Need Help - DIY Built-in Subs

I'm looking at building two sealed subs that will go in recesses I'm building in the front wall of our HT. I will shamelessly admit that although my carpentry skills are good, my DIY subwoofer build knowledge is non-existent. I'm hoping some here have done similar projects and can guide me so I don't have to re-invent the wheel. Dan @EndersShadow has been invaluable so far and has graciously invested lots of time and phone calls helping me get going. Although through his efforts, it seems I may get a little more out of ported subs, I'm trying to keep it as simple as I can, and get good sound. I currently have the SVS PCi25-31 sub, and as long as I can equal or better that sub, I'll be happy.

Current plan (not set in stone) is to build two sealed subs using Dayton UM15-22 drivers (or something similar) and power them with a Crown XLS1502 (or similar).

I currently have two cubby's built into the rough framing of the front wall of the HT. The rough opening dimensions are 19"Wide x 33"High x 23"Deep. I did frame it so the sub would slide in OVER the stacked 2x4 base of the wall (so it will sit up 3" off the floor). I have a concrete floor. Would it be better to cut out the stacked 2x4 and sit the subs directly on the concrete floor? It would also gain me 3" in height resulting in larger volume subs. If I do set them directly on the floor, should I install the carpet into the cubby's and set the subs on the carpet? Or should I set them directly on the concrete or on the concrete with a rubber mat under them? Or should I stick with my original plan and set them up off the ground 3 inches ON the stacked 2x4s?

Additionally, the cubby's that will house the subs will be built under a counter in a spare bedroom behind the theater. Would it help minimize vibrations in the bedroom (wall and counter) by installing some insulation, polyfill, thin foam sheeting in a small (say 1/4" - 1/2") space around all sides, back and top of the sub boxes to eliminate direct contact of the sub cabinets to the framed wall/counter?

Here's an older picture of the wall with the cubby's for the two subs on either side, and the cubby for the built in equipment rack. It's a little further along now, but this photo shows the stacked 2x4 base at the bottoms of the sub cubby's. I CAN cut them out if that would be better.

j2idx46um447.jpg

As always, the help and experience of the members here is greatly appreciated.
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Comments

  • scubalabscubalab Posts: 2,971
    TLDR version:
    1. Should I place the new DIY sealed subs directly on the concrete floor, directly on the concrete with a rubber type mat under the, or place them on the 2x4 base (3" above the concrete floor?
    2. Should I build the boxes smaller (say 1/4" - 1/2" gap all around and cushion/insulate them from the studded wall/counter in the cubby's (to eliminate direct contact and minimize vibration) with something like carpet padding, foam sheeting, insulation/polyfill?
    Thanks!
  • scubalabscubalab Posts: 2,971
    Any thoughts on the Dayton drivers and Crown amp? Looks like the Daytons are out of stock and will not be back in stock for three months... :( Although I'm not in that big of a hurry, I was hoping to finish sooner than mid-summer.
  • scubalabscubalab Posts: 2,971
    Here is what Dan has done for me so far (can't thank him enough). Thoughts? Comments? Suggestions?

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  • EndersShadowEndersShadow Posts: 17,165
    edited March 2016
    Awww crap, your gonna show the guys how bad my grammar is :blush:

    JK, its good you posted that so we can also discuss the reasoning for going sealed v ported and all that jazz....

    Who knows maybe my public school edumication math skills are off :biggrin:....

    @scubalab

    I could always take a look at the other 15" Dayton drivers like the Titanic, HO or HF... it may change the numbers a bit but its not that hard to redo my graphs....

    Not sure how much price diff there is between them all but shouldnt be much...
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • scubalabscubalab Posts: 2,971
    Yeah... but look how pretty those graphs are?!? B)

    I did see the Dayton HO and HF... didn't see the Titanic. The TC Sounds you also mentioned looked like a nice driver, but you can't find them anymore... Would like to keep the driver prices under $200 each.
  • EndersShadowEndersShadow Posts: 17,165
    edited March 2016
    scubalab wrote: »
    Yeah... but look how pretty those graphs are?!? B)

    I did see the Dayton HO and HF... didn't see the Titanic. The TC Sounds you also mentioned looked like a nice driver, but you can't find them anymore... Would like to keep the driver prices under $200 each.

    LOL.... since I have an idea of box size I can see what each sub looks like ported v sealed and tweak the boxes WITHIN those parameters to see how they model.... then compare those to the UM15's...

    I will graph up the HO and HF drivers later tonight and get another document or two to you :wink:.

    It looks like they may have retired the Titanic, not surprised given the UM is more popular. TC Sounds went under/stopped making and selling subs so you'd need a used driver, and those are both scarce and pricey. Rumors persist they will re-emerge with a revamped lineup at some point, but I wouldn't hold your breath. Their subs were QUITE good however.

    Just so you can understand what the HO and HF are, the models indicate High Output and High Fidelity. Never heard either so will have to go based off how things model.

    I believe the HF is "supposed" to be more geared toward music with the HO more of a movie sub given the description of the drivers...

    Both drivers are under 200 a pop and less than the UM15 we were looking at.

    Will get graphs up later tonight
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • scubalabscubalab Posts: 2,971
    You da man Dan!!
  • EndersShadowEndersShadow Posts: 17,165
    To keep things sane for us both, since your leaning sealed I will just to graphs of these three subs in sealed enclosures. Will make the graphs easier to read (and less work for me, but thats not the driving reason to just do sealed :wink: )

    I will probably draft up and email you another document like the one I already did with breakdowns, so you can print it as reference for yourself.

