Jussi said:
The NoBaffle was just a test to see (hear) how it would work after I noticed how much bass was possible from a 15 w/o a baffle on the floor when I was loosening up the surround of a new driver. While the 18db that I lose from Fequal down to 37hz seems huge at first glance, I've got to be getting very close to the full +6db from the floor boundary and probably some benefit from the side walls a meter away in the lowest octave. Then add in Linkwitz's # for the perceived gain from directivity of dipole bass, +4.8db, and the result is surprising. I end up adding 10db of shelving boost EQ at 30hz.
I often do things backwards from most and start with what I want the form to be, and then figure out how to make it work. Here's the baffle for the support structure above. I tried mounting the 8" Visaton to the baffle, and it vibrated too much, so I built the magnet mount pictured earlier.
Before the woofer cutout:
An externally hosted image should be here but it was not working when we last tested it.
Closer to complete:
An externally hosted image should be here but it was not working when we last tested it.
Hi John
Very nice looking work on your open baffles!
I do have some questions, if you allow me. You are using the B200 supported by its magnet. Can you tell me, or show a better picture, how you fastened the B200 to this support? I do have this driver too, mounted in open baffle at the moment, but am willing to do some more DIY'ing to mount it as you are doing. Still about the B200...how do you like it? I am sure you already have had and tested lots of fullrange drivers and I am curious how the B200 compares. Did you do any modification to its physical structure?
Another thing...I remember you were using dipole subwoofer in a W style. Did you completely quit them, and substituted for OB?
This days I was looking into the behringer DCX2496 again and its functions and I think it has got enough DSP power to tweak a two way open baffle speaker. Also modifying seems to be quite worthwhile, and not that hard. But you are using PC based crossover, do you think it is better and with more functions? Easier?
Just very curious, and with lots of question...
Thanks for the attention, Erik
Very nice looking work on your open baffles!
I do have some questions, if you allow me. You are using the B200 supported by its magnet. Can you tell me, or show a better picture, how you fastened the B200 to this support? I do have this driver too, mounted in open baffle at the moment, but am willing to do some more DIY'ing to mount it as you are doing. Still about the B200...how do you like it? I am sure you already have had and tested lots of fullrange drivers and I am curious how the B200 compares. Did you do any modification to its physical structure?
Another thing...I remember you were using dipole subwoofer in a W style. Did you completely quit them, and substituted for OB?
This days I was looking into the behringer DCX2496 again and its functions and I think it has got enough DSP power to tweak a two way open baffle speaker. Also modifying seems to be quite worthwhile, and not that hard. But you are using PC based crossover, do you think it is better and with more functions? Easier?
Just very curious, and with lots of question...
Thanks for the attention, Erik
Erik,
I'll PM you. I don't want to hijack Jussi's thread any more, especially since his project is more of an all out approach than my simple projects.
I'll PM you. I don't want to hijack Jussi's thread any more, especially since his project is more of an all out approach than my simple projects.
Jussi,
I wonder if the lack of enclosure (free from standing waves and box resonance) is the main reason we like dipole speakers. I found the sound from a dipole is cleaner, i.e. lower distortions. As for radiation patterns, etc, they are more concerned with interactions with the rooms. As far as sound is concerned if the rooms match / work with the speakers then there should not be much difference between open baffle speakers and enclosed speakers, apart from the free of box colourations.
From what I read people found dipole bass a lot more attractive. i.e. the main advantage of having a dipole speaker is that the bass is better. It does not appear that people strongly prefer the dipole midrange or treble. So why? One factor may be room-interaction, but I suspect that may be because at low frequencies the standing waves within the boxes can not be damped sufficiently which mess up the sound in a closed / ported box. Fibreglass or wool can provide adequate damping only with frequencies from perhaps 200Hz up. Nothing can be used to damp 100Hz sufficiently, for example. Think of the majority boxes out there the woofers are crossed at between 100Hz to 500Hz probably second order, so how can the standing waves be damped sufficiently? They can't be. And this must mess up the sound. Perhaps for that reason nearly every one hearing the dipole speakers likes them.
