Aperiodic box for B200. Vent size and box shape? - diyAudio
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Old 12th October 2006, 10:04 AM   #1
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Question Aperiodic box for B200. Vent size and box shape?

I have use the B200 in an OB for over a month now, but for my tiny room and taste, I am thinking about putting the B200 in a aperiodic box to improve the bass over the OB and perhap a sharper imaging as well.

Now I know there is the Omega version but I am looking for a thin tall box if possible. Also, is there any formula to calculate the vent size?
If I use a long box and put the vent at the bottom, will this turn into a TL?

TIA.

Chuck T
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Old 12th October 2006, 12:31 PM   #2
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I don't think there have ever been any formulas for aperiodic loading -at least, not that are of any use to us now. Closest are Scan Speak's remarks about their aperiodic vents -aperiodic will behave as a critically damped sealed box of 20% greater volume than is acutally the case. How accurate that is, I've no idea. Probably roughly correct.

No, if you make a tall cabinet with the vent at the bottom, it won't be a TL, or not exactly, but you might have some QW issues unless you make sure the enclosure is suffiencntly damped, & perhaps have a coupel of internal panels to break up standing waves. You should be able to simply double the height of the Omega cabinet though without any problems. As a general rule, for sealed boxes & their variations, bigger = better LF performance.
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Old 12th October 2006, 12:54 PM   #3
foniton is offline foniton  Spain
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Hi.

Omega Loudspeakers is preparing a floorstanding version of the discontinued A8...
http://www.omegaloudspeakers.com/news.htm

There is an especialized forum in Audio Circle about Omega loudspeakers with very friendly people. Moderator is Louis Chochos (president of Omega). Sure they can help...
http://www.audiocircle.com/circles/index.php?board=31.0

Some information about aperiodic loading on this thread...
Aperiodic boxes for Ciare CH250

Best regards.

Antonio.
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Old 12th October 2006, 01:51 PM   #4
Dumbass is offline Dumbass  British Antarctic Territory
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The thinner and longer it is, the more likely you are to get box resonances.

AFAIK the Omega enclosure uses a pair of Scan-speak vents you can get at madisound. 6 bucks each, not too bad. Or you could fabricate the vent(s) yourself.

IIRC one way to think of an aperiodic is as a sealed box, but with the vents increasing the effective volume. So model the box as a normal sealed box, with the actual size as a lower bound to the effective size. I've never seen any calcs as to how much volume the vents add to the effective size.
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Old 12th October 2006, 02:50 PM   #5
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You can model aperiodic in Martin King's MathCad worksheets. Used the Ported box or ML TQWT sheet, and add stuffing to the port.
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Old 12th October 2006, 03:29 PM   #6
Dumbass is offline Dumbass  British Antarctic Territory
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Quote:
Originally posted by Scottmoose
You can model aperiodic in Martin King's MathCad worksheets. Used the Ported box or ML TQWT sheet, and add stuffing to the port.
I did not know that. [/carson]

Thanks for the head's up.
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Old 12th October 2006, 03:53 PM   #7
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I only found out myself a few months back. Best to do an initial design in the Sealed Box sheet as a control response, then re-model in the ported box sheet using the above method.
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Old 12th October 2006, 04:27 PM   #8
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Default visaton solo100

Hi

you may also want to look at the original Visaton designs for the B200, the Solo 50, or Solo 100 -details are here....

and there's a Solo 75 in the visaton forum, it's about as long as the 100 but thinner - Solo 75

The Solos are double chamber bass reflex designs with a damped inner port.

best, LC
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Old 12th October 2006, 04:54 PM   #9
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Thanks for the reponse.
I have already read a few of those threads.

I notice the Omega like to use wide and shallow boxes, I wonder if there is advantages for wide baffle as I would like use narrow box if possible. The vent looks big and is located directly behind the driver.

I'll probably use a large square vent as well.

I have the old Martin King worksheets. For the ported box, which is the port stuffing density? Is it the Dp0 ~ Dp4 ? why is there 4 of those variables?
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Old 12th October 2006, 05:23 PM   #10
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Wide baffles can give an interesting wave-launch and lowers the frequency at which baffle-step loss occurs.

Re the sheets, scroll down further until you see the heading 'Port Section of the Enclosure' The right hand of the 4 columbs lists stuffing density. Normally it's set to 0.0. Adjust as per requirements, but don't go beyond 0.999lbs ft^3 or MathCad will thpow a fit.
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