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Old 2nd March 2004, 12:46 PM   #1
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Default Multiple bass drivers in single sealed enclosure...

One of the things that's not clear to me is the effect of using multiple drivers in a single sealed cabinet.

I was thinking of using multiple 8" seas or scanspeak woofers in a sealed cabinet, and I'd like to know what the effect is, and also which values I should divide or multiply when using calculation sheets.

Is there also something available that replicates a Linkwitz transform circuit but then "off the shelve"?

Furthermore, If I buy a Behringer EMC8000 Mic, which preamp should I use to interface with my computer...is a M-Audio Duo USB up to the task?

Regards,

Richard
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Old 2nd March 2004, 05:24 PM   #2
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Vas and Sd double. Depending how they are wired Le will halve in parallel, double in series. Generally this means a doubling of the cross-sectional area. SPL is +6 in parallel, unchanged in series.
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Old 2nd March 2004, 07:30 PM   #3
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Assuming that

a is the number of elements that are connected in series, electrically,
b is 1 for normal configuration 2 for isobaric configuration and
n is the total number of elements,

Vas1=Vas*n/(b^2)
Bl1=Bl*a
Sd1=Sd*n/b
Re1=Re*a^2/n
Le1=Le*a^2/n

Isobarik mounting meaning mounted in pairs, no more. Index 1 are the new values.
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Old 2nd March 2004, 08:00 PM   #4
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Default Re: Multiple bass drivers in single sealed enclosure...

Quote:
Originally posted by richardkrol

......

Furthermore, If I buy a Behringer EMC8000 Mic, which preamp should I use to interface with my computer...is a M-Audio Duo USB up to the task?

Regards,

Richard
Have this combo and it works great with a laptop. But I canít manage the USB duo to work higher than 16 bits @ 48 kHz under Win2K with my measurement software (Audiotester and Sample Champion).

If you want to connect the mic to a regular build in soundcard buy a low cost Behringer mixing console with phantom power like the UB820.

Cheers
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Old 2nd March 2004, 08:09 PM   #5
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Thanks all !

Does that mean that say with two drivers a lower f3 point can be had and/or that the excursion of the driver is less for the same spl..?

As for the M-audio duo usb, I am running mac osx. what I like about this unit is that it can interface with the pc and work as a standalone preamp / converter.

regards,

Richard
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Old 2nd March 2004, 08:33 PM   #6
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I used a pair of SS 21W/8555-01 per side in 45 litre sealed boxes, below 200Hz in 4-ways. For LT; I used & highly recommend the Marchand WM8. With a 3-way XM9 & a passive umid-tweet XO; those were phenominal speakers! I prefer Excel woofers (seem clearer) to the Scans.
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Old 2nd March 2004, 08:37 PM   #7
Svante is offline Svante  Sweden
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Quote:
Originally posted by richardkrol
Thanks all !

Does that mean that say with two drivers a lower f3 point can be had and/or that the excursion of the driver is less for the same spl..?

regards,

Richard

With two drivers in a double-sized box, the frequency response will be the same. The maximum output will be +6dB, alternatively, the cone amplitude is halved for a given level.

With two drivers in the *same* box (as you had for the one driver) F3 will *increase*, since Vas is doubled. How much it increases depends on the Vas/Vb ratio.
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Old 4th March 2004, 02:00 AM   #8
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Quote:
Originally posted by Timn8ter
Vas and Sd double. Depending how they are wired Le will halve in parallel, double in series. Generally this means a doubling of the cross-sectional area. SPL is +6 in parallel, unchanged in series.
Can you reconcile that with the info in this thread? Gain when using nore speakers

I would think the SPL would increase by 3db, not 6. Perhaps I need the Dummies (tm) explanation of SPL and sensitivity.

Also, 'splain this to me if you can: I have MTM speakers (Lynn Olson Ariels) that use two mid/bass units with rated sensitivity of 88 and a tweeter that's rated at 90. The cross-over has resistors in it to pad down the tweeter. How can that be? The measured response is nice and flat. I can't reconcile those numbers.
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Old 4th March 2004, 02:08 AM   #9
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Quote:
Originally posted by Dave Jones
Also, 'splain this to me if you can: I have MTM speakers (Lynn Olson Ariels) that use two mid/bass units with rated sensitivity of 88 and a tweeter that's rated at 90. The cross-over has resistors in it to pad down the tweeter. How can that be? The measured response is nice and flat. I can't reconcile those numbers.
I don't understand what there is to reconcile. The tweeter is more sensitive so they padded it down to bring to the level of the woofer.
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Old 4th March 2004, 04:16 AM   #10
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Quote:
Originally posted by ooheadsoo


I don't understand what there is to reconcile. The tweeter is more sensitive so they padded it down to bring to the level of the woofer.
There are TWO woofers per tweeter.
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