Great work indeed! Like John, I would be interested in an investigation with a multiple sub solution (as suggested by Welti) or a Double Bass Array. It would probably be best if these would be performed in the same room, although that might be difficult for the DBA... Dipole bass is better, but in small rooms or for very low frequencies it may not always be a very practical solution.
Elias, do you see any further experiments coming up?
Elias,
Please loose it like this, exactly like my OB bass setup. I don't know how you figured it out but this it is:
I am glad you could catch it at it's best moment.
Otherwise I certainly think you are near the thruth.
/Erling
Please loose it like this, exactly like my OB bass setup. I don't know how you figured it out but this it is:
An externally hosted image should be here but it was not working when we last tested it.
I am glad you could catch it at it's best moment.
Otherwise I certainly think you are near the thruth.
/Erling
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I suppose I tried to be a bit too funny with my post above. However to me there is significant information in your measurements. I haven't gone trough all different modes in your stated room dimensions, but it is not to different from what I am playing my speakers in.
Some of you might recognize my Blindstone OB with Acoustic Elegance IB15s int the bass. I am using this basses in what the germans would call an Ipod small baffle 45 x 55 cm and EQed with a shelving LP filter 6 dB slope at 80 Hz to be level down to 30 Hz. I have tried different crossover frequencies and characteristics for a long time now. But today I have settled for 280 Hz crossover and 48 dB/octave Butterworth in phase crossover to the 18 sound 6ND430. To me this sounds most pleasing.
My point, besides beeing interested in different angles and room response to that, is also to the point of speaker damping. When I listen to the IB15 alone I hear a very articulate sound when listening to music and speech. This unit should have a neutral damping characteristic with a Q-value of 0.7 So how would other speakers compare with different damping values in your measurements, like for instance the high Q-value Eminence Alpha 15s .
/Erling
Some of you might recognize my Blindstone OB with Acoustic Elegance IB15s int the bass. I am using this basses in what the germans would call an Ipod small baffle 45 x 55 cm and EQed with a shelving LP filter 6 dB slope at 80 Hz to be level down to 30 Hz. I have tried different crossover frequencies and characteristics for a long time now. But today I have settled for 280 Hz crossover and 48 dB/octave Butterworth in phase crossover to the 18 sound 6ND430. To me this sounds most pleasing.
My point, besides beeing interested in different angles and room response to that, is also to the point of speaker damping. When I listen to the IB15 alone I hear a very articulate sound when listening to music and speech. This unit should have a neutral damping characteristic with a Q-value of 0.7 So how would other speakers compare with different damping values in your measurements, like for instance the high Q-value Eminence Alpha 15s .
/Erling
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I did an analitical study of the transient response of different formats a long time ago. Of interest is the impulse response for the different formats about 3/4 way down the page. You can see that when only axial modes are included all the formats look the same. When all modes are included thing change but the dipole still looks pretty good when aligned with the room axis. When rotated 45 degrees, even the dipole get messy. But over all the best bass response is obtained when the woofer is placed close to the listening position. This suggests that if the delays and levels can be adjusted, with the correct crossovers point coffee table woofers (monopoles), close to the listening position may provide the best simple solution.
...or just put it at ear height behind the listening position. I used to listen with a dipole sub behind the couch for quite some time.
Hello,
At first I was confused by the first post of this thread, until I visited the website of Elias and saw he measured on a forward radiating monopole. Somehow, the term monopole allways makes me think of an omnidirectional up or downward radiating system, probably because I spend so much time on Sigfried Linkwitz's website reading about the Pluto.
SL says on http://www.linkwitzlab.com/Pluto/subwoofer.htm:
This suggests that a downward radiating omnidirectional monopole and a dipole share much the same character. I would really love it if a third set of data could be published, using the same subwoofer in a downward radiating setup with a bit of standoff from the floor, and see wether SL's observations are again confirmed by measurements. I feel confident they will.
If so, those measurements would give validation for the cheapest audio upgrade ever to be enjoyed by many, 4 sticks to nail on your subwoofer to have it fire downwards.
I would also like to thank Elias for publishing his work for free, it'll prolly take me a year to wrap my head round the math behind it, but once I will it'll be a usefull tool.
Regards,
René
At first I was confused by the first post of this thread, until I visited the website of Elias and saw he measured on a forward radiating monopole. Somehow, the term monopole allways makes me think of an omnidirectional up or downward radiating system, probably because I spend so much time on Sigfried Linkwitz's website reading about the Pluto.
SL says on http://www.linkwitzlab.com/Pluto/subwoofer.htm:
This suggests that a downward radiating omnidirectional monopole and a dipole share much the same character. I would really love it if a third set of data could be published, using the same subwoofer in a downward radiating setup with a bit of standoff from the floor, and see wether SL's observations are again confirmed by measurements. I feel confident they will.
If so, those measurements would give validation for the cheapest audio upgrade ever to be enjoyed by many, 4 sticks to nail on your subwoofer to have it fire downwards.
I would also like to thank Elias for publishing his work for free, it'll prolly take me a year to wrap my head round the math behind it, but once I will it'll be a usefull tool.
