Hello diyer,
I would like to ask you for help on the positioning of the woofers with respect to the front baffle.
In particular, I am interested in the positioning with respect to the y-axis.
With a net height of 76cm, the first fundamental wave occurs at about 225hz.
To minimize the vertical standing waves, if I understood correctly, the woofer should be positioned between 1/4 and 3/4 of the height or between 1/3 and 2/3 of the height (acting a little less on the fundamental and a little more on the harmonics).
What is, if there is, the ideal compromise between the management of the standing waves and the minimization of the frontal lobing?
Thanks in advance to everyone.
I would like to ask you for help on the positioning of the woofers with respect to the front baffle.
In particular, I am interested in the positioning with respect to the y-axis.
With a net height of 76cm, the first fundamental wave occurs at about 225hz.
To minimize the vertical standing waves, if I understood correctly, the woofer should be positioned between 1/4 and 3/4 of the height or between 1/3 and 2/3 of the height (acting a little less on the fundamental and a little more on the harmonics).
What is, if there is, the ideal compromise between the management of the standing waves and the minimization of the frontal lobing?
Thanks in advance to everyone.
Attachments
For actual frequency response and less cancelation, mount woofer as shown, as close as possible to each of for
tight center to center.
In a box or rectangle the longest area is the " uh oh" region. That gets fixed with absorption material.
For offset no distance should be equal. Which helps with diffraction
Golden ratio or something close often used. for cabinet shape and driver placement towards one edge. Technically
it is 1.618. But for all the goobers that like to argue or people who simplify.
1:6 ratio or rounded up often falls closer to 1:7 so any magical division or science you want to make up close to 1:6 to 1:7 ratio
is good enough.
You can also subtract 1:6 divisions to get different shapes, the Greeks were pretty good at it.
tight center to center.
In a box or rectangle the longest area is the " uh oh" region. That gets fixed with absorption material.
For offset no distance should be equal. Which helps with diffraction
Golden ratio or something close often used. for cabinet shape and driver placement towards one edge. Technically
it is 1.618. But for all the goobers that like to argue or people who simplify.
1:6 ratio or rounded up often falls closer to 1:7 so any magical division or science you want to make up close to 1:6 to 1:7 ratio
is good enough.
You can also subtract 1:6 divisions to get different shapes, the Greeks were pretty good at it.
Since your 760mm wide or tall, whatever the orientation
Simplified golden ratio with no decimal points can be divided to
1260
*760 *
470
290
179
111
69
42
Next upward is 1260 rather tall and can subtract smaller values for more ideal height/tall
whatever orientation
1218
1191
1149
1081
* 970*
500
So your 970 dimension is a rather good choice actually
970
599
371
229
142
88
54
Simplified golden ratio with no decimal points can be divided to
1260
*760 *
470
290
179
111
69
42
Next upward is 1260 rather tall and can subtract smaller values for more ideal height/tall
whatever orientation
1218
1191
1149
1081
* 970*
500
So your 970 dimension is a rather good choice actually
970
599
371
229
142
88
54
Last edited:
Your application is important to know..?
I guess you mean pulling the woofers away from the range above them. It is manageable, though often spoken about critically.. but you'd have to develop the cross in the acoustic sense to see where you're at.
For this you would need to know whether you will try to avoid the region or need to play through it. Woofers in the middle raises the frequency of the first.
What frontal lobing?
I guess you mean pulling the woofers away from the range above them. It is manageable, though often spoken about critically.. but you'd have to develop the cross in the acoustic sense to see where you're at.
To minimise internal standing waves one adds stuffing to the inside of the cabinet where the particle velocity is highest (i.e. in the middle rather than at the walls). The rule of thumb for stuffing to be effective is that it needs to be quarter of a wavelength thick which is usually straightforward to achieve. The placement of the woofers on the baffle is normally best determined by how they interact with cabinet geometry and the boundaries of the room which in turn is determined by how the speaker is intended to work.
Thank you for the suggestions.
I attach another image to better clarify the final use context.
Above there is an iwata horn with a 2" driver.
I would like to create the crossover between iwata and woofers between 500 and 600hz.
I asked about lobing because I would like to position the woofers for the best possible integration between the bass and midrange (iwata horn).
The final result will also depend on the mechanical alignment on the Z axis of the horn and the slope and type of filter between bass and midrange, but at the moment I am interested in understanding, given the size of the bass cabinet, where it is best to open the holes for the two woofers, to obtain the best possible compromise between the management of internal resonances and the overall frontal response.
I attach another image to better clarify the final use context.
Above there is an iwata horn with a 2" driver.
I would like to create the crossover between iwata and woofers between 500 and 600hz.
I asked about lobing because I would like to position the woofers for the best possible integration between the bass and midrange (iwata horn).
The final result will also depend on the mechanical alignment on the Z axis of the horn and the slope and type of filter between bass and midrange, but at the moment I am interested in understanding, given the size of the bass cabinet, where it is best to open the holes for the two woofers, to obtain the best possible compromise between the management of internal resonances and the overall frontal response.
Attachments
That Iwata is quite short vertically. It won't do much holding below maybe 1.5kHz, is that less important than lobing in your case?
Placed horizontally, the wavelength of the center to center distance between the woofers is ~825Hz.
To prevent off axis horizontal lobing/comb filtering, the drivers should be within ~1/4 wavelength, which could be achieved if the crossover was lowered to ~206Hz.
Obviously, that crossover frequency is too low for your high frequency horn/driver.
Having made the mistake of placing 15" woofers side by side below a HF horn in monitors with a crossover in the 500-600Hz range, and hearing the resultant terrible off axis response in the crossover region, I'd say from experience that compromise far overwhelms the minimal differences internal resonances make from speaker positioning.
A vertical woofer/HF arrangement is far preferable.
I prefer the midway point between the upper woofer's center and the horn driver to be at or above ear height, rotating the woofer cabinet seems to be near that.
Art
Can I ask you if you explain it to me in a different way?, I didn't understand well, thanks
The bass cabinet was originally turned with the 76cm side as depth.
We tried to divide the chambers, tilt the rear wall internally, we tried to change woofers with others with parameters adaptable to the available internal volumes, but in the end the sound was terrible, very confused.
I agree that the wavelength determined by the distance of the two woofers is 825Hz, causing the first nulling at half frequency around 410hz.
But does this also concern the iteration between woofer and horn?
The distance between the woofers and the horn, whether horizontal or vertical, does not remain more or less the same?
I intend in any case to filter the woofers separately, making only one of the two rise to cross with the horn.