Easier to explain when I post pics later ...
If you look at my 'S19' basically I'm using upper half of the sub as monopole (block the rear using a plank of wood). So 1x sealed sub each side. Disconnect the lower woofers.
What I will do later is block both opening of the sub, voila... 2x monopoles per side, push-pull. = 4x monopoles for stereo.
Why don't do it now? Because I ran out of MDF!
edit: I still didn't like it that a 'full dipole' is not the answer to all things. But whatever works I guess.
If you look at my 'S19' basically I'm using upper half of the sub as monopole (block the rear using a plank of wood). So 1x sealed sub each side. Disconnect the lower woofers.
What I will do later is block both opening of the sub, voila... 2x monopoles per side, push-pull. = 4x monopoles for stereo.
Why don't do it now? Because I ran out of MDF!
edit: I still didn't like it that a 'full dipole' is not the answer to all things. But whatever works I guess.
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gainphile, what topology is your xo to low bass? I found that LR4 was too deep, it left 100-200-300Hz room response too low.
LR2 sounds best, eg. drums have the natural pressurizing feel and yet I can locate each can when they are panned like in drum solos. Also well recorded double bass and tubas etc. can be localized easily.
Despite of the dspersion model, I think that overall room response is most important factor. My current system works well - nearfield response is straight and room response is declining to highs. Bass level around 50-200Hz is 5-10dB above 1000Hz, which is 2dB above 5000Hz. Of course at low levels even this house curve sounds too lean because of ear/brain loudness curve.
LR2 sounds best, eg. drums have the natural pressurizing feel and yet I can locate each can when they are panned like in drum solos. Also well recorded double bass and tubas etc. can be localized easily.
Despite of the dspersion model, I think that overall room response is most important factor. My current system works well - nearfield response is straight and room response is declining to highs. Bass level around 50-200Hz is 5-10dB above 1000Hz, which is 2dB above 5000Hz. Of course at low levels even this house curve sounds too lean because of ear/brain loudness curve.
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Yes, it had been discussed elswhere by JohnK, Gedlee etc. that speaker dispersion at lower frequencies are moot point. Dipoles, for example will not form in-room at 100hz or below etc.
I am using textbook 80hz LR4, sounds great. There's the typical modes showing which I am not content to fix yet.
What I am sure of from this exercise is dipoles simply can't pressurize the room at the lowest octave, and to me at least this is a problem.
Perhaps an ideal solution is Orion++ after all. Dipole all the way to 40hz then a pair of massive sealed subs (Thor). I wonder why it was left out of Orion4 and LX521. Surely the lack of bass is readily noticable?
I am using textbook 80hz LR4, sounds great. There's the typical modes showing which I am not content to fix yet.
What I am sure of from this exercise is dipoles simply can't pressurize the room at the lowest octave, and to me at least this is a problem.
Perhaps an ideal solution is Orion++ after all. Dipole all the way to 40hz then a pair of massive sealed subs (Thor). I wonder why it was left out of Orion4 and LX521. Surely the lack of bass is readily noticable?
Room pressurization is possible below first (lowest) room mode which is typically 40-50Hz, in large rooms around 30Hz. Mode excitation is moot and discussed a lot. SL and JK know more of this yes but they largely disagree at many practical issues.
SL listens mostly to classical music where lows don't have much energy or transients. He suggests placing dipole woofers at least 1,5m from front wall and also at home has a rather large room. I don't know of JK's music taste but he emphasizes small room acoustics and says that only way to hear dipole low bass "energy" is to Place it in the nearfield.
This dilemma is well known and many people have strong opinions about it. I have not even tried to make the dipole to xo below 100Hz. I can't place a dipole sub capable of that in my living room. A well balanced multisub system and preferably with delay management ála CABS woudl be ideal to me, but again my room is not symmetrical and I don't have room for 4 separate subs. So - a "sub" for each main channel is my practical choise. I get measurable pressurization below 40Hz, enough to make response straight from 16Hz up. Two bass radiators help to mix room modes/response to tolerable level. dsp-controlled fully adjustable xo, eq, delay and gain are needed to do that.
It is sort of a compromise yes, like any system!
SL listens mostly to classical music where lows don't have much energy or transients. He suggests placing dipole woofers at least 1,5m from front wall and also at home has a rather large room. I don't know of JK's music taste but he emphasizes small room acoustics and says that only way to hear dipole low bass "energy" is to Place it in the nearfield.
This dilemma is well known and many people have strong opinions about it. I have not even tried to make the dipole to xo below 100Hz. I can't place a dipole sub capable of that in my living room. A well balanced multisub system and preferably with delay management ála CABS woudl be ideal to me, but again my room is not symmetrical and I don't have room for 4 separate subs. So - a "sub" for each main channel is my practical choise. I get measurable pressurization below 40Hz, enough to make response straight from 16Hz up. Two bass radiators help to mix room modes/response to tolerable level. dsp-controlled fully adjustable xo, eq, delay and gain are needed to do that.