That leads me to re-think of the speakers I have. My WWMTMWW has the MTM part open back. But the wings on the side were so deep the speaker does not work as a dipole any more. For the midrange drivers they don't see the air spring behind them any more as if they are working in an infinite baffle. The XO is at 200Hz 3rd order so standing waves can be adequately treated. I have to say the MTM part, although not dipole, sounds very fine. But the bass of this speaker in ported enclosures is not good at all.
I said I am interested in trying a pair of 26W8661 in a sealed box with a Q of 0.7. This is also one stone to kill two birds. First, it may replace the NaO U-frame. The NaO U-frame has a quarter wave resonance that can't be fully damped (readers please note mine is the older NaO not the new NaO II that has the U-frame shortened so the first resonance frequency is raised). For the sealed enclosure the lowest resonance frequency is much higher in the next octave. So the sealed box will be free of resonances! Secondly, I have not done the maths but I guess 4 x 26W8661 10" in sealed boxes will less likely be bottomed when playing 40-Hz comparing to 2 x XLS 12" in the U-frames. Due to the lack of resonances, better quality drivers and the large size of my room they may turn out to be better than what it is now.
Secondly, if the U-frame still sounds better than the sealed box, I can use the sealed boxes to replace the WW parts of my WWMTMWW. 4 x 26W8661 10" in push-pull should sound much better than 8 x HDS 8" in ported enclosures. Because the first resonance of the sealed box will be at 300Hz, if the sealed box is fully stuffed and the 3rd order XO at 200Hz is applied, standing waves should not be a big problem.
Last, if they all fail, it would give me a perfect opportunity to do exactly what you are doing. With all the drivers I have, I will have the NaO panel from 150Hz up, the 26W8661 to do 80Hz to 150Hz in a dipole, and a pair of XLS to do 20Hz to 80Hz in sealed boxes. There is the convenience that the U-frame, when added the back-panel, can work perfectly as a sealed box because it happens to have the perfect size for a sealed box. Of course, I don't have your deep level of knowledge and don't have the software / measurement equipment so it would be a very long journey for me to get into that route.
Sorry I have been talking about my speakers but I guess I expressed my views on why dipole speakers sound good and am exploring if non-dipole speakers are designed and implemented properly they would give the same level of performances. There is a high price to pay for dipole speakers - massive EQ, active EQ (except crossing with the tweeters), which add a lot of capacitors and opamps in the signal path hence distortions, massive cancellations, high excursions of the drivers (which increases distortions), large speakers with relatively low SPL at low frequencies, high costs (active components, additional power amps), etc. While, I have to say I am very pleased with my NaO, and if all else fail, I would just cut the NaO U-frame slightly shorter, add in another U-frame to double the SPL capability, and raise the XO point to 120Hz - which will make it very similar to the NaO II, and I am sure I would be pretty happy with it, although it would not provide the SPL I like, at least it would get rid of the U-frame resonance.
Regards,
Bill
I wonder if the lack of enclosure (free from standing waves and box resonance) is the main reason we like dipole speakers. I found the sound from a dipole is cleaner, i.e. lower distortions. As for radiation patterns, etc, they are more concerned with interactions with the rooms. As far as sound is concerned if the rooms match / work with the speakers then there should not be much difference between open baffle speakers and enclosed speakers, apart from the free of box colourations.
From what I read people found dipole bass a lot more attractive. i.e. the main advantage of having a dipole speaker is that the bass is better. It does not appear that people strongly prefer the dipole midrange or treble. So why? One factor may be room-interaction, but I suspect that may be because at low frequencies the standing waves within the boxes can not be damped sufficiently which mess up the sound in a closed / ported box. Fibreglass or wool can provide adequate damping only with frequencies from perhaps 200Hz up. Nothing can be used to damp 100Hz sufficiently, for example. Think of the majority boxes out there the woofers are crossed at between 100Hz to 500Hz probably second order, so how can the standing waves be damped sufficiently? They can't be. And this must mess up the sound. Perhaps for that reason nearly every one hearing the dipole speakers likes them.
