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Discussion Starter #1
Just picked up a 15” HO yesterday from PE. Looking for a modest LR set up.

What is the smallest enclosure possible for this driver in a ported enclosure? Same question in sealed?

Room is 18x20x8 opens up into the kitchen. Not looking for wall cracking just a good bass for everyday tv/movie watching?

I’ve read anywhere from 1.5-3 cuf for sealed and 3.5 cuf and up for ported

Any help would be appreciated!


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that is a lot of volume . . what is the total to deal with
and got a pic of the proposed spacing / set-up?
 

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Discussion Starter #3
My apologies it’s only 16x17. Not sure where my brain was at

House is currently being built but here is a picture of the floor plan. I’ll have a basement for dedicated theater in the future but want to get a system built for when we move in August.



IMG_0504.jpg



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It may be better to build it according to the size you can spare. What is the size limit you are working with? Subs aren't locked into any one size and shape. You can use that 15 in a variety of internal volume boxes and tune accordingly. I will run the numbers once you tell me the size that you can have.

Where are you located?
 

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Discussion Starter #7
I haven’t really decided yet. I’d like to go as small as possible, simply for WAF. I’ll most likely be pushing it either with a inuke100dsp or Crown xti 1002. Haven’t really decided yet on the power though.

I would rather go ported, but don’t know if that’s possible because of size.


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I haven’t really decided yet. I’d like to go as small as possible, simply for WAF. I’ll most likely be pushing it either with a inuke100dsp or Crown xti 1002. Haven’t really decided yet on the power though.

I would rather go ported, but don’t know if that’s possible because of size.


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No one can help you until you state the dimensions is can be. Once that is settled, it can be run in software to see if it can be ported or not. One compromise would be to use a passive radiator to save size.
 

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I just went through the same process with my RSS 390HO. My room size was a bit larger, but similar. My first cut was a 3 cubic foot sealed cab. It was OK for music, but not impressive for HT. Everyone urged me to go ported, so I built the largest one I could squeeze in my limited space. I ended up with 4.5 cubes tuned to 20 Hz with a 4" round port 14.5" long. Both builds were powered by a Dayton 500W plate amp, which seems adequate.

How did I like ported? BIG difference! HT is much more enjoyable now. I say port that thing!
 

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Discussion Starter #11
No one can help you until you state the dimensions is can be. Once that is settled, it can be run in software to see if it can be ported or not. One compromise would be to use a passive radiator to save size.


There isn’t really a specific size/shape as I can be flexible with placement. I would however like to keep it smaller than 4cuf. Just trying to figure what’s the smallest ported configuration that would work well. I understand a micro Marty is around 3.7 cuf. Just curious if anyone has went smaller than that and had success


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Discussion Starter #12
I just went through the same process with my RSS 390HO. My room size was a bit larger, but similar. My first cut was a 3 cubic foot sealed cab. It was OK for music, but not impressive for HT. Everyone urged me to go ported, so I built the largest one I could squeeze in my limited space. I ended up with 4.5 cubes tuned to 20 Hz with a 4" round port 14.5" long. Both builds were powered by a Dayton 500W plate amp, which seems adequate.



How did I like ported? BIG difference! HT is much more enjoyable now. I say port that thing!


Definitely leaning to ported. Looks like I need to jump on Winsd and see what I can come up with


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I haven’t really decided yet. I’d like to go as small as possible, simply for WAF. I’ll most likely be pushing it either with a inuke100dsp or Crown xti 1002. Haven’t really decided yet on the power though.

I would rather go ported, but don’t know if that’s possible because of size.


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They work very well for the enclosure/driver size and a pair fit behind a couch perfectly. I don’t recall what cu ft they are but much smaller than a marty cube, maybe around 3cu ft each tuned to 21Hz. If interested, search for dual 390 slim build and that should pull it up.
 

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There isn’t really a specific size/shape as I can be flexible with placement. I would however like to keep it smaller than 4cuf. Just trying to figure what’s the smallest ported configuration that would work well. I understand a micro Marty is around 3.7 cuf. Just curious if anyone has went smaller than that and had success


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The smaller you make a ported box, the longer the port has to be for a deep tuning. To get away from this issue, you can use a passive radiator instead of a port and they both accomplish the same thing. You can use 4 cubic feet and the passive radiator will create the same low end. There are some efficiency losses below tuning because the weight of the passive radiator eats mechanical power to make it move. If you go too low with a port, the length of the port becomes so long that it doesn't fit the box without creating turns in the tube. Once you say that you can use a specific size, it can be modeled for you. So if you can use a 20" cube, it's about 3.6 cubic feet inside and coupled with an 18" passive radiator, it can accomplish a 20hz tuning. It will act like a ported sub. Ports use up internal volume so if you choose to use a port the volume of the port takes away from the volume that is used for the sub.

