# Just got a sdx15, what to do.........



## RodK

I am looking to upgrade my thump on a budget. My system is 50/50 HT and music. I want a clean, low sub but don't need mega spl's. I am thinking of building a sealed sub (size is an issue) using an O-audio 500W plate amp. My alternative, if ported is the best option, is a sonosub as long as it looks good (WAF). Anyone have suggestions?

If I go sealed , it will be a 4 cu ft horizontal sono. Ported would be a vertical sono.


----------



## RodK

forgot to mention:

I am currently running a Denon 989 with Paradigm Titan v5's and cc 290 up front with Mirage omnican 6's in the ceiling for surrounds. I currently have a Polk sub that is only rated to 35hz and has alot of port noise when pushed. I would like to get "closer" to 20hz but still be quite musical (no one note wonders) Size and looks are a factor as this is our main livingroom.


----------



## tundraSQ

start here...

http://www.hometheatershack.com/for...-sound-solutions-build-projects-database.html


----------



## Mike P.

Sealed compared to a couple of ported sizes using the O-Audio amp.


----------



## Binary

I love this driver, Its my current music/theater sub, in a LLT type enclosure. It definitely gets low! Sonosub it at 10 cubes, with an 18 hz tuning, this thing is pretty beefy and has ALMOST no need for a HPF.

If youre willing to tune for about 15, you will basically bypass any need for HPF.

With 30mm Xmax, and 40mm XMech, this driver is going to be a joy to try to bottom out  i've tried, gotten close with my QSC RMX2450 wired for 4 ohm bridged. (2400w rms) but my house complains so much before i run out of steam that i have to turn it down for fear of breaking stuff. lol.


----------



## RodK

If I did a ported sono, would the o audio plate amp still be ok to use ( would I still need the subsonic filter and eq)? Pro amps seem to be alot more expensive here in Canada compared to the States. I don't want to drown out the rest of my system with the sub. What would be a recommended amp? This is my first diy sub and there is alot to take in. I am trying not to screw this up.


----------



## Mike P.

What size is your living room?


----------



## Binary

youre better off avoiding pro amps, unless you've got a giant space to work with. My QSC amp is noisy, and i drive it hard once in a while, so a fan mod isnt an option to me. Granted, Pro amps can be purchased cheap! theyre always for sale by some failed DJ or readily available from sites that will ship internationally. I mean, i paid $350 for my RMX2450 - used of course, but it also came with 100ft of 14 gauge speaker wire with bananas. 

The scary part is that for 99% of use, you'll use less than 50w. Unless you crave bass.

And there is no need for a HPF if you tune 15 or under, if you tune 15 or above, there will be a need for one around the 13-15hz range.

My box is almost 16 cubes internal minus bracing of course, and its tuned for 15 hz. i have no need for a high-pass, but like i said, i have come close to bottoming it out. and im sure i could if that was my goal. but anyone who can hear their sub struggle, won't need a HPF.


----------



## Mike P.

> but anyone who can hear their sub struggle,


 needs another sub! :bigsmile:


----------



## Mike P.

RodK said:


> If I go sealed , it will be a 4 cu ft horizontal sono. Ported would be a vertical sono.


Have you decided what you are going to do?


----------



## Binary

lol @ mike p.

My sentiments exactly, but its not always an option, and some people (even with more than 1 sub) still push their equipment to its limits. If you know what an unhappy subwoofer sounds like, you can avoid subwoofer death.

This is a sweet sealed sub, but ALL of the magic comes from LLT (10+ cubes with a 15hz or lower tuning). I speak from experience.


----------



## RodK

Mike P. said:


> What size is your living room?


It is 16 feet wide, but open on 1 side and the back all the way to the kitchen. Here is a pic of the room to give you an idea.

For reference, that is a 50" plasma and my screen is 110" diag.


----------



## Binary

with a room of that size, you're gonna wanna go ported, just for the extra output. you've got tall ceilings, and a fairly deep room. I can't help but suggest two subwoofers, based on how that room is shaped. but its not always an option. Sometimes that "open concept" can cause a lot of audio issues. lol.


----------



## RodK

ya, 2 is definitely not an option at this time. The ceiling is 12' high. I figured once people saw the room they would suggest ported, but I do like the sound of a good sealed sub.


