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Woofer Stands/Module

muad

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Jun 8, 2019
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I posted about this awhile back but didn't really get anywhere. I am ready to put some money down and something built before my next kid comes (likely the end of my DIY opportunities).

I need to build a subwoofer that can play from 200hz to 20hz (150hz to 30hz is fine too). I need it double as speaker stands due to space limitations. My plan was to build something that could be used to turn a bookshelf (LS50M/Sierra LX) into a pseudo 3 way if needed, or use low order crossovers. I was planning on using a minidsp 2x4hd and crown xls 1502 for the woofer/sub. I have a hypex 252nc for the mains.

I was aiming for something 24-26" tall, and 10-12" wide. Approximately 50L or 1.75 cu ft plus or minus 20% or so. The plan was ported with the ability to seal the port. So I am targeting a QTC 0.707 for the sealed volume. I was looking at using Jeff Bagby's Woofer modules active but when I looked at the CSS SDX10, the official parameters are all over the place (likely from newer iterations or changes in manufacturing? . The audioexcite review also showed what I thought were inconsistent parameters to model with. So really I'm not sure where to go with this.

I am open to side mounting a12" driver but worried it can't play high enough and blend with the mains. I am also open to front mounted dual 8s, triple 6s, or single 10 inch drivers.

I was considering single:
SB satori wo24p4
CSS sdx10
Dayton RSS265 or bigger (not sure HO, HE, HF)

Other suggestions are welcome!
 
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I build some small subs as stands for my LS50. I wanted to keep the enclosure width the same, so I had to use 5" drivers. Ended up with this: https://audiosciencereview.com/forum/index.php?threads/mini-micro-subwoofer-thread.22870/post-762094

You could use multiple of these chassis to build some nice towers.

For your application. How about


It is 50l, you could change the enclosure shape no problem at all if you need it taller or something.


Frequenz(249).jpg


The chassis seem to be able to run up to 200hz.
 
That is tricky to answer, it will be different in some ways and much the same in others. The wavelength at 150 Hz is 2.29m 1/4 being ~57cm. Anything within that distance will sum at that frequency as if it was one driver.

But when you rotate the driver the energy is directed into the room in quite a different way as seen in the polar plot below. Even though most of the frequency response measurements look the same the in room response will be different due to the likely increase in SBIR.

RSS390HF simulation straight
RSS390HF.png


and turned to be on the side

RSS390HF-Side.png
 
Damn... I was told bass is omnidirectional. That's not what I'm seeing in those polars. So what's next. I guess I could go with the 10" version. Or dual 8?

The SBIR shouldn't be worse... just different? I mean having the woofers rear facing pushes the SBIR all the way up to 400hz... but looking it up it looks like rear facing would put the cancellation around 200hz. That plus floor bounce should be devastating.
 
Damn... I was told bass is omnidirectional. That's not what I'm seeing in those polars.
There is much information that persists despite not being accurate. Below 50Hz you could consider the response to be omnidirectional but above that there is directivity. To put it into perspective as the polar plot may easily make things look worse than they are in reality at 100Hz the level on axis and directly behind is the same at 85dB, the 90 degree output is 88dB, so 3dB extra directed sideways.
The SBIR shouldn't be worse... just different?
Different for sure, better or worse will depend on the distances to the walls.
 
I can't really afford 4 wo24p drivers. I looked at some dual 8 builds, but they do seem to give up Vd compared to a single 10, and limit my spl in a sealed configuration.

Right now I'm modeling the Dayton RSS265HF-4. I want to go sealed but I worry that it wont be sufficient in my moderately sized living room. I want to build the sub so that I can stuff a sock in the inside or outside opening of the port to try sealed, but have to option to run ported as well. This will be my only chance at building a box, as I will no longer have access to a shop in a few months. This way I don't have to commit to sealed.

Gonna use a minidsp 2x4hd and Crown XLS 1502.

PORTED
2 cu ft gross enclosure
3" x 20" port, tuned to 22hz
1.6cu ft net (port/driver volume)
Cone excursion and port velocity will require a filter -4db filter @20hz
After filter - Expected f3 28hz f6 23hz

SEALED
Sock on the outside: 1.85cu ft
QTC: 0.656 - 38.68 Fsc
F3 42hz
F6 31hz

Sock in the inside: 1.6cu ft
QTC: 0.680 - 46hz Fsc
F3 42hz
F6 31hz

1. Is a stupid idea?

2. I can't decide between the Dayton RSS265HF-4 or CSS SDX10
, they model very similarly. The dayton has a little more sealed SPL, but the CSS has more excursion head room. The CSS also has 4m/s higher port velocity with a 3" x 15" port tuned to 26hz. The spl between the 2 drivers track identically in WINISD. I don't know which driver to pick :(

Any feedback is appreciated
 
You will likely be perfectly fine with side mounted drivers up to 200hz. We have a dual driver sub with side mounted drivers, and we have a sub with downfiring driver. They both measure flat and essentially the same up to almost 300hz regardless of orientation.
 
I'd go for something that plays cleanly even extending above 1kHz. Plugging the ports on the bookshelf speakers, you might be able to get a low end roll-off on them that's low Q, and if so, in the simplest case that could be combined with a 1st order HPF, which could be a line-level one (a cap with the right value for the amp's input Z), resulting in a xo slope that would match up with a low Q 2nd order LPF on the woofer at some frequency, resulting in a 2nd order, low GD xo with passive parts. Could be modeled using Vituix.

I've dumped an idea into this thread below about a 56l woofer cabinet.
The point here is that it could be made by gluing two subwoofer flatpack kits together resulting in a well braced cabinet with the least amount of woodworking, and I also thought the driver is cool, f6 is 30Hz in such a cabinet, if I get the port sizes right. Although personally I think I'd rather go for something more compact than that (or even very small volume, also meaning less woodworking required) and sealed/aperiodic and use LT and amplification for bass extension. The CSS SDX10 for example is very suitable for very small sealed.
 