It is sort of a compromise yes, like any system!
No problems there. Pure dipole range for both. The "problem" is highish distortion of double 4" drivers, but I can't hear that. The real problem I have is around 2kHz but I believe that I have a solutuion knockin at my door! Check my thread http://www.diyaudio.com/forums/multi-way/231353-aino-gradient-collaborative-speaker-project.html
More like doesn’t have any energy below 35-40 Hz. And in any case there is no “pressurization” in the concert hall . . . “pressurization” is a tool used to extend bass response in a small room (especially for “special effects"), but the price is that it does not accurately replicate the “character” of the original, especially if carried too high in frequency.
My listening room is both (relatively) large and possessed of walls and ceiling that are acoustically transparent at low bass frequencies, so “pressurization” is not an option for me even if I wanted it . . . but it is not an “issue” since the clarity of non-reverberant non-pressurized bass in the acoustic instrument range is exactly what I’m looking for. I’m sure I’d be seeing the issue differently if I were listening in a 12x16 ft. concrete walled “man cave”.
Dipoles don’t “pressurize the room” at any frequency, and that’s not really an issue . . . there is no “lack of bass” for acoustic sources with any of those speakers. And a subwoofer is not “left out” of the later ORION or LX521 any more than it was “left out” of the original ORION . . . you can add a subwoofer to any of them for “special effects” sounds, but it’s not needed for any “acoustic” source, unless necessary to deal with room problems or to play at “louder than life” levels.
Yes, they all are . . . "compromised" in one way or another . . .
I think dewardh has pointed out the key to a lot of the bass issues that led to this thread; Playing bass at louder than life is what many seek for many styles of music.
Gainphiles many prototypes led to his magnificent cabinet, and now he has it the bass isn't to his liking so cardoid, more power and now monopoles are being tried. One set of speakers and many music tastes to accomodate means compromises: but the benefits of dipoles and the implications of room modes are too interesting to lose out to a music dependant house curve, just yet.
Continuing the thread of thoughts on gainphiles migration to a monopole bass: In the context of the analysis here: Dipole_modesA, what is everyones thoughts or experiences on running the two channels of monopoles in mono rather than stereo? Spacially distributed multiple monopole sources would be directionally correct for reducing density of excited modes, for whatever that might be worth in each unique application. This was fashionable decades ago and works for me in either standard placement or dipole near field placement.
Going a step further, is there merit in assessing the system as a 4.5 way (or whatever it is) with the single driver Monopole for each speaker covering the range 20-40 Hz and the single driver dipole covering 20-80Hz. With left and right speakers running the same signal (ie mono rather than stereo) this would be still within the signal handling capability of the MiniDSP 4x2 and two channels of bass amplifiers?
Gainphiles many prototypes led to his magnificent cabinet, and now he has it the bass isn't to his liking so cardoid, more power and now monopoles are being tried. One set of speakers and many music tastes to accomodate means compromises: but the benefits of dipoles and the implications of room modes are too interesting to lose out to a music dependant house curve, just yet.
Continuing the thread of thoughts on gainphiles migration to a monopole bass: In the context of the analysis here: Dipole_modesA, what is everyones thoughts or experiences on running the two channels of monopoles in mono rather than stereo? Spacially distributed multiple monopole sources would be directionally correct for reducing density of excited modes, for whatever that might be worth in each unique application. This was fashionable decades ago and works for me in either standard placement or dipole near field placement.
Going a step further, is there merit in assessing the system as a 4.5 way (or whatever it is) with the single driver Monopole for each speaker covering the range 20-40 Hz and the single driver dipole covering 20-80Hz. With left and right speakers running the same signal (ie mono rather than stereo) this would be still within the signal handling capability of the MiniDSP 4x2 and two channels of bass amplifiers?
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I am too running a waveguide + cardioid + monopole bass setup and I'm very happy with the results. I have 4x 7" woofers in cardioid per speaker and I tried running them without a subwoofer but it didn't work. I'd say from around 40Hz down the excursion was way too much. I crossed over to a subwoofer at 80Hz LR4 and I could barely feel them moving when touching the cone.
I can't say what the ideal crossover point is but I saw an extreme difference of excursion in just the range of an octave. I think protecting the woofers from excessive excursion should take priority over room mode concerns. My take is that any point below 100Hz that allows for comfortable excursion should do.