----------



## Binary

You might actually want a horn. 

Teasing aside, in all reality, this is a semi-tough room to get "great" bass response in, but the SDX15 is no slouch. I have a feeling that you're not expecting 110DB through the spectrum, and as long as you know that a single driver will be limited in that space, you will just have to understand that if it starts to sound bad, you've got it up too high.

You can get 110, but it will push your sub to the limits, and thats when things go wrong.

Nice house by the way, i really like the stone inlay on the walls.


----------



## Binary

come to think of it, if youre willing to do some renovation, those columns on either side of your fireplace would make awesome built-in sub enclosures. and you could finish them almost exactly the same as you've got em now.


----------



## RodK

they would, but........ they are actually built in closets on both sides. The foyer is on the other side of the fireplace.


----------



## RodK

Binary said:


> You might actually want a horn.
> 
> Teasing aside, in all reality, this is a semi-tough room to get "great" bass response in, but the SDX15 is no slouch. I have a feeling that you're not expecting 110DB through the spectrum, and as long as you know that a single driver will be limited in that space, you will just have to understand that if it starts to sound bad, you've got it up too high.
> 
> You can get 110, but it will push your sub to the limits, and thats when things go wrong.
> 
> Nice house by the way, i really like the stone inlay on the walls.


Thanks.

I'm using a Polk psw10 right now, anything will be a great improvement. My mother in law lives in the basement (walk out) so I am not really aiming for 110 db.

I want nice clean deep sound without :hsd:


----------



## Binary

LOL!!! youre gonna put a downfiring sonosub above your mother in law!?! you've got balls of steel buddy!

Anyways, if you were getting even semi-decent (or at least what youre willing to consider acceptable) results with the polk, the SDX 15 will blow it away in every aspect. Even in a sealed box.


----------



## RodK

Binary said:


> LOL!!! youre gonna put a downfiring sonosub above your mother in law!?! you've got balls of steel buddy!
> 
> Anyways, if you were getting even semi-decent (or at least what youre willing to consider acceptable) results with the polk, the SDX 15 will blow it away in every aspect. Even in a sealed box.


That was my thinking as well, thats why I am leaning towards the sealed design. either way, I am going to build a homemade subdude to help out. I have sponge hockey pucks under my Polk right now.


----------



## Mike P.

You should go with a Q of .6 for a sealed sub.


----------



## RodK

According to winisd , that would be a cabinet size of 6.5 cu.ft. That is bigger than I want to go sealed as I want to keep it front firing. I was thinking more on the size of a stuffed 4 cu.ft. size.


----------



## Mike P.

4 cu.ft. stuffed will work fine.


----------



## RodK

I am thinking of something that looks like this. it would be corner loaded on the left side. Will the Oaudio 500w amp and a 4 cu.ft box corner loaded give me what I am looking for? I am hoping


----------



## Binary

yeah that box youre looking at is 140L sealed. I would try to go for 4.5cu with stuffing if 6.5 is what you need. at best stuffing can yield you a bonus of 40% internal volume. From what i heard, that test enclosure you got a pic of was only really beaten by a TC sounds LMS ultra 18"..


----------



## RodK

If I decide to go ported, would I still be ok using the Oaudio amp or should I look at something else?


----------



## Mike P.

It will work with the right cabinet size and tuning frequency.


----------



## Binary

as silly as it sounds, having a smaller amp than the RMS rating of the subwoofer means you can aim for a larger box that will run out of steam faster. Most people try to optimize box size vs power handing at max excursion. I wouldnt recommend ported unless you want to tune low 20's, not if you want to use it for theatre, it'll just bottom out like crazy if tuned any higher.

I think your idea of ~4-5 cubes stuffed sealed would be your best bet, especially if you don't want to implement a high-pass filter.

my box is 24x24x42 which is gigantic, but after port and bracing, it works out to just under 12 cubes internal, I use a bit of polyfill to gain some volume, gets me results that model very similarly to 14 cubes tuned for 16hz
Its an LLT type setup, but whats fantastic about it, is how effortless the low end is. It models to be able to produce basically 116db down to 16hz, and when you factor in room gain, im in the cool 120's  I constantly have people hearing content in songs/movies/television they didnt know was there. It also doesn't disappoint in the midbass range, the model works out to have about a 1.5db hump around 30-50hz so the midbass is very clean. My neighbours agree.