It takes time to come up with a specific alignment so if that fits, the rest of the info can be supplied to you.
 

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Discussion Starter #15
The smaller you make a ported box, the longer the port has to be for a deep tuning. To get away from this issue, you can use a passive radiator instead of a port and they both accomplish the same thing. You can use 4 cubic feet and the passive radiator will create the same low end. There are some efficiency losses below tuning because the weight of the passive radiator eats mechanical power to make it move. If you go too low with a port, the length of the port becomes so long that it doesn't fit the box without creating turns in the tube. Once you say that you can use a specific size, it can be modeled for you. So if you can use a 20" cube, it's about 3.6 cubic feet inside and coupled with an 18" passive radiator, it can accomplish a 20hz tuning. It will act like a ported sub. Ports use up internal volume so if you choose to use a port the volume of the port takes away from the volume that is used for the sub.



It takes time to come up with a specific alignment so if that fits, the rest of the info can be supplied to you.


Let’s say I can go as big as a micro Marty. Can the box be modified to be a narrower/taller? And use rounds ports instead of slotted?


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Let’s say I can go as big as a micro Marty. Can the box be modified to be a narrower/taller? And use rounds ports instead of slotted?


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Yes, it's volume and not dimensions that matter. You can use internal damping to control standing waves in the box.

Port shape also doesn't matter but it has to be enough cross sectional area so it doesn't compress. You may find that tuning to a low frequency in a small box starts to use > 25% of the internal volume for the port itself hence why I'm suggesting a passive radiator instead of a port. It also won't compress. The smaller the box, the larger the port volume has to be to maintain a low tuning frequency. Once you say the exact dimensions you can fit, I will run the alignment to tell you the exact required port diameter and length.

If you are waiting for someone to tell you what works, anything does, but it has compromises. Will 3.5 cubic feet work? Yes but there will be losses in deep bass and the port will be really long. Will 12 cubic feet work, yes with the same cross section for the port with very little length. 12 cubic feet has deeper bass than 10 cubic feet. 10 has more than 8 and so on. 4 cubic feet works but it will loss plenty low bass extension.

If you just say a set of measurements of what fits, I will run the alignment.

The marty subs, if I recall, were designed to maximize the wood in a given sheet and are not the only alignments that work. Once you depart from 'marty' dimensions, it isn't using the wood as effectively and is no longer a marty sub. There are infinite variations that work as well. Basically bigger is better.
 

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A 4 cubic foot box tuned to 20hz models 112db at 20Hz.
A 5 cubic foot box tuned to 20hz models [email protected] 20Hz.
A sealed 4 cubic foot box models 104db @ 20hz with a Qtc of .82

A passive radiator will give the same performance above 20Hz as a ported box but will roll off faster under 20Hz.

There is also port compression if you don't have enough cross sectional area.

A 5 cubic foot box means net volume after subtracting the port and driver volume.
 

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One option is to run an Alpine SWR1522d in a 4 cubic foot box tuned to 20hz. It has a motor that is nearly twice as strong as the UM15 and thus works in a much smaller box. It will hit 116db in that small box. I've run 4 of them before I moved up to crazy.

It has been discontinued but they are on Ebay from time to time. Ricci tested the driver and it's pretty good.
 

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Discussion Starter #19
One option is to run an Alpine SWR1522d in a 4 cubic foot box tuned to 20hz. It has a motor that is nearly twice as strong as the UM15 and thus works in a much smaller box. It will hit 116db in that small box. I've run 4 of them before I moved up to crazy.

It has been discontinued but they are on Ebay from time to time. Ricci tested the driver and it's pretty good.
I would rather not have to by another driver, but i appreciate the suggestion. I got a pretty good deal on 15" HO so i would try to utilize it first if possible.
It seems as if sealed could be my best option, understanding that i will have to feed it a bunch of power. I would be intrigued into the PR build, but then cost starts adding up.

id like to keep it close to the size of a pb-3000. 18x21x26 or so. just an estimate. Again not looking for earth shattering stuff, just decent output in a smallish form.
 

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I would rather not have to by another driver, but i appreciate the suggestion. I got a pretty good deal on 15" HO so i would try to utilize it first if possible.
It seems as if sealed could be my best option, understanding that i will have to feed it a bunch of power. I would be intrigued into the PR build, but then cost starts adding up.

id like to keep it close to the size of a pb-3000. 18x21x26 or so. just an estimate. Again not looking for earth shattering stuff, just decent output in a smallish form.
I had 3 posts above which covered a lot more material than just an Alpine suggestion.

The dimensions you just gave will have a net volume of 4 cubic feet allowing for driver and about .4 cubic feet for the port. that's a 6" port about 43" long.

It will hit about 112db at 20hz and near 118db near 40hz using the UM15.
 
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