    Your welcome to post it here as you did the last one to get additional thoughts.
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • scubalabscubalab Posts: 2,971
    Awesome... Thanks Dan. And yeah, for the sake of keeping it simple, I'm 99% sure I'm going sealed. Unless there is some really good reason or opinions why it'd be worth the additional work building ported boxes. Absolutely do whatever is easier for you. I'll post it up here if you email it to me. No rush on this... enjoy your family and your Easter weekend!
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    scubalab wrote: »
    Current plan (not set in stone) is to build two sealed subs using Dayton UM15-22 drivers (or something similar) and power them with a Crown XLS1502 (or similar).

    The 15's don't really save anything on the size of your box. If you can do an ultimax 15 then you can probably do an 18.

    Also the Crown XLS is a good amp but be aware that it's not that great for home theater. There is a 6 db per octave slope below 20 hz. Doesn't really mean much until down below 17 or so. At 10 hz, it really struggles. It can do very short bursts and still be respectable but with material that lasts for any amount of time, it will cut out. This is the 2502 as well, the 1502 will just be worse. I'd at least get a 2502 or rethink this amp choice. Otherwise I really like these amps. I destroyed one just trying to break in some woofers though, they're just not very tough down low.


    scubalab wrote: »
    Additionally, the cubby's that will house the subs will be built under a counter in a spare bedroom behind the theater. Would it help minimize vibrations in the bedroom (wall and counter) by installing some insulation, polyfill, thin foam sheeting in a small (say 1/4" - 1/2") space around all sides, back and top of the sub boxes to eliminate direct contact of the sub cabinets to the framed wall/counter?

    Only thing I would think might help in this situation is if you could seal off the baffle instead of taking a big cutout and shoving a not so big box in there. Otherwise you're kind of firing just as much sound into that bedroom as your theater room.
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    scubalab wrote: »
    Awesome... Thanks Dan. And yeah, for the sake of keeping it simple, I'm 99% sure I'm going sealed. Unless there is some really good reason or opinions why it'd be worth the additional work building ported boxes.

    The reason would be that two sealed 18" ultimax's aren't all that powerful for home theater to be honest. :) Sounds great for music but you'll be struggling below 25 hz. I have four of them and I'm just now happy with the performance down real low. I ran two of them for a year, with both an iNuke 6000 and Crown 2502. Run them hard at 18 hz and there's lots of distortion. With ported you're going to get a 6 db gain down low and less distortion.

    Keep in mind that you're going to need quite a bit of EQ with sealed subs. Can't just throw two DIY sealed subs in a room and expect it to sound great.
  • scubalab wrote: »
    Yeah... but look how pretty those graphs are?!? B)

    I did see the Dayton HO and HF... didn't see the Titanic. The TC Sounds you also mentioned looked like a nice driver, but you can't find them anymore... Would like to keep the driver prices under $200 each.

    If you're considering other drivers, the new Stereo Integrity ones just came out, 4" voice coil, 27mm xmax, they're bad mamma jammas. $259 shipped. Going to be hard to beat these.

    http://www.avsforum.com/forum/155-diy-speakers-subs/2206417-stereo-integrity-ds4-18-a-12.html

    http://sundownaudio.com/ht_order.htm
  • EndersShadowEndersShadow Posts: 17,165
    scubalab wrote: »
    Yeah... but look how pretty those graphs are?!? B)

    I did see the Dayton HO and HF... didn't see the Titanic. The TC Sounds you also mentioned looked like a nice driver, but you can't find them anymore... Would like to keep the driver prices under $200 each.

    If you're considering other drivers, the new Stereo Integrity ones just came out, 4" voice coil, 27mm xmax, they're bad mamma jammas. $259 shipped. Going to be hard to beat these.

    http://www.avsforum.com/forum/155-diy-speakers-subs/2206417-stereo-integrity-ds4-18-a-12.html

    http://sundownaudio.com/ht_order.htm

    We cant do 18" subs given his space constraints (19" width including box)... its would be REALLY tight.... otherwise we would be looking at that one or the UM18 driver....
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • We cant do 18" subs given his space constraints (19" width including box)... its would be REALLY tight.... otherwise we would be looking at that one or the UM18 driver....

    Where does that black door go to? Is there a second entrance into whatever room it leads in to? Can't you just bring the subs in through that room and scoot them over? If so you have all kinds of room.

    I think you can do it anyway to be honest. I wouldn't settle with a 15 over this. The lip of an 18 can go all the way to the edge of the box. No reason why an 18.5" wide or so box couldn't be made that slips right in. The cutout is like 16.7", you wouldn't even be cutting into the walls. You'd just probably have to use a normal screw instead of T-nuts on the far outsides. I use them everywhere anyway.
  • scubalab wrote: »
    Here is what Dan has done for me so far (can't thank him enough). Thoughts? Comments? Suggestions?

    A few comments struck me as being odd.


    1. For an ultimax 15 in a ported box, 4.5 cubic feet and tuned to 15 hz is pretty tiny. Just to put it in perspective, the similar 18's need nearly twice that for just 20 hz. For the 15, Dayton recommends 6 cubic feet even for an 18 hz tune. Tuning even lower while taking away 25% of the volume doesn't make much sense, especially since you're also having to make the ports longer to maintain the same tuning.

    Run it through a port calculator to see how odd it would be. At 4.5 cubic feet tuned to 15 hz, if maintaining the port area recommended by Dayton, you'd have two 4" ports that are 64" long. That's 5' 4" each. You would have nearly 11 feet worth of PVC tubing in a 4.5 cubic foot box! Only way to make that shorter is with a smaller port, but then you run the risk of having port chuffing noises. For example you could just ditch one port and have a single 4" port that is 30" long. That would fit just fine and would theoretically be tuned properly if you don't consider cone excursion. You're also cutting the minimum recommended port area in half, for a tuning that is even lower. Just a very bad idea. I wouldn't go along with this idea.