I've also noticed that some content in movies can hit as low as 7hz, so in very rare cases, i have come close to bottoming out. theres 40mm of suspension on this driver, and 30mm xmax, Which means you gotta move some serious air before you damage the driver. I can however bottom out at 800w at 13.8hz, this content is ALMOST non-existant though.


----------



## Binary

This is the difference between sealed 6.5 cubes, 8 cubes tuned to 20, and my box 14 cubes tuned for 17.
As you can see, the 8 cubes tuned to 20 is the best compromise, its a decent size, and can handle just about anything you throw at it. These are all at 500w input power for the SPL chart.

You can see why i went the way i did, (blue)
But the grey line (8 cubes) is very respectable, and can do some serious output!

I can't stand the response of a sealed box.


----------



## Binary

This is the difference between sealed 6.5 cubes, 8 cubes tuned to 20, and my box 14 cubes tuned for 17.
As you can see, the 8 cubes tuned to 20 is the best compromise, its a decent size, and can handle just about anything you throw at it. These are all at 500w input power for the SPL chart.

You can see why i went the way i did, (blue)
But the grey line (8 cubes) is very respectable, and can do some serious output!


----------



## RodK

I do like the flatter response of the ported. Is there no problems with xmax at 16hz? If I went ported, would the CSS bash 500 be a better amp to use?


----------



## Binary

like i said, content at 16hz is very rare, and often low amplitude. If your current little sub hasnt exploded yet without a high-pass, the SDX15 definitely won't. and you'll have to drive it to 40mm just to hit the suspension limits. i highly doubt you'll have it that loud with your mother in law living downstairs. lol.

As for amp, i know its contradictory to what i said earlier, but i love my pro-sound amp. nothing like a large amount of power cheap. Parts-express also has the dayton 1000w rackmount amp.
I'm one of those guys that know that the 50lbs sdx15 doesnt get any easier to move when a 20 odd pound amp gets added to the enclosure. Plus theres more heat, and leaks to deal with for plate amps.
Plus it makes it easier to plug in, i find a lot of subwoofers good placements, is out of reach of the nearest electrical socket, which leads to compromises. speaker wire is cheap.

Btw, SPL at 100w which is under where you will hit xmax, is litterally 108dbs down to 20hz for the 8 cubes ported box.
At 200w, you'll have 0 issues. 10hz hits 28mm xmax, when you've got 40mm travel to play with. You'd also be cracking 110dbs. which is louder than reference.


----------



## RodK

I am having a hard time converting what I see in winisd to what I should expect. Binary, you explained what to expect from 8 cu.ft ported very well. What would I expect from the 4 cu.ft sealed and stuffed , powered with the Oaudio 500w?



p.s. pro audio amps do not come as cheap where I live. I am also not keen on the fan noise, I already want to throw my PS3 against a wall.


----------



## Binary

Well, like i said, Dayton has a 1000w Rackmount amp that is far more flexible than plate amps, and will keep the weight of your subwoofer down to a somewhat manageable 100lbs+ lol.

The 4 cubes box would actually look very similar to the 6.5 cube box i modelled, the drop off would be faster however, with a smaller box. the model changes very little between 4 and 6 cubes. So you'd be looking the -3db point would be around 33hz, and the max spl would be very similar. Like i said earlier, i just don't like how a sealed box models most of the time.


----------



## Binary

I always forget to explain that a sealed sub does work well with room gain, depending on the room. I just like to have that extra headroom in the low freqs so i can EQ any way i want. A sealed sub tends to integrate into the room gain, if you plan for it, a ported sub, can take the room out of the equation, at least in this case. 

If you're flat to 20 without room modes, you will actually get hotter than flat output on the lowest end.

Basically, as you get lower in freq, the room gain goes up, so its like a reverse crossover slope, getting louder as you move down an octave. The sealed sub drops off very similar to the room gain, so a sealed sub, models as not flat. but can often in room, get very good results.

a big ported box, can inflate the low end numbers, and therefore have more authority in this range. however it would not be flat, in fact it often looks to have a peak at the tuning frequency, and then a falling response into the midbass range.


