sides or not
Have a look at: http://home.pacbell.net/donwm/PrototypeTestResults.htm
While there seem to be a few minor inconsistencies, it seems clear that the sides help on the high end side. Differences at the low end are not that important.
Have a look at: http://home.pacbell.net/donwm/PrototypeTestResults.htm
While there seem to be a few minor inconsistencies, it seems clear that the sides help on the high end side. Differences at the low end are not that important.
Dave,
thanks very much for your effort in designing the nomograph. There are still some remarks to make:
The Olsen equation (which is used by Linkwitz too) refers to the lowest SPL peak of an ideal dipole speaker. The Linkwitz and DML equations refer to the (still lower in frequency) -6dB point, where the dipole speaker has the same output as an equivalent monopole speaker (in theory). So the Olsen and Linkwitz curves base on the same assumptions.
In the DML equation you should cancel the factor 2. I didn´t find it in Kuei Yang Wangs original expression. After that the DML curve in the nomograph will look even more „optimistic“. I can´t believe it´s based on real life evidence.
Rudolf
thanks very much for your effort in designing the nomograph. There are still some remarks to make:
The Olsen equation (which is used by Linkwitz too) refers to the lowest SPL peak of an ideal dipole speaker. The Linkwitz and DML equations refer to the (still lower in frequency) -6dB point, where the dipole speaker has the same output as an equivalent monopole speaker (in theory). So the Olsen and Linkwitz curves base on the same assumptions.
In the DML equation you should cancel the factor 2. I didn´t find it in Kuei Yang Wangs original expression. After that the DML curve in the nomograph will look even more „optimistic“. I can´t believe it´s based on real life evidence.
Rudolf
Looking at the chart I see that Linkwitz's calculations are closest to my own experience. My EV LS12's have a fs of around 45-50 Hz. They are in a baffle 30" wide by 36" high. The -3 dB point is 80 Hz, which is almost exactly as Linkwitz predicts.
I wonder how the others get their results?
Dave
I wonder how the others get their results?
Dave
Konnichiwa,
I find it works just fine in real life. The problem is that are virtually no drivers that have a Qt of 0.7 or higher with a reasonably low resonance. Having a Qt of less than 0.7 means the driver will be already more than 3db down at it's resonance. Using a driver with Qt = 0.5 means the driver output will be down 6db at the resonance and so on. When you "overlay" these responses and the nomograms from Backman and DML Article you get very close to reality.
However, the BAFFLE induced rolloff (as opposed to driver rolloff) is much less than both Olson and Linkwitz predict. When I get the time I'll put the nomograms into a speadsheet to add to my existing spreadsheet simulators. These will then show driver response, baffle response AND combined. Maybe I have time tonight.
Sayonara
Rudolf said:
I find it works just fine in real life. The problem is that are virtually no drivers that have a Qt of 0.7 or higher with a reasonably low resonance. Having a Qt of less than 0.7 means the driver will be already more than 3db down at it's resonance. Using a driver with Qt = 0.5 means the driver output will be down 6db at the resonance and so on. When you "overlay" these responses and the nomograms from Backman and DML Article you get very close to reality.
However, the BAFFLE induced rolloff (as opposed to driver rolloff) is much less than both Olson and Linkwitz predict. When I get the time I'll put the nomograms into a speadsheet to add to my existing spreadsheet simulators. These will then show driver response, baffle response AND combined. Maybe I have time tonight.
Sayonara
Results will be welcome.
Hi Kuei Yang Wang,
Please put up some charts to help with the design. I wanted to make a dipole sub but I just seem to get more confused and am drifting .
Some practical calculations or charts will be really helpful.
Is there any way we can bring up the Qts of the woofer , short of building one's own.
Here in my city we can buy everything needed to build speakers ourselves. At least they should be OK for bass but I doubt the results for any other aplication. Coils will have to be wound . The ones they supply will give you a heart attack !
The only reason why this would be interesting is that we might be able to make a driver with a very high Q ! One easy way is to make a longer coil than usual ! Efficiency will also be quite low!
We could stack magnets ...............
Get one -- loose another ...................
Cheers.
Hi Kuei Yang Wang,
Please put up some charts to help with the design. I wanted to make a dipole sub but I just seem to get more confused and am drifting .
Some practical calculations or charts will be really helpful.
Is there any way we can bring up the Qts of the woofer , short of building one's own.
Here in my city we can buy everything needed to build speakers ourselves. At least they should be OK for bass but I doubt the results for any other aplication. Coils will have to be wound . The ones they supply will give you a heart attack !
The only reason why this would be interesting is that we might be able to make a driver with a very high Q ! One easy way is to make a longer coil than usual ! Efficiency will also be quite low!
We could stack magnets ...............
Get one -- loose another ...................
Cheers.
Now I'm getting lost. All of this is starting to get beyond me.
I can't understand why all these graphs and everything else says that there are peaks and dips, and an extreme lack of bass from 40 or 50Hz on down?
If that's the case, then why am I getting such a great bass response out of my dipoles?
All I have to test the response of my system with is a RatShak SPL meter, a couple test CDs, and a warble tone generator built into my AudioControl Ritcher Scale that ranges from 250Hz down to 22.5Hz, along with it's own built-in SPL meter with seperate calibrated lab mic.
With the SPL meter mounted on a tri-pod at the listening position, I have only seen about a -2dB drop at 22.5Hz as on the AudioControl. The built-in meter on the AudioControl comes out about the same as well, -2dB @ 22.5Hz.
Everything from 25Hz on up to 250Hz seems to be perfectly flat via the built-in meter and the RatShak meter, even at the crossover point (90Hz), from the dipoles to the Maggies.
