesign.com/Boundary_reflections.html
btw. It's pretty easy to convert W-Frame subs as push-pull monopoles !
The 8" W22 is the ORION midrange . . . ORION uses two high-excursion 10" in an "H" frame for woofers. ORION owners who add subwoofers (which are seldom if ever necessary for "acoustic" or "orchestral" music) typically cross to them at 40-50 Hz.
I had a pair of 12s a side with mine, and still needed a sub. And still blew a couple.
I also wonder what the thrashing of a dipole bass unit as it attempts to go low does to distortion, vibration etc etc.
My current feeling is that the easy availability of EQ for monopole subs, and use of multiples has reduced the qualitative advantage of dipole bass to the extent that the negatives of numerous drivers and massive EQ make it more trouble than it is worth.
Given an Orion can get down to 90 with a single W22 (per the 3.0 and above) wouldn't it make sense to simply lop off the most expensive and troublesome part? I find it increasingly odd to spend more than 70% of the cost of the speaker just to cover one octave.
The Lyngdorf concept of dipole satellites out in the room and stereo boundary woofers with EQ makes sense to me. Since I happen to have a pair of Rythmik servo subs, plus a Velodyne servo for LFE, plus MiniDSPs and ARC room correction from my Anthem prepro I may as well give it a bash.
Certainly trying it with my Apogees produced exceptionally good subjective and measured results.
So to answer your question Andi, it depends if you have stereo subs or not. If yes, then 90hz should be OK. If not, 60hz for me.
I also wonder what the thrashing of a dipole bass unit as it attempts to go low does to distortion, vibration etc etc.
My current feeling is that the easy availability of EQ for monopole subs, and use of multiples has reduced the qualitative advantage of dipole bass to the extent that the negatives of numerous drivers and massive EQ make it more trouble than it is worth.
Given an Orion can get down to 90 with a single W22 (per the 3.0 and above) wouldn't it make sense to simply lop off the most expensive and troublesome part? I find it increasingly odd to spend more than 70% of the cost of the speaker just to cover one octave.
The Lyngdorf concept of dipole satellites out in the room and stereo boundary woofers with EQ makes sense to me. Since I happen to have a pair of Rythmik servo subs, plus a Velodyne servo for LFE, plus MiniDSPs and ARC room correction from my Anthem prepro I may as well give it a bash.
Certainly trying it with my Apogees produced exceptionally good subjective and measured results.
So to answer your question Andi, it depends if you have stereo subs or not. If yes, then 90hz should be OK. If not, 60hz for me.
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My approach with AINOgradient is to xross mono/dipole around 130-150Hz LR4. I have tried lower and higher, LR2 and LR4. I use a single 12" as lowest dipole and it heeds HEAVY eq if I want to cross below 100Hz. I get the floor cancellation around 200Hz, this is why I want the mono woofer to give some output up to there. Room/power response at farfield is the main goal, outdoor/pseudoanechoid/nearfield measurements are needed too , but real "end user" environment is the final goal, with all it's reflectins and cancellations. Listening tests are very important too. Poor delay/phase match leads to missing "oomph" Well tuned closed subs sound very clean and twin "subs" help to alleviate room mode problems.
Mono+dipole=cardioid
This is difficult in practise, because of nearness of walls. In the crossing range there is a measurable cardioid response area, quite wide with LR2, narrow with LR4
A friend has an excellent dipole system down to 30Hz with 2xSLS12 in H-frames. There is wild excursion at his rather loud listening spl, but sound is good. I wonder that distortion must be quite high. He has a special room, most people don't.
dsp eg. minidsp is a wonderful helper with these tests!
My room response 300ms left and right. Speakers are at similar position to front and side walls, but back wall is different - low modes are different.