----------



## RodK

Looking at the pic of my room, do you think I will be getting much room gain at all? I am corner loading it in the left front corner, but it is a BIG room. Seeing as I am 50/50 ht/music, I also seem to be floating at 50/50 sealed/ported. I am hoping someone much more knowledgable than myself can guide me to what will suit my use and system best.


----------



## Binary

room gain is a function of shape, size, and location of the subwoofer. Corner loading it is the best place to get a little bit of extra gain, but in your case, theres a reason people recommended ported for your room. Its large, high ceilings, and very open to the house. Youre prolly gonna be pumping bass into more than just your listening area with the open concept of the house.

Like i said, ported can generally take the room out of the equation when tuned low enough, sealed however, the room plays a large part in getting it pretty flat to about 20hz. In your room, I wouldnt expect it to do much better than modeled.


----------



## RodK

Thanks Adam, I think you have me leaning towards a ported build. I have read that ported builds require less power, yet I still see guys using pro amps on them. Is 500w still good for a ported build? If so I think I would use the bash 500 instead of the Oaudio 500. Would 300w be enough? would I need a highpass filter?


----------



## Binary

im not familiar with the o-audio amp, other than its output power. the bash amp is very good, but the subsonic filter is fairly high, 30hz i believe, you'd wan't to ask the amplification section which one they'd reccomend, apparently the o-audio has an adjustable high pass. which is what you'd want.


----------



## Mike P.

The default hi-pass on the Bash 500 is 30 hz but it can be changed to a lower frequency by soldering in 2 resistors. Bob at CSS offers this service for $15 if you buy the amp from him.


----------



## Binary

If bob will change out the HPF then definitely do the BASH, i've only heard good reviews. Bob also carries a 1300w rackmount sub amp if im correct...

Long story short, if someone whos is professional is willing to modify the amp for you, take it. lol.


----------



## RodK

The rack mount at CSS is 1000 watt and out of my budget. Chuck at AVS measured the rack mount sub amp putting out only 580w @ .33% dist into 4 ohms. The Oaudio measured at 430w @ .1%dist and 460w @ .4% dist. into 4 ohms. The Oaudio looks like a better bang for the buck to me. He did not measure the Bash 500 so I don't know how that compares.


----------



## Binary

isn't the o-audio amplifier a BASH style amplifier?

I'd expect it to perform similar to most BASH style amps.

also, i don't think you're paying attention. at 200w youre gonna be doing 110db in room down to 20hz without any room gain factored in.

Youre not gonna need the extra watts.

Doubling the wattage to 400, only gets you 3db.


----------



## RodK

Binary said:


> also, i don't think you're paying attention. at 200w youre gonna be doing 110db in room down to 20hz without any room gain factored in.
> 
> Youre not gonna need the extra watts.
> 
> Doubling the wattage to 400, only gets you 3db.


Just to be fair Adam, you were the one recommending the rack mount sub. I am pretty sure I will be happy enough with 500 watts. ( So will the mother in law......lol )


----------



## Binary

it was because of the flexibility of non-plate amps, but they seems to be outside your budget. lol. I personally wouldn't put a plate amp in a sub, as its too heavy, doesnt get the best cooling, and they generally leak air.


----------



## Mike P.

All controls on Bash amps are completely sealed, unlike Dayton style plate amps which are not.


----------



## Binary

that still doesnt defeat the weight argument, and the arguement that you've gotta end up putting that sub somewhat near the power outlet in that case. But i've given the benefits, its not my system.

I find it hard to seal a unit that needs cooling. so its counter-productive either way you look at it.
Just my 2c


----------



## Mike P.

I'll give you the power outlet, that can be an issue sometimes. But cooling is an non issue, the amps are designed for cabinet mounting. As for weight, I don't see a 8 pound plate amp being a problem in a 100 pound sub.


----------



## Binary

okay, okay, you got me on weight. I assumed closer to 20lbs, but usually thats enough to make a somewhat manageable object, a two person job.

My pro-sound amp is closer to 50lbs.

At 8 lbs i'd be worried the amp doesn't have enough metal to dissipate the heat! 


I like to play devils advocate by the way. lol.


----------



## Mike P.

Apparently they do dissipate the heat, I haven't seen a reported case of of an overheating Bash amp. My wife tortures a SDX10 with a Bash 300, it barely gets warm.


