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Multi-Way Conventional loudspeakers with crossovers

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Old 27th August 2008, 03:50 AM   #4411
sba is offline sba
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Ahh...so that's why they stopped using the multicellular. Well, then, that's great for the acoustics, but otherwise unfortunate for the aesthetics, because the Urei has a sort of dimestore look.
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Old 27th August 2008, 10:22 AM   #4412
SamL is offline SamL  New Zealand
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It look as Hiraga's 604 has treated cone as it is white gray in colour. Or it is a new cone material?
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Old 27th August 2008, 05:22 PM   #4413
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The new 604-8h-III uses a UREI style horn. There are pics of it over at Audio Asylum and at the Altec hostboard site.

I have a pair on order, but don't have anything to show for it yet. I was inspired by the sound of the Shindo Latour when I heard it at Pitch Perfect.

Chris
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Old 27th August 2008, 06:42 PM   #4414
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"The new 604-8h-III uses a UREI style horn."

Which version?? There were several. The original was no foamed edges. Then it went to edges and dots then slots then slots edges and sides.

Here's a C version horn.
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Old 27th August 2008, 06:47 PM   #4415
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Robh3606,

You will need to tell me which one it is most like...as it is a bi-radial horn, but I don't think it is a copy of any of the old ones.

http://www.audioasylum.com/cgi/vt.mpl?f=hug&m=135848

http://www.hostboard.com/cgi-bin/ult.../f/3729/t/3812

Either way, it is different and more spendy than the Mantaray.

Chris
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Old 27th August 2008, 08:08 PM   #4416
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The 604B used a larger multi-cell than subsequent 604s, it crossed over lower too.
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Old 29th August 2008, 08:13 PM   #4417
mige0 is offline mige0  Austria
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Default flying a speaker

Although we do not hear too much from Lynn I assume his project to be in good progress.

As most likely it develops step by step towards a real world something, I would like to come back to what was hardly touched yet in this thread (LOL at #4000+) and present some additional thoughts about interesting aspects when considering variants to keep a speaker in place.

As I mentioned earlier, flying is a simple alternative to bolt a speaker to a rigid structure, though not very common in home-fi.
To explore this some further and put things into perspective lets do quick calculation.





Lets keep things simple and lets therefor take a speaker with a total mass of 10kg and a membrane mms of 10g.
Lets further assume the peak force from the motor of that speaker to the membrane to be 10 Newton.

Given the above, the membrane will move a certain amount depending on frequency.
Now lets imagine the speaker being in outer space.
The force produced by the motor will not only move the membrane towards one direction but also will move the speaker towards the opposite direction.

The ratio of movement is determined simply by the ratio of masses.
In our example the speaker will move 1/1000 the excursion of the membrane the ratio of 10g to 10kg.

Without too much penalty exactly the same applies when hooking a real world speaker by a string!

If we calculate the membrane excursion from a sinus force of 10N (peak) to a 10g membrane mass, at 150Hz. we roughly get 1mm one way excursion of the membrane and 0,001mm excursion of the speaker.

At 1500Hz we would get 0,01mm excursion of the membrane and 0,00001mm excursion of the speaker.

Just remember:
a constant force over frequency from the motor in case of an ideal speaker - means the same current flow through the voice coil and it also means a constant SPL over frequency for any frequencies way above resonance at least!






Now we come to the most interesting part comparing the two alternatives.

Variant one (speaker bolt to a ideal rigid structure):
It is easy to imagine that if the speaker is bolt to a ideal rigid structure than this structure has to withstand the 10N peak over the whole frequency range. NO excursion of the speaker would (ideally) happen then.

Variant two (flying the speaker):
If the speaker is hooked by a string of lets say 100mm the (sinus- ) horizontal force can be calculated without too much error by the ratio of string length to excursion multiplied by the weight of the speaker.
In case of 150Hz we already calculated a excursion of the speaker of 0,001mm which translates into a peak horizontal force at the hook of about 1 Newton
In case of 1500 Hz we get a peak horizontal force the structure behind the hook has to withstand of 0,01 N.

Bottom line:
given the above example which easily could apply to a midrange speaker we can achieve a force attenuation of 20 dB at 150Hz and of 60dB at 1500Hz to whatever structure we'd like to build by rather flying the speaker than bolt it down.

Well, this is quite something no?



Greetings
Michael

PS:
I'd go nuts to do all this calculations in imperial system
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Old 29th August 2008, 08:46 PM   #4418
Variac is offline Variac  United States
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Very interesting!

Of course if the driver is suspended by cables in a triangulated manner it would be a lot lot less.. Maybe more rigid that a steel frame
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Old 29th August 2008, 10:37 PM   #4419
mige0 is offline mige0  Austria
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sorry I have to correct my last posting - just slipped into the wrong row (the one of membrane excursion instead of speaker excursion) in my spreadsheet

the last part should have been:

###################

Variant two (flying the speaker):
If the speaker is hooked by a string of lets say 100mm the (sinus- ) horizontal force can be calculated without too much error by the ratio of string length to excursion multiplied by the weight of the speaker.
In case of 150Hz we already calculated a excursion of the speaker of 0,001mm which translates into a peak horizontal force at the hook of about 0,001 Newton (100N of speaker weight multiplied by 0,001/100mm)
In case of 1500 Hz we get a peak horizontal force the structure behind the hook has to withstand of 0,00001 N.

Bottom line:
given the above example which easily could apply to a midrange speaker we can achieve a force attenuation of around 80 dB at 150Hz and of around 120 dB at 1500Hz to whatever structure we'd like to build by rather flying the speaker than bolt it down.

#####################


Well, even better now no?



Quote:
Originally posted by Variac
Very interesting!
Thanks!

Greetings
Michael
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Old 1st September 2008, 08:00 PM   #4420
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As one cannot remember all written here, may be this is presented before: http://www.audiogon.com/cgi-bin/cls....ull&1225420119 .

/Erling
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