dual sealed SW-12B's completed (PICS)

tryin · « **on:** 30 Mar 2010, 12:43 am »

Well it's been done for about a week now. I have been doing some listening and have mixed results so far. The output is there, it is just a little more boomy than I was hoping for. I have two issues that I know is killing me. The first, my receiver, it's an old Kenwood VR-507 that has no bass management. From the research I've done if I set the front speakers to normal it low passes the sub at 100hz. It sure doesn't sound like it to me, sounds like I'm getting much more than that. My old sub had a crossover on the back of the amp that I could turn down so it sounded decent. My second problem, my room sucks. I have a brick floor, half the wall is stone, I have eighteen windows, three sets of french doors, and a cathedral ceiling! If you listen right at the sub you can tell to much high frequency is getting through though.

Output is pretty impressive, although, the more you crank on it, the more boom you get. You can tell that the potential is there for nice tight, clean bass. So far I have my amp turned up slightly over half way. Speaking of the amp, I played with the crossover that is selectable on the back of the amp. From my understanding I should be using the 135 setting for a sealed enclosure. I can't tell any difference at all between the 135 and 35. This amp gets HOT! Even with just tv watching you cant hold your hand on the back of it at all. I must say for such a small amp, it delivers the wattage to move some air with the SW-12B's. I can't confirm that it is down -3db at 25hz but it seems like it will play low, I don't have any idea how low though.

I watched the last Star Trek movie the other night and was pretty impressed with the output for movies, it'll slap you right in your chest! Just wish I could get it a little cleaner. I know that it sounds like I'm not to happy with it but I am, I know that with the proper EQ and a better room it would sound fantastic. It is a much better movie sub than my previous and that is the main reason I built it. I'll include some final assembly pictures. When my brother sends me the build pictures from his iphone I'll include them as well. I can tell you this much it is built stout, probably weighs over 130 lbs.

grubyhalo · « **Reply #1 on:** 30 Mar 2010, 04:03 am »

That looks pretty darned good!

persisting1 · « **Reply #2 on:** 30 Mar 2010, 07:37 am »

Very nice looking sub, but by no means should be boomy.

jdbrian · « **Reply #3 on:** 30 Mar 2010, 10:35 am »

The sub looks great!!

Placement is everything when it comes to getting the best sound from a sub. Experiment with moving it around. Sometimes a near field position (close to the listening position) will give you better sound because you don't need to turn the sub up as much and it can minimize room modes to some extent. It seems odd that it runs so hot. If it runs hot even when playing at low levels you should check your connections and also check for a DC offset on the amp output. Perhaps Danny can let you know what is normal.

Brian

corndog71 · « **Reply #4 on:** 30 Mar 2010, 12:07 pm »

I know with my sealed servo sub it took several days for the driver to settle down. I had the level on the amp turned up pretty high initially but then later I had to turn it down a bit.

And as the other guy said sometimes subs don't work their magic where we would like them to.

tryin · « **Reply #5 on:** 30 Mar 2010, 12:58 pm »

I know subs are tricky to integrate into the system. I've tried nearfield placement and it was much worse output wise, very big nulls, very little output. The corner it is in gets the best output, and it works pretty good because it is close to power and the reciever. I think my main issue us my receiver letting to much high frequency through.

The more I listen to it the better it is sounding though.

corndog71 · « **Reply #6 on:** 30 Mar 2010, 02:01 pm »

You probably would benefit from a better receiver too.

poseidonsvoice · « **Reply #7 on:** 30 Mar 2010, 02:29 pm »

Quote from: tryin on 30 Mar 2010, 12:58 pm

I know subs are tricky to integrate into the system. I've tried nearfield placement and it was much worse output wise, very big nulls, very little output. The corner it is in gets the best output, and it works pretty good because it is close to power and the reciever. I think my main issue us my receiver letting to much high frequency through.

The more I listen to it the better it is sounding though.

Have you started making measurements of your speakers + the subs in room? It can help especially if you are dealing with room nulls and peaks as we all have.

Best,
Anand.

mlbrand · « **Reply #8 on:** 30 Mar 2010, 03:37 pm »

Great looking sub, excellent work!

As far as boominess, get it out of the corner if possible. IMHO corner placement can make any sub sound "boomy" and is the worst location for an even frequency response. With one sub the best placement would be in the middle of one of your walls, ideally front or back, but even sidewalls will work. If that can't be done, move it as far from a corner as possible, ideally locating it where your response is the flattest. Measurement software is best, but the old trick of placing the sub in your main seating location and then crawl around possible locations in your room until you find the best sounding spot, then put the sub there. Good luck, and again very nice build!

walkern · « **Reply #9 on:** 30 Mar 2010, 04:32 pm »

I can't see what the bottom of the sub looks like, but if you put it on sturdy spikes (Danny sells nice ones that are quite reasonable) that will also help tighten up the low end and give your bass more apparent speed and articulation. Beautiful build by the way!

Neil

tryin · « **Reply #10 on:** 30 Mar 2010, 08:50 pm »

Thanks for all the help so far guys. If I get a chance tonight I'll pull it out of the corner and move it around some more. One thing I have noticed is that behind the sub in the corner it is really boomy. I haven't had a chance to measure anything yet, when I do I guess I'll just buy a radio shack spl meter and find some test tones, I've never looked into computer software, just guessing it is out of my budget for now. Unfortunately, so is a new receiver.

