What would you recomend?

**nickwin** · **05-07-08, 07:48 PM**

I'm new to DIY subwoofers, and I was hoping you guys could give me some advise. I have an old sealed 12" subwoofer, that I am thinking about gutting out and using the enclosure with a new driver and amp. I've narrowed down my options to these three posibilitys.

1. Rythmik ds12 kit

2. OAudio 300watt amp with Dayton Reference Series HF 12"

3. OAudio 500watt amp with Dayton Titanic III 12"

The enclosure is around 2.6-2.9 cu. ft. I plan on using it about 50%-50% music/movies

**BoomieMCT** · **05-07-08, 07:51 PM**

How well braced is the enclosure?

**nickwin** · **05-07-08, 08:29 PM**

Its actually an old M&K Volkswoofer enclosure. Its made from 3/4" MDF. The only bracing it has is 2 perpendicular MDF beams that cross in the middle to form a "t" . I'm not sure if that is sufficient bracing for the subs I mentioned or not.

**nickwin** · **05-07-08, 08:55 PM**

*Correction: I measured the INSIDE of the enclosure and it turns out my first measurement was quite a bit off. The actual internal volume is about 2 cu feet.

**mayhem13** · **05-07-08, 10:19 PM**

That makes things a bit easier. I would use the Dayton HO version for it's higher power handling and its ability to work in a much smaller box. Two cubic feet ported with the Oaudio 500watt amp should work nicely. The nice feature with the amp is its selectable high pass for below tuning protection of the driver. Tune to 28-30hz for a managable port length. you'll have to use a 4" round port 23" long so given your box, you may have to include an elbow inside. Hope this helps.

**John58** · **05-08-08, 02:31 PM**

2 recommendations

1. Rythmik servo DS12- after driver and amp displacement, you should end up with about 1.7-8^ft3.
This combo should work well, especially for the HT side of your plans. I currently run this sub in a 2 channel system, and IMHO, it can't be beat for music.

2. Dayton DVC 12, part#295-185. Combined with the 250 watt Rythmik amp, you should see a F3 of around 33-35Hz.
I also own this sub, in a slightly larger enclosure, and it is definitely a work horse. May not meet your needs for HT tho.

Hope this helps

**nickwin** · **05-08-08, 03:58 PM**

John, thanks for the input...

I think I have my choices narrowed down to these two options now

1. Rythmik DS12 kit @ $460

2 Dayton RS HF 12" and OAudio 500 watt amp @ about $360

I'm having a really hard time deciding between those two, the Dayton is a little cheaper, but I think the Rythmik might perform a little better with music. Has anyone heard both of these subs?

**eyekode** · **05-08-08, 09:08 PM**

Depending on your goals, if you are planning on spending 460$ then you might as well replace the cabinet. The small volume limits you to a sealed alignment.

I think the Rythmik would give you more sub-30hz output due to the LT circuit built into the amp. The Dayton HF would probably sound pretty good for music but it has an f3 of 40hz and is 12 db down at 20hz. I would not recommend the HO version. The HF is the same cost and plays lower. Also if you ever decide to build a new enclosure the HF models great as a home theater sub when ported.

**mayhem13** · **05-08-08, 11:02 PM**

I offered the HO version for it's ability to work in his small enclosure. Ported in 55liters, i'm showing flat at 110db to 24.6 hz. Pretty not bad for 2 cubes. The selectable high pass in the oaudio will allow the design to control below tune quite effectively. I own both the HF and HO version and listening to both, acoustically i can't tell them apart in there designs except on the really low stuff where the HO can't go. But i only need look at the bar-fridge sized mdf box in my basement to remind me of the difference. I don't have any personal experience with the Rythmik kits, but i have modeled their drivers according to posted T/S and they do model quite well but not in 2cuft. The best sounding small box sub i've used at reasonable cost that plays Loooooww is Infinity Kappa Perfect 12s. Verrryy clean sounding.

**eyekode** · **05-08-08, 11:11 PM**

Quote:

mayhem13 wrote:

I offered the HO version for it's ability to work in his small enclosure. Ported in 55liters, i'm showing flat at 110db to 24.6 hz. Pretty not bad for 2 cubes. The selectable high pass in the oaudio will allow the design to control below tune quite effectively. I own both the HF and HO version and listening to both, acoustically i can't tell them apart in there designs except on the really low stuff where the HO can't go. But i only need look at the bar-fridge sized mdf box in my basement to remind me of the difference. I don't have any personal experience with the Rythmik kits, but i have modeled their drivers according to posted T/S and they do model quite well but not in 2cuft. The best sounding small box sub i've used at reasonable cost that plays Loooooww is Infinity Kappa Perfect 12s. Verrryy clean sounding.