    That being said, the 3x15 slot port that was recommended is actually way bigger in area than what Dayton recommends, but unfortunately that isn't the correct tuning. See #6 below.


    2. Turning around and having the sealed box being 1 cubic foot larger than the ported box that's supposedly tuned to 15 hz doesn't make much sense. If you have that much room for a sealed box then you have enough room to build the ported one the right way. Most people would say that's too big as well, the ideal QTC of .707 is actually at 3.1 cubic feet.


    3. "sealed box... requires no high pass / subsonic filter which is an extra piece of gear that costs money"... with either of these DIY solutions you need to be running a DSP, and typically models like MiniDSP are going to include functionality where you can add this. No you don't typically need such a filter with sealed, but, you need this piece of gear anyway and therefore it's not really a money issue. Sealed with no DSP will look like a ski slope on the low end unless you bring it up. 1 or even 2 subs in the same location will also produce an ugly response graph due to modal issues, and you have to fix that with a DSP. This subsonic filter is a small part of the reasons to be running one with DIY subs.


    4. "sealed box... requires less wattage than the ported".... do what? This is backwards if anything. Sealed boxes are very inefficient down low. You have to have multiple drivers and give them a ton of power. Ported boxes will sip power comparatively at the same output down low. This makes no sense.


    5. "because it is ported it is less likely to walk"... possibly so but the reasoning is a little misled. With sealed, your cone will move more down low. These cones are heavy, an 18 is moving like a pound and a half of mass back and forth. That's just a lot of mechanical energy when they really get going. Unless you put such a thing in a force cancelling configuration like dual-opposed or counter it with something heavy like granite or just make a really overbuilt box, then you might get some extra vibration. It's not because on ported the air is escaping. If anything, the air pressure inside of a ported box is nearly twice that of a sealed box due to port backpressure, which is what keeps the cone from moving as much as a sealed box if you're playing at or slightly above the tuning frequency. Walking has nothing to do with air escaping, if anything the additional internal air pressure of ported boxes is what would keep it from walking as bad due to less cone excursion.


    6. "verify port length with AVS, I am not sure the port needs to be that long"... Look at a port calculator with these dimensions and tuning. For a 3x15 port in 4.5 cubic foot box, it would need to be 112" long, so if that's correct it's actually over twice what you're saying. 54" long as recommended would be tuned to 21 hz in a 4.5 cubic foot box as recommended. Otherwise it would have to be in an 8.8 cubic foot box to be tuned to 15 as stated. I used two different calculators to make sure one wasn't off.

    http://www.carstereo.com/help/Articles.cfm?id=31

    http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CAL Port lenth 1.htm



  • scubalab wrote: »
    Here is what Dan has done for me so far (can't thank him enough). Thoughts? Comments? Suggestions?

    A few comments struck me as being odd.


    1. For an ultimax 15 in a ported box, 4.5 cubic feet and tuned to 15 hz is pretty tiny. Just to put it in perspective, the similar 18's need nearly twice that for just 20 hz. For the 15, Dayton recommends 6 cubic feet even for an 18 hz tune. Tuning even lower while taking away 25% of the volume doesn't make much sense, especially since you're also having to make the ports longer to maintain the same tuning.

    Run it through a port calculator to see how odd it would be. At 4.5 cubic feet tuned to 15 hz, if maintaining the port area recommended by Dayton, you'd have two 4" ports that are 64" long. That's 5' 4" each. You would have nearly 11 feet worth of PVC tubing in a 4.5 cubic foot box! Only way to make that shorter is with a smaller port, but then you run the risk of having port chuffing noises. For example you could just ditch one port and have a single 4" port that is 30" long. That would fit just fine and would theoretically be tuned properly if you don't consider cone excursion. You're also cutting the minimum recommended port area in half, for a tuning that is even lower. Just a very bad idea. I wouldn't go along with this idea.

    That being said, the 3x15 slot port that was recommended is actually way bigger in area than what Dayton recommends, but unfortunately that isn't the correct tuning. See #6 below.


    2. Turning around and having the sealed box being 1 cubic foot larger than the ported box that's supposedly tuned to 15 hz doesn't make much sense. If you have that much room for a sealed box then you have enough room to build the ported one the right way. Most people would say that's too big as well, the ideal QTC of .707 is actually at 3.1 cubic feet.


    3. "sealed box... requires no high pass / subsonic filter which is an extra piece of gear that costs money"... with either of these DIY solutions you need to be running a DSP, and typically models like MiniDSP are going to include functionality where you can add this. No you don't typically need such a filter with sealed, but, you need this piece of gear anyway and therefore it's not really a money issue. Sealed with no DSP will look like a ski slope on the low end unless you bring it up. 1 or even 2 subs in the same location will also produce an ugly response graph due to modal issues, and you have to fix that with a DSP. This subsonic filter is a small part of the reasons to be running one with DIY subs.


    4. "sealed box... requires less wattage than the ported".... do what? This is backwards if anything. Sealed boxes are very inefficient down low. You have to have multiple drivers and give them a ton of power. Ported boxes will sip power comparatively at the same output down low. This makes no sense.