You will likely be perfectly fine with side mounted drivers up to 200hz. We have a dual driver sub with side mounted drivers, and we have a sub with downfiring driver. They both measure flat and essentially the same up to almost 300hz regardless of orientation.
Thanks, everywhere I read it states that the bass is omnidirectional. The Sims earlier in this thread made me question that. But I guess the room overrides the directivity at those frequencies?
 
Thanks, everywhere I read it states that the bass is omnidirectional. The Sims earlier in this thread made me question that. But I guess the room overrides the directivity at those frequencies?

It becomes gradually less omnidirectional as you move up in frequency. In practice you will be fine with the 200hz crossover you are planning.
 
Thanks, everywhere I read it states that the bass is omnidirectional. The Sims earlier in this thread made me question that. But I guess the room overrides the directivity at those frequencies?
Drivers in a box are not omnidirectional at all frequencies that can be considered bass (most are not that directive either) but that does not mean that it should stop you from using it as you have proposed. The simulation shows what will occur but it's not so easy to interpret that in terms of how it will look with another driver crossed over above. The simulation was also of a 15" driver which will become more directional earlier than a 10" one will. The room doesn't override the directivity, the directivity will change how the speaker responds in the room. You can try this with any speaker, filter the response to 200Hz and below and play pink noise. Turn the speaker to the left and then to the right, listen to the difference.

The point of the simulation was to show you the difference, not to suggest that it was a bad idea just something to think about.
 
What would be better at getting even low end to the LP, a vertical array of LF transducers, or fewer, larger ones? I.E. Kii BXT vs. W371.
 
What would be better at getting even low end to the LP, a vertical array of LF transducers, or fewer, larger ones? I.E. Kii BXT vs. W371.
I heavily considered this option. Namely 4x6" or 3x8". What held me back was the loss of spl vs a bigger driver, and the expense of buying multiple drivers. I struggled to find affordable drivers that would work in this application. my maximum driver cost is $600.
 
I heavily considered this option. Namely 4x6" or 3x8". What held me back was the loss of spl vs a bigger driver, and the expense of buying multiple drivers. I struggled to find affordable drivers that would work in this application. my maximum driver cost is $600.

Hmm that is something I didn't consider. I thought the SD of 4 6" would come close to a 15" but it doesn't. I think I'll go with the big boy, unless someone chimes in with some other things in the thread I made.
 
Hmm that is something I didn't consider. I thought the SD of 4 6" would come close to a 15" but it doesn't. I think I'll go with the big boy, unless someone chimes in with some other things in the thread I made.
Yeah I tried modeling 2 x 8" drivers, but I couldn't get them to perform like a 10". Although the Sd were similar the Vd is larger. I would have to find the right 8s for the right price.

I do like the idea of woofer arrays...
 
What would be better at getting even low end to the LP, a vertical array of LF transducers, or fewer, larger ones? I.E. Kii BXT vs. W371.
Both the BXT and W371 aim for cardioid type radiation and are probably more similar than different when measured in room.

That is quite different than a vertical array of drivers vs a lesser number of larger ones which will end up having quite different radiation patterns.

I heavily considered this option. Namely 4x6" or 3x8". What held me back was the loss of spl vs a bigger driver, and the expense of buying multiple drivers. I struggled to find affordable drivers that would work in this application. my maximum driver cost is $600.
I just bought 8 of these Sica woofers used here to go with one of their coaxes in a symmetric array, just under $600 USD including shipping for me to Australia. The quality vs price is amazing, sigbergaudio would probably agree :)

http://www.donhighend.de/?page_id=5291

Yeah I tried modeling 2 x 8" drivers, but I couldn't get them to perform like a 10". Although the Sd were similar the Vd is larger. I would have to find the right 8s for the right price.

I do like the idea of woofer arrays...
Comparing Vd to price you will struggle to find something better than the 10" Dayton sub. For well behaved 8" woofers at a reasonable price look at Scanspeak 22W8534G00 but if you want a subwoofer that can play higher up too these are not them. Using two of these in a woofer module and putting a smaller true subwoofer or two somewhere else in the room would probably be a good solution if they fit.

https://www.dibirama.altervista.org...peak-22w-8534g00-woofer-8-8-ohm-120-wmax.html
 
Both the BXT and W371 aim for cardioid type radiation and are probably more similar than different when measured in room.

That is quite different than a vertical array of drivers vs a lesser number of larger ones which will end up having quite different radiation patterns.


I just bought 8 of these Sica woofers used here to go with one of their coaxes in a symmetric array, just under $600 USD including shipping for me to Australia. The quality vs price is amazing, sigbergaudio would probably agree :)

http://www.donhighend.de/?page_id=5291


Comparing Vd to price you will struggle to find something better than the 10" Dayton sub. For well behaved 8" woofers at a reasonable price look at Scanspeak 22W8534G00 but if you want a subwoofer that can play higher up too these are not them. Using two of these in a woofer module and putting a smaller true subwoofer or two somewhere else in the room would probably be a good solution if they fit.

https://www.dibirama.altervista.org...peak-22w-8534g00-woofer-8-8-ohm-120-wmax.html
I ended up deciding on a side mounted rss316hf sealed in 1.6cu ft. Qtc 0.690. models well, can take EQ well. Stays well away from max excursion and at a much higher SpL than any of the 10s. Hopefully I can still get these up to 125hz if needed?

I plan on using them with sierra Lx, which has good output to 40s. I was wanting to cross at 80hz with a 1st order crossover, hopefully to get a more even in room response?
 
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