That leads me to re-think of the speakers I have. My WWMTMWW has the MTM part open back. But the wings on the side were so deep the speaker does not work as a dipole any more. For the midrange drivers they don't see the air spring behind them any more as if they are working in an infinite baffle. The XO is at 200Hz 3rd order so standing waves can be adequately treated. I have to say the MTM part, although not dipole, sounds very fine. But the bass of this speaker in ported enclosures is not good at all.
I said I am interested in trying a pair of 26W8661 in a sealed box with a Q of 0.7. This is also one stone to kill two birds. First, it may replace the NaO U-frame. The NaO U-frame has a quarter wave resonance that can't be fully damped (readers please note mine is the older NaO not the new NaO II that has the U-frame shortened so the first resonance frequency is raised). For the sealed enclosure the lowest resonance frequency is much higher in the next octave. So the sealed box will be free of resonances! Secondly, I have not done the maths but I guess 4 x 26W8661 10" in sealed boxes will less likely be bottomed when playing 40-Hz comparing to 2 x XLS 12" in the U-frames. Due to the lack of resonances, better quality drivers and the large size of my room they may turn out to be better than what it is now.
Secondly, if the U-frame still sounds better than the sealed box, I can use the sealed boxes to replace the WW parts of my WWMTMWW. 4 x 26W8661 10" in push-pull should sound much better than 8 x HDS 8" in ported enclosures. Because the first resonance of the sealed box will be at 300Hz, if the sealed box is fully stuffed and the 3rd order XO at 200Hz is applied, standing waves should not be a big problem.
Last, if they all fail, it would give me a perfect opportunity to do exactly what you are doing. With all the drivers I have, I will have the NaO panel from 150Hz up, the 26W8661 to do 80Hz to 150Hz in a dipole, and a pair of XLS to do 20Hz to 80Hz in sealed boxes. There is the convenience that the U-frame, when added the back-panel, can work perfectly as a sealed box because it happens to have the perfect size for a sealed box. Of course, I don't have your deep level of knowledge and don't have the software / measurement equipment so it would be a very long journey for me to get into that route.
Sorry I have been talking about my speakers but I guess I expressed my views on why dipole speakers sound good and am exploring if non-dipole speakers are designed and implemented properly they would give the same level of performances. There is a high price to pay for dipole speakers - massive EQ, active EQ (except crossing with the tweeters), which add a lot of capacitors and opamps in the signal path hence distortions, massive cancellations, high excursions of the drivers (which increases distortions), large speakers with relatively low SPL at low frequencies, high costs (active components, additional power amps), etc. While, I have to say I am very pleased with my NaO, and if all else fail, I would just cut the NaO U-frame slightly shorter, add in another U-frame to double the SPL capability, and raise the XO point to 120Hz - which will make it very similar to the NaO II, and I am sure I would be pretty happy with it, although it would not provide the SPL I like, at least it would get rid of the U-frame resonance.
Regards,
Bill
hells bells ...
Jussi ,
most impressive ! I'm more than keen to see where you end up. I have pretty much the same reservations about Orions - I really like the sound but I'm scared that they simply won't have enough oomph in my large (8x6x3m) room.
As far as dampening of steel, there is an excellent product called green glue (it has phenomenal dampening capabilities) :
http://www.greengluecompany.com/soundproofingDampingOptions.php
A proper sandwitch of some sort using this glue could be as good as it gets (short of using insanely expensive solutions like marble/corian/leadshot combinations). I'm thinking of aluminium/lead/aluminium sandwitch myself for OB. Al can be anodized which is hard wearing and nice looking at the same time.
Bratislav
Jussi said:
Jussi ,
most impressive ! I'm more than keen to see where you end up. I have pretty much the same reservations about Orions - I really like the sound but I'm scared that they simply won't have enough oomph in my large (8x6x3m) room.
As far as dampening of steel, there is an excellent product called green glue (it has phenomenal dampening capabilities) :
http://www.greengluecompany.com/soundproofingDampingOptions.php
A proper sandwitch of some sort using this glue could be as good as it gets (short of using insanely expensive solutions like marble/corian/leadshot combinations). I'm thinking of aluminium/lead/aluminium sandwitch myself for OB. Al can be anodized which is hard wearing and nice looking at the same time.
