Subwoofer build suggestions wanted

[Bear]

So, I'm leaning towards either buying or building one of two options based on WAF and budget. I don't want to get much north of $1200 and if I can build for less, that would be awesome. I have the tools and skills to build the enclosures, but I need plans. Im not capable of designing my own enclosure. I know Parts Express sells typical 12" and 15" enclosures, but I imagine they may not be of ideal dimensions and size for this. Any suggestions would be appreciated. I love the idea of sealed heart pounding and quality sound, but I also would be disappointed if the LFE in movies was missing. To clarify room measurements 18' wide by 20' deep listening area (with an additional 15' behind which is the kitchen and only a half wall separating the two) with vaulted ceiling peak of 12'.

1. Two Rhythmic L12's
2. One Rythmik F15HP

Thoughts?

Two 12" are better than a single 15" under almost all practical circumstances except budget, and even then, good 15" subs start to get very expensive (2x12" that share a single amp get a lot of the benefits of dual subs, but they are better when driven separately with DSP affecting each separately and as a group).

[rick844]

Now I'm more confused then ever. Not on the 2 12s vs a single 15, but I reached out to Rythmik and they said the sealed subs would be too small for my room. They suggested either a ported 15 or ported 18.

Per Rythmik "In such a big room, I would recommend a ported subwoofer like the FV15HP or the FV18. The F15HP won’t be enough in a such a large room."

Thoughts guys?

[Scottg]

Here is a thread by Danny Ritchie, building the SW-12-04 driver in a sandbox enclosure

https://www.audiocircle.com/index.php?topic=53675

Back when I was using sketchup I helped a forum member on DIYAudio with this design:

https://3dwarehouse.sketchup.com/model/b9c1bb384817cd2b47a0bdeabc8fa6d5/Gregs-Box?hl=zh-CN

[Scottg]

Now I'm more confused then ever. Not on the 2 12s vs a single 15, but I reached out to Rythmik and they said the sealed subs would be too small for my room. They suggested either a ported 15 or ported 18.

Per Rythmik "In such a big room, I would recommend a ported subwoofer like the FV15HP or the FV18. The F15HP won’t be enough in a such a large room."

Thoughts guys?

He's basically saying there isn't enough output without compression, which isn't too surprising.

Really depends on how loud and low you want to go, particularly with respect to dynamics and compression. There is no "free lunch" here.

An average in the upper '80s with some dynamics approaching 96db, and loaded near the floor and wall should be OK assuming the higher dynamic peaks in spl aren't terribly low in freq..

The band-pass sub with the 15" driver that the Dark Lord presented will play louder, though it's lower-freq. response is necessarily limited (..meaning it doesn't play as low near the average as something like the servo's assuming no high-pass/"rumble" filter).

[rick844]

That all makes sense. I was able to get the enclosure design from rythmik. Its roughly $1,000 in parts and materials if I make the box myself. I'm going to look at Greg's post model as well and do some pondering.

[rick844]

Another question I had. Does a forward firing subwoofer vs down firing provide more punch or is it basically about dispersion?

[rick844]

So in your design Greg, it appears to be sealed enclosure with a separate section for the amp. The rounded corners look slick, but I don't hint I want to attempt that.

[Bear]

Now I'm more confused then ever. Not on the 2 12s vs a single 15, but I reached out to Rythmik and they said the sealed subs would be too small for my room. They suggested either a ported 15 or ported 18.

Per Rythmik "In such a big room, I would recommend a ported subwoofer like the FV15HP or the FV18. The F15HP won’t be enough in a such a large room."

Thoughts guys?

SPLmax is a function of frequency and piston volume. Rhythmik doesn't seem to disclose Xmax or Xmech that I saw (quick glance), but they do disclose Sd (cone area).
DS15 - 809cm^2
DS12 - 530cm^2

So, dual 12" drivers will have +25% more cone area, and the recommended volume for the 15" is 3cf sealed. Dual 12" would need ~3.6cf sealed. So, if the stroke for the dual 12s is within 25% of the 15", then you have equivalent piston volumes and equal-or-better SPLmax. you have a net of +20% box volume with the 12" drivers, though the gross volume is likely higher (double-up those baffles!).

In terms of SPL, think of it as every time you double the cone area, you get +3dB (holding power delivered to the driver constant). Depending upon where you want the extra SPL, going with a bigger box can be a lot more cost effective than going with duplicates.