    5. "because it is ported it is less likely to walk"... possibly so but the reasoning is a little misled. With sealed, your cone will move more down low. These cones are heavy, an 18 is moving like a pound and a half of mass back and forth. That's just a lot of mechanical energy when they really get going. Unless you put such a thing in a force cancelling configuration like dual-opposed or counter it with something heavy like granite or just make a really overbuilt box, then you might get some extra vibration. It's not because on ported the air is escaping. If anything, the air pressure inside of a ported box is nearly twice that of a sealed box due to port backpressure, which is what keeps the cone from moving as much as a sealed box if you're playing at or slightly above the tuning frequency. Walking has nothing to do with air escaping, if anything the additional internal air pressure of ported boxes is what would keep it from walking as bad due to less cone excursion.


    6. "verify port length with AVS, I am not sure the port needs to be that long"... Look at a port calculator with these dimensions and tuning. For a 3x15 port in 4.5 cubic foot box, it would need to be 112" long, so if that's correct it's actually over twice what you're saying. 54" long as recommended would be tuned to 21 hz in a 4.5 cubic foot box as recommended. Otherwise it would have to be in an 8.8 cubic foot box to be tuned to 15 as stated. I used two different calculators to make sure one wasn't off.

    http://www.carstereo.com/help/Articles.cfm?id=31

    http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CAL Port lenth 1.htm



  • EndersShadowEndersShadow Posts: 17,165
    edited March 2016
    I figured I would try to explain myself so I will take each of the comments one by one
    1. For an ultimax 15 in a ported box, 4.5 cubic feet and tuned to 15 hz is pretty tiny. Just to put it in perspective, the similar 18's need nearly twice that for just 20 hz. For the 15, Dayton recommends 6 cubic feet even for an 18 hz tune. Tuning even lower while taking away 25% of the volume doesn't make much sense, especially since you're also having to make the ports longer to maintain the same tuning.

    Run it through a port calculator to see how odd it would be. At 4.5 cubic feet tuned to 15 hz, if maintaining the port area recommended by Dayton, you'd have two 4" ports that are 64" long. That's 5' 4" each. You would have nearly 11 feet worth of PVC tubing in a 4.5 cubic foot box! Only way to make that shorter is with a smaller port, but then you run the risk of having port chuffing noises. For example you could just ditch one port and have a single 4" port that is 30" long. That would fit just fine and would theoretically be tuned properly if you don't consider cone excursion. You're also cutting the minimum recommended port area in half, for a tuning that is even lower. Just a very bad idea. I wouldn't go along with this idea.

    That being said, the 3x15 slot port that was recommended is actually way bigger in area than what Dayton recommends, but unfortunately that isn't the correct tuning. See #6 below.

    6. "verify port length with AVS, I am not sure the port needs to be that long"... Look at a port calculator with these dimensions and tuning. For a 3x15 port in 4.5 cubic foot box, it would need to be 112" long, so if that's correct it's actually over twice what you're saying. 54" long as recommended would be tuned to 21 hz in a 4.5 cubic foot box as recommended. Otherwise it would have to be in an 8.8 cubic foot box to be tuned to 15 as stated. I used two different calculators to make sure one wasn't off.

    http://www.carstereo.com/help/Articles.cfm?id=31

    http://www.mobileinformationlabs.com/HowTo-1Woofer-Box-CAL Port lenth 1.htm

    I dont disagree that I may have been off on the math of the ported. That said ported will normally lose out if your talking about low frequency bass. Ported also is more difficult hence him not wanting to do that, and I understand.

    You could very well be right on that port length, but WinISD didnt seem to have a problem with it, however perhaps it wasnt updating right. I did also figure on a MASSIVE slot port running basically the entire width of the box and up the back a bit similar to the "Marty" variants because its easier than a PVC pipe.
    2. Turning around and having the sealed box being 1 cubic foot larger than the ported box that's supposedly tuned to 15 hz doesn't make much sense. If you have that much room for a sealed box then you have enough room to build the ported one the right way. Most people would say that's too big as well, the ideal QTC of .707 is actually at 3.1 cubic feet.

    Yes, however since we had the space one of the options is to build a bigger box to fully utilize the space. A 3 cubic foot box also is going to have a higher F3 than a larger sealed box. In addition to a lower F3, the larger box requires less power BECAUSE its a larger box.

    Which explains the statement below:
    4. "sealed box... requires less wattage than the ported".... do what? This is backwards if anything. Sealed boxes are very inefficient down low. You have to have multiple drivers and give them a ton of power. Ported boxes will sip power comparatively at the same output down low. This makes no sense.

    NORMALLY I agree, a sealed box will want a TON more power to get loud, but the larger the box, the lower that becomes, especially once you get larger than the driver needs. In this case, increasing the power would result in over excursion of the driver.

    If this was a 18" driver, we could hit it with a TON more power, but the 15 is in a oversized box and without a subsonic filter you need to protect it from excursion limits under 10hz.

    If we had either a larger driver, or a subsonic filter in place we could hit it with a lot more wattage, however thats not the situation we are presented with.
    3. "sealed box... requires no high pass / subsonic filter which is an extra piece of gear that costs money"... with either of these DIY solutions you need to be running a DSP, and typically models like MiniDSP are going to include functionality where you can add this. No you don't typically need such a filter with sealed, but, you need this piece of gear anyway and therefore it's not really a money issue. Sealed with no DSP will look like a ski slope on the low end unless you bring it up. 1 or even 2 subs in the same location will also produce an ugly response graph due to modal issues, and you have to fix that with a DSP. This subsonic filter is a small part of the reasons to be running one with DIY subs.

