StigErik & 6.283
With two W15s on a minimal baffle JohnKs model shows ~110dB with 4mm XMAX and a 200Hz LR4 XO. Also my calculations show that two W15s will be able to reproduce 110dB without reaching max power handling of 70W. Am I somehow mistaken? I am pretty new to this speaker design stuff so maybe I have missed some finer point of engineering?
With two W15s on a minimal baffle JohnKs model shows ~110dB with 4mm XMAX and a 200Hz LR4 XO. Also my calculations show that two W15s will be able to reproduce 110dB without reaching max power handling of 70W. Am I somehow mistaken? I am pretty new to this speaker design stuff so maybe I have missed some finer point of engineering?
There are two problems with running the mids down to 200 Hz.
1) Distortion. Assuming we use a W15 nude with no baffle, the driver is going to be 15 dB or so down at 200 Hz compared to 2 kHz. That means that the harmonics distortion components will be amplified by up to 15 dB, which is not a good idea.
2) Floor bounce. Mids mounted a meter or so from the floor will experience a broad and very deep suck-out centered around 300 Hz, depending somewhat on your prefered listening distance. Most designers shut their eyes and ears to this problem, including some of the famous guys around....
1) Distortion. Assuming we use a W15 nude with no baffle, the driver is going to be 15 dB or so down at 200 Hz compared to 2 kHz. That means that the harmonics distortion components will be amplified by up to 15 dB, which is not a good idea.
2) Floor bounce. Mids mounted a meter or so from the floor will experience a broad and very deep suck-out centered around 300 Hz, depending somewhat on your prefered listening distance. Most designers shut their eyes and ears to this problem, including some of the famous guys around....
Hi,
what measures do you propose,to bypass this anomaly? I am planning to use a 200 mm mid,mounted on an open baffle.The center of the mid is destined to be 60 cm off the floor,above a 300 mm woofer.Listening spot is 2 meters from the axis of the speakers.
My current listening room is smallish.
Mind you, I don't like pants flapping bass 🙂
B.L
Thanks StigErik
If I XO at 300Hz should I think about moving the AE Dipole 15 up so the drivers are closer together? They will still be within 1 wavelength without moving things but is there some benefit to be gained by reducing vertical spacing as much as possible?
If I XO at 300Hz should I think about moving the AE Dipole 15 up so the drivers are closer together? They will still be within 1 wavelength without moving things but is there some benefit to be gained by reducing vertical spacing as much as possible?
Zodiac,
Now if you go let's say 5 way there are two main issues:
1. The size of the drivers and their spacing have a direct connection to the acoustical size of a source, which ideally is small compared to wavelenght.
2. Traditional xover alignments have an inherent bad effect on the vertical response and with a 5 way speaker you have 4 xover points.
Now add to that a non-ideal vertical response of a driver maybe like some famous planar rectangular dipole tweeter or mid.
The "thing" could measure well horizontally though.
Oliver
Douh ! 😀 I totally forgot about "Thor". This is because I consider it only an optional part of Orion, not an essential one.
Many things are diffuclut to rate without direct audible comparison or experience. But the vertical dispersion makes half of the sound power. And everybody knows and accepts that a uniform or best case flat sound power is one or the major building block for a decently sounding speaker. Unfortunately it is the vertical response that is cumbersome to measure and I believe this is the reason why we don't see such diagrams very often.
Now if you go let's say 5 way there are two main issues:
1. The size of the drivers and their spacing have a direct connection to the acoustical size of a source, which ideally is small compared to wavelenght.
2. Traditional xover alignments have an inherent bad effect on the vertical response and with a 5 way speaker you have 4 xover points.
Now add to that a non-ideal vertical response of a driver maybe like some famous planar rectangular dipole tweeter or mid.
The "thing" could measure well horizontally though.
I have only pointed you to the correct xmax.
Oliver
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Cancellation frequency is path length difference related by the formula: cancellation frequency = 1140 / (2*path length difference)
At 9ft listening distance and 3' off the floor the path length difference is 1.8' (find this using pythagoras) which equates to 316Hz. If you crossover the mid to the woofer above this frequency then you can avoid the floor bounce. Or you can use a thick 4" absorber on the floor to absorb the reflection (obviously not a high WAF / SAF solution)
6.283 thanks for the insight, what is your philosophy on the open baffle / vertical dispersion conundrum?
I'm not sure.. it could affect the vertical off-axis response somewhat maybe ?
When I made my 3-way dipole with 21" - 8" - AMT I crossed at 350 Hz, and the 21" and 8" was pretty close to each other. The off-axis response of that speaker is pretty good. Maybe its a good idea to keep them close?
I think that I'll take curtain no 1.Surely,a 4" inch absorber is not an option.
Or else,I 'll be the insignificant factor
Thanks.
B.L.
stigerik do you know if the new Mundorf AMTs can be run dipole?
I have asked Mundorf via email (no response), the US distributor Madisound (they didn't know) and have posted it here a few times
I have asked Mundorf via email (no response), the US distributor Madisound (they didn't know) and have posted it here a few times
Zodiac,
pick the low hanging fruits frist as implied above. And BTW, this applies not only to OB.
1. Keep things small compared to wavelenght
2. Avoid unnecessary xover points
In addition use drivers with good dispersion if possible. That is where you sometimes need to weigh vertical vs. horizontal behavior.
Finally, one could look for alternative filters that avoid vertical dispersion issues.
Oliver
Exactly. If some of you guys can even talk about baffles 😀 So let's say mechanical structures and drivers.
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