So, that's the core physics. Let's look at the box alignment...

Generally, a sealed enclosures will fall-off at 12dB/Octave below Fb (this is dependent upon the Q of the box). A vented enclosure will fall off at 24dB/Octave below Fb/tuning. The key trade-off is that a vented enclosure will have a lower tuning frequency (Fb) at the expense of a (much) larger enclosure. So, you get more bass with a vented enclosure, but the price is a bigger box (you also have a worse transient response, but let's focus on the SPL aspects...).

So, what are they telling you?

• They think you have a big room (so do I)
• They are concerned about being able to give you a pleasurable SPL at your seating position
• The method to get more SPL is to increase driver size (more piston volume) and to shift to a vented enclosure (lower the Fb)

An 18" driver is going to give you 1100 - 1200 cm^2 of cone area, and almost surely will give you a bump in stroke as well (subwoofers are almost always designed as "long stroke" drivers these days, though that is still a relative term). So, moving up to the 18" will give you about +50% more cone area than a comparable 15" unit with some amount of additional excursion. Sealed, this is likely an 8cf monster for exterior dimensions (2' cubed), with a vented unit being a lot larger (the FV18 is 21x33x32)

For testing results and how many popular units on the market compare, check out the Data Bass:

https://data-bass.com/#/?_k=orndud

[Bear]

Another question I had. Does a forward firing subwoofer vs down firing provide more punch or is it basically about dispersion?

Both. Boundary loading gives you more reinforcement, but it will cause ongoing suspension sag over time (i.e., reduced longevity). You can get boundary reinforcement by putting the driver near a wall or corner. If you use a pretty low XO frequency, then downward firing subwoofers have a lot of advantages. Plus, they are easy to build into end tables or simlar furniture.

If you are crossing in the 100Hz - 120Hz range, then you might hear a "cleaner" presentation from front-firing drivers.

Finally, you get some mechanical advantages with dual-opposed drivers in a cabinet (back to back). Plus, you get some of the advantages of multiple subs with dual-opposed (you need more spacing between drivers, really, to get the full benefits).

[Scottg]

So in your design Greg, it appears to be sealed enclosure with a separate section for the amp. The rounded corners look slick, but I don't hint I want to attempt that.

Oh, I'm not suggesting you do this. (..if you need more output and still want excellent sound, the bandpass the Dark Lord mentioned is the way to go ..at the expense of requiring a bit more volume.)



That project was for ultimate performance with stereo sealed subs in a specific application (..where the box above this box had an identical baffle and needed the lower diffraction profile.)

I just provided the link as alternative view to the GR Research sand-damped design, which has some flaws..

I don't think any sand-damped enclosure is appropriate when you are limited with space.


..btw, with respect to the large round-overs:

https://www.tapeease.com//4rounds.htm

[rick844]

Man you guys are exceptional at explaining and I know it takes time to type this all out for a novice like me, so for that i am GREATLY appreciative. I know it can become tiresome to answer the same questions, so again, thank you.

I spent about 5 hours today researching and discovered that there are easy box design software out there that I could use.

I'm going to process this information and try to decide on a plan. I may ask you guys for approval on my plans. Lol

[Bear]

Man you guys are exceptional at explaining and I know it takes time to type this all out for a novice like me, so for that i am GREATLY appreciative. I know it can become tiresome to answer the same questions, so again, thank you.

I spent about 5 hours today researching and discovered that there are easy box design software out there that I could use.

I'm going to process this information and try to decide on a plan. I may ask you guys for approval on my plans. Lol

We seem to have collectively got you hooked on the Rhythmik products, and they do have a good reputation. I would make one last effort to have you go an alternate route. Consider the RSS265HO-4 from Parts-Express. Do two sets of two drivers wired in series in a dual opposed configuration (the drivers are on opposite sides of the enclosure from each other). To keep it simple, go with two boxes that are each a 14" cube (adjust as you see fit). Stuff about 1.4lbs of AcoustaStuff, long-fiber wool or even a basic dacron pillow stuffing (polyfill) into each box. Each box will be ~8ohms to your existing plate amp, and then wire in series at your plate amp (4 ohm load total). You will have an absolute excess of SPL (threshold of pain) at 100Hz. Spend the money you just saved on some flavor of EQ/DSP:
1) set a limit that kicks-in around 40Hz (shelving filter)
2) put a +3 - 6dB boost at 22Hz - 24 Hz
3) put a high-pass filter (rumble filter) at something like 16 - 18Hz