    The DSP would be provided by his AVR. The MiniDSP for a ported sub is needed because with a pro amp you DO NOT have a subsonic filter. If we were talking about a plate amp, diff story as they all tend to have them built in which is why lots of DIY guys go pro amps so they DONT have a subsonic filter build in.

    I dont disagree that a MiniDSP might not be "helpful" however I dont think its a requirement in his setup. Both subs will be equidistant from the main LP which helps.

    He currently has ARC which is PHENOMENAL from what I've read, and if not that if he goes with a Audyseey AVR with XT32 that is also great at working with subs.
    5. "because it is ported it is less likely to walk"... possibly so but the reasoning is a little misled. With sealed, your cone will move more down low. These cones are heavy, an 18 is moving like a pound and a half of mass back and forth. That's just a lot of mechanical energy when they really get going. Unless you put such a thing in a force cancelling configuration like dual-opposed or counter it with something heavy like granite or just make a really overbuilt box, then you might get some extra vibration. It's not because on ported the air is escaping. If anything, the air pressure inside of a ported box is nearly twice that of a sealed box due to port backpressure, which is what keeps the cone from moving as much as a sealed box if you're playing at or slightly above the tuning frequency. Walking has nothing to do with air escaping, if anything the additional internal air pressure of ported boxes is what would keep it from walking as bad due to less cone excursion.

    Thanks for that, I learned something new today.

    Hopefully that clarifies things.
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • txcoastal1txcoastal1 Posts: 11,544
    2-channel: Modwright KWI-200 Integrated, Dynaudio C1-II Signatures
    Desktop rig: LSi7, Polk 110sub, Dayens Ampino amp, W4S DAC/pre, Sonos, JRiver
    Gear on standby: Melody 101 tube pre, Unison Research Simply Italy Integrated
    Gone to new homes: (Matt Polk's)Threshold Stasis SA12e monoblocks, Pass XA30.5 amp, Usher MD2 speakers, Dynaudio C4 platinum speakers, Modwright LS100 (voltz), Simaudio 780D DAC

    erat interfectorem cesar et **** dictatorem dicere a
  • scubalabscubalab Posts: 2,971
    This is some really great stuff here. I'm now wondering if I'm in over my head! :o

    I've been working on the wall, lights, electrical, and the AV rack all weekend and am just now settling down for a needed rest. I'll try to digest this all over the next couple days. My brain is just not working now and my entire body is aching!

    I can add that the black (actually dark brown) door in the pic above leads to a spare bedroom. That door (and wall) is coming out and the bedroom's 'nook' will fill that space entirely (right up to the back of the AV rack and subs). So, unfortunately I cannot make the subs any bigger than the dimensions given.

    I'm looking for decent bass, but doesn't need to be earth-shaking. It will be 99% video (very little audio listening). The room is approx. 10' x 20' and a 7'4" ceiling. There's a bar in the back off to the right approx. 8'x10'. So, the room is essentially an L shape. The screen and subs will be at the top of the L facing the bottom...

    I have not decided on anything for the subs yet. I can always scrap the built-in idea and just keep my SVS PCi25-31. Was hoping to 'better' that sub and free up the floor space by building in though.

    I MAY be able to make 18" drivers work but they'd be right to the edge of the boxes.

    I currently have an Anthem MRX-500 AVR and a B&K 200.7 amp but will be replacing the Anthem with a Marantz AV7702 pre. The Anthem's ARC is fantastic. Hoping the Marantz's Audyssey Platinum (XT32) does as good. It can calibrate dual subs.

    Don't know if this helps or further complicates things.

    Here are a couple pics of the wall today (with the built-in AV rack almost complete. Subs will be on either side of the rack and will be the same depth and height.
    15p6audf37yx.jpeg
    s9otbn7yy8po.jpeg
    h2ferpsyo3kj.jpeg

  • EndersShadowEndersShadow Posts: 17,165
    edited March 2016
    ^Now that looks sexy! Great idea on making it a Flexi rack variant for sure!

    And we will get you there. If you can go with 18" subs then honestly your options open up a bit as the 18" boxes sealed will do a bit more SPL and take a LOT more power so you'd be able to open the 1502 open wide. But like you said your gonna be close clearance wise, so thats your call. I'm open to throwing together as much documentation as you want with graphs and whatnot.

    Your only 2 "real" options are either the Ultimax 18, which is just the next step up from the 15" we've been discussing OR the new Stereo Integrity 18" driver which they released to replace the older HT18 everyone has.

    Because I've already modeled it for myself for giggles, here are the main differences between dual UM15 v UM18. The SPL graph (assuming 1500 watts TOTAL) is 4 db higher across the entire spectrum. Excursion is EXACTLY the same (number wise) as the UM15, however since maximum excursion rating on the UM18 is MORE than the 15, you are not driving it to its max.

    To give you an idea what that would take, in a 6 cubic foot sealed box you'd need 2400 watts (1200 each sub) to get it to almost max out. So that would mean the XLS 2500, but the increase in SPL with that isnt huge (+2 db across the entire range), so I'd keep the 1502 and just know if you "needed" more performance, a bigger more powerful amp would add that for you.

    Going sealed makes it quite easy to graph stuff. As you can see ported can make it a bit harder....
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    ported will normally lose out if your talking about low frequency bass.

    On a typical driver like the Ultimax, ported only loses out on ultra low frequencies if we are under the tuning frequency. At that point, the driver becomes unloaded, the port doesn't really add much of anything to the output, and the cone basically flops around like a fish out of water, with the front and rear waves cancelling each other out somewhat, and the rolloff is very steep due to all of this. Sealed typically wins much below this point, because although it is rolling off itself, it is not nearly as steep, so if you get down under the tuning frequency enough, eventually the nosedive of the ported box's response is going to get lower than the sealed box's output. Sealed undoubtedly wins below this point.