----------



## Binary

You lucky dog you! i wish i had a wife that would let me turn my subwoofer on, let alone torturing her own.

Her little logitech computer sytem as a 3" woofer in it, and she turns it down till its almost off, because theres "too much bass"...


----------



## Mike P.

I am lucky, I had two Ascendant Audio Atlas 15's in 10 cu.ft. tuned to 18 hz in the HT room. After watching a couple of movies she said, "we need more subs". Then came a pair of IXL-18's in 12.5 cu.ft. tuned to 16 hz. Her response was, "Sounds good. Can I have a sub for my workout room?" Thus the SDX10 with PR's. Life is good!


----------



## RodK

Even with my piece of junk Polk, my wife isn't complaining about lack of bass. We watched WOW last week and the port noise made me want to throw it out my window!


----------



## Mike P.

Even a SDX15 sealed would kill the Polk in output.


----------



## Binary

my other half absolutely hates bass, its almost a reason to replace her with an upgraded model. lol!

As far as the polk being port noisey, i've noticed that of all ported commerical subs, they want small boxes, and low tunings, but won't pay to use PR's. So the ports are often driven to a small enough diameter to tune low, but overdrive as soon as the woofer starts moving. a 1" diameter port is shorter than a 2" diameter one right?

My problem is that my other half has an amazing ear, she hears stuff that i can't. But its also a curse, she always knows when my sub is on, even if i've got it turned way down to blend in or "fade away" 

If i could get away with 2 15's and 2 18's in my room, i'd be in heaven. My single sdx15 in a LLT is more than she can bear. (id add another one, and a couple of 18's just cuz. lol.)


----------



## RodK

Binary said:


> my other half absolutely hates bass, its almost a reason to replace her with an upgraded model. lol!


I hope for your sake your wife doesn't read these forums..lol.




Binary said:


> If i could get away with 2 15's and 2 18's in my room, i'd be in heaven. My single sdx15 in a LLT is more than she can bear. (id add another one, and a couple of 18's just cuz. lol.)


This is what has me leaning towards sealed


----------



## Binary

Nope she doesn't. lol! this is the same girl that thinks a 3 inch logitech "subwoofer" puts out too much bass, so don't worry about her mentality.

8 cubes @ 20hz is perfect! not to mention 8 cubes is a 24" cube. add port and bracing, you'd be looking about a 24 inch wide, 26 tall, 24-26 deep cube, with a slot port. or of course any way you'd like to adjust those measurements as long as the face is 17x17, you'll fit the sub.

I think you'd want a pair if you went sealed.

Or sonosub it, which is by far the easier enclosure to build.


----------



## Mike P.

From reading the specs on the Polk sub green would be its estimated output, yellow is the SDX15 in 4 cu.ft. sealed with the O-Audio amp's 20 hz HPF. Quite an improvement.


----------



## Binary

and thats if the polk sub performs anything like its rated to!

I'd still be running ported.


----------



## RodK

Yes, but your mother in law doesn't live under you...........lol


----------



## RodK

WOW, that Polk drops like a rock at 35 hz.


----------



## Mike P.

Here's a couple of project files for you, save them to the Projects folder in WinISD.

View attachment SDX15 4 cu.ft. sealed.wpr


View attachment SDX15 8.cu.ft. tuned to 20 hz.wpr


----------



## dboff01

Mike P. said:


> My wife tortures a SDX10 with a Bash 300, it barely gets warm.


A wife? I kind of always assumed you were actually just a computer program stored on the Home Theater Shack mainframe, designed to provide WinISD simulations and timely, useful information on building subwoofers. :bigsmile:


----------



## Mike P.

Truth be told, I am real. Just don't let the word get out. Need a sub simulation?


----------



## Binary

Mike P. You're a liar. I saw your source code. lol.

So, any idea's based on those plots as to what design youre going for? I still advocate ported. But then again, i like max performance for the build.


----------



## RodK

Mike is our H.A.L. , I just hope he doesn't turn on us!!

To be honest, I am thinking I will like the sealed sound better.


----------



## RodK

I figure if I build a sealed sub and don't like it, I can always rebuild it ported as the box and my time is the cheap part.


