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Old 20th August 2013, 10:51 PM   #11
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It takes 4 times the displacement (or excursion) to maintain the same SPL for every octave lower you go.

Here is a calculator that will help you,

Piston Excursion calculator

Yes, an isobaric setup does allow you to use a box that is half the volume of what it would otherwise take for that of a single woofer.

But, this does nothing to increase displacement when adding the second driver and doesn't have the advantage of increasing the displacement by adding the second woofer.

Many like this type of setup, But IMHO it is a waste of a driver and the extra power required to drive it.
Increasing Displacement is the only way to increase the SPL

jer

Last edited by geraldfryjr; 20th August 2013 at 11:03 PM.
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Old 21st August 2013, 12:30 AM   #12
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Originally Posted by bitSmasher View Post
What environment is your work? this is almost contradictory, in that you don't want attention but you want good bass response... will the environment be conducive to bass reproduction?
Now we are getting to the heart of the matter, the environment, and specifically the boss and the boss' own attitude toward a nice little sub. You could just ask him point blank, but if there's already a hint of resistance or chance of getting fired then don't bring anything.
But if you want to take a chance on being the cool kid at work for once, young Bradsworth, here's what you do: Discretely determine your boss' receptiveness toward one for his own office. Then if he is, take up a collection from your coworkers telling them it's some appreciation gift or whatnot, and then make another sub for him. Instant brownie points all around!

PS. Use at least an 8 inch...
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Old 21st August 2013, 12:45 PM   #13
zobsky is offline zobsky  India
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I get the feeling that headphones would be better at your workplace
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Old 21st August 2013, 12:54 PM   #14
lolo is offline lolo  France
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Quote:
Originally Posted by bitSmasher View Post
What environment is your work? this is almost contradictory, in that you don't want attention but you want good bass response... will the environment be conducive to bass reproduction?
surely contradictory, especially when taking Fletcher Munson curves into consideration..
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Old 21st August 2013, 01:28 PM   #15
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I"m more worried about drawing attention to myself walking through security than when actually playing music. I have a corner formed by a cubicle wall and a filing cabinet that may reinforce the bass slightly. but the ceiling and other walls are 100+feet away. my boss's office is a few hundred feet away in a completely separate room. I"m not concerned about moderate listening levels disturbing anyone else.

And I don't know how I feel about that being the cool kid at work for once comment, i'm always the cool kidClick the image to open in full size.. hahaha... Just kidding

I would think if I keep the sub only a few feet away and at head height I shouldn't need all that much surface area, because I will not need very high spl.
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Old 21st August 2013, 02:11 PM   #16
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I get fair but not super deep bass out of my desk top system down to about 35Hz to 45HZ or so at maximum SPL of about 95db using a sealed 5 1/4" woofer

I do have to use added filtering and the excursions do get very extreme at this level but it is good enough for for good sounding music.

Make sure that you choose a driver with the highest Xmax you can because of this.
At the lowest frequency's I am getting about 4 to 6mm peak (one way) of excursion and I am sure it is more than what the driver was designed or rate for.

Parts Express had a few drivers that would have been perfect for your application but I think that they are all sold out of them now.

I just found this one that two of them might work well,

Tang Band W5-876SE 5" Shielded Woofer 16 Ohms 299-135

Here is a picture of what I am working with and the frequency response as well.

Don't let the drop off fool ya, drums and bass sound very punchy and clean as long as it is at a reasonable level (90db) and EQ'd properly.
At less than 2 feet away 95db is quite loud and I believe the EQ's were set flat for that measurement.

But, like I said it takes the driver to the extremes of its Xmax at about 40hz.

I also have to 5.5" bose drivers similar to the PE drivers that were in dual chambered box a that perform well also.
The original box sounded muddy but the drivers themselves sound great for such an application.

You might try a small TL type of enclosure with the PE drivers.
By Small I mean a small box and a long line inside of it like the Bose (there's that word again!!) Wave Radio system.

FWIW

jer

P.S. This was an earlier picture and since then I have sealed up that port as they weren't tuned right from the factory.
I found this out after measuring the TL parameters of the driver and they sound much better sealed especially when under high excursions.
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Last edited by geraldfryjr; 21st August 2013 at 02:28 PM.
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Old 21st August 2013, 07:18 PM   #17
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I'd go with a single Tang Band 6.5" subwoofer.

You won't run out of output with one of those. At those listening levels, you could probably eq to <30Hz without excursion being an issue - they'll move ~1" p/p, which is roughly similar in output to a 12"er moving 1/4" p/p. Still gonna be pretty loud

I'd advise that these drivers can be very power hungry. I've driven a 275w/ch amp to clipping with those little guys - they just sit there and take it. At those power levels, the voice coils are very well ventilated

Chris
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