Need new sub, thought i would build one!

**Eric Mathews** · **01-07-08, 02:24 AM**

Hello all i am new to this forum and new to DIY. Right now i have 2 Velodyne 12" sub, they are more of a music sub and not a HT sub. The room that i have my theater set up in is used 100% for Movies. I have been looking into an SVS for about 6 months now but they figured, its just a cylinder with a sub i can build that lol. I have my mind set on a sonosub and just picked up a css SDX15. Found out that i live 20 min from their location in Abbotsford BC lol. I have seen a couple of people build the sonosubs with this driver and i was wondering if anyone had any suggestions about size of tube and port length and size. I have read a lot and it seems like Steve is the sonotube god lol. size does not matter at all the whole room is made for it and i got no wife to please!! OHH the amp im using is a pro amp bridged to 560 wrms, im hoping thats enough. thanks in advanced for your wealth of knowledge

Eric

**Ricci** · **01-07-08, 10:43 AM**

Nice driver choice Eric. You could use more watts for that driver but 500 or so should be fine. You are doing a single driver build, correct? I think that about 330L tuned to 15hz looks about right for this driver. You would use a 6" port or possibly 3 4" ports if you wanted more vent area. Do you have winisd? You can simulate this stuff yourself with it.

**Eric Mathews** · **01-07-08, 11:52 AM**

ya im going to be getting winisd tonight and fooling around with it, i had the amp from before thats why im using it. In the future i might make another one, and then ill get a better amp. Is there any differenace between using 3 smaller ports instead of one large one? besides one is easyer to make :P thanks for the fast reply!

**Mike P.** · **01-07-08, 12:18 PM**

As long as the 3 smaller vents have the same total area of the bigger vent then it's the same. Since you've decided on a sonosub design here is an excellent program that will help.

http://www.subwoofer-builder.com/sonosub.htm

**Eric Mathews** · **01-07-08, 03:13 PM**

THANKS!! that is awesome when i get home from work i will down load it. there is so much to learn and you all know so much! thanks again for the feed back.

Eric

**Ricci** · **01-08-08, 03:54 PM**

3 4" ports will have slightly more vent area than a single 6" vent. If you want to keep your airspeed as low as possible the more port area the better. That said I don't think that you will have any problems with a single 6er.

**Eric Mathews** · **01-08-08, 07:49 PM**

Quote:

Ricci wrote:

Nice driver choice Eric. You could use more watts for that driver but 500 or so should be fine.

i was looking around for other amps and i cam across a Yorkville AP-3400 for $450

it puts out 1200 wrms x2 @ 4 ohms

http://www.yorkville.com/default.asp...2=120&p_id=115

that is a link the the manual (scroll down and select the AP 3400)
it seems like its got good specs. just wanted to know your opinion on that amp for that price. thanks

Eric
ohh the reason i was looking for a 2 ch, i might build another sub.

**Ricci** · **01-09-08, 10:04 AM**

I'm not familiar with that model, but Yorkville has a good rep so I'm sure that it's a solid design. You could probably find a Crown XS1200 on e-bay for about that much, which should be even better. There were 2 that went for about 500 awhile back.

**Owen Bartley** · **01-10-08, 02:54 PM**

Eric, good driver choice. And if you have no real space or design constraints, and you're used to two smaller subs but want more bottom end for your HT, a nice large enclosure will do you wonders. The LLT seems to be a great option for HT if you can fit it physically, and it sounds like you can, so I'll second Josh's suggestion.

Oh, and don't worry about the amp for now, unless you really want to spend the money on the new one. As long as you're careful when you fire it up, and you increase the volume/gain slowly to make sure you don't clip, you should be ok. And if you get everything up and running and decide you really do need more power, it's easy to get something and sub it in at that point.

**Eric Mathews** · **01-11-08, 02:26 AM**

ok im done cutting all my holes, well except for one small one. There is a picture of my rigged up router jig lol. Getting my 24" sonotube on sat then i should be able to finish all the cutting and gluing. thanks for all the help and the info!!

**thxgoon** · **01-11-08, 10:52 AM**

Coooooooool. I can't wait to hear what you think of this vs your Velodynes. Nice jig btw

**Eric Mathews** · **01-11-08, 10:42 PM**

ya the pictures that i took where way bigger, image shack shrinks them

too bad lol

**Eric Mathews** · **05-13-08, 09:03 PM**

ok so here is the update. i was gone for a couple of months so i couldnt really post but i finished the sub.... but im not very happy with it. im not sure whats wrong but i will post the SPL levels.

ohh and i think the sub is defective because any ware around 30 hz i can hear the voice coil rubbing :S. I didnt know if was supposed to use the "a" or the "c" weighting so i recorded them both. tell me what you think. Oh and im using an old carvin amp rated at 800 RMS into 4 ohms.

"A"
30 - 96
35 - 102
40 - 107
45 - 112
50 - 111
55 - 106
60 - 104
65 - 105
70 - 105
75 - 104
80 - 100

"c"
30 - 83
35 - 85
40 - 95
45 - 91
50 - 90
55 - 88
60 - 86
65 - 87
70 - 88
75 - 88
80 - 85

this was running at JUST under clipping for my amp. i was kinda hoping for a little more then that since my sub box is HUGE. Could that be the problem right there, maybe a standing wave or something. i was thinking i might just rip the sub out and try it in a sealed box. please tell me what you think!!