Depending upon the DSP, #2 and #3 are going to mess with each other. In-room, you should be able to hit close to a flat 110dB at 1m peak, depending upon how honest your 800 watts are. At a 10 - 12' listening position, you ought to be close to a 100dB peak, which will be somewhere between noticeable to downright unpleasant. Also, because you would be building twin boxes, you could start with a pair of 10" drivers, and then see if you needed to double-up. Depending upon the other kit you have in the house, include a Dayton OmniMic and a tripod/mic stand in the mix to take measurements, or just go with something like the DDRC-24 from miniDSP, which includes a suitable microphone:

https://www.minidsp.com/products/dirac-series/ddrc-24

Servo-driven subs can work great, good quality DSP works great for subs, and well-constructed boxes with good drivers work great. I'd bias on the last two (obviously) if there isn't budget for all three.

Final note: a pair of 10" drivers will have a similar cone area to a single 15" driver. If you want to get absurd with a slightly larger box, follow this same recipe with a set of RSS315HO-4 drivers. Power handling jumps about 4x, which is really there to give you the ability to boost bass further in the 20Hz - 40Hz range. Realistically, I'd expect that 4x10" subwoofers will give you all that you realistically want.

[Scottg]

Note: Dayton Audio should be coming out with a higher stroke (larger xmax) higher quality subwoofer (than their UMAX series). I could see something like 2 15's in an isobaric sealed configuration along with a filter for the impedance in-box to "flatten it" for higher spl with still good quality sound. Volume would likely "jump" to about 4 cubic feet though.. ops: (..and that's with the Isobaric design almost halving Vas.)

https://youtu.be/I1ShW5NjS3Y?t=141

[scottvalentin]

I would throw in my hat with the CSS SDX10 or 12. They provide HUGE bass in small boxes, have exceptionally low distortion, and their excursion will allow you to take advantage of some EQ to get into the low 20's for movies. If those are too expensive, 2 of the dayton RSS315 would be ok as well, but would not have as much output.

[Bear]

I would throw in my hat with the CSS SDX10 or 12. They provide HUGE bass in small boxes, have exceptionally low distortion, and their excursion will allow you to take advantage of some EQ to get into the low 20's for movies. If those are too expensive, 2 of the dayton RSS315 would be ok as well, but would not have as much output.

I think that this highlights the relative nature of how different people describe speaker size. I'd describe the SDX10 as using a medium size box vs something like a SEAS L26 or the Dayton RSS265-HO, which need half the volume. In any event, smaller boxes are going to need more power for a given amount of low bass. You never get around Hoffman's Iron Law.

[rick844]

All of the input is great guys, I really appreciate it.

I'm still drowning in options. Im going to download WinISD and try to find a way to get it on my macbook. Then I'm going to play with some designs and come back with some options. Then I'll ask for a vote from you experts on one of the few options I come up with. It might be a few days, since I've never done this before, but I'll try to some things posted soon.

[Scottg]

I think that this highlights the relative nature of how different people describe speaker size. I'd describe the SDX10 as using a medium size box vs something like a SEAS L26 or the Dayton RSS265-HO, which need half the volume. In any event, smaller boxes are going to need more power for a given amount of low bass. You never get around Hoffman's Iron Law.

Ah, but the SDX10 has a lot more "linear" excursion, which can net higher spl.

Note the quotes on linear.

I'm sure the force and compliance curves suffer with excursion like most drivers. ..hmm, might want to add Klippel's "law" to Hoffman's. :P

It's all a bit of a juggling-act with performance, build complexity, and cost. ops:


I think the first thing that needs to be determined is: what is loudest spl average in-use in-room? What is the largest dynamic range expected?

From there I'd think about using a rumble/subsonic filter (high-pass). DSP should allow for this along with nice phase/time integration with speakers and even modal eq. for room-effects for a given listening location, miniDSP comes to mind, but if you've got an iOS phone there is the Dayton Audio DSP-LF. You'd want to be able to turn that filter on and off. Likely "off" for music listening, and "on" with home theater..

[rick844]

Well, apparently wine doesn't work on the latest version of Mac OS, so no WinISD unless I can get it on my linux machine.

