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Multi-Way Conventional loudspeakers with crossovers

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Old 6th June 2007, 08:56 PM   #971
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Let's try again. The original Beyma link downloads fine for me, but it did appear on my desktop with a malformed extension, "TPL150.pd", instead of "TPL150.pdf", as it should have. If your browser is set to auto-launch instead of downloading the target file to the desktop, I could see how this would happen.

As it was, I just retyped the extension, and it became visible to Adobe Acrobat. (My OS is set up to always display extensions in file-names.)

Beyma TPL-150
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Old 6th June 2007, 09:10 PM   #972
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Quote:
Originally posted by Lynn Olson
As it was, I just retyped the extension, and it became visible to Adobe Acrobat. (My OS is set up to always display extensions in file-names.)
Same here... but i use Preview as the default pdf reader. Since it doesn't have a recognizable extension, it should probably download instead of open in the browser.

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Old 6th June 2007, 09:17 PM   #973
Paul W is offline Paul W  United States
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Quote:
For a 3-driver array, the upper and lower drivers are connected in parallel, and both are shunted with a 3~4 kHz value capacitor.
Lynn,
This approach works well for increased headroom but you may have meant in series...otherwise the upper and lower drivers carry a lesser "LF" burden. Still, only one cap is needed with the (physical) middle driver wired (electrically) on either end of the 3 driver chain.
Paul
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Old 6th June 2007, 09:44 PM   #974
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Default Resistors

Thanks, Lynn and guys for help on the inline resistor problem. It's been bugging me for years.
Michael Percy carries a heat sinkable mounting resistor. Looks pretty good.
One more question (Colombo)?
If I use one that adds only pure (OK, more pure) resistance will I defeat most of the negative aspects, especially dynamics problems?
I will do some testing, but didn't want to spend a fortune on resistors and find they were not worth the effort.
I'm building two systems at the same time, one all horn and other OB.
It will all be modular so I can mix and match. For instance OB coaxes with my horn bins. That is where the resistor idea originated so I can
manipulate the crossover regions. Incidentally, system will be all active as I have an Ashley stereo 4 way crossover to make experimenting a lot easier. Plus I am finishing an 18" sub that I can sneak over from HT to hi fi room if I want to try something radical. Combinations will be many. I'm not immune to trying something stupid.

Zene
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Old 7th June 2007, 04:50 AM   #975
terry j is offline terry j  Australia
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Hope the people that need to are making notes as this thread gets longer, I forget from a couple of pages ago let alone the beginning!!!

I realise things are not finalised yet (are we close??) but was just idly wondering to myself what the estimated cost of this is at the moment, things are starting to gel and variations are lessening so that may make a preliminary costing feasible.
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Old 7th June 2007, 05:01 AM   #976
el`Ol is offline el`Ol  Germany
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Quote:
Originally posted by mige0

110 dB / 4m down at 200 Hz is really impressive. Is this ESL really available? The plots are measurements of a prototype as far as I can see.

I once ordered the price list, they charge 4000 Euro for the large one! I forgot what the others cost.
The magnetostat is 1200 Euro, if I remember correctly, but it`s no dipole.
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Old 7th June 2007, 06:15 AM   #977
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Hi Zene,

The voltage dropped by a series resistor is proportional to current flow.

Current flow through a LS is NOT proportional to applied voltage, not even with a tiny ribbon, and especially not with a horn/compression driver. Current flow through a LS varies in time with applied waveform according to reactance and priorly excited energy storage mechanisms.

If you put a resistor in series with an ultra-low distortion power amplifier (voltage output) then the voltage on the LS side of a series resistor (or longer cable with its own inductance) will be distorted by both the passive and dynamic characteristics of the LS.

This would not apply to an amplifier having current output when only a single driver is in use because inserting series R will merely waste output.


Cheers ......... Graham.
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Old 7th June 2007, 09:42 AM   #978
mige0 is offline mige0  Austria
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Hi

The pro audio ELS just made me thinking abut some side aspects of highly asymmetric directivity loudspeakers like line arrays, small long ribbons / AMT's or the multiple speakers of the current OB project radiating within the same frequency band.

One of the effects here is that the SPL does not seem to fall at 6 dB with double distance but only around 3 dB du to the cylinder shape of the wave front.
Lynn made a side note elsewhere that there might be a possibility to virtually HEAR the shape of the wave front.

Correct FR equalisation presumed, I doubt that this is possible in free field but within a room I see a possible explanation.
Air is also a frequency dependant absorber which is varying with pressure, temperature and humidity. With around 6 dB at 90 m and 20 kHz at normal temperatures and humidity (needing 4 times the distance for any half frequency to achieve the same 6 dB) this effect is NOT very distinct but may be enough to add a slight coloration that can be detected.



Click the image to open in full size.
http://www.doctorproaudio.com/doctor/temas/ref_humd.htm

http://www.earthworksaudio.com/tech/hf_sound.pdf


The reflected wave fronts from the walls and furniture preserve a fraction of the original wave front depending on the reflection area with respect to the wave length. The oftener the sound was reflected the smaller the fractions will get. Frequencies below that wave lengths most certainly will change their decay behaviour back from 3 dB to 6 dB each distance doubling.

The interesting point now is that we should be able to compare the characteristic of the original wave front to the characteristic of the decay part.

In an normal listening environment this means that the decay attenuation of the sound due to diffraction of the cylinder shape will be lowest for the highest frequencies.

This overlays the "normal" absorption characteristic of any room and should provide a possibility to discriminate different wave front shapes originating form the speaker.
For highly asymmetric directivity speakers I would expect a brighter sound perception in rooms with same FR equalisation.


Maybe I am just splitting hairs here.
Any thoughts on this?

Greetings
Michael


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Old 7th June 2007, 10:12 AM   #979
jirka is offline jirka  Czech Republic
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mige0
Nice explanation
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Old 7th June 2007, 12:25 PM   #980
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Quote:
Originally posted by Lynn Olson
Close reading of the specs makes it fairly evident that crossing below 1.5 kHz would be unwise
...
This prompts the thought that if you stacked two of these things, the upper one could be 1st-order lowpassed at 4 kHz, so there would two working in parallel in the 1.5~4 kHz region, and gradually transitioning to a single driver above that.

Meaning that those two Beyma's can be crossed at 1.5 kHz to e.g. 12NDA520 (LF supported by two 15NMB420), just before cone breakup ((mis)reading the 12NDA520 curves there...).

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