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Old 22nd September 2014, 01:35 PM   #1
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Default Help to choose an enclosure to these speaker

Hi all. Id like to some help to choose an enclosure to following image speaker.

Its a car sound brazilian speaker. But some people are using in a transmission line project here, the Baubos Speakers.

Is the transmission line the best enclosure to go with these speaker ?
Can I use the Tapered Quarter-Wave Tube design ?
Is there any other option ?


thanks in advanced.

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Old 22nd September 2014, 03:53 PM   #2
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I was able to find some photos and a building blog of the baubos. I didn't find a measurement or even a simulation, however, so it is difficult to state if this is the correct enclosure, as a TL has to be correctly modeled. If you have some link I'd be interested.
In general a car speaker is designed to work in a car (!), thus designed for a closed box in an infinite baffle, and the crossover deals with those conditions (more on this later). The bass is gained from the minimal volume of the car, giving a huge bass boost, compared to a normal room.
The enclosure only defines the bass part of the speaker, so the TL could be a viable solution to give bass on those drivers, but I don't know if the particular enclosure is correctly designed to work with the driver.
For the crossover, if the speaker use the car crossover, then the tonal balance is off. This is because in a car the enclosure is behind an infinite baffle, while on a speaker in a room there is the baffle step effect that has to be counted (usually using a bigger inductor for the mid-woofer).
Ralf
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Old 22nd September 2014, 05:14 PM   #3
Lojzek is offline Lojzek  Croatia
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Sealed box is the way to go, around 20 lit and stuffed.
Use simulation for making it more clear.
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Old 22nd September 2014, 06:00 PM   #4
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Thanks for replys.

I do not want to clone the Baubos because the crossover is sold by the project owner.

I still dont know how to simulate in software, I am googling it !

Thanks again.

Measurement: http://www.diyaudio.com.br/2014/04/b...a-montada.html

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Last edited by OliveiraCarlos; 22nd September 2014 at 06:15 PM.
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Old 22nd September 2014, 08:07 PM   #5
Lojzek is offline Lojzek  Croatia
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There is loads of software. I use woofer box and circuit designer:

Jeff Bagby's Software Page
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Old 22nd September 2014, 08:34 PM   #6
GM is offline GM  United States
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Quote:
Originally Posted by OliveiraCarlos View Post
Is the transmission line the best enclosure to go with these speaker ?
Can I use the Tapered Quarter-Wave Tube design ?
Is there any other option ?
Greets!

Yes, or OB.

Yes, though rather than tuning to Fs as is usually done, its Qts is high enough to tune it a bit higher while still having good LF extension, making it a shorter, smaller TL.

At a glance then, IME a TQWT [inverse taped] is best overall for drivers with a < 0.4 Qts, so using the Excel SS on MJKs site to calculate a straight tapered TL, I get 60.25 i.d long x 86^2 i.d. width x depth with the driver down 21 from the top.

For an Alpha TL, I get a 54 i.d. long x 70^2 i.d. width x depth with the driver down 18.85, so closer to an average seated ear height.

For either, its a matter of damping to taste with your preferred stuffing/lining material.

GM
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Old 22nd September 2014, 10:17 PM   #7
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Is this site trusted ? mh-audio Tapered Quarter Wave Tube

Please, I am completely, where is the Fs param in the image ? Is Fs = F0 Hz ?

thanks again.
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Old 23rd September 2014, 06:28 AM   #8
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It appears to be based on a simple ‘rule-of-thumb’ calculation from decades ago before the general DIY public was made aware of how to properly design them, so do not recommend using it. Note too that it calculates a considerably smaller cab than what I recommended, so will have less bass.

Yes, so Fs = 52.708 Hz.

GM
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Old 23rd September 2014, 07:17 AM   #9
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This software might be better?:
Transmission Line Modelling Software
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 23rd September 2014, 11:51 AM   #10
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Sir, is this a rule: Bigger the transmission line = more bass ?

I could not find: "Excel SS on MJK’s site".

thanks.
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