I noticed a suggestion of putting spikes on the bottom, the reason I didn't is I didn't think it would play nicely with the brick floor. Right now I just have it sitting on a doubled up piece of speaker box carpet.

Something else I need to do is buy some more no rez and do the rest of the cabinet. Right now I used a full sheet (left over from a previous build) but it only did about 1/3 of the sub. The rest I did the cheap method and used 12x12 floor tiles and covered with polyfill. I stuffed each chamber with about 10oz or a little over half full of polyfill as well.

Danny Richie · « **Reply #11 on:** 31 Mar 2010, 01:29 am »

Just out of curiousity, how high are you playing it?

tryin · « **Reply #12 on:** 31 Mar 2010, 08:20 pm »

Quote from: Danny on 31 Mar 2010, 01:29 am

Just out of curiousity, how high are you playing it?

Danny, I'm guessing how loud? I would say between 80-85 db. The gain on the amp is about 5/8. It will go much higher but my mains are junk and sound like crap any higher anyway. I would say during watching a movie it is over 100db during peaks though.

I moved it out of the corner last night and it does sound better along my side wall. It definately has less output in this area though. If I go over to the corner that the sub was in and listen it is very boomy. Would this be a good place to put in some kind of room treatment? What if I moved the sub back to the corner and put some kind of bass trap behind it? I noticed that every corner has the same boominess sound just not as bad as the one closest to the sub. The sub looks much nicer and fits into my room better in the corner for sure.

corndog71 · « **Reply #13 on:** 31 Mar 2010, 08:38 pm »

It sounds like those corners are definitely where you do NOT want to put the sub. What you should put in the corners are bass traps. Big bass traps. And all of those hard surfaces really are working against you but it doesn't sound like there's much you can do about that.

If the sub is doing its job then there should only be boom when there's supposed to be boom.

Danny Richie · « **Reply #14 on:** 31 Mar 2010, 09:08 pm »

Quote

Danny, I'm guessing how loud?

No, not how loud. How high is it playing as in frequency range? I am just wondering if it is overlapping onto the main speakers and causing a peak in the response because of it.

Quote

If I go over to the corner that the sub was in and listen it is very boomy. Would this be a good place to put in some kind of room treatment? What if I moved the sub back to the corner and put some kind of bass trap behind it?

Yes, those corners could really use some help. Keep the sub away from the corners and add tube traps in those corners.

Cacophonix · « **Reply #15 on:** 31 Mar 2010, 09:14 pm »

One of the ways of determining subwoofer location is to place it where you normally listen, and then move around the room until you find a spot where the bass sounds about right. Mark that spot, and place the subwoofer there.

tryin · « **Reply #16 on:** 1 Apr 2010, 02:13 am »

Danny,
Not really sure where the receiver is cutting it off at. It is supposed to cut it off at 100hz in stereo with speakers set to small and that is where I have it set. Unfortunately, I don't have much flexibility with my receiver and the adjustments, they just aren't there. I suspect the cutoff would be much better at 80hz or even lower but I can't adjust it. I really could use a new receiver but it's just not going to fly right now.

As of now, the sub is out of the corner and sounding much better. I am enjoying listening to this sub, I swear it is sounding better every time I listen to it. I would LOVE to hear this thing in a better room and EQ'd. To think that you could have two sets of these for about $800 with materials, it would be an amazing setup for music or HT.

Now I need to save up some coin for some new mains. Thinking N1's or N2's in my near future. Maybe sneak in a new receiver around Christmas or something. I would rather have really nice speakers first and then save up and by a new receiver. Kind of holding off on the receiver until all the 3-d stuff comes out.

Still wondering why this amp is running so hot though, I swear, you can't touch this thing even while just watching TV. If it is on, it is hot! Doesn't seem to be affecting it in any way, just wondering if is the lack of a heat sink or something. I have noticed a slight difference in adjusting the crossover on the back. For music I seem to get the tightest bass right about half way.

Danny Richie · « **Reply #17 on:** 1 Apr 2010, 03:11 am »

Just keep in mind that when you cross two drivers over to each other, you want them to both be -6db down at the crossover point. So if the receiver will cut the lows from the mains at 10Hz with a second order slope, then you might need to set the crossover on the plate amp to somewhere closer to the 70 or 80Hz range (maybe even lower if you have room gain in that area). Try turning the crossover to a lower setting and see if some of the boom goes away.

tryin · « **Reply #18 on:** 1 Apr 2010, 12:27 pm »

Quote from: Danny on 1 Apr 2010, 03:11 am

Just keep in mind that when you cross two drivers over to each other, you want them to both be -6db down at the crossover point. So if the receiver will cut the lows from the mains at 10Hz with a second order slope, then you might need to set the crossover on the plate amp to somewhere closer to the 70 or 80Hz range (maybe even lower if you have room gain in that area). Try turning the crossover to a lower setting and see if some of the boom goes away.

Yep, about half way seems to be yeilding the best results.

rythmik · « **Reply #19 on:** 3 Apr 2010, 11:22 am »

This is a nonservo sub. That means you need to put in an LT circuit as minimal to extend the bass. It also change the Q value of the response. Without LT circuit, the Q value can be in the neighborhood of 0.8 and in box fs can be as high as 30hz. If you have got the amp from Apex and you know how to solder, I have a bunch of LT circuit board that you can use for that purpose. I don't offer LT to my customers anymore, so if there is no other use for those boards, I would throw them away very soon. The mounting hole fits Apex Senior amps.