[csmielke]

The L26 is a great driver but, I don't think it models any better in a sealed enclosure than the SDX10 which has an F3 of 44hz in 24liters (less than a cubic foot). I seem to remember the L26 modeled somewhere around 55hz in just over a cubic foot? Maybe my memory is failing me? Both would require some boost to get into the 20s in a sealed box.

[Bear]

The L26 is a great driver but, I don't think it models any better in a sealed enclosure than the SDX10 which has an F3 of 44hz in 24liters (less than a cubic foot). I seem to remember the L26 modeled somewhere around 55hz in just over a cubic foot? Maybe my memory is failing me? Both would require some boost to get into the 20s in a sealed box.

Updating this since apparently the T/S parameters did change when SEAS brought production back to Denmark.

Using factory data and Unibox, I get right at 21L (Qtc = 0.706 fully stuffed) and ~250W of power handling for the L26ROY. At 20Hz, SPL is 94 dB before room gain or any other boundary loading. The CSS SDX10 clocks-in at 26L (Qtc = 0.705 fully stuffed) and ~400W of power handling. At 20Hz, it has 95.6 dB of SPL. Unless I transcribed the data wrong (it's happened before, it will happen again), these are pretty close. though the SDX10 definitely gets the nod in power handling and SPL at 20Hz. Both are modeling with F3 in the 44Hz range with current data (previously, the L26 was more woofer-like with an F3 around 54dB). The SEAS product is also more expensive.

With the T/S parameter changes (and the +50% increase in Le for the SEAS...), the box sizes are a lot more comparable. Both are incredibly well regarded. And both are significantly cheaper than the top-of-the-line Morel or Wavecor 10" units. I just wish that the L26 came in a black anodized version.

[Scottg]

Well, apparently wine doesn't work on the latest version of Mac OS, so no WinISD unless I can get it on my linux machine.

Virtualbox + Windows 10 image. All free ("10" can run without a software key, you'll just have a little graphic in the lower-right corner of the windows begging you for a key after a few months).

Your system just needs enough memory (..minimum 8 GB).

Search for Videos on this.

[rick844]

Thanks, went ahead and got a new windows laptop. We needed one anyways, and although I hate windows, it will get much use with 2 in the house going to college. Going to play with some drivers tomorrow.

[csmielke]

Bear,
I agree and I am sure our own Evil Twin would support your wish on taking it back to black. They must have gotten that feedback before. Rick, sorry for getting off track.
Chris

[rick844]

No worries.

[FroDaddy]

Interesting. I live in florida, so no basements unfortunately. The adjacent room my daughters, so unless I want to get hell from her and my wife, that's not an option either. This is the first time I have seen servo design. Is this snake oil, or is it really difference making?

I'll take a look at the seas as well.

You could use the attic, many people have went with IB subs using attic space. When I had my IB sub I used an adjacent room, however.

[Bear]

You could use the attic, many people have went with IB subs using attic space. When I had my IB sub I used an adjacent room, however.

Infinite Baffle subs are always a great way to go, especially for new builds. Given the room dimensions posted, though, I expect that there will be some mounting challenges:

1. The ceiling height will require a fair bit of overhead work on a tall ladder (16' ceilings)
2. An 18" sub will require 24" on-center joist spacing, which is unlikely given the way that most houses are built. Using 12" or 15" subs seems more applicable in this case.
3. The ceiling height suggests a "cathedralized" attic, i.e., no room above
4. The distance from the attic to where an amp and/or source will be located means that there will be wiring problems (long runs in some potentially challenging walls/transitions)
5. The (potentially) longer distance to the listening position will require a higher 1m SPL to deliver the same SPL at the listening position
6. Wiring problems can be mitigated with wireless transmitters, but those are expensive and require putting the electrical gear in the attic which can affect near-term (heat dissipation) and long-term (longevity) performance issues.

If everything after #1 can be solved, then I'd still recommend more smaller drivers. That overhead work will be easier trying to mount a 12" driver than a typical 15" driver.

[dwk]

As I was mulling over options and playing with WinISD, I realized that I had the parts on hand to basically build this: https://www.parts-express.com/powere...t-ds--300-7152 . It's an RSS2565-ho4 plus two RSS265 passive radiators. It builds into a cube 13" on a side, and models rather well. It doesn't actually need the DSP amp as such - it's flat to 30Hz, so if you have DSP or room correction elsewhere in the chain you could consider another option. It takes a bit of power, but this is a remarkably impressive design for the size.

the main problem for the OP is that with cones on 3 sides and potentially the amp in the back, veneering to match the other speakers wouldn't really work. The best you could do is top/bottom caps and grille cloth wrapped around if you want to hide the drivers.

