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Beautiful Swingin' Speaker
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Old 28th September 2011, 03:41 AM   #121
twest820 is offline twest820
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Physics that's actually convenient for once. I can deal. Thanks for the confirmation.
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Old 11th September 2020, 12:14 AM   #122
LewinskiH01 is offline LewinskiH01  Argentina
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Location: Buenos Aires
Quote:
Originally Posted by mige0 View Post
You possibly should get into contact with the users of the

"Prima Luce" or the
Beautiful Swingin' Speaker - diyAudio
"Roksan Darias"
Beautiful Swingin' Speaker - diyAudio


Michael
Resurrecting an old one.

I'm testing this with midrange and woofers. Does it make a difference to hang a large AMT tweeter like the TPL-150H on a swing?

thank you!
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Old 11th September 2020, 01:36 AM   #123
OllBoll is offline OllBoll  Sweden
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Quote:
Originally Posted by LewinskiH01 View Post
Resurrecting an old one.

I'm testing this with midrange and woofers. Does it make a difference to hang a large AMT tweeter like the TPL-150H on a swing?

thank you!
Not really. The real benefit is in the octaves where you have to push a lot of air to produce sound hence a lot of movement / vibration.

If we plug in Linkwitz SPL-max spreadsheet and calculate volume of air pushed needed to get 110 dB SPL:

Frequency dipole
Hz cm^3
25 89521
35 31650
50 11190
71 3956
100 1399
141 495
200 175
283 61.8
400 21.9
566 7.7
800 2.7
1131 1.0
1600 0.3

The volume increases by 8x for each octave. I wager you'd it'd make a minimal difference above 400 hz as long as the construction is sound.

If you want to try it then hook the tweeter up to an amp and hold it in your hand in free air while blasting pink noise or say a 1 khz sinewave. If you can't feel any significant vibrations then you will probably only make the speaker construction more complicated.

In the lower frequencies of course it works amazingly well.

EDIT: While making the tweeter swing might not make a difference in that sense, but if you by mounting it in a swing can decouple it from the midrange or the woofer which will vibrate a lot then that of course is a completely different thing. In that case then it is of course beneficial since the vibrations of the lower driver won't transfer into the tweeter.

Last edited by OllBoll; 11th September 2020 at 01:41 AM.
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Old 11th September 2020, 09:34 AM   #124
LewinskiH01 is offline LewinskiH01  Argentina
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Join Date: Nov 2014
Location: Buenos Aires
Quote:
Originally Posted by OllBoll View Post
Not really. The real benefit is in the octaves where you have to push a lot of air to produce sound hence a lot of movement / vibration.

If we plug in Linkwitz SPL-max spreadsheet and calculate volume of air pushed needed to get 110 dB SPL:

Frequency dipole
Hz cm^3
25 89521
35 31650
50 11190
71 3956
100 1399
141 495
200 175
283 61.8
400 21.9
566 7.7
800 2.7
1131 1.0
1600 0.3

The volume increases by 8x for each octave. I wager you'd it'd make a minimal difference above 400 hz as long as the construction is sound.

If you want to try it then hook the tweeter up to an amp and hold it in your hand in free air while blasting pink noise or say a 1 khz sinewave. If you can't feel any significant vibrations then you will probably only make the speaker construction more complicated.

In the lower frequencies of course it works amazingly well.

EDIT: While making the tweeter swing might not make a difference in that sense, but if you by mounting it in a swing can decouple it from the midrange or the woofer which will vibrate a lot then that of course is a completely different thing. In that case then it is of course beneficial since the vibrations of the lower driver won't transfer into the tweeter.
Thank you for the excellent answer!

Your input is right in light with my intuition. Directly mounting the tweeter makes it much simpler, and will allow me to more easily test it playing OB and other alternatives. Thanks for including the table, BTW!

The paragraph you added when editing has been been in my head too: I'm thinking the swings holding the midrange/woofers would absorb any vibration in the horizontal front-to-back (which is what the motor-cone are generating), and I'm thinking there wouldn't be other vibrations - except those coming from the floor and up through the structure. I guess I'll build it and test.

Good food for though in your point about whether it makes any difference above 400Hz. My 8" midrange is to be crossed around 300Hz so your input makes me revisit. I guess I might as well try it since it's already on its swing.

Hopefully over the weekend I can finalize assembling one speaker for testing and start listening to some music. Looking forward to hearing OB bass!