Mono+dipole=cardioid
This is difficult in practise, because of nearness of walls. In the crossing range there is a measurable cardioid response area, quite wide with LR2, narrow with LR4
A friend has an excellent dipole system down to 30Hz with 2xSLS12 in H-frames. There is wild excursion at his rather loud listening spl, but sound is good. I wonder that distortion must be quite high. He has a special room, most people don't.
dsp eg. minidsp is a wonderful helper with these tests!
My room response 300ms left and right. Speakers are at similar position to front and side walls, but back wall is different - low modes are different.
Attachments
In addition to the first link, this may be of interest, Crossovers between different sources types
You may also remember the NaO Mini which used a midrange/tweeter panel, similar to the NaO II, coupled to monopole woofer. The idea was that in the crossover region between the mids and woofers the polar response would undergo a transition from dipole to cardioid at the crossover point, and then to monopole at low frequencies. The intermediate cardioid response is in the 100 Hz region, typically the range where reflections from the wall behind the speaker have an impact on the response. Also note that the boundary effects are only part of the story as the full modal response needs to be considered.
The thing I had noticed with dipole woofers is that you do indeed loose bass as the speakers are pushed toward the wall behind them. The image source for the dipole woofer forms a compound dipole with 12dB/octave roll off so that an additional 6dB/oct eq is required. More importantly, since the woofer response is affected by distance to the wall it makes it more difficult to position the speakers to optimize the midrange. I notice this as a significant difference when setting up the NaO II RS and the Note II RS in the same room. With both speakers designed for flat response, when the speakers are placed similarly the NaO II RS has significantly stronger bass response at low frequency. It is easily compensated for with additional bass eq for the Note, but it does place additional demands on the woofers.
You may also remember the NaO Mini which used a midrange/tweeter panel, similar to the NaO II, coupled to monopole woofer. The idea was that in the crossover region between the mids and woofers the polar response would undergo a transition from dipole to cardioid at the crossover point, and then to monopole at low frequencies. The intermediate cardioid response is in the 100 Hz region, typically the range where reflections from the wall behind the speaker have an impact on the response. Also note that the boundary effects are only part of the story as the full modal response needs to be considered.
The thing I had noticed with dipole woofers is that you do indeed loose bass as the speakers are pushed toward the wall behind them. The image source for the dipole woofer forms a compound dipole with 12dB/octave roll off so that an additional 6dB/oct eq is required. More importantly, since the woofer response is affected by distance to the wall it makes it more difficult to position the speakers to optimize the midrange. I notice this as a significant difference when setting up the NaO II RS and the Note II RS in the same room. With both speakers designed for flat response, when the speakers are placed similarly the NaO II RS has significantly stronger bass response at low frequency. It is easily compensated for with additional bass eq for the Note, but it does place additional demands on the woofers.
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Kimmo Saunisto nick "kimmosto" has measured cardioid vs dipole woofers in a room, go to his homepage and to "Cardioid bass"
This is not presented at pages, but it has twin cardioid bass boxes, cardioid mids and monopole treble.
Leo Kirchner has developed a V-frame double dipole-cardioid bass speaker and it was measured outdoors. and partially in a room http://www.kirchner-elektronik.de/~kirchner/DIPOL-CARDIOIDeng.pdf where Fig. 3.16 shows that in a room, response drops rapidly below 50Hz.
Troublesome... Web contains lots of inof about cardioid bass arragement for large halls (PA). But we have walls at home...
This is not presented at pages, but it has twin cardioid bass boxes, cardioid mids and monopole treble.
An externally hosted image should be here but it was not working when we last tested it.
Leo Kirchner has developed a V-frame double dipole-cardioid bass speaker and it was measured outdoors. and partially in a room http://www.kirchner-elektronik.de/~kirchner/DIPOL-CARDIOIDeng.pdf where Fig. 3.16 shows that in a room, response drops rapidly below 50Hz.
Troublesome... Web contains lots of inof about cardioid bass arragement for large halls (PA). But we have walls at home...