    If we're comparing a capable driver though, 15 hz from a well designed ported box tuned to that frequency will typically run all over the same driver in a sealed box. All depends on what frequency we're talking about playing, and what the tuning frequency of the ported box is. Most people would consider 15 hz "low frequency bass". If you had designed a good 15 hz ported box, then no sealed box with that same driver would be able to touch it, that's too much lost ground to make up for.


    You could very well be right on that port length, but WinISD didnt seem to have a problem with it, however perhaps it wasnt updating right.

    Something isn't right with Dayton's parameters, I usually can't even enter the stuff right for an 18" ultimax in WinISD, which is buggy in the first place. It just gets stupid on me, has locked up multiple times. I've got it working in the pro version before though.




    Yes, however since we had the space one of the options is to build a bigger box to fully utilize the space. A 3 cubic foot box also is going to have a higher F3 than a larger sealed box. In addition to a lower F3, the larger box requires less power BECAUSE its a larger box.

    I haven't modeled this particular one but just to put this in perspective, look at the recommendations for the 18" version on Dayton's site. Upping from a 4 cubic foot box to a 7 cubic foot box gains you literally zero in terms of F3, and only gains you 2 hz on the F10. It's just usually not much of anything, like 1 db at the lowest frequencies. I think you are overstating the effect of a larger sealed box here.

    Regardless, my main point was that I don't believe that the recommended ported box is sized properly, so if you can afford to make a sealed box that big, then you should be able to go bigger on the ported one.


    NORMALLY I agree, a sealed box will want a TON more power to get loud, but the larger the box, the lower that becomes, especially once you get larger than the driver needs. In this case, increasing the power would result in over excursion of the driver.

    If this was true in general then we could get ultimate bass just by taking any random driver and installing it as an infinite baffle sub. It's more complicated than that. :)


    The DSP would be provided by his AVR. The MiniDSP for a ported sub is needed because with a pro amp you DO NOT have a subsonic filter. If we were talking about a plate amp, diff story as they all tend to have them built in which is why lots of DIY guys go pro amps so they DONT have a subsonic filter build in.

    Audessey isn't really a good solution for counteracting the rolloff of a DIY sealed sub. It will help somewhat with that, and will help with the modal stuff at least somewhat as well, but counting on getting a flat response with Audessey with no other compensation going on isn't really a good plan. Most pre-made consumer subs nowadays have a DSP built into the amp so you can typically get away with it. We are starting from scratch here though. The idea is usually to get at least close with a DSP, but with minimal EQ'ing, meaning don't use like 10 bands or anything, then you can let Audessey fine tune it. Audessey will really be straining its guts trying to tame raw subs and a raw amp with no other correction. Getting this part right is the hardest part. Blowing it off in the name of Audessey supposedly taking care of it all automatically isn't the best plan. :)


    Last but not least, re-reading your original comments, saying that a 6 db difference would be very hard to tell... that is actually a huge difference.
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    scubalab wrote: »
    I'm looking for decent bass, but doesn't need to be earth-shaking. It will be 99% video (very little audio listening). The room is approx. 10' x 20' and a 7'4" ceiling. There's a bar in the back off to the right approx. 8'x10'. So, the room is essentially an L shape. The screen and subs will be at the top of the L facing the bottom...

    Just so I'm clear, two 15" sealed Ultimax's are not going to do what you and the other guy thinks it will. :) You have room for 18's, no reason to not do it, especially with sealed boxes. Like I mentioned before, I'm just now happy with four 18's, and I usually listen to stuff no louder than -20 db. You need to consider distortion and not just SPL. Larger and more subs isn't only necessary when you want to rattle your teeth out. Bass is smoothest when you spread the subs around the room and don't drive them very hard. A small number of subs moving like crazy to keep up will not have the overhead, frequency response, or low distortion that I imagine you wanted when you decided to upgrade in the first place.


    scubalab wrote: »
    I MAY be able to make 18" drivers work but they'd be right to the edge of the boxes.

    It will be fine. Only reason why anybody would think they're not is because they're used to seeing inset/flush baffles on home speakers. This just doesn't matter with subs. Doesn't do anything, acoustically speaking. Another half inch of wood on each side won't gain you jack. My boxes are 19.5" tall, cutting a half inch off of each side isn't going to affect it one bit. Your boxes would look very similar to half of one of these.

    20160107_082239_zpse3xnovzh.jpg
  • EndersShadowEndersShadow Posts: 17,165
    edited March 2016
    On a typical driver like the Ultimax, ported only loses out on ultra low frequencies if we are under the tuning frequency. At that point, the driver becomes unloaded, the port doesn't really add much of anything to the output, and the cone basically flops around like a fish out of water, with the front and rear waves cancelling each other out somewhat, and the rolloff is very steep due to all of this. Sealed typically wins much below this point, because although it is rolling off itself, it is not nearly as steep, so if you get down under the tuning frequency enough, eventually the nosedive of the ported box's response is going to get lower than the sealed box's output. Sealed undoubtedly wins below this point.

    If we're comparing a capable driver though, 15 hz from a well designed ported box tuned to that frequency will typically run all over the same driver in a sealed box. All depends on what frequency we're talking about playing, and what the tuning frequency of the ported box is. Most people would consider 15 hz "low frequency bass". If you had designed a good 15 hz ported box, then no sealed box with that same driver would be able to touch it, that's too much lost ground to make up for.