Thank you!!
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Old 11th September 2020, 09:36 AM   #125
picowallspeaker is offline picowallspeaker  Italy
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Using rubber instead of stell, no, eh?


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Old 11th September 2020, 10:08 AM   #126
LewinskiH01 is offline LewinskiH01  Argentina
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Join Date: Nov 2014
Location: Buenos Aires
Quote:
Originally Posted by OllBoll View Post
If we plug in Linkwitz SPL-max spreadsheet and calculate volume of air pushed needed to get 110 dB SPL:

Frequency dipole
Hz cm^3
25 89521
35 31650
50 11190
71 3956
100 1399
141 495
200 175
283 61.8
400 21.9
566 7.7
800 2.7
1131 1.0
1600 0.3

The volume increases by 8x for each octave. I wager you'd it'd make a minimal difference above 400 hz as long as the construction is sound.
BTW, could you please post a link to the Linkwitz spreasheet you are referring to? I searched his website but couldn't find it.

Seeing those numbers I tested my hypothesis of crossing my twin 10" woofers at 50Hz to my sealed subs. Since Sd for the 10" is 380cm2, both would need to move 14.7mm to achieve that displacement...while Xmax is 7mm. Back to the drawing board! At 70Hz, though, each 10" would need to move 5.2mm, which is 74% of Xmax and higher than what I would usually shoot for, but then again 110dB SPL peak.

Would love to use the spreadsheet to understand intermediate points.

Thanks again!
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Old 11th September 2020, 06:50 PM   #127
Steve Lee is offline Steve Lee
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Love the wave guide!
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Old 11th September 2020, 08:02 PM   #128
OllBoll is offline OllBoll  Sweden
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Join Date: Nov 2010
Quote:
Originally Posted by LewinskiH01 View Post
BTW, could you please post a link to the Linkwitz spreasheet you are referring to? I searched his website but couldn't find it.

Seeing those numbers I tested my hypothesis of crossing my twin 10" woofers at 50Hz to my sealed subs. Since Sd for the 10" is 380cm2, both would need to move 14.7mm to achieve that displacement...while Xmax is 7mm. Back to the drawing board! At 70Hz, though, each 10" would need to move 5.2mm, which is 74% of Xmax and higher than what I would usually shoot for, but then again 110dB SPL peak.

Would love to use the spreadsheet to understand intermediate points.

Thanks again!
Of course I can, here it is: https://www.linkwitzlab.com/spl_max1.xls

I used the lower graph: SPL = 110 dB, Effective path difference D = 100 mm.

With a sub you can extend the distance D, for each doubling of the distance you halve the required volume displacement. In my 10" W-frame Dipole Woofers I have a distance D closer to 400 mm.

From the perspective of efficiency you want the distance D to be as high as possible while still having the dipole peak be outside of the target response. So if you cross lower, you can have a larger distance D thus higher low frequency output.

EDIT: Note that the spreadsheet assumes a perfect driver, in practice cone drivers for example starts to loose off-axis response above a certain frequency and we can use this to our advantage. If we put the dipole peak in the region where the rear and off-axis response has dropped off then we can pretty much avoid the dipole peak altogether.

Last edited by OllBoll; 11th September 2020 at 08:08 PM.
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Old 16th September 2020, 02:18 AM   #129
LewinskiH01 is offline LewinskiH01  Argentina
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Join Date: Nov 2014
Location: Buenos Aires
Quote:
Originally Posted by OllBoll View Post
Of course I can, here it is: https://www.linkwitzlab.com/spl_max1.xls

I used the lower graph: SPL = 110 dB, Effective path difference D = 100 mm.

With a sub you can extend the distance D, for each doubling of the distance you halve the required volume displacement. In my 10" W-frame Dipole Woofers I have a distance D closer to 400 mm.

From the perspective of efficiency you want the distance D to be as high as possible while still having the dipole peak be outside of the target response. So if you cross lower, you can have a larger distance D thus higher low frequency output.

EDIT: Note that the spreadsheet assumes a perfect driver, in practice cone drivers for example starts to loose off-axis response above a certain frequency and we can use this to our advantage. If we put the dipole peak in the region where the rear and off-axis response has dropped off then we can pretty much avoid the dipole peak altogether.
Thank you!

Assembled the swinging midrange, have the OB woofers in place and tweeter. Ready to test!

Doing digital xo so plenty of options. What's a good starting point for xo type & slope for OB/bafflesless? LR2?

So not to clutter someone else's thread, here's mine. You are all very welcomed to chime in!!
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