I know the Qts of these Pyle Pro drivers are 0.67 and the Fs is 26Hz.
So what gives here?! Any ideas anyone?!
I can't understand why all these graphs and everything else says that there are peaks and dips, and an extreme lack of bass from 40 or 50Hz on down?
If that's the case, then why am I getting such a great bass response out of my dipoles?
All I have to test the response of my system with is a RatShak SPL meter, a couple test CDs, and a warble tone generator built into my AudioControl Ritcher Scale that ranges from 250Hz down to 22.5Hz, along with it's own built-in SPL meter with seperate calibrated lab mic.
With the SPL meter mounted on a tri-pod at the listening position, I have only seen about a -2dB drop at 22.5Hz as on the AudioControl. The built-in meter on the AudioControl comes out about the same as well, -2dB @ 22.5Hz.
Everything from 25Hz on up to 250Hz seems to be perfectly flat via the built-in meter and the RatShak meter, even at the crossover point (90Hz), from the dipoles to the Maggies.
I know the Qts of these Pyle Pro drivers are 0.67 and the Fs is 26Hz.
So what gives here?! Any ideas anyone?!
Re: Results will be welcome.
Konnichiwa,
My point is that non of the charts tell anything useful. You always need to see the baffle and driver as a unit.
Drive it from a high source impedance. The easiest is to just use a resistor, but that looses a lot of power. The smarter way is to build an amplifier with a controllable positive output impedance , something that is laughably simple.
Sayonara
Konnichiwa,
ashok said:
My point is that non of the charts tell anything useful. You always need to see the baffle and driver as a unit.
ashok said:
Drive it from a high source impedance. The easiest is to just use a resistor, but that looses a lot of power. The smarter way is to build an amplifier with a controllable positive output impedance , something that is laughably simple.
Sayonara
Spreadsheet done
Konnichiwa,
I have sat down and entered the "numbers" into one of my spreadsheets. This seems to be pretty close first to the numbers from the German report which COMPARED cone dipoles to DML.
Also, when simulating the Phoenix main panel with Vifa P21-W0-20-08 (a woofer unsiuted for use in dipoles, UNLESS heavily equalised) I come within 2 - 3db of the Figures measured by SL via MLSSA, I think both my throth and peaks are slightly out, maybe a result from not accounting for the stubby wings.
Anyway, I'll consider the simulation as "good enough ballpark" for a basic "feasibility study" thing, which is all any of my Q&D Spreadsheets ever where intended for.
Here attached the simulation result for different baffles and drivers. The spreadsheet even zipped is still nearly 1MB, so I'll need a moderator to help upload it.
Sayonara
Konnichiwa,
I have sat down and entered the "numbers" into one of my spreadsheets. This seems to be pretty close first to the numbers from the German report which COMPARED cone dipoles to DML.
Also, when simulating the Phoenix main panel with Vifa P21-W0-20-08 (a woofer unsiuted for use in dipoles, UNLESS heavily equalised) I come within 2 - 3db of the Figures measured by SL via MLSSA, I think both my throth and peaks are slightly out, maybe a result from not accounting for the stubby wings.
Anyway, I'll consider the simulation as "good enough ballpark" for a basic "feasibility study" thing, which is all any of my Q&D Spreadsheets ever where intended for.
Here attached the simulation result for different baffles and drivers. The spreadsheet even zipped is still nearly 1MB, so I'll need a moderator to help upload it.
Sayonara
Attachments
Can you email me a copy.
Hi Kuei Yang Wang,
If uploading the file is going to take time can you please email it to me. My mail box is large enough for this file.
You can email me at amadhavan_@_eth.net
You can remove the two underscore lines on either side of the @.
I am receiving plenty of junk mail on my other email ID and I wanted to protect this one.
Thanks.
Ashok.
Hi Kuei Yang Wang,
If uploading the file is going to take time can you please email it to me. My mail box is large enough for this file.
You can email me at amadhavan_@_eth.net
You can remove the two underscore lines on either side of the @.
I am receiving plenty of junk mail on my other email ID and I wanted to protect this one.
Thanks.
Ashok.
@planet10
Sorry Dave,
but what you call the "DML Study" curve in your nomograph does explicitly relate to the behaviour of a piston-radiator. The original study is very clear in that. IMO your "DML" nomograph should get another name and still work with w=0.07*c/f, ommitting the factor 2 as I suggested.
I do agree that Distributed Mode Loudspeakers will behave very different from the above equations and graphs.
Rudolf
Sorry Dave,
but what you call the "DML Study" curve in your nomograph does explicitly relate to the behaviour of a piston-radiator. The original study is very clear in that. IMO your "DML" nomograph should get another name and still work with w=0.07*c/f, ommitting the factor 2 as I suggested.
I do agree that Distributed Mode Loudspeakers will behave very different from the above equations and graphs.
Rudolf
The fix for my charts is in the works, Throsten has mailed me his XL workshhet, but haven't posted it... but in the mean-time i have plotted the empiral results from one of the links above.
The best correlation with any of the curves is just the width of the baffle (no wings) which drops on top of Linkwitz's curve.
The curves are bottom to top: 1/width vrs cutoff 2/ width + 1 side vrs cutoff 3/ width + sides vrs cutoff 4/ average of width + height.
dave
The best correlation with any of the curves is just the width of the baffle (no wings) which drops on top of Linkwitz's curve.
The curves are bottom to top: 1/width vrs cutoff 2/ width + 1 side vrs cutoff 3/ width + sides vrs cutoff 4/ average of width + height.
dave
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