Eric
ps ill post the pictures i took later

**eyekode** · **05-13-08, 09:51 PM**

Quote:

Eric Mathews wrote:

ok so here is the update. i was gone for a couple of months so i couldnt really post but i finished the sub.... but im not very happy with it. im not sure whats wrong but i will post the SPL levels.

It does seem to roll-off very early. Does your amp have a high-pass filter?
Silly question: at what distance did you take these measurements?

**Eric Mathews** · **05-13-08, 10:29 PM**

i took them at about 2 meters, but then again it is in a room so there should be gain from that as well..... i dont know it seems like Ilkka got better results with this sub out side in a 100L sealed box. http://www.hometheatershack.com/foru...-100l-new.html

**Ricci** · **05-14-08, 03:08 PM**

Are you sure that it is the VC rubbing that is making the sound you hear? could it be something loose or buzzing around the driver or in the cab? Amp clipping/ have you taken the driver out to check this?

Your roll off does seem kind of early, but you might have a big peak at 40-45hz.

**looneybomber** · **05-15-08, 04:04 PM**

It's not so much that it's rolling off early, it's that the standing wave at the mic position is causing a huge bump in the 40-50hz area. I would try measuring it outside where room interactions wont be a problem.

**thxgoon** · **05-15-08, 04:27 PM**

Where are you measuring the sub from? If you are just measuring the driver then you are not going to pick up any output from the port which plays a larger role the lower you go so that would explain a roll off in measurements.

Were both of your A and C measurements taken at full output of your amp? This looks suspicious because C weighted is a flat response on your meter where A weighted is designed to approximated the human ear which is less sensitive at lower frequencies. Thus under A weighting you should be seeing like -30db at 30hz. Strangely in your results not only is your A weighted flatter but also louder. This defies all convention so I would think there is either something wrong with your meeter or inconsistent with your set up. I'd suggest downloading REW and running a few sweeps at the listening position and posting those. They can tell a lot.

What are you dissapointed in sound wise? Have you tried moving the sub to different room locations? With that driver and amp you should be blowing your velodyne out of the water. Move the cone in and out by hand to see if there is any VC rubbing. I suspect that the sound you hear at 30hz is likely a leak or spider noise.

**BassThatHz** · **05-15-08, 11:58 PM**

hmmm, I was planning on moving from velodynes to two SDX-15's... Not good news.
I see you're in my area (cool); which velodyne series are you running?

Is there any way you could post a youtube video so we can hear em in action or at least more pics.

Graph seems decent, could you post plots of 25, 20 and 15hz too?

What kind of excursion are you getting during these measurements?

These are dual 2ohm drivers. I assume you hooked it up in series for 4ohm, the thought of running in bridged mode @ 1ohm eek!

I can't think of anything else other than defective amp or driver.

**Eric Mathews** · **05-16-08, 02:21 AM**

ya i tryed moving the sub all around the room and in one of the corners was the best place. Both of the measurements where taking at about +6 db on my reciever.... pretty loud if other things where playing and not just the sub. any louder and the amp would start to clip. I have tryed 3 different amps, a QSC, Carvin and an Art. the carvin is what im using now. the sub looks like its moving ALOT, but maybe the box is just the wrong size for my room? so i might pull out the sub and throw it in a sealed box for a test. Ya im running it at 4 ohms lol i dont have an amp that will do 1 ohm. The Velodynes that im using im not sure what model but they are only 125 wrms so i think i should notice a huge difference. right now im running all 3 and it sounds ok, but i was kinda hoping to not have to use my other subs.

**thxgoon** · **05-16-08, 12:19 PM**

Double check you measurements. Can you post an REW graph? If it's moving a lot then it's making noise, nothing wrong with the driver or amp. Could just be a bad room...

**Eric Mathews** · **05-21-08, 12:14 AM**

im starting to think your right MR THX!. i think this is more of a room issue. i went down there again but this time tryed putting the sub on its side in all different areas and it just made it even quieter then in the corner standing. but then once i moved it up i could not hear any noise at really low frequencies anymore!!!! so im thinking it was some dirt or something but its ok now. do you think that maybe the box is just too big? i could pull the sub out and make a sealed box for it. i just cant for the life of me figure out why its not as loud as 2 125 W 12" subs....

like i said before i can see the sub move alot, just must be some kinda standing wave. but moving it around does not make it any better... maybe i need a smaller sub then a 15? thanks for all your help!!

**Blaser** · **05-21-08, 06:21 AM**

Eric,
A 15 incher won't be specially louder than 2 12" sealed drivers (all paramaters other than size assumed equal), specially when it comes to the heard bandwidth of bass... it looks to me like you need another sub.

From its measurments, would like to say the SDX 15 is an excellent driver. Pls post an REW FR. How much is the enclosure volume? 350L? Did you measure the actual tune? Let us know.

**thxgoon** · **05-21-08, 10:10 AM**

Ya, another possibility is that your new sub is so clean and distortionless that it doesn't sound as a loud. A lot of times high output subwoofers can introduce a lot even ordered harmonic distortion which increases percieved output. Your new sub won't have this. I don't have WinISD atm so can't model your sub but I think your design looks good. You may just need more

**Blaser** · **05-21-08, 12:20 PM**

I agree!

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