Regards,
René
Indeed. Perhaps SL wanted to point out the importance of low frequencies for the perceived tonal character of a speaker.
By the way, two monopole subwoofers along the side wall already provide better bass quality than one because they excite less modes along the width of the room (just like a dipole woofer), which makes for a better comparison with dipole bass.
By the way, two monopole subwoofers along the side wall already provide better bass quality than one because they excite less modes along the width of the room (just like a dipole woofer), which makes for a better comparison with dipole bass.
Hello !
Thanks for everyone for responses ! Finally I find some time to continue this interesting quest, the comparison of monopole and dipole bass speakers in small acoustic space or a living room.
I added more analysis to my page:
Elias Pekonen Home Page - Dipole Bass vs Monopole Bass
Now including modulation analysis with ERB wavelets.
Also added modulation transmission analysis.
All is for comparison of monopole vs dipole bass.
Here for example modulated ERB wavelet at 3 Hz modulation freq:
Ideal impulse:
Monopole bass:
Dipole bass:
Which one better for you ?
And here, the monopole bass horror in animation with modulated ERB wavelet live ! Modulation freq is swept 3 Hz - 30 Hz.
(4M file)
http://dl.dropbox.com/u/2400456/diyaudio/anim_100-1_2m5_640_384_einorm_20dB_liukuva_oma7.gif
- Elias
Thanks for everyone for responses ! Finally I find some time to continue this interesting quest, the comparison of monopole and dipole bass speakers in small acoustic space or a living room.
I added more analysis to my page:
Elias Pekonen Home Page - Dipole Bass vs Monopole Bass
Now including modulation analysis with ERB wavelets.
Also added modulation transmission analysis.
All is for comparison of monopole vs dipole bass.
Here for example modulated ERB wavelet at 3 Hz modulation freq:
Ideal impulse:
An externally hosted image should be here but it was not working when we last tested it.
Monopole bass:
An externally hosted image should be here but it was not working when we last tested it.
Dipole bass:
An externally hosted image should be here but it was not working when we last tested it.
Which one better for you ?
And here, the monopole bass horror in animation with modulated ERB wavelet live ! Modulation freq is swept 3 Hz - 30 Hz.
(4M file)
http://dl.dropbox.com/u/2400456/diyaudio/anim_100-1_2m5_640_384_einorm_20dB_liukuva_oma7.gif
- Elias
What I can say with my limited understanding :
More quantity, but less quality : the dipole is closer to the ideal impulse.
Under 100 Hz, the monopole is really late, it's energy is in the badly dampened oscillations rather than in the main impulse.
Is the monopole subject to more post-ringing or is it the coupling with the room ?
More quantity, but less quality : the dipole is closer to the ideal impulse.
Under 100 Hz, the monopole is really late, it's energy is in the badly dampened oscillations rather than in the main impulse.
Is the monopole subject to more post-ringing or is it the coupling with the room ?
When I see this right first is test signal second monopole with a lot of reflection or poor transient response. And last the monopole with very original response with holes in it.
I am testing my dipole bass with Kugelwellen horn( this all to control room response). I never though of building a OB because of the poor efficiency.
Now I build a set with my narrow living room with speakers in the corner I have about 94 1 Wmtr(1mtr from backwall) and flat response down to 35 Hz warm sound with good transient response.
I did build OB to hear them and I hope better response because of the dipole polar behavior. It works good and I like good bass.
The reflected wave of the dipole ads to the sound at 30-40Hz where as the reflected wave of the back-wall by the monopole kills the subbass in my room.
I am testing my dipole bass with Kugelwellen horn( this all to control room response). I never though of building a OB because of the poor efficiency.
Now I build a set with my narrow living room with speakers in the corner I have about 94 1 Wmtr(1mtr from backwall) and flat response down to 35 Hz warm sound with good transient response.
I did build OB to hear them and I hope better response because of the dipole polar behavior. It works good and I like good bass.
The reflected wave of the dipole ads to the sound at 30-40Hz where as the reflected wave of the back-wall by the monopole kills the subbass in my room.
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lower cost? will not do much different cost of a extra driver there for the wood work is more simple and inexpensive.
Easily lower cost, output to output. Unless where you live drivers are cheap and wood is comparatively high cost. Box sub might be harder to build, but how hard is it to build a box? I could do it at 12yrs old w/o any training on my first try. Can't be too hard. I just built a 6 cuft box for $20. It did take me all day though, but my dipole projects have taken just as long though I did make them nicer. The only evidence I (or apparently any of us) have seen says this isn't an audible phenomenon. Do we believe our eyes or ears when it comes to sound? I suppose others may just not be sharing what they know. That's possible. I'll ask again... My dipole bass module had no real deep bass--I have yet to hear deep bass from a dipole. There are reasons for that. They are simply not good at it. I have taken boat loads of measurements with it and nada. It's a purpose built driver to boot! Truly, I'm boxing up my dipole bass as we speak. I've got cheap box subs that blow it away! Separate amp and all for less than the cost of the dipole woofer.
Dan
Dan
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