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can i use some type of sealant foam to cover any gaps along the edges? my cuts arent gonna be super accurate and some of the corner are messed up from dropping after the last cut.
 

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can i use some type of sealant foam to cover any gaps along the edges? my cuts arent gonna be super accurate and some of the corner are messed up from dropping after the last cut.
I have also had gaps building speaker boxes and typically will cut a strip of wood to cover the gap and glue the strip to the inside of the box. Once all of the gaps are covered from the inside, you can caulk along the inside edge of the box. Alternately, you can use something like bondo to fill the gaps from the outside, sand or trim flush and then caulk the inside seam of the box for a cleaner look. I have four VBSS's and they are not perfect but are all air tight and work perfectly :)
 

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I already have an amp for this planned project, Parasound HCA 1200II, 625 watts at 8 ohms, It does not come with DSP, HT setup is 2.0 only. Will Mini DSP work with this ? Is there a configuration file I can use to setup mini dsp for this sub driver?

My enclosure cannot follow the same dimensions of the the one posted on this thread, as long as I get the same volume and port volume, I should be good, right ?
 

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how much polyfil does one sub need? im trying to be cheap here.
Are you building a sealed sub?

If not, you don't need poly, just some lining inside the ported cab (mattress topper foam).

Sent from my Pixel 2 XL using Tapatalk
 

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While the frequency response is nearly the same, that is only because there is more boost added through DSP. In the lower tuning modes you will run out of output (xmax) faster then the higher tuning modes. You are trading max output for more extension with the lower tunings.
I'm having trouble wrapping my head around this. Wouldn't the output be the same for any given cone area and excursion? One box volume/tune may take more power to get to a certain excursion, but DSP can correct that if its within the power ratings of the sub and amp. Are you saying with the 15Hz tune, there isn't enough power handling to reach the same excursion levels as you can reach with the 31Hz tune?

 

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I'm having trouble wrapping my head around this. Wouldn't the output be the same for any given cone area and excursion? One box volume/tune may take more power to get to a certain excursion, but DSP can correct that if its within the power ratings of the sub and amp. Are you saying with the 15Hz tune, there isn't enough power handling to reach the same excursion levels as you can reach with the 31Hz tune?





In a sealed box, output is limited by either input power or driver excursion, dependent on frequency.

A ported box is somewhat more complex, as you both minimize excursion at port tuning as well as increase output.

So comparing a 15hz tune to a 20hz, you will lose output near 20hz that you can’t gain back with dsp.

A rule of thumb for port tuning is you start to get very limited returns by tuning lower than 2/3 of fs. Since the pa460 has a fs of 28hz, lower than 20hz tuning greatly hurts output.

Modeling these situations should give you a nice visual representation of this. The max spl feature demonstrates the maximum possible output for driver xmax and rated power. You can use dsp to shape response under this curve, but you can’t exceed it.

Chris
 

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Discussion Starter #1,711 (Edited)
I'm having trouble wrapping my head around this. Wouldn't the output be the same for any given cone area and excursion? One box volume/tune may take more power to get to a certain excursion, but DSP can correct that if its within the power ratings of the sub and amp. Are you saying with the 15Hz tune, there isn't enough power handling to reach the same excursion levels as you can reach with the 31Hz tune?
Since the tuning frequency is changing so is the range of contribution from the port which is the part your are overlooking. At the 31Hz tune a large portion of the output comes from the port so it requires less power and far less excursion to reach any giving output level in that range then the 15hz tune where the port contribution comes in much lower (and thus requires more power and cone excursion for equal output).

Here are graphs of the SPL and excursion for each tune at roughly max power without DSP. You can see that in the 31Hz tune output is maximized and excursion minimized in that range do to the port.
 

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In a sealed box, output is limited by either input power or driver excursion, dependent on frequency.

A ported box is somewhat more complex, as you both minimize excursion at port tuning as well as increase output.

So comparing a 15hz tune to a 20hz, you will lose output near 20hz that you can’t gain back with dsp.

A rule of thumb for port tuning is you start to get very limited returns by tuning lower than 2/3 of fs. Since the pa460 has a fs of 28hz, lower than 20hz tuning greatly hurts output.

Modeling these situations should give you a nice visual representation of this. The max spl feature demonstrates the maximum possible output for driver xmax and rated power. You can use dsp to shape response under this curve, but you can’t exceed it.

Chris
What DSP setting (15, 20, 31) would you suggested I should use if I have 2 X V.B.S.S in HT with approx. Volume of ~1600 ft3?
 

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In a sealed box, output is limited by either input power or driver excursion, dependent on frequency.

A ported box is somewhat more complex, as you both minimize excursion at port tuning as well as increase output.

So comparing a 15hz tune to a 20hz, you will lose output near 20hz that you can’t gain back with dsp.

A rule of thumb for port tuning is you start to get very limited returns by tuning lower than 2/3 of fs. Since the pa460 has a fs of 28hz, lower than 20hz tuning greatly hurts output.

Modeling these situations should give you a nice visual representation of this. The max spl feature demonstrates the maximum possible output for driver xmax and rated power. You can use dsp to shape response under this curve, but you can’t exceed it.

Chris
That is a huge help once again, Chris. I've been using Unibox because WinISD won't install on my work laptop. Without the ability to limit output by both power and excursion simultaneously, it's a crap shoot trying to model the hundreds of scenarios and checking to see where excursion limits are hit. I haven't figured out how to create and import an FRD file in Unibox.

I was leaning towards an 18Hz tune based on the curves I've modeled, so your advice to stay above 2/3 Fs confirms that's the right ballpark for what I'm trying to accomplish.
 

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Discussion Starter #1,714
The DSP setting used should reflect the tuning of the enclosure you build. The idea behind the original cabinet design is that you could easily swap between all three turnings with little work.

That said for HT use I recommend either the 20 or 15hz. 20Hz will give a little more output at the expense of some extension while the 15hz tune is the other way around.
 

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The DSP setting used should reflect the tuning of the enclosure you build. The idea behind the original cabinet design is that you could easily swap between all three turnings with little work.

That said for HT use I recommend either the 20 or 15hz. 20Hz will give a little more output at the expense of some extension while the 15hz tune is the other way around.
So, if I have one nearfield and one in behind AT screen I would be ok with 15Hz setting in that small volume room or I should wait till I get a microphone and do REW measurement and see? Any rough advise to give me an idea.
 

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So, if I have one nearfield and one in behind AT screen I would be ok with 15Hz setting in that small volume room or I should wait till I get a microphone and do REW measurement and see? Any rough advise to give me an idea.

As Matt stated, the dsp is dependent on the tuning the box is built at. They are not interchangeable.
What tune did you build the boxes at?

Chris
 

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That is a huge help once again, Chris. I've been using Unibox because WinISD won't install on my work laptop. Without the ability to limit output by both power and excursion simultaneously, it's a crap shoot trying to model the hundreds of scenarios and checking to see where excursion limits are hit. I haven't figured out how to create and import an FRD file in Unibox.



I was leaning towards an 18Hz tune based on the curves I've modeled, so your advice to stay above 2/3 Fs confirms that's the right ballpark for what I'm trying to accomplish.

I’d probably just build the 20hz design for simplicity and so you can run the existing eq file. Output should be very similar to 18hz tune.

I’m sure 18hz will work as well, just have to change the box design a bit and refine the eq on your own.

Chris
 

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As Matt stated, the dsp is dependent on the tuning the box is built at. They are not interchangeable.
What tune did you build the boxes at?

Chris
Oh wow, you got me there. I think I need a bit of information before I answer this question. I just built them according to specifications on the first page. Tuning the box?
 
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