    I agree, however ported makes this more complex for him, and again requires more hardware as he'd need a subsonic filter to ensure the driver doesn't unload below port tuning. I "think" the MiniDSP would allow him to set a filter that low but dont really remember from mine if that is the case..

    But yes, if you can do a ported box with a low tuning then it walks all over a sealed sub until below tuning then sealed takes over. Also factor in your going to get some sort of room gain regardless on both subs to help out.
    NORMALLY I agree, a sealed box will want a TON more power to get loud, but the larger the box, the lower that becomes, especially once you get larger than the driver needs. In this case, increasing the power would result in over excursion of the driver.

    If this was true in general then we could get ultimate bass just by taking any random driver and installing it as an infinite baffle sub. It's more complicated than that. :)

    Didnt say you'd get a MORE SPL, simply that the power to get to that SPL would be lowered. You are correct in that its more complicated.

    I'm simply stating that if you have the same driver a 10 cubic foot box with less power can hit the same SPL as a 5 cubic foot box with MORE power. The max SPL you can get from the driver is still limited by the Xmax of said driver.

    Something isn't right with Dayton's parameters, I usually can't even enter the stuff right for an 18" ultimax in WinISD, which is buggy in the first place. It just gets stupid on me, has locked up multiple times. I've got it working in the pro version before though.

    I grabbed the files from HomeTheaterShack and the driver integrity checked out so I'm assuming they are fine....

    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
  • This is what the modeling is looking like on my end. I included the 5.5 cubic foot sealed box, as well as the recommended ported one.

    If you were to actually build a large 15 hz tuned box with decent ports, you'd end up with about what the magenta one is. At 15 hz it is 10 db louder than the previously mentioned ported one, and about 11 db louder than the sealed one. You cannot mess with these types of boxes, you're not going to beat one or even come close to remotely sounding the same with a sealed box.

    ultimax%2015_zpsmmojmxid.jpg
  • To give you an idea what that would take, in a 6 cubic foot sealed box you'd need 2400 watts (1200 each sub) to get it to almost max out. So that would mean the XLS 2500, but the increase in SPL with that isnt huge (+2 db across the entire range), so I'd keep the 1502 and just know if you "needed" more performance, a bigger more powerful amp would add that for you.

    Put it this way, the 2502 is questionable for these subs in a home theater environment, and the 1502 is two steps down.

    Let's do some math. You're saying to run it in stereo. You're looking at 525 watts per channel rms being ran to these subs into 4 ohms. That's like best case scenario.

    That's not the whole picture though. Look at the impedance curve. These aren't 4 ohm subs. With the voice coils wired in series you're looking at more like twice the impedance for anything above 10 hz.

    Plus, these are only rated to 20 hz. Below that they start suffering. There is a 6 db per octave slope below that. Considering that 3 db equals a doubling of power, you're looking at 1/4 the power at 10 hz just to put it in perspective. Like 130 watts. I've ran sine waves on these amps, I don't really doubt this. What happens is that the limiter that is tied to the power supply will click on a relay and cut the entire amp out. It's bad mojo and happens almost immediately.
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    scubalab wrote: »
    I can add that the black (actually dark brown) door in the pic above leads to a spare bedroom. That door (and wall) is coming out and the bedroom's 'nook' will fill that space entirely (right up to the back of the AV rack and subs). So, unfortunately I cannot make the subs any bigger than the dimensions given.

    Since you're apparently sealing this thing in anyway, what about an infinite baffle setup? Replace that door with a baffle that can be removed if necessary, load it up with some 18" infinite baffle specific subs such as the Acoustic Elegance IB18HT. Would be awesome. No box necessary, all you have to do is build a baffle. That entire spare bedroom would be your "box". You could bolt the baffle to the door frame so you could remove it in the future. Just use an acoustically transparent screen and have acoustically transparent material over those sub holes, the bass would just fire right through your screen wall.

    http://aespeakers.com/shop/ibht-woofers/ib18ht/

    Personally I think all these issues would be averted if your screen wall were built differently. You're kind of painting yourself into a corner. Screen walls need to allow for access to everything behind them. You should be able to take the screen off and walk through, be able to move large boxes through that hole. All this should be a non-issue. I just think there's a few too many unnecessary vertical 2x4's. Your new wall isn't load bearing and doesn't need to be on 16" centers if it isn't.
  • scubalabscubalab Posts: 2,971
    GRRRRR.... I just spent a half hour typing something... hit the backspace key (and bumped another adjacent key at the same time), and this ****%!ing website went to the previous page and I LOST everything I typed.... Bear with me, and I'll try to remember what I typed, and post again shortly. This time, I'm doing it in Word, then cutting and pasting... this isn't the first time this has happened...
  • scubalabscubalab Posts: 2,971
    Metro – Thanks so much for all the input. You and Dan (EndersShadow) have been so generous with your time and efforts in helping me out.

    It’s probably best to give a little more information so you understand my limitations in what I can and cannot do. First, I completely agree that this is not an ideal situation. Since it’s not new construction, I don’t have a blank canvas to work with. I have a space in an existing house and I’m trying to make it work for a HT. So, in a sense, yes, I sort of am painting myself into a corner (the only one I have! :/ ).

    Our house is mostly on slab, so we don’t have a basement. Therefore, storage space is at a premium. The area behind the screen used to be storage (a closet under the stairs, and some shelves hidden behind the screen and accessible from that old door in the guest bedroom). There is another door to the guest bedroom, so that door was rarely used.

