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Old 16th June 2012, 01:43 PM   #21
system7 is offline system7  United Kingdom
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Quote:
Originally Posted by chris661 View Post
I'm sorry, but this simply isn't so.

You could use the same argument to "show" that a midbass in a small cabinet would also have modulation issues in the midrange.

Remember each bass driver would "see" half the cabinet volume, as, being identical, they'll each pressurise their own half of the cabinet exactly.
Imagine there is a dividing wall between the two chambers. When the woofers move, they each press on the wall. They have moved the same amount and occupy an equal volume of air to each other, so the pressure on the dividing wall must be the same on both sides. The forces cancel exactly and there's no movement of the wall because of this.
So if the wall does not experience any net force, why bother with it?

Doing without will yield the same results (so long as the cabinet is otherwise mechanically braced).

Chris
Sorry Chris. Utterly wrong reasoning from YOU. These bass drivers are operating on separate filters so it's really a matter of opinion what is going to work best. One is rolling off at 200Hz with inevitable phase shift. The other is going up to 1kHz in flyingtele's plan

This is not your usual parallel woofer arrangement if you read the first post.

[sarcasm]BTW, thanks for squashing my much more INTERESTING post about domes. I really wonder why I bother sometimes. [/sarcasm]
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Old 16th June 2012, 01:53 PM   #22
tinitus is offline tinitus  Europe
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Originally Posted by system7 View Post
... so it's really a matter of opinion what is going to work best.
a matter of opinion ?
well, if thats all it is

calculate one with a mutual box for both woofers
and calculate one with seperate chambers for each woofer
and tell us the result, please
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Old 16th June 2012, 01:59 PM   #23
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Clearly, you don't understand that I fully comprehend the situation.

What the OP is creating is an acoustical clipper/compressor.

The mid-range voicing will be heavily influenced by the pressure of the bass. These are not balanced pressures cancelling each other.
In this case the box dampening the mid-range frequencies "sees" fluctuates wildly, much more then a typical scenario.

Here's an experiment for you, put a 3"speaker and a 12" woofer in a sealed box, crank it up.
Notice now how the 3" speakers cone is now torn apart? -Pressure imbalance.

This will be the force that effects the voicing of the mid-range frequencies.
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Old 16th June 2012, 02:01 PM   #24
fpitas is offline fpitas  United States
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Originally Posted by Alvis View Post
Clearly, you don't understand that I fully comprehend the situation.

What the OP is creating is an acoustical clipper/compressor.

The mid-range voicing will be heavily influenced by the pressure of the bass. These are not balanced pressures cancelling each other.
In this case the box dampening the mid-range frequencies "sees" fluctuates wildly, much more then a typical scenario.

Here's an experiment for you, put a 3"speaker and a 12" woofer in a sealed box, crank it up.
Notice now how the 3" speakers cone is now torn apart? -Pressure imbalance.

This will be the force that effects the voicing of the mid-range frequencies.
Alvis, you do realize these are equal size speakers putting out equal amounts of bass?
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Old 16th June 2012, 02:05 PM   #25
tinitus is offline tinitus  Europe
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Originally Posted by system7 View Post

This is not your usual parallel woofer arrangement if you read the first post.
no, its a 2.5way principle converted to a 3.5way
some say one of the two similar woofers is operating in 0.5way, because its crossed lower/earlier than its upper 'mate' woofer

whats special about it ?
its a known and well documented principle

btw, I think JacgueMahul presented the first commercial one in a small Focal tower speaker with 2x 5" and a tweeter
and we all thought, what the hell is the guy doing
looked weird and strange
some of the more skilled said, that cant work at all
but it tested really well
so ofcourse it got some 'attention'

and here are some 30 years later, and still have no idea how it works
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Old 16th June 2012, 02:08 PM   #26
system7 is offline system7  United Kingdom
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Utterly dull and pointless debate going on here.

FWIW, it's blatantly obvious that you chamber the two woofers separately.

Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories

This allows you to reflex the subwoofer in a bigger box for good bass. The top woofer is in a smaller box that controls its cone movement and distortion better.

I'd rather talk about midrange domes. A good topic, IMO.
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Old 16th June 2012, 02:12 PM   #27
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Alvis View Post
Here's an experiment for you, put a 3"speaker and a 12" woofer in a sealed box, crank it up.
Notice now how the 3" speakers cone is now torn apart? -Pressure imbalance.

This will be the force that effects the voicing of the mid-range frequencies.
why would I do that

woofer and mid is the exact same driver here, and both playing the exact same bass
if you calculate a box, you will get the same result for both

the different impedance of the different xo inductors might influence the result a bit
but I doubt it will enough to make significant difference
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Old 16th June 2012, 02:18 PM   #28
tinitus is offline tinitus  Europe
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Originally Posted by system7 View Post

FWIW, it's blatantly obvious that you chamber the two woofers separately.
no its not, but it certainly wont hurt either

maybe seperate chambers does give a very small improvement
and it does give more room for 'playing' with differnt 'allignments', yes
I said that too from the start

but it will still work as intended with both woofers sharing the same chamber/box, no real problem at all
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Old 16th June 2012, 02:24 PM   #29
tinitus is offline tinitus  Europe
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Originally Posted by system7 View Post

This allows you to reflex the subwoofer in a bigger box for good bass.
excuse me, what subwoofer

we are talking about 2x 6" midwoofers in 0.5 setup, as part of a 3way speaker, hence the 3.5way

please respect the subject, and the described project
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Old 16th June 2012, 02:24 PM   #30
fpitas is offline fpitas  United States
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Originally Posted by tinitus View Post
no its not, but it certainly wont hurt either

maybe seperate chambers does give a very small improvement
and it does give more room for 'playing' with differnt 'allignments', yes
I said that too from the start

but it will still work as intended with both woofers sharing the same chamber/box, no real problem at all
I'm not sure different alignments is a good idea; the two woofers won't be in phase synchronism if the low frequency responses are different.
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