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Old 25th February 2015, 03:01 PM   #1
PhilEV is offline PhilEV  United Kingdom
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Default Will baffle size affect sealed enclosure size?

I'm planning to mount a driver on a large baffle (it's part of a bigger project) but then have a smaller, sealed enclosure behind it. Will the larger baffle affect the sealed box calculations at all or should I not worry about this?

Thanks,
Phil
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Old 26th February 2015, 03:43 PM   #2
chrisb is offline chrisb  Canada
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wouldn't affect the sealed enclosure calculations, but should be taken into consideration for baffle step loss and selection of crossover frequencies
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Old 27th February 2015, 07:09 AM   #3
PhilEV is offline PhilEV  United Kingdom
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Thanks for the reply, chrisb.

I'm pretty new to all this so forgive me if I've misunderstood what I've read about step loss but wouldn't a larger baffle mean a smaller step loss and a response closer to manufacturer specs? Or will I need to compensate for the gain?

I'm going to use active crossovers so can adjust them.
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Old 27th February 2015, 05:33 PM   #4
chrisb is offline chrisb  Canada
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A timely reference to manufacturers' published specs - it would be nice if they were all taken under exactly the same conditions, such as IEC baffle * in anechoic chamber of specified dimension, using identical calibrated microphones, etc, but that's not likely the case, so opinions as to the best way to approach those in the real world (if that's necessarily even desirable in all cases), can vary significantly.

* http://www.rjbaudio.com/Audiofiles/IEC%20baffle.jpg

As to your question of Baffle Step Loss - there's a lot written about the subject, here's a brief summary of the subject with resource links

Baffle Diffraction Step

There are numerous methods to deal with this, including something as simple as actively biamping, with the crossover point at the frequency calculated by baffle dimensions. The affordability of power with SS amps these days, particularly class D, greatly simplifies this particular approach.
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Old 27th February 2015, 05:54 PM   #5
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Quote:
Originally Posted by PhilEV View Post
I'm planning to mount a driver on a large baffle (it's part of a bigger project) but then have a smaller, sealed enclosure behind it. Will the larger baffle affect the sealed box calculations at all or should I not worry about this?

Thanks,
Phil
"Sealed Box Calculations" e.g. those based on Thiele Small parameters like Fs, Qts, Vas, Vb, etc. really only apply to the lower end of the driver's response. They describe the "shape" of the frequency response at the lowest end of the driver's passband in the box. The baffle has no significant impact on this part of the frequency response (for a woofer).

On the other hand, the size of the baffle will influence middle frequencies, e.g. between around 200Hz and 2kHz - this is the typical region where the "baffle step" takes place, and the size and shape of the baffle definitely has an influence in this FR region.

The above is my long winded way to answer your question with a "no".
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Last edited by CharlieLaub; 27th February 2015 at 06:00 PM.
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Old 27th February 2015, 08:42 PM   #6
PhilEV is offline PhilEV  United Kingdom
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Thank you both. With other references I've read as well I'm starting to get it. A lot more learning to do though.

I'm planning a 4.1/5.1 surround setup (not sure about centre speaker as I'll be dead centre anyway and lacking room). 4 channel amp driving the mids and another 4 channel amp driving the tweeters with a separate amp for the sub/bass driver (is this horizontal biamping?).

I've calculated the xover point they should be at but not taken the baffle into account. I'm hoping I can fine tune them when I have everything setup.

I'm going to post full specs in another thread to divulge my mad plan so will do that later when I'm not about to go to bed. Keep an eye on the PC Based forum if you're interested.
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Old 27th February 2015, 08:48 PM   #7
PhilEV is offline PhilEV  United Kingdom
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^ ooh may even be tri-amping
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