DIY Stereo Integrity HT 18" V2, with baltic birchwood enclosure flatpanel kit.

[aweir]

This is the kit I am building. The front baffle does not provide enough room to create a grill and since I don't want a huge ugly 18" subwoofer staring at me all the time unprotected, I decided to turn it into a down firing subwoofer by attaching 4" furniture buns to the front purchased from Home Depot. I used Parts Express dual ended binding posts as you can see in the last picture.

http://stereointegrity.com/product/ht18-v2-subwoofer/
http://www.diysoundgroup.com/sealed-subwoofer-flatpacks/si-4-sub-flat-pack.html

 

[panteragstk]

Very nice. I'll be grabbing some of these when it's time to upgrade the theater subs.

Off topic question...what kind of clamps are those?

 

[everettT]

Very nice. I'll be grabbing some of these when it's time to upgrade the theater subs.

Off topic question...what kind of clamps are those?

Bessey clamps, very good but not cheap. My preferred choice now, built my clamps before that for lengths over 30".

 

[lovinthehd]

Bessey clamps, very good but not cheap. My preferred choice now, built my clamps before that for lengths over 30".

Curious that the tags are still attached to the clamps....

 

[aweir]

Curious that the tags are still attached to the clamps....

I rented the clamps. OK, I bought them and returned them but they were in pristine condition when I returned them. I wasn't about to spend $30 per clamp and only use it one time.
The sub is hooked up and working. My fist impression of sealed enclosures is that there is no port noise but the roll off is high. I added about 4 lbs. of Poly-Fill and unfortunately without testing equipment I can't be sure it even makes a difference. If I boost the equalizer's 20Hz setting I can get it to about 25 Hz. Room gain is giving me a huge boost at 40-50Hz so I might cut that frequency out rather than boost the 25Hz region.
I'm sure the placement of the sub is bad. Right now it's positioned on the long wall about halfway. I'm going to try it in the corner next. This was just a power test basically.

Some reviewers say this enclosure doesn't need Poly-Fill, but other reviewers say the enclosure is a bit too small for the parameters. (4 cu. Ft sealed...10 cu. Ft. ported!!?)

My live-and-learn mistake was thinking I could make this a down-firing sub with only 4" of clearance. Little did I know that there would not be not enough room between the sub and the floor given the cone area. The cone area is 855 In Sq. but the area of the space around the bottom when on it's legs is only 264, with all four sides taken into consideration.

The calculations determined I need about 12" height for proper air displacement. Unless I attach 12" long 4" PVC pipe to the feet this may have to remain a front firing, or top firing sub woofer.

 

[lovinthehd]

I rented the clamps. OK, I bought them and returned them but they were in pristine condition when I returned them. I