Bratislav
HiFiNutNut said:
Better behavior in the room. Imho. Below the Schröeder frequency dipole has clear advantages. Above say 300Hz difference is smaller and dipole midrange has its drawbacks. Diffraction problems, uneven rear radiation behavior and so on.
Actually the open baffle isn't exactly non-resonant. There aren't that much cabinet problems (standing waves and shaking walls) but the baffle itself vibrates and it's much harded to get controlled than more three dimensional cabinet. Thick flat MDF panel just isn't that stiff and it can't even be that thick without ruining rear radiation and polar response.
Basically I think dipoles are just different than monopoles. They behave differently in room, they need different positioning, they just sound different because of their operating principles. Which one is better? Personally I don't know. Dipole has it's advantages with acoustic instruments while monopole has more grunt with amplified material. Well designed box, well designed dipole. Positioning ideal and room acoustics treated. How different they really sound?
Room pressuresation is the difference between them. Or I think so. This creates some differences between character how different instruments are played. Is big drum suppose to hit you in the chest or is it more like a bang with all its frequencys on it but with less physical effect? How does it sound in live? And I'm talking about acoustic instrument, not amplified and already reproduced drum in a livegig.
Basically this doesn't mather. If one likes his drums hit the chest even while they don't kick that much in live, so be it. This hobby is all about serving each ones personal tastes and I don't see that much sense doing something just because it's right thing technically or something like that. Not when personal taste argues with the result.
But the whole difference has many perspectives. One, and the final (if everything else is in order), are personal preferences. More important is the operation in the room. How can you position your speakers, how far from walls can you have them, do you have concrete walls, perhaps wood, how large listening distance do you use, how loud you need to play and so on.
In my case I know what I want to play and how loud (even theoretically). My room is what it is. Pretty small, lots of concrete. I need directivity. Listening distance is rather short and room boost quite a bit. Configuration, needs and possibilities are pretty different than in twice larger space etc.
Standing waves are pretty simple thing to optimize. Just make a matrix inside the cabinet so the shortest distance between two opposite surfaces is way higher than highest frequency in the cabinet. Angled walls are also one possibility. As you know standing waves can occur only between two surfaces in the same direction. Rigid matrix also reduces cabinet wall vibrations.
The lowmids are running pretty narrow range. Propably doesn't push all of their potential while uppermids would still move quite a bit. I'd suggest that 250-300Hz gentle slope if you choose to go this way. 26W can handle it easily, you don't have to dipole-eq uppermids at all and have all of their efficiency in use.
And if you have space and size isn't that big issue I'd also suggest dipole woofercolumns to cover couple lowest octaves. 140cm tall column in Beethoven Grand style should have pretty adequate grunt. Eight 12" woofers on each side. Even better if you can place them along sidewalls.
No problem. It's good to read some alternative views for a change. Keeps my own perspective a bit wider without stucking into old habbits. I'm sure non-dipole speaker can give same level of performance as a dipole does. Perhaps a bit differently (mather of taste, described above) and they interact with the room differently. I'd first consider what I need, how can I position speakers (consider different configurations recommended positions and how well your room can reach them), how much they can cost, how large they can be, how large sweetspot you need, what kind of material do you listen, how do you like that material reproduced etc.
I think it's high price to pay for any kind of high quality system. Top notch monopole speaker like big Wilson style isn't easy thing to make. Helluva task to R&D cabinet structures, drivers that suit, vents, crossovers etc.
If the room is very big dipoles advatanges start to turn against it. Just like with any directive system. Situation is even more critical if massive SPL levels and killer dynamics are required. I don't think dipole can do that well in a huge room compared to high efficiency cabinet speaker. Distances to walls increase and reflections appear with greater delay. Not so big needs for directivity.
Naturally dipole can keep up if it's overkilled enough. I think Beethoven Grand is just fine in pretty large spaces. Actually their tweeters is the weakpoint there. It's only 90dB efficient and all alone. Other ranges have multiply drivers with multiply power handling and more efficiency. I know few cases where heavily build large speakers have started burning their tweeters when lifelike dynamics and high SPLs in big room and long listening distance are required. This is why I value that sensitivity.