Interestingly, on a whim i modeled the same 2 passive radiators (with a bit less weight) with 2x Anarchy woofers. A slightly bigger box (1.5 cu ft), but it results in a nice EBS alignment down to the mid-20's. ~105dB w/200W input. Those little Anarchy drivers are impressive. I think this is close to the concept being used in the Ardent-D (although I'm not sure whether an Anarchy version of that is still in the cards)

[Bear]

As I was mulling over options and playing with WinISD, I realized that I had the parts on hand to basically build this: https://www.parts-express.com/powere...t-ds--300-7152 . It's an RSS2565-ho4 plus two RSS265 passive radiators. It builds into a cube 13" on a side, and models rather well. It doesn't actually need the DSP amp as such - it's flat to 30Hz, so if you have DSP or room correction elsewhere in the chain you could consider another option. It takes a bit of power, but this is a remarkably impressive design for the size.

the main problem for the OP is that with cones on 3 sides and potentially the amp in the back, veneering to match the other speakers wouldn't really work. The best you could do is top/bottom caps and grille cloth wrapped around if you want to hide the drivers.

Interestingly, on a whim i modeled the same 2 passive radiators (with a bit less weight) with 2x Anarchy woofers. A slightly bigger box (1.5 cu ft), but it results in a nice EBS alignment down to the mid-20's. ~105dB w/200W input. Those little Anarchy drivers are impressive. I think this is close to the concept being used in the Ardent-D (although I'm not sure whether an Anarchy version of that is still in the cards)

It looks like a good little-to-no-hassle kit. And, uh, Memorial Day sale. If the enclosure is like other Dayton MDF flat packs, you do need to be careful with screws -- which aren't included. But they do include Sonic Barrier, which ought to do almost nothing for a sub, especially as thin of a sheet as PE includes. They'd do better to double-up the front baffle, instead.

[dwk]

It looks like a good little-to-no-hassle kit. And, uh, Memorial Day sale. If the enclosure is like other Dayton MDF flat packs, you do need to be careful with screws -- which aren't included. But they do include Sonic Barrier, which ought to do almost nothing for a sub, especially as thin of a sheet as PE includes. They'd do better to double-up the front baffle, instead.

I wasn't necessarily recommending the kit as much as suggesting it as design inspiration. The kit does have an extra layer on the front baffle, but it seems to be an overlay and so doesn't help with the screw issue you note - probably only 1/2" of mdf to bite into. If you take the same driver and PRs and put them into a 1.2 cu ft cabinet, you get basically flat into the mid-20's, with max spl of 109dB - pretty impressive for the size. The kit isn't a bad deal, but if you don't need the upscale DSP amp you can probably come out ahead just using it as a guide.

[rick844]

Thanks all. Going into the attic is just not an option. Way too hot and full of insulation and whatever else makes you itchy.

I have decided to build a ported sub, but I'm still playing with winisd to figure out which one. I have had the software crash on me 3 to 4 times, so I had to walk away. I tried both pro and non pro versions, both crashed in different ways.

It might be the version of windows I have (latest version of 10).

Still tinkering and investigating. Love the suggestions though.

[Scottg]

Some sim tools:

Web calculator:

https://speakerboxlite.com/subwoofer-box-calculator/tab-graphs

Programs:
More advanced:

http://www.tolvan.com/index.php?page=/basta/basta.php

Much more advanced:

https://kimmosaunisto.net/Software/Software.html

[Bear]

Thanks all. Going into the attic is just not an option. Way too hot and full of insulation and whatever else makes you itchy.

I have decided to build a ported sub, but I'm still playing with winisd to figure out which one. I have had the software crash on me 3 to 4 times, so I had to walk away. I tried both pro and non pro versions, both crashed in different ways.

It might be the version of windows I have (latest version of 10).

Still tinkering and investigating. Love the suggestions though.

If you've got Excel, try grabbing Unibox. It's an Excel workbook, but functions the same as the standalone programs. It may even work on MacOffice.

[rick844]

Thanks guys. I'll check them out.