The problem with 2cu ported is the port length. A 4" port is not large enough to get all of the power from a good 12" without compression/chuffing. And the port length is 36.5" for a 20.5Hz tune. This would make the port volume ~.25cu. This is a large percentage of 2cu. If you tune higher, say 28hz you are still looking at 22" or so. And I think it would be hard to fit a 22" long 4" diameter tube in a 2cu box.

Take this with a grain of salt because I have not actually built a 2cu ft ported enclosure. But I don't see how you can do it without having serious port limitations.

**mayhem13** · **05-08-08, 11:57 PM**

I did consider that in the model, but port air speed won't begin to be a problem in this design until 22hz or so and only at max output. Given a 28hz tune i mentioned in the model,he could fit it in there if the box is 24x24x24 with an elbow at the inlet-i've used em before with no ill effects. I agree with you that 2cubes isn't much to work with. I'd mention a PR design but the OP may not have the tools to install them in his box. If he does, then i would suggest 2 side mounted 15 PRs from AE-At 500watts that would be some sub. The 4" port i offered in the model will displace about .18 cuft internal volume and given his box size-resultant is around 54L. The design can and will work with some tradeoffs as always. I offer it as the most cost effective relative to box size. If the OP is still listening and is interested in a Passive Radiator design-pls inquire.

**eyekode** · **05-09-08, 07:42 AM**

Hrm, with 300w it looks like trouble at 34hz and below with respect to air speed. And 24x24x24 is 8cu (not considering wall thickness). If you can fit a 22" long port in a 2cu box then I agree it would offer bang for the buck. I think I would still prefer the HF personally. Would give more HT options if you decide to build a new box. But then again you actually have both drivers so I guess you are the expert

.

**John58** · **05-09-08, 07:58 AM**

I also own the Dayton RS HF sealed, combined with the 500 watt PE amp. Good sub, great SQ, but not really for HT use. The Rythmik beats it hands down.

**evad** · **05-09-08, 09:36 AM**

Quote:

John58 wrote:

I also own the Dayton RS HF sealed, combined with the 500 watt PE amp. Good sub, great SQ, but not really for HT use. The Rythmik beats it hands down.

Could you please give me more details? In what way does the Rythmik win hands down? Is it also sealed? How large are your boxes?

**bobgpsr** · **05-09-08, 11:18 AM**

Does not the Rythmik DS12 kit use a special driver and amp that implements servo correction feedback? Would think that it would give lower distortion and better (normal volume -- not max) frequency response than a non-servo subwoofer. IMHO go for the Rythmik kit.

**evad** · **05-09-08, 11:48 AM**

Quote:

bobgpsr wrote:

Does not the Rythmik DS12 kit use a special driver and amp that implements servo correction feedback? Would think that it would give lower distortion and better (normal volume -- not max) frequency response than a non-servo subwoofer. IMHO go for the Rythmik kit.

Everything you write is true with the exception of the combo having less distortion. That's speculation. I was wondering what the circumstances were when John58 made his comparison between the Dayton HF and the rythmik.

**John58** · **05-09-08, 11:57 AM**

bobgpsr is right, this is a servo controlled sub, lower distortion equals better sound. The driver used has excellent distortion numbers even without the servo. My sealed cylinder was built to 1.9f3, because the cylinder is a more efficient cab than a cube. 2.1f3 is what Brian at Rythmik recommends for a cube, but you could get by with around 1.7-1.8f3. The servo also allows for more extension, around 13Hz in my 12x14x7.5 room. My sub is located here just a little moe than halfway down on the page.
Give Brian a call, he is very helpful and more than willing to answer any questions you may have.

**bobgpsr** · **05-09-08, 12:00 PM**

The reason to bother with doing servo control on a sub is to reduce distortion. If a non-servo sub design is intended to be "better in distortion" than a servo one it will need something normally hard to do to better it. This is assuming same driver size, same enclosure size and type (sealed or ported). So a big Xmax yet very linear BL curve driver? Tough and expensive to do.