----------



## Mike P.

Build a sealed cube shape, if you don't like it you can add Passive Radiators to it.


----------



## Binary

PRs are more expensive than rebuilding the box. Time is free for most people...

I think the SDX will still blow you away compared to that polk. and you won't have to worry about overdriving it, ever. at least not till like 2000+ w/rms. lol.


----------



## RodK

Will a down firing sub be more noticable downstairs than a front firing sub would?


----------



## Binary

Firing into the floor will definitely make it more noticeable than front firing it.


----------



## RodK

Thats what I thought. I'm just trying to keep the peace here (as best I can anyway) :devil:


----------



## RodK

OK, I am finally almost ready to start building this thing but I have a couple of questions. I am doing the 4 cu ft sealed in a 20" horizontal sono (with the Oaudio 500w plate amp) similar to the pic I posted earlier. If I double up the back plate to 1.5" thick, is it still ok to mount the plate amp in there or sould I build a seperate box for the plate amp. If it is ok to cut that big of a hole in the back plate, how close to the plate amp can the stuffing be?


----------



## RodK

I've seen a couple of builds on here that are ported around 5 - 5 1/2 cu ft. If I want to go ported , what is the smallest size I can get away with that will still sound good. I am using the Oaudio 500w amp, so if I go ported I would use the 20 hz ssf. Would I be better staying with the 4 cu ft sealed plan with the amount of music I listen to ? The sub is here and the amp is on the way so I would like to build this next weekend if I can nail a design down. I will start a seperate build thread once I get going.


----------



## SubNub

Iirc Winisdpro optimally sticks the driver in a 7 (ish) cubic feet box tuned to around 19Hz.

Forgive me as I haven't got anything installed atm after a recent format.

I have mine in 11.5 (ish) cubic feet tuned to ~14Hz, running it in as I type this listening to bassdrive.com's aac stream.


----------



## RodK

Have I used up all my help?


----------



## Binary

Nope you haven't used up all your help, I was just away for a bit. I can't speak for the other members though, i figured they had you under control. :dontknow:


----------



## Mike P.

I missed this thread too. I see you went sealed in 3.75. cu.ft.

http://www.hometheatershack.com/for...-ft-sealed-sdx15-w-oaudio-500w-plate-amp.html


----------



## RodK

Ya, I thought I should open a new thread for the actual build. the box was just over 4 cu ft to start. With the driver and bracing it is about 3.75 cu ft now.


----------



## RodK

Mike P. said:


> From reading the specs on the Polk sub green would be its estimated output, yellow is the SDX15 in 4 cu.ft. sealed with the O-Audio amp's 20 hz HPF. Quite an improvement.
> 
> View attachment 30783


Mike , can you give me the specs you used for the polk. I am thinking of modifying it and would like to check out the differences in winisd first.


----------



## Mike P.

I don't have any specs for it, I used a low excursion 10" driver from the WinISD driver files ( don't remember which one) and altered the box size and tuning frequency to show a falling response below 35 hz which the PSW10 has. What are you thinking of doing to the sub?


----------



## RodK

it seems to be a very small box for a ported sub. I was thinking of pulling the port out and sealing the box as there is an awful lot of port noise when watching movies. any other suggestions that don't cost much, but can improve this sub?


----------



## Mike P.

It is a small box but that's the specific design of the sub. The driver, box size, tuning, and amp all work together for a certain price point and performance level. As for performance, this sub was designed for moderate listening levels in small rooms. Port noise is a symptom of the sub being asked for too much. Bottom line is the PSW10 is an entry level sub.

Below is just an example of what you're thinking of doing. Green is ported, yellow is sealing up the port. As you can see you lose the low end of the ported.










Sealing the sub will effectively kill any low end output that it does have. There are a couple of cheap solutions you can try to improve the port noise issue. Take the amp out and see if the port has a flare on the intake. I'm guessing it doesn't. See if it's possible to install one if there's enough room for it. If the port tube is up against the side wall of the cabinet then you could redo the port with a 45 degree elbow to get it away from the wall and add a flare.

Adding polyfill may help. One pound should do it. make sure there's a couple on inches of clearance between the polyfill and port intake. Polyfill might work or it might not. It wouldn't cost much to find out.


----------