I begin to see irregularities as early as 200Hz in some parts of the room, particularly close to the walls. I'm not sure if a monopole speaker will help there but my subwoofer won't allow me crossover that high anyway. With some EQ on the sub I can get fairly smooth bass measurements in the middle of the room and it sounds very good.
I can't say what the ideal crossover point is but I saw an extreme difference of excursion in just the range of an octave. I think protecting the woofers from excessive excursion should take priority over room mode concerns. My take is that any point below 100Hz that allows for comfortable excursion should do.
I begin to see irregularities as early as 200Hz in some parts of the room, particularly close to the walls. I'm not sure if a monopole speaker will help there but my subwoofer won't allow me crossover that high anyway. With some EQ on the sub I can get fairly smooth bass measurements in the middle of the room and it sounds very good.
There is no problem mixing monopole subs with dipoles, a classic combination being stacked quads with 2x15 bass unit. I know, because I had this set up back in the 70's.
I recently simulated the capability of a 6 x 15" dipole and the results were as expected. With a -3dB of around 35Hz, the 6 x 15 was only capable of handling single figure watts before Xmax of 4mm was exceeded. You could of course use greater Xmax drivers but power handling is still poor. Having said that, the efficiency was high and levels of around 105dB were possible. Loudspeakers behave as band pass filters, so you could use drivers with substantially more Xmax, but you tend to find these drivers are around 10dB less efficient than "pro drivers".
I know some pro 15's have Xlimits of anything up to 65/70mm but of course they are no longer "linear" and distortions rise...
A very different story emerged as soon as you implemented a crossover around 80-100Hz...now power handling for Xmax exceeded the rated power handling of the driver and the 6 x 15 was now capable of 130dB+ whilst remaining within Xmax...
Plus of course if you have 2 x monopole subs you can create 2 x monopole or 1 x dipole back to back..or even 2 x cardioid back to back or side to side implementing required delay, easily achieved in dsp. Latency isn't an issue at these wavelengths plus you have the benefit, if it makes you happy, to use the dsp delays to "align" the subs with the satellites...again, mostly futile unless you live in a stadium!!
I recently simulated the capability of a 6 x 15" dipole and the results were as expected. With a -3dB of around 35Hz, the 6 x 15 was only capable of handling single figure watts before Xmax of 4mm was exceeded. You could of course use greater Xmax drivers but power handling is still poor. Having said that, the efficiency was high and levels of around 105dB were possible. Loudspeakers behave as band pass filters, so you could use drivers with substantially more Xmax, but you tend to find these drivers are around 10dB less efficient than "pro drivers".
I know some pro 15's have Xlimits of anything up to 65/70mm but of course they are no longer "linear" and distortions rise...
A very different story emerged as soon as you implemented a crossover around 80-100Hz...now power handling for Xmax exceeded the rated power handling of the driver and the 6 x 15 was now capable of 130dB+ whilst remaining within Xmax...
Plus of course if you have 2 x monopole subs you can create 2 x monopole or 1 x dipole back to back..or even 2 x cardioid back to back or side to side implementing required delay, easily achieved in dsp. Latency isn't an issue at these wavelengths plus you have the benefit, if it makes you happy, to use the dsp delays to "align" the subs with the satellites...again, mostly futile unless you live in a stadium!!
Ah, memories... I have been running LR2@150Hz xo for 3 years now, after 4 years of experiments. Speaker placement and furniture are the same. i use only low Q tonal eq adjustment, nothing for the high peaks. My "subs" are SEAS L26Ry sealed in 40L boxes. 6dB Q=0.8 shelf at 45hz to boost lowest freqs.
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Yes, bass is tricky stuff! In terms of polar responses and interference a good starting point is EV's laps 2 software..
It can't replicate a domestic listening space that well but will give you a good starting point. As we know a pair of monopole satellites used full range can be a disaster in terms of "bass alley" cancellation and lobing.
A pair of dipoles avoids this problem in the octaves from low bass to 150Hz or so but the tricky area is the all Important 150-250ish! After that both monopole and dipole perform in a similar fashion...in a perfect world!
It's probably the case that your ears and a range of different music styles will still be your best route. After all, it's you that has to listen to it!
My point was having a bass system that can be configured as monopole, dipole or cardioid may give you the best chance of optimising the system?
It can't replicate a domestic listening space that well but will give you a good starting point. As we know a pair of monopole satellites used full range can be a disaster in terms of "bass alley" cancellation and lobing.
A pair of dipoles avoids this problem in the octaves from low bass to 150Hz or so but the tricky area is the all Important 150-250ish! After that both monopole and dipole perform in a similar fashion...in a perfect world!
It's probably the case that your ears and a range of different music styles will still be your best route. After all, it's you that has to listen to it!
My point was having a bass system that can be configured as monopole, dipole or cardioid may give you the best chance of optimising the system?
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