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struggling with 1st design... (Shiva vs Brahma)

3K views 18 replies 6 participants last post by  angelod307 
#1 · (Edited)
This is my first ported build and I'm unsure of box and port size/type.

My sub is an Adire Audio Brahma (late model)
It will be powered by a 500w Oaudio plate amp.

Fs 19 Hz
Qms 11.6
Qes 0.41
Qts 0.39
Vas 92.3
Re 2x1.4 Ohm
Le 2x0.5 mH
Sd 436 cm2
BL 12.8 N/A
Xmax 28.5mm one way linear
Pmax4 600W RMS
SPL 83.8 dB @ 1W, 1m

I plugged some numbers into isdonline and came up with 3ft3 tuned to 20hz, but not sure.

Any recommendations for an optimal build? (volume & port type/size)
Thanks in advance.
 
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#5 ·
Re: struggling with 1st ported design...

Thanks a million. (I keep getting "access violation" errors with WinISd.)

One final question... What size port(s)?

Using various port calculators I am coming up with ridiculously long ports.

Will a 3" flared port 14.5" long whistle?

What type/size do you recommend?
 
#7 ·
Re: struggling with 1st ported design...

The net volume will be about 3 cu.ft., tuning it to 18 hz will require a slot port 2.5" x 8" x 51" long. This would be if you use the 20 hz hi-pass filter on the amp. A pair of CSS 12" passive radiators would be a much better choice if you budget would allow it.
 
#8 ·
Re: struggling with 1st ported design...

I've been racking my brain but still don't know what to do...

Passive Radiators are definitely an option but I have no experience with them.

If the Brahma doesn't work well in a HT setting, I am willing to use a different driver. If a pair of PRs and the Brahma can play nice together I'm all for that route...

Any Ideas? Shiva X2 with PRs?
Would the EX-PR15 PRs be a good match for the Brahma?

Two things are for certain, I will be using the OAudio amp, and box size isn't an issue.
 
#9 ·
Re: struggling with 1st ported design...

Personally I feel that a pair of 15" PR's from Exodus Audio would be your best bet with this driver.

http://www.diycable.com/main/product_info.php?cPath=24&products_id=685

Make the cab about 3.8 cu ft net after displacements and put all 14 100g discs on each pr to tune to 18hz. This will keep the cab smaller in total outside volume compared to a ported one and you'll have no port noise to deal with. 500w will be fine for both the PR's and the driver. a 15hz hpf or close to it will be needed to keep the driver from over excursion below tune. it's an extra chunck of money for the PR's but this would end up as a nice moderately sized sub.
 
#11 ·
Re: struggling with 1st ported design...

Now I have a decision to make...

The PR's and Mass kits are going to run me $238+ shipping.
The Shiva PR Package (One Shiva, Two PRs/kits) is only $134 more.

If I decide to go with the Shiva Package, which sub (Shiva or Brahma) do you think will be the better performer in this situation?

I figure, I could always put the sub I don't use in my car or find some other use for it.
 
#12 ·
Re: struggling with 1st ported design...

Now I have a decision to make...

The PR's and Mass kits are going to run me $238+ shipping.
The Shiva PR Package (One Shiva, Two PRs/kits) is only $134 more.

If I decide to go with the Shiva Package, which sub (Shiva or Brahma) do you think will be the better performer in this situation?

I figure, I could always put the sub I don't use in my car or find some other use for it.
They are both pretty similar in performance. I'd just get the PRs unless you do want to but the Brahma in your car. The Shiva likes a much larger box and requires more power to max out. 110 db at 20 hz is more than enough for most folks. 90db at 20 hz is usually satisfactory.
 
#17 ·
hello. i would highly recomend that the box be tuned closer to 30hz as the twenty is closer to ruler flat, but the room will comensate for the stuff lower than 30hz to some extent as well as corner loading the enclosure. it will have a little more gain and output. last, and most important, by having a little more efficient box, that means less power to get the same output where it counts as there is not that much at 20hz in most music and a handfull of movies really growl that low. if you are looking for true bottom end, and have more power than not, then sealed may just be your ticket as sealed actually plays lower with better power handling than ported as the power handling goes south past the tuning freq. of the port/box. just my two cents and many,oh so many years building boxes. ported is great when power is an issue because the box will play louder. sealed will play lower with better sound quality and power handling thoughout the entire spectrum, it just needs twice to four times the power of ported for simular results.
 
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