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This is not about dipoles, but an example that 150Hz xo worked better than 110Hz
NHT Xd active loudspeaker system Follow-Up Measurements | Stereophile.com
NHT Xd active loudspeaker system Follow-Up Measurements | Stereophile.com
I see the Lyngdorf crosses it's 6.5" dipole mid satellites to the separate woofer units at 300Hz.
Lyngdorf Audio - Loudspeakers
This seems to fly in the face of conventional wisdom regarding LF localization and the dipole to monopole transition. Can DSP/room correction really make this work?
Lyngdorf uses 2 woofers and dsp. Yes it works but xo is a bit too high to my taste. These woofers will produce lots of transients eq. for drum sound, and they will be localized. The benefit is elimination of typical floor bounce. Never heard them though and I see many sets for sale on forums...
What about Bass U-frame : DIpole Vs Cardioid : Near a dipole without damping but can be set up with extensive damping and good length to beam cardioid with (more easy than true cardioid bass box )?
Is there a great interest to have a dipole woofer... 90 to something 300 hz vs a good damped closed box ?
Is there a great interest to have a dipole woofer... 90 to something 300 hz vs a good damped closed box ?
That analysis is very limited. It's one dimensional and doesn't consider orientation of the dipole. It's designed to show the best case scenario for the dipole. Additionally, the optimal position for a monopole woofer is different than that for a dipole.
To see a more realistic analysis look here Modal Analysis-Frequency Response and here Modal Analysis-Transient Response
On the 1st link, skip the math and scroll down to the first figure (on the left) where the text starts "To demonstrate the utility of this approach to estimating the behavior..."
On the 2nd link skip down to below Eq 15 and look at the plots of impulse response. In particular, look at the 3rd set of 3 plots where the dipole and cardioid are orientated at 45 degrees from the room axis.
Hi,
For myself understanding : is it important below 90 hz ?
Do we have avoid U-frame design > 90 hz ?
Yes, and Linkwitz correctly recognizes that "theoretical" analysis quickly degrades to meaningless when the behavior of real rooms (and listener preference) is factored in.
My experience is similar to that of Linkwitz: while “theoretical” analysis of woofer/subwoofer performance is not only useful but essentially necessary for determining equalization (getting “in the ballpark”) it is all but useless in describing the real behavior of real speakers in all but the most simple of real rooms. All speakers will excite room modes (some more than others), and the differences in perceived bass “quality” will depend on which modes and how many modes are excited. The reason(s) for the difference(s) are simple and obvious:
Room “modes” are resonances, and all resonances degrade both frequency and impulse response.
It is a clear advantage of dipole woofers that when co-located with a dipole midrange in a room position (and room) favorable to the latter the dipole woofer will excite fewer room modes, and those it does excite will be of (typically) lower intensity than either a monopole or cardiod. The resulting perception will be of “less”, but typically “cleaner” (more “accurate” or “true to the original”) bass. This “accuracy” is mooted for “electronic” source material below the human vocal range (electric bass or movie sound effects), where “boom” rules and there is no “original” sound to be accurately “reproduced”. For acoustic sources, however, freedom from (or reduction of) room resonances in the bottom octave (80 to 40 Hz.) often has substantial perceived benefit and a resultant strong preference for dipole woofers among listeners who prefer, or optimize for, the reproduction of orchestral or small acoustic ensemble sources. For HT and rock-and-roll, however, it is hard to make an argument “for” dipole woofers (or dipole speakers at all, for that matter), and all but impossible to justify a dipole subwoofer in any case, since “accuracy” is not a primary subwoofer goal.
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Yes? Has this shown to be true? What is "favorable to the latter" in this case?
Look at Make Your Sub Directional post.
From listening position monopole, dipole, and cardioid can be equalized to same response with virtually identical IR.
From this perspective I find dipole bass to be waste of driver excursion, and invitation for IMD.
From listening position monopole, dipole, and cardioid can be equalized to same response with virtually identical IR.
From this perspective I find dipole bass to be waste of driver excursion, and invitation for IMD.
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