Sub design/selection advice needed

[Java Doc]

So this will be my first foray into the world of DIY subs, which has brought up a few questions before I get started.

I plan to build a matching pair into a set of end tables. As a result, these will be down-firing. I have not decided on ported vs sealed yet. I know that sealed will be easier to build, but I’m more than willing to make the attempt with a ported. This leads to a question. Given the size constraint of a reasonable end tabe, I figure I can do either a sealed/ported 15, or a sealed 18 (I think a ported 18 will just be too big). My space is approx 1,500 ft^3, but opens to another den area plus a kitchen. Total volume is probably somewhere around 4,000 ft^3. I figure I can probably fit a max of 8 ft^3 into an end table, and keep it looking relatively normal.

It also appears as though there is not a ton of selection when it comes to actual speakers. My total budget for drivers/amp is around $1,000. Some that I am considering are the following:

Dayton Audio RSS390HO-4 15" Reference HO Subwoofer 4 Ohm
http://www.parts-express.com/pe/show...number=295-469

Dayton Audio TIT400C-4 15" Titanic Mk III Subwoofer 4 Ohm
http://www.parts-express.com/pe/show...number=295-420

I would consider something along the lines of the following if the performance jump justifies the cost jump:

TC Sounds Axis 15Q1 15" Quad VC Subwoofer
http://www.parts-express.com/pe/show...number=293-642

One of the SoundSplinter RL series:
http://www.soundsplinter.com/rlp15_s...formation.html

Also perhaps something from Ascendant, or AE. Any recs for specific brands or models would be helpful.

I am open to just about anything at this point. I’ve heard that some work better for downfiring than others due to sag, so that needs to be kept in mind as well.

Thanks all!

 

[jliedeka]

Based on hearsay, I wouldn't go with the Titan. It's not the cleanest driver.

For a room your size, dual 12" or 15" will be more than adequate and not need much power.

If it were me, I'd probably go with one of the Dayton HF sub drivers. I bought the 12" one for a bedroom sub, going to go sealed with 2 to 3 ft^3 box. Since I haven't built it yet, I can't comment on performance characteristics. It's a really good driver, especially for the money and, even sealed, I'll get adequate extension for my needs.

I'm currently using a Hsu VTF 3.3 that has a 12" driver in my 1500 ft^3 living room. It's complete overkill. It can get down to subsonic frequencies with plenty of power to fill the room. (I was ready to puke after listening Saint-Saens organ music at moderately loud levels ) My sub almost qualifies as a LLT, large low-tuned sub. You may want to look into that alignment. I think there are some good discussions about it on Home Theater Shack.

Jim

 

[BoredSysAdmin]

Before going DIY: did you considered getting a pair of eD A2 - 300 ??

http://www.edesignaudio.com/product_info.php?cPath=2_41&products_id=407

 

[Java Doc]

Before going DIY: did you considered getting a pair of eD A2 - 300 ??

http://www.edesignaudio.com/product_info.php?cPath=2_41&products_id=407

Considered it, however we'd like to make our own.

_______

It's interesting that you mention the Dayton HF's. I've seen other recs for the HO's in other threads...I looked at the spec sheet, but don't understand the real function difference between the two, except that the HO has a higher power handling.

I've also read about the LLTs, but unless I'm misunderstanding, the enclosures have to be quite large, at least for a 15".

Amp choices are still in the air, but I figured I'd pick up a Behringer Europower 4000 to power both of the subs, also based on reading many other recs.

 

[annunaki]

Hello and welcome to the DIY cult.. er.. ehm... world.

I am interested in helping out here but need some additional information.

How will the end tables be oriented into the room? Will they be both placed near a wall? Perhaps if you could provide a rough layout of the intended design I can help you out more.

What type of music/movies are you watching regularly and what are your overall expectations? This will help out with driver choice.

How do you plan to power these as well? Were you thinking each one to be passive?

I am actually pursuing a dual end table sub design in my soon to be finished theater/rec room. I have a unique solution going there but I will save that for its own thread at a later date

 

[Java Doc]

Hello and welcome to the DIY cult.. er.. ehm... world.

I am interested in helping out here but need some additional information.

How will the end tables be oriented into the room? Will they be both placed near a wall? Perhaps if you could provide a rough layout of the intended design I can help you out more.

What type of music/movies are you watching regularly and what are your overall expectations? This will help out with driver choice.

How do you plan to power these as well? Were you thinking each one to be passive?

I am actually pursuing a dual end table sub design in my soon to be finished theater/rec room. I have a unique solution going there but I will save that for its own thread at a later date

Nice, that sounds pretty neat too.