Bratislav said:
Thanks.
Sounds like a bit different problem that I'm wrestling here. But you're very welcome to share your thoughts. Maybe we can all learn something.
I have few pretty potential dampening materials here. I'll have to try them after I get those woodpanels done.
Sounds reasonable. Unfortunately I don't have that much chances to make n^2 prototypes and really test what's the best solution. So this whole steelframe plus MDF sheets is just a guess. Hopefully a succesful one.
Jussi
Does anybody know how Seas Excels distorsion measurements are done? By Seas. Present specs don't have them anymore.
At least the responses are measured in a closed cabinet using certain size baffle. Bafflestep effect is visible. I think that response isn't Eqd flat when distorsion under "operating power" (power required for 96dB SPL at nominal sensitivity). Therefore results are better than they really are. At least there should be more distorsion below 200Hz where cone excursion start to rise. With bafflestep SPL at and below 100Hz would be around 90dB instead of 96dB. Then the result is in line how for example very similarly build high quality Scan Speak units distort.
Basically this doesn't apply my project since I'm using open baffle which should lower the distorsion at certain excursion and Excels are also highpassed around 250-300Hz.
Does anybody have a good idea how to create a connection panel to these panels? I already have 8-pole Neutrik Speakons invested. Their female connector is 38 x 38mm.
Jussi
At least the responses are measured in a closed cabinet using certain size baffle. Bafflestep effect is visible. I think that response isn't Eqd flat when distorsion under "operating power" (power required for 96dB SPL at nominal sensitivity). Therefore results are better than they really are. At least there should be more distorsion below 200Hz where cone excursion start to rise. With bafflestep SPL at and below 100Hz would be around 90dB instead of 96dB. Then the result is in line how for example very similarly build high quality Scan Speak units distort.
Basically this doesn't apply my project since I'm using open baffle which should lower the distorsion at certain excursion and Excels are also highpassed around 250-300Hz.
Does anybody have a good idea how to create a connection panel to these panels? I already have 8-pole Neutrik Speakons invested. Their female connector is 38 x 38mm.
Jussi
Member
Joined 2003
Jussi,
You could mount a block of MDF built onto the rear of the speaker to mount the connectors. Maybe run the wire up to the drivers inside a didao channel cut on the inside of the rear MDF panel.
I have the old Seas distortion curves (W22 and W26, but not W18). Distortion does rise significantly below 100-200Hz.
Paul
You could mount a block of MDF built onto the rear of the speaker to mount the connectors. Maybe run the wire up to the drivers inside a didao channel cut on the inside of the rear MDF panel.
I have the old Seas distortion curves (W22 and W26, but not W18). Distortion does rise significantly below 100-200Hz.
Paul
Paul W said:
I think I'll lure the wires behind the cloth. I'm just searching for some personal touch to the connection panel. I had an idea of flat MDF piece with the connection on it but the spine ruins this idea.
Yep but not enough. I heard today that Seas has measured drivers distorsion without eq so the usable signal is the shape as it is in the free field response. Therefore 96dB operating power level is just 90dB or so at lowmid and bass area. This goes along with SS measurements.
Jussi
Have I thought this all the way? Missed something relevant? Overkilled too much? Compromissed for wrong reasons?
Could you just shoot this idea full of holes and lets see is there many new ones?
Jussi
Could you just shoot this idea full of holes and lets see is there many new ones?
Jussi
I just had an idea regarding the floor bounce. If you use an asymmetric layout (WWMT for instance) and cross the woofers sufficiently high, you can avoind floor bounce since your floor bounce relevant frequencies will be emitted close to the floor at a very flat angle. Say you cross the woofers at 300-350 Hz to 1.1 m high mids and your woofer is 30-50 cm above floor height.
Thinking of which, maybe your floor bounce is sufficiently smoothed out by a symmetric layout as well, since your top driver will be at a different incident angle.
Thinking of which, maybe your floor bounce is sufficiently smoothed out by a symmetric layout as well, since your top driver will be at a different incident angle.
