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 Post subject: Enclosure size confusion
PostPosted: Fri Jun 16, 2017 2:47 am 

Joined: Thu Jun 15, 2017 6:17 am
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I have a pair of 15" Phoenix Gold Titanium Ti15D (each with 2x 4ohm) I bought new back in 2003. I'll feed them with a the pair of R500X1D Rockford Prime amps. I want to install them in a sealed enclosure. My main question is what volume does my enclosure needs to be? How does polyester filling is taken into account? Is there an advantage to partition the enclosure so each sub is separated? The Phoenix Gold datasheet states 1.25ft3 (musical) and 1.75ft3 (SPL). However, most subwoofer online enclosure calculators are giving me a volume of 6.5-7.0ft3 per sub. That a world of difference! I look forward good musicality (a lot of metal music Rob Zombie, Metallica, Korn). My parameters are FS 26.21Hz Qms 9.26; Qes 0.594; Qts 0.558; Vas 114.63 liters (4.0259ft3), Sd 792 cm2 (122.76in2). I install this into an '84 Fiero... kidding :mrgreen: , it's a 2006 Nissan X-Trail, so I have enough room.

Anyone help me point in the good direction?


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 Post subject: Re: Enclosure size confusion
PostPosted: Fri Jun 16, 2017 8:20 am 
the Floor Sweeping Hack with Golden Ears

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something is wrong with the online calculators but I am not sure how your going about trying to find the recomended volume since it is given already. The calculators are more for ported enclosures if I am not mistaken? If you want SQ try to get as close to 1.25 if you want spl go closer to 1.75.



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 Post subject: Re: Enclosure size confusion
PostPosted: Fri Jun 16, 2017 9:10 am 

Joined: Thu Jun 15, 2017 6:17 am
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Ok good for the size. What about the poly filling and partition inside the box?


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 Post subject: Re: Enclosure size confusion
PostPosted: Fri Jun 16, 2017 9:47 am 
the Floor Sweeping Hack with Golden Ears

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separating the enclosure is helpful if you blow a sub, one can keep playing in the correct airspace. The only time I have used polyfill was when I was not happy with out it sounded in hopes of correcting some error. Its cheap and easy to try and can change the sound, some like it and some do not.



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 Post subject: Re: Enclosure size confusion
PostPosted: Fri Jun 16, 2017 11:08 am 
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Separate chambers for sure when using multiple channels. I think it makes it easier to tune. I have played with Polly fill. Never heard a difference. I think it's a myth.



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 Post subject: Re: Enclosure size confusion
PostPosted: Fri Jun 16, 2017 11:45 am 
the Floor Sweeping Hack with Golden Ears

Joined: Fri Dec 19, 2008 9:53 pm
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I can't remember where I heard it and now wonder if its true but I thought I heard that it is slightly louder when the subs share an enclosure?



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 Post subject: Re: Enclosure size confusion
PostPosted: Mon Jun 19, 2017 1:32 am 
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Most enclosure calculators are for use with subwoofers in a large room environment. When you put a sub in a small space like a vehicle, the calculation needs to be different. In this small space, the volume of the vehicle's interior becomes a large influence on what the subwoofer will do.



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 Post subject: Re: Enclosure size confusion
PostPosted: Wed Jun 21, 2017 1:13 pm 
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Also note, that back in those days PG was notorious for skewing their numbers, getting them crossed. I think that's the case here. Typically a smaller enclosure will be your SPL and a larger one for musical. I'm willing to bet those got crossed.

Polyfill mostly benefits sealed boxes, but does have some effect on ported.

With each sub having its own amp I would definitely go with separate chambers.

Back in the 90's I was told the same thing about being louder sharing the same air space.if it's ture or not, I've never noticed.



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http://phoenixphorum.com/viewtopic.php?f=10&t=16998
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 Post subject: Re: Enclosure size confusion
PostPosted: Wed Jun 21, 2017 7:05 pm 

Joined: Thu Jun 15, 2017 6:17 am
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Thank you very much for your replies. It's much appreciated. Based on your comments, I'll be using 1.5cu.ft. per sub; that'll make me fall in the middle of the SQ vs SPL volumes specified by PG and won't be an issue if PG crossed the values in their spec. I'll split the enclosure in two sepatated sections, the partition acting at the same time as a brace. I'm eager to get this built but it won't happen before a month or so. I'll post pictures of the results when I'm done!


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