    I have a wife. She’s made it abundantly clear that SHE is giving ME some additional space. (I’m taking some of her storage space.) Imagine the screen wall being one that is 2’ deep. I’m getting that 2’ for the bottom 3’ of wall height for my equipment and subs. She keeps the top 4’ for a counter and some storage cabinets. The wall with the door is coming down and will then be part of the guest bedroom. So, just to clarify, it would be easier to move a mountain than it would be to get any more space from the wife!

    This new wall is a LOT more complicated than it looks. Although it is not entirely load bearing along its length (since there was no wall for a portion of that area previously), it is load bearing at a point. The wide stud near the center with the two blue boxes on it IS load bearing. It supports a floor joist and the one stringer of the stairs. I had to get creative with this, since the equipment cubby extended under it (hence the stacked 2x6 bridge spanning the equipment cubby). So, at best, I could possibly have eliminated the two studs to the left if I had to. But, since there’s no acquiring that space behind the screen anyway, they are needed for the wall in the BR and the new cabinets behind the screen.

    I’m not sure I entirely understand everything about the acoustically transparent screen and AT material over the sub holes. If I were able to use all that space as you suggested for IB subs, I sort of see what you mean. Just don’t understand where the drivers would be in this situation. Regardless, that can’t happen, but I do agree it would be better.

    So, with what I have, I can at best get two 19” wide, by 36” high, by 23” deep ‘spaces’ for built-in subs. I have to admit that I don’t have the knowledge, tools, or experience to design them and am relying entirely on you guys to guide me in a decent direction. I’m perfectly content with my current SVS sub, but if I can equal or better its sound and eliminate that very conspicuous cylinder in the room by investing a little labor and funds into built-in subs, I’m all for it! Worst case is the built-ins aren’t worth it. Then my wife gets another 19”x36”x23” storage cabinet, and I get the other one for storage of movies and games! I’d just keep the SVS and put it in the left front corner (where it used to be).

    All that said, can I make something work? Again, I trust the expertise here, as I’m completely new to all this. My previous subs have always been pretty much plug-n-play, with perhaps a LITTLE fine tuning on my part at the sub. I usually just run the room correction, and go with it. If I do these built-ins, I appreciate any help you guys can give me…! I'm NOT entirely against ported subs either. I'd just need a lot more hand-holding... (what additional equipment would I need, how do I 'tune' them, how big/long are the port tubes, etc., etc.)

    Hoping this can work. And, if it can still work, I want to make sure I do what I can now to eliminate any excessive sound/vibrations in the guest BR. So, my first two questions in the second post would still remain...

    Thanks again for all your help!

    -Al

    Here's a rough sketch I did a while back. It might help in understanding the space and house layout...

    kvgfz2af9275.jpg
  • MetropolisLakeMetropolisLake Posts: 128
    edited March 2016
    scubalab wrote: »
    I’m not sure I entirely understand everything about the acoustically transparent screen and AT material over the sub holes. If I were able to use all that space as you suggested for IB subs, I sort of see what you mean. Just don’t understand where the drivers would be in this situation.

    First of all, we need to back up a little here and study up on this stuff before you get too carried away and build anything else. At this point you have an incredible opportunity to do something how it ought to be done, which is to say, the speakers ought to be behind the screen. You do this by getting a projector screen that is made of acoustically transparent fabric. At that point, you get three identical speakers for your mains, not two towers and a center like you would on a TV, and put them behind the screen. There are too many advantages to this to list here, but trust me, that's how it ought to be. Take some time and read up on this. It truly needs to be your goal and I'm getting the feeling that it is not at this point even though you have all of the architecture in place to do so. Right now you have a 2x4 right where your center actually needs to be.

    At the minimum, that third speaker needs to be behind your screen. Yeah you can put towers to the side and subs in those cubby holes, but your center will always be a huge compromise unless it is the same speaker as your towers and is located behind your screen. Make sure you make this a priority before you do anything else, you will kick yourself so hard later on if you don't. Just stop building temporarily and read on acoustically transparent screens, baffle walls, things like that.



    scubalab wrote: »
    All that said, can I make something work?

    You have an insane amount of room from what I can tell. You can do about anything you want.


    scubalab wrote: »
    Again, I trust the expertise here, as I’m completely new to all this. My previous subs have always been pretty much plug-n-play, with perhaps a LITTLE fine tuning on my part at the sub. I usually just run the room correction, and go with it.

    That's the problem, with factory subs nowadays you're getting some DSP magic built into them. That's how they are flat so low. Audessey isn't starting from scratch. You can do this yourself but it's not nearly as simple as was previously mentioned if you want it to be right.



    scubalab wrote: »
    If I do these built-ins, I appreciate any help you guys can give me…! I'm NOT entirely against ported subs either. I'd just need a lot more hand-holding... (what additional equipment would I need, how do I 'tune' them, how big/long are the port tubes, etc., etc.)

    It's not that bad really. Biggest question is whether you're a fan of sealed subs or ported subs, generally speaking what your goals are. All sub solutions have its pros and cons.


    Biggest question at this point is your overall budget, or do you have one.
  • List of questions here along with possible suggestions.

    1. Overall budget?

    2. Is your riser complete? If not can you scoot the thing forward? Your side surrounds need to be at least 90 degrees to the side of the front row if possible, plus if you scoot it forward you could fit two more subs in the back corners at least eventually. Four subs, one in each corner, is about the best you can hope for in terms of smooth response seat to seat.

    3. Can you make the room symmetrical? Right now it is offset to one side. Ideally it needs to be symmetrical with the seats in the middle.

    4. Can you put those rear 7.1 surrounds together more? I think they are spread out too far. Direct radiating speakers that are closer together and firing forward would work better.

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