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Discussion Starter · #1 ·
I'm needing a little help with my pending subwoofer build. I just bought a Bash 300 amp and 15" Dayton RSS390HF-4. I have been messing with WinISD and this is what I came up with. Does this look good for a build? The response isn't completely flat but it's as good as I can get it. The cone excursion goes a little past the red line but if I drop the watts down to 280 it stays below. So if I just don't crank the amp as far as it will go I will be okay right? Thanks for the help.

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Looks fine.

The red line is xmax(linear excursion limit), and most drivers have sufficient throw before they hit their physical excursion limits (xmech). You might hear some distortion on the loudest notes but it won't damage the driver.

What is the "rear port air velocity"?
 

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Discussion Starter · #3 · (Edited)
Looks fine.

The red line is xmax(linear excursion limit), and most drivers have sufficient throw before they hit their physical excursion limits (xmech). You might hear some distortion on the loudest notes but it won't damage the driver.

What is the "rear port air velocity"?

The highest the rear port air velocity gets is around 17.5 m/s at 18 hz.

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I was planning on buying 4" pvc pipe at Lowes. Do I need to flare the ports?

Thanks for the help.
 

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Discussion Starter · #5 · (Edited)
My ports were going to be a little too close to the back of the enclosure if I put them on the front along with the driver. Does it make a difference in sound where the ports are located? What if I just put them on the top of the box so I don't have to mess with doing pvc elbows? I was messing with Google Sketchup. Would this picture work?

port3.jpg
 

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No, it won't matter too much where your ports are located on the box. If you can, glue in your pvc ports and then use a router and roundover bit to add a flare to the side mounting to wood. Flares will reduce turbulance and help avoid port noise. That being said, your port velocities looks sufficiently low.

As mentioned already, you are well within the safe zone if your simulation predicts excursion barely passing xmax at your amps rated RMS power.

I'd guess the best way to get flatter/deeper response would be to increase cab volume. The RS HF prefer biiiig vented boxes. Looks like a solid build though, as is. Do it to it!
 

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Discussion Starter · #8 ·
So on Winisd if I go over xmax by not quite 2 mm is that still acceptable as long as I don't completely crank the amp?
 

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Over by 1mm (<10% xmax) at full rated amp power won't be a concern. You'd have to be well over xmax to have to worry about "not cranking it."
 

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Discussion Starter · #10 · (Edited)
I'd guess the best way to get flatter/deeper response would be to increase cab volume. The RS HF prefer biiiig vented boxes. Looks like a solid build though, as is. Do it to it!
I decided to take your advice and go bigger. The response ends up being flatter and it goes deeper. It's only down 1 db at 20hz. It's big but I like it.
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Now that looks like a recipe for some rumble :D

What HPF are you modelling?
 

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Yes! There are a few different ways to try and duplicate the HPF response in the BASH manual, I don't know that anyone knows exactly what it is in textbook terms. Long story short, I think your sim should be plenty accurate :)
 

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Discussion Starter · #14 ·
Yes! There are a few different ways to try and duplicate the HPF response in the BASH manual, I don't know that anyone knows exactly what it is in textbook terms. Long story short, I think your sim should be plenty accurate :)
Very good, thanks for the tips. I'm a rookie at box building so I called up my cabinet making cousin today and he's going to help me build it Monday (and also supply wood for free!). I got the 6 inch pvc for the port from my brother in law who's a plumber, so I think I'm all ready to go. Hopefully it's a step up from my Bic H100. I think I could fit 8 of them inside this box.
 

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Discussion Starter · #15 · (Edited)
How much bracing should I have in a box like this? I planned on doubling up the front panel (double baffle I think they call it).

Also, I already have a terminal cup that I pulled out of an old prefab box that looks like this



but should I spring for these binding posts on Parts Express?

 

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Doubling the baffle is always good for a sub, and more bracing never hurts. Just keep track of your net volume to account for bracing, port and driver displacement. You don't need the fancy binding posts.
 
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