MBK said:
That's the idea. And it works best with gentle crossover slope, 2nd order or even 1st order, between mids and lowmids. This creates kind of four driver linesource type situation at the overlap area. Overlap range is played through drivers in different heights so it should smooth the floor reflection quite a bit. That's one advantage from this kind of 4-way solution over for example Orion style system which crosses woofers much lower and with high order.
But is that MTM top too much? Should it be MT? At least the behavior is smoother than WWMTM Phoenix style (again low cross to woofers).
Jussi
Well it depends. I personally don't think simulations give much of the answers, and that real life is "smoothed out" a lot, simply by non ideal behavior. And our ears are actually accostumed to blend much of the remaining real effects out anyway. I would not bother with MTM on top, just take care to cross the midwoofers rather high to the mids. The MTM will generate some lobing, or with low order filters create other issues, and all of these will likely be worse in real life than the floor bounce appears to be *in the model*...
Actually I apologize, it's late here and my brain must be having a hard time - I completely blocked out that this thread started with your very idea of smoothing out the floor bounce. So suffice to say I think a WMT or WWMT likely works the same or better if W is positioned low and crossed high, minus complexity and therefore error probablility.
Jussi,
If you use 2nd order or even 1st order to cross your midwoofers SS25W8565 at 250Hz - 300Hz, will you be using a big notch filter from around 600Hz to 6kHz?
Regards,
Bill
If you use 2nd order or even 1st order to cross your midwoofers SS25W8565 at 250Hz - 300Hz, will you be using a big notch filter from around 600Hz to 6kHz?
Regards,
Bill
I would appreciate the same info too. It is not clear to me from the pictures how you achieve that, be it for the B200 or the woofers. It looks very interesting though.
How do you isolate the driver from the baffles? Lovely craftmanship!
TIA
Giulio
hey, any more progress? i'd love to see some more pictures or measurements if you have any. I'm going to be desinging and building my own 3-way dipoles soon here. thanks!
Matt_Tillard said:
Unfortunately not yet. Expecting woodpanels in a week or so. I'll try to get them running before chrismas. Not so sure will I make it. Just the first setup of cource. There is a very long way with these...
Jussi
What do you think, is there any point to even consider anything else than dipole(sub)woofers to go along with this project? Is single or stereo monopole subwoofers inferior in this case?
My room is 2,6m (8,5ft) high, 5,2m (17ft) long and 3,7m (12ft) wide. I'll try Linkwitz recommended "ideal" dipole positioning first. Listening spot center against room width, 1,5m (5ft) from rear wall. Speakers in symmetrical 2,5m (8ft) listening triangle toed towards the listener. Another 1,5m (5ft) from panels to frontwall. 0,6m (2ft) from center of the panel to sidewalls.
Therefore placing dipole subwoofers along the sidewalls make the setup pretty tight. Woofers are just along the wall and along the panels on other side.
Other solution is single or stereo monopole subwoofers. Most monopole subwoofer preferences are along the front wall. There might be enough space for single heavy duty cabinet. That would mean a monosub setup. This solution leaves the room a bit more open. Just a single box along front wall, not two along sidewalls.
Recommendations, thoughts, ideas?
Jussi
My room is 2,6m (8,5ft) high, 5,2m (17ft) long and 3,7m (12ft) wide. I'll try Linkwitz recommended "ideal" dipole positioning first. Listening spot center against room width, 1,5m (5ft) from rear wall. Speakers in symmetrical 2,5m (8ft) listening triangle toed towards the listener. Another 1,5m (5ft) from panels to frontwall. 0,6m (2ft) from center of the panel to sidewalls.
Therefore placing dipole subwoofers along the sidewalls make the setup pretty tight. Woofers are just along the wall and along the panels on other side.
Other solution is single or stereo monopole subwoofers. Most monopole subwoofer preferences are along the front wall. There might be enough space for single heavy duty cabinet. That would mean a monosub setup. This solution leaves the room a bit more open. Just a single box along front wall, not two along sidewalls.
Recommendations, thoughts, ideas?
Jussi
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