**John58** · **05-09-08, 12:41 PM**

Quote:

evad wrote:

Everything you write is true with the exception of the combo having less distortion. That's speculation. I was wondering what the circumstances were when John58 made his comparison between the Dayton HF and the rythmik.

Make no mistake, the RS HF is a fine sub, but the Rythmik with the servo provides less distortion.
There was no A-B testing, no high dollar gear was used, just lived with the RS for about 6 mo. and then the Rythmik for the last two years, and IMO the Rythmik wins hands down.
I am not a professional tester, but I know what sounds right to me.

**evad** · **05-09-08, 12:45 PM**

Thank you John58,
I'm trying to determine the difference between the performance of a sealed RSS315 HF and the sealed 12" Rythmik. You are the first person I've come across who has had both. What about the Dayton disappointed you?
It appears we were working the page at the same time.

**John58** · **05-09-08, 12:59 PM**

No disappointment at all, the RS is a very musical sub, but in my opinion, the Rythmik does everything better. If I lost the Rythmik today, I could live just fine with the RS, one reason I have resisted selling it.
I have a friend that has a Velo 15 servo, it is my opinion, and his, that for music, the Rythmik has the edge.

**nickwin** · **05-09-08, 01:22 PM**

Thanks for the advice everybody...

The reason I am sticking with the box I have is because this is my first DIY attempt, and I don't have the tools, or knowledge to build another enclosure. I'm sticking with sealed becuase I want to keep it simple, and I like the way sealed subwoofer's sound with music. (plus I have a ported sub in my main HT already). If all goes well with this project, I may try something a little more complex next time...

It seems that the general concensius is that the Rythmik would sound slightly better all togather, but the RS would only be slightly behind in performance. (and maybe not at all with music?)

**mayhem13** · **05-09-08, 05:43 PM**

If you do build the rythmik, let me know as i've never heard one. Maybe ship swap with my RS ported box and compare-good luck.

**mayhem13** · **05-09-08, 05:56 PM**

[quote=eyekode;97298]Hrm, with 300w it looks like trouble at 34hz and below with respect to air speed. ]

I used to buy into that 26ms spec until i built a test box with an infinity kappa12 that modeled almost 60ms port air speed at tune. Dammed if i ever heard a peep from the port that resembled chuffing. Someone actually modeled an SVS sub using all the actual parameters and box data and the model showed over 50ms port air speed! I'm not saying to ignore the 26ms limit, I get more concerned about 1st resonant freq. Maybe if that was in the passband i would hear the chuff but it's all the way around 250hz where the sub will NEVER play.
Have you ever experienced any unusual port noises with your builds?

**eyekode** · **05-09-08, 07:15 PM**

[quote=mayhem13;97368]

Quote:

eyekode wrote:

Hrm, with 300w it looks like trouble at 34hz and below with respect to air speed. ]

I used to buy into that 26ms spec until i built a test box with an infinity kappa12 that modeled almost 60ms port air speed at tune. Dammed if i ever heard a peep from the port that resembled chuffing. Someone actually modeled an SVS sub using all the actual parameters and box data and the model showed over 50ms port air speed! I'm not saying to ignore the 26ms limit, I get more concerned about 1st resonant freq. Maybe if that was in the passband i would hear the chuff but it's all the way around 250hz where the sub will NEVER play.
Have you ever experienced any unusual port noises with your builds?

I have been using this as a guideline and have not empirically verified it myself: http://www.subwoofer-builder.com/flare-testing.htm

I will admit I have not heard chuffing from my sub, and from this data I should have heard it at 103db 20hz. But really I cannot be sure because by this SPL everything is shaking in my room. Including the blinds and the walls even seem to make noise. Hopefully I can do some better tests this weekend. But honestly I don't care about the result. If my room is shaking I don't think I will be able to detect port chuffing

. And just walking through a hi-fi store makes me doubt chuffing as well. Have you ever seen even a 4" port on a commercial sub? Not too often but they sure claim to deliver SPL that would require at least that port area to keep the port speed down. I know commercial claims are crap, but I still believe they do deliver enough SPL to exceed 30m/s in a 4" port.

It is funny you mention first port resonance. I really want to believe this one from a simple physics perspective. But oddly ported full-range speakers always have the first port resonance in the passband. But I don't hear much talk about it.

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