I've attached a rough pic of the living room layout. Sub 1 and Sub 2 will be the end tables (obviously). Sub 1 may get move toward the edge of the 10.5ft wall on the north-east side of the living room (becoming opposing corners) if we decide to get an L-shaped sectional.

Their function will be mostly for movie watching, as well as some non-critical Pandora listening. Being as how they are mostly for movies, my biggest concern is deeper extension. I plan to have the 2 to take care of nulls, and so each individual driver won't have to play as loud. As I mentioned, a main requirement is that they will be down-firing.

The rough dimensions are the tables are in my first post. As for powering them, I can get anything within reason, but have read good things about the Behringer EP 4000.

 

[Java Doc]

WinISD Plots

I was able to put together a WinISD sim for the 2 Dayton drivers (HO vs HF) in Open and Vented, at 5 ft^3 with the vented boxes tuned at 20 Hz. After talking to the wife, I think the max dimensions I'll be able to go are 24 X 18 X 26" whd. I rounded down to account for the driver and bracing.

How will adding insulation to the box change these numbers? I seem to be getting conflicting information on that aspect.

 

[lsiberian]

The EP4000 is a good option, but it may not be the best for your given situation. Once we decide on drivers we'll have a better idea. I always believe in getting the lowest cost driver that meets expectations. Because the hidden costs of a build do add up. Tools alone not cheap, toss in the wood, glue, blades, first aid kit, and wiring. Paint or veneer. Make sure you do a thorough cost analysis so you don't get any hidden surprised.

Do you have access to a panel capable table saw, circular saw or panel saw?

Have an excellent blade?

Do you have access to a plunge router and a circle cutting jig?

Have a good bit?

Clamps? I recommend corner clamps. I have eight of them for the purpose of intial glue up and it makes it much easier.

For the panels I prefer birch ply 11 ply or greater because it's much lighter and less messy than mdf.

Even if you have the tools make sure you have the proper blades. Building a sub box requires more precision than many other projects.

A good blade or bit makes life much easier.

 

[Java Doc]

Well I talked to the wife again last night, and she agreed that if I built something smaller now, I can upgrade in a couple of years when we move.

As a result, I'm looking at doing a 12" in about 4.0-4.5 ft^3 (24 x 18 x 24" whd). I've attached a WinISD for the 12" vs 15", and it appears as though a ported 12" models better than the 15" in that size space anyway.

Next post I'll attach the comparisons between the different 12s.

 

[jonnythan]

If you're looking at a closed box at all, there's absolutely no need for it to be as large as 4.5 cf!

I also notice you don't seem to be looking at actual SPL output or cone excursion. You should probably also be using WinISD Alpha (0.50a7) which has more features.

FWIW I have the Dayton RF 12" HF in a 2 cf sealed box.

 

[Java Doc]

I'll try to get Alpha working. Each time I tried before, it kept giving me errors even with the included database. Also tried reinstalling it multiple times, but I'll give it an other shot.

I kept the sealed box at 4.5 cf for comparison purposes. The end tables we build will likely be the same size no matter how much internal volume I have inside.

 

[jonnythan]

One more point. You might want to build a sub, or even a prototype, and place it next to the couch and see how it sounds. I built my current sub intending to use it as an end table, but when I placed it in between the recliners used as primary listening points, something about the sound pressure that nearfield made me uncomfortable. The room response was fine, but sitting that close to the sub just didn't feel right.

 

[Java Doc]

I'm not going to have as much leeway in the actual placement. It's one of the reasons there will be 2 of them. That way I can keep the sound more spread out, but can dial them down if they are a bit much in the nearfield.

Still having issues with getting winisd alpha working...

I was looking at Rythmik's DIY offerings, and they actually suggest a volume of 4cf for a vented 15" (http://www.rythmikaudio.com/DS1500driver.html). Have people had much luck with these?

 

[jliedeka]

If you are thinking about the 12" Dayton HF, try modeling 2 or 3 cubic feet for sealed. Zaph posted a design using 2 cubic feet that he is really happy with. My own modeling suggests 3 cubic feet gets closer to a box Qtc of 0.7.

The larger ported box will probably be fine as well because you won't be dumping a ton of power into them.

Jim

 

[annunaki]

If we are talking Dayton RS series here they are out of the question for a down firing application. They have too much sag in the suspension to be used in a down firing configuration.

I would look into a rear firing solution if you want to do the Dayton.

I would also look into the CSS Trio 12. This is a linear (XBL^2 motor) low cost driver with even more linear excursion capability than the Dayton. You will again here want to go rear firing as opposed to a down firing design

A 4.0ft^3 enclosure tuned to 21hz using a slot vent of 2.0" x 16.5" x 46.5" will get you there with a vent velocity below 17m/s at full rated RMS input power. The f3 is at 20.6hz and f6 at 17.8hz. Room gain will give you plenty of low end output here. response is nice and linear as well with a lower -1db point of 24hz and an upper -1db point of 70hz.**

You would only require 700 watts of rms amplifier power for the pair to achieve about 111.4db of output at 20hz anechoic. In room this could be significantly more.

Here is the big problem I see for you though. Because you are going vented, your dimensions will need to increase to even achieve a net internal volume of 4.0ft^3. The proper slot vent I highlighted above in an enclosure like this displaces 1.12ft^3.

If you can go to 24" x 18" x 27.5" everything works, which allows .3ft^3 for bracing and woofer design.





** All models assume 350 watts of rms input power, a 4th order (24db/oct) low pass crossover at 80hz, vent velocity kept below 17m/s, excursion kept below rated xmax through the usable range, and

 

[jonnythan]

The 12" is fine for down-firing. Something like 3% sag.

 

[Java Doc]

If we are talking Dayton RS series here they are out of the question for a down firing application. They have too much sag in the suspension to be used in a down firing configuration.

I would look into a rear firing solution if you want to do the Dayton.

I would also look into the CSS Trio 12. This is a linear (XBL^2 motor) low cost driver with even more linear excursion capability than the Dayton. You will again here want to go rear firing as opposed to a down firing design

A 4.0ft^3 enclosure tuned to 21hz using a slot vent of 2.0" x 16.5" x 46.5" will get you there with a vent velocity below 17m/s at full rated RMS input power. The f3 is at 20.6hz and f6 at 17.8hz. Room gain will give you plenty of low end output here. response is nice and linear as well with a lower -1db point of 24hz and an upper -1db point of 70hz.**

You would only require 700 watts of rms amplifier power for the pair to achieve about 111.4db of output at 20hz anechoic. In room this could be significantly more.

Here is the big problem I see for you though. Because you are going vented, your dimensions will need to increase to even achieve a net internal volume of 4.0ft^3. The proper slot vent I highlighted above in an enclosure like this displaces 1.12ft^3.

If you can go to 24" x 18" x 27.5" everything works, which allows .3ft^3 for bracing and woofer design.





** All models assume 350 watts of rms input power, a 4th order (24db/oct) low pass crossover at 80hz, vent velocity kept below 17m/s, excursion kept below rated xmax through the usable range, and

I will definitely look into the CSS.

The calculations for sag came from http://www.parts-express.com/resources/woofer-mount-up-down.cfm, which stated that as long as it remained <5%, it was appropriate to use for down-firing. Does this seem incorrect? The measurements for both the HF and HO were less than this 5% value.

 

[generalkorrd]

Something to consider: Unless the driver has an ULTRA light cone( which very few subs have) then you WILL eventually have sag in any down or upfiring situation. As the suspension loosens up-- which they all do-- it will sag more and more. If you really look around at the better built home subs out there, the larger ones-- 12" and up-- are usually only front/ side firing due to the weight of the cone assy. I usually only see 6.5 - 8 inch drivers that fire down.

Another thing is that a 15 is going to create a lot of vibrations that will cause things to slide off the box. You should probably count on doubling all the walls, maybe sandwich some dynamat or similar in there to give a completely dead enclosure. Internal bracing will not be enough to counteract these vibrations, you actually need to deaden the walls. Side effect will be an amazing sounding sub.

just my .02

 

[GranteedEV]

I recommend this driver:

http://www.amazon.com/W15GTi-MKII-5000-Competition-Subwoofer/dp/B000KQIFL0/ref=sr_1_1?ie=UTF8&qid=1314846904&sr=8-1

It has decent xmax for a 15 (it is no SDX-15 mind you), but it's also fairly sensitive meaning you could plausibly drive not one, but two off of an EP2500. For sound quality, two of these subs spaced throughout the rom, would be tough to beat. Inductance is very low too.

Personally, I don't feel comfortable with downfiring. Not only does it lose you around a mm or two of linear excursion, but i just don't see the advantages.

 

[generalkorrd]

I recommend this driver:

http://www.amazon.com/W15GTi-MKII-5000-Competition-Subwoofer/dp/B000KQIFL0/ref=sr_1_1?ie=UTF8&qid=1314846904&sr=8-1

It has decent xmax for a 15 (it is no SDX-15 mind you), but it's also fairly sensitive meaning you could plausibly drive not one, but two off of an EP2500. For sound quality, two of these subs spaced throughout the rom, would be tough to beat. Inductance is very low too.

Not in a down firing situation I wouldn't. That particular driver has a fairly heavy cone/ coil combo.