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Multi-Way Conventional loudspeakers with crossovers

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Old 23rd July 2008, 07:05 AM   #1
gpapag is offline gpapag  Greece
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Hi all

Speaker-room interference is a well investigated trouble area, also a topic exploited in many current and past threads.

Triggered by this post, I did a quick and dirty experiment by placing 2 speakers close together and found promising results.

Now, taking the idea a bit further, and thinking out loud that one speaker would be better than two in terms of interference and cross coupling, what about having one speaker producing L and R channels (assuming a stereo music material)?

There is the option of passively summing L +R at low level stage -easy and cheap- but it has it’s acoustic shortcomings.

An idea is to sample both channels at a high sampling rate and feed the outcome to a single amplifier that will drive a single loudspeaker.

What do you think about this?

Is it a sound idea?

Is it implementable?

Regards

George
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Old 23rd July 2008, 01:27 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

Is it not the same as the electrical summing ? Only mechanical / acoustic ?

I cannot see the difference and therefore any point at all ...

/sreten.
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Old 23rd July 2008, 04:55 PM   #3
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Sounds like you're going from stereo to mono - ? Or one enclosure with drivers for L + R channels? Then you have no imaging.

If it's a matter of room interference then treat the room.

Or have I completely misunderstood your intent?
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Old 23rd July 2008, 04:58 PM   #4
gpapag is offline gpapag  Greece
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Hi Sreten

“Is it not the same as the electrical summing ? “

I do not know if it will end up the same.
My 0.000 in electronics does not allow me to know.

I was thinking of a multiplexer reading the L then the R, successively, forming a “stream” of instantaneous L1, R1, L2, R2…Ln, Rn
(where 1,2…n = successive in time sample numbers).

This I think may be done in analoque, like in pseudo-dual channel oscilloscopes, but it certainly could be done better in digital.

This all hoping that L , R instantaneous differences will be retained in this electrical signal. If they can not be retained, then null .

But if they can be retained, then, this signal amplified, feeds a single speaker.

There comes your second question: “Only mechanical / acoustic ?”

Will the acoustical outcome of this signal be (or perceived) in a different way from an acoustical outcome of a simple L+R signal?


It may be there is no point at all. Yes

But in case that there might be a point,

Regards
George
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Old 23rd July 2008, 06:21 PM   #5
gpapag is offline gpapag  Greece
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Sorry sdclc126. I missed your post. We were typing almost simultaneously.

Quote:
Sounds like you're going from stereo to mono - ?
No. See above

Quote:
Or one enclosure with drivers for L + R channels? Then you have no imaging.
No. This has been done here and it seems to work OK in terms of imaging.
This is what I tried ("I did a quick and dirty experiment by placing 2 speakers close together and found promising results. " in my first post).

Quote:
If it's a matter of room interference then treat the room.
If it was that easy! It might not even be appropriate.

Quote:
Or have I completely misunderstood your intent?
It is not your fault. I have not managed to explain it in a plain way.

Regards
George
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Old 23rd July 2008, 06:44 PM   #6
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Well I thought you had meant you put two speakers next to each other facing FORWARD - definitely no imaging there; but facing in opposite directions for a bipole (not dipole) effect to create stereo imaging by room reflection?

Intuitively I don't see an advantage over the traditional - in fact I see fault in that there WILL be interference due to the fact that the listener will still receive off-axis sound directly from the speaker before the intended room reflections that create the stereo imaging. This could wreak havoc on phase and frequency response and make room treatment even MORE important and more complicated to get right.

With my limited understanding of how your idea would be executed electronically I honestly don't see an advantage - it seems like a solution that would just create a new set of problems.
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Old 23rd July 2008, 09:49 PM   #7
gpapag is offline gpapag  Greece
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sdclc126

You may try to implement the idea behind "STEREOLITH" yourself.
It is easy.
Then report back

You also might like to go through this thread.

And mind these links:

http://www.carlssonplanet.com/downlo...sson_ortho.pdf

http://www.youtube.com/watch?v=VC-sxvNzC8I

Regardless of my idea, these are enlightening staff

Regards
George
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Old 23rd July 2008, 09:54 PM   #8
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perhaps if a phase/time component was added to the signals somehow an illusion of imaging could be achieved?
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 23rd July 2008, 10:08 PM   #9
gpapag is offline gpapag  Greece
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Quote:
perhaps if a phase/time component was added to the signals somehow an illusion of imaging could be achieved?


I am under the impression that nothing extra should be added. Timing and phase relations of L, R should be preserved if sampling is properly done.

If the electronic part was built, this idea could be tested.

The problem is that I am not capable to do it (design it).

I am only good in soldering

Regards
George
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Old 24th July 2008, 01:31 PM   #10
sreten is offline sreten  United Kingdom
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Quote:
Originally posted by gpapag
Hi Sreten

Will the acoustical outcome of this signal be (or perceived) in
a different way from an acoustical outcome of a simple L+R signal?

George
Hi, the very short answer is a simple no. /sreten.
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