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Multi-Way Conventional loudspeakers with crossovers

My open baffle dipole with Beyma TPL-150
My open baffle dipole with Beyma TPL-150
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Old 30th December 2009, 10:13 AM   #511
mige0 is offline mige0  Austria
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“The perception of beauty is a moral test.”
Henry David Thoreau


Nice quote , Charles!

the perception of inherent misuse and unbalance in current economic paradigm would be too "a moral test" - or maybe better put - a worldwide ethic challenge ....

Last edited by mige0; 30th December 2009 at 10:17 AM.
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Old 31st December 2009, 01:14 PM   #512
StigErik is offline StigErik  Norway
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Quote:
Originally Posted by cport View Post
While these steps may indeed reduce panel resonances, it does not address a primary source of closed-box coloration: The sound retransmission out the driver cone via internal box reflections. There is almost no way to treat this. Needs to be OB to deal with this issue.

To (also) quote SL:

"Conclusions"
An open baffle circumvents the box problems of delayed radiation through cone and enclosure panels. They occur typically in the mid-frequency range and are difficult to suppress.

This is why I find Stig's ideas so very interesting -- we are down to the native resonances/problems within the drivers themselves, which I envision are in the basket/magnetic assembly, but are of a whole lower order of magnitude than what we see in boxes.

-- Charles
Reports from other people I know that have tried decopled/suspended drivers without baffles are that they're totally amazed by the lack of coloration!

I'm quite sure that paying attention to decoupling can improve box speakers as well, but you'll never get rid of the delayed energy inside the box completely. An other thing is that I think its easier to get good off-axis response with a dipole design.

I think I've found the drivers I want to use for the main dipole. The next thing up is to improve a bit on them. The Excel drivers have very stiff, but light magnesium chassi, which rings quite a lot. I will try do damp a little here with bitumen sheets.

For the bass there will be four 21" H-baffles for sure. Two is just not enough!

In time I will build a "finished" version of all this that looks a lot better that the current prototype speaker of course.

Here's a new picture. The only thing new is the amplifiers you can see on the floor behind the main dipoles....

Click the image to open in full size.
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Old 31st December 2009, 01:34 PM   #513
adason is offline adason  United States
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Hi Stig,

one quick question. I follow this thread with great interest, because I am open baffle fan, built quite a few of them, but never baffle-less speakers. I am just afraid of too much equalization needed due to too much cancellation.

So here is my question: in order to prevent cancellation, yet not to have speakers mounted on the baffle itself, what if there would be baffle attached to your frame? Just approaching the drivers, not touching them really, maybe some soft suspension between.
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Old 31st December 2009, 01:42 PM   #514
StigErik is offline StigErik  Norway
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There's approx 12 dB compensation for both the 5" and 8", which is not all that much. Both the 5" and 8" is crossed over below their dipole peak to get a clean off-axis respons, which would not be that good with baffles.

The 21" in H-baffle is EQ'ed a lot more... close to 30 dB @ 25 Hz!
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Old 31st December 2009, 02:02 PM   #515
mige0 is offline mige0  Austria
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Quote:
Originally Posted by adason View Post
...
So here is my question: in order to prevent cancellation, yet not to have speakers mounted on the baffle itself, what if there would be baffle attached to your frame? Just approaching the drivers, not touching them really, maybe some soft suspension between.
You certainly could give that a try.
Make sure you do your sealing as soft as can be in order to keep the "leakage path" as low energy transmitting as possible

Michael
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Old 31st December 2009, 02:04 PM   #516
adason is offline adason  United States
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+30 dB at 25 Hz is insane! .... that's why I am still stuck with closed box woofers, lets forget the woofers for the moment, lets talk about 200Hz up...

I understand your rational about off-axis response and dipole peak and higher crossover points, and no baffle vibration, its all compromises...I am just trying to imagine what the outcome would be if the speaker was mounted on some pole by the magnet, not attached to the baffle, the baffle would be quite large, hence little cancellation, baffle would be softly suspended away from vibration, so clean open baffle sound, baffle peak would be shifted low enough...how would the off-axis response looked like?
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Old 31st December 2009, 02:10 PM   #517
mige0 is offline mige0  Austria
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Quote:
Originally Posted by StigErik View Post
Reports from other people I know that have tried decopled/suspended drivers without baffles are that they're totally amazed by the lack of coloration!
I totally agree.

The freedom of (additional) coloration simply is second to none.
The concept of suspending a speaker on a swing and omitting any baffle is a wonderful combination

I have done it also with my small NEO3 horn and a nude Peerless 12" as a two way - correcting for the dipole loss with a simple inductor in series with the 12" and it works amazingly well given the extreme low investment.



Quote:
Originally Posted by StigErik View Post
...The only thing new is the amplifiers you can see on the floor behind the main dipoles....
New AMPs or new housing?

Michael

Last edited by mige0; 31st December 2009 at 02:15 PM.
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Old 31st December 2009, 02:24 PM   #518
mige0 is offline mige0  Austria
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Quote:
Originally Posted by adason View Post
.....I am just trying to imagine what the outcome would be if the speaker was mounted on some pole by the magnet, not attached to the baffle, the baffle would be quite large, hence little cancellation, baffle would be softly suspended away from vibration, so clean open baffle sound, baffle peak would be shifted low enough...how would the off-axis response looked like?
I sadly didn't get ready over Christmas, but actually am working on this - If you have some patience I might come up with a comparison for complete nude 12" on a swing and 12" in baffle - both on swing. Most certainly I will cut the hole in the baffle with some play only and not use any sealing


Michael
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Old 31st December 2009, 04:54 PM   #519
twest820 is offline twest820
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I've been thinking along these lines as well, specifically an Orion type speaker with a minimal baffle and lower cost drivers than what Erik's using. This would be a four way but bit more accessible due to lower driver cost. Latest concept sketch attached; it starts out as a no baffle at high frequency and transitions to an H frame sub. From the top the drivers would be something like BG Neo3 PDRW, BG Neo8, Peerless 830884 (8" woofer), 830668 (10" sub), and 830669 (12" sub) with crossovers around 2kHz, 700Hz, and 175Hz.

The BG magnetostats are light enough attaching them to the minimal support frame that would hold them above the 8" shouldn't be a problem. The woofers would all be magnet mounted to the blades behind them---it's not clear from the sketch but the 8" would have a separate support from the subwoofers---and the blades isolation mounted to a plinth.
Attached Images
File Type: png OpenBaffleFourWay.png (16.9 KB, 1109 views)

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Old 31st December 2009, 05:36 PM   #520
badman is offline badman  United States
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Quote:
Originally Posted by StigErik View Post
There's approx 12 dB compensation for both the 5" and 8", which is not all that much. Both the 5" and 8" is crossed over below their dipole peak to get a clean off-axis respons, which would not be that good with baffles.

The 21" in H-baffle is EQ'ed a lot more... close to 30 dB @ 25 Hz!
WOW.

That much eq (I'd describe 12dB as quite a lot) sure brings thermal artifacts into question. Everything's a tradeoff, but if thermal issues are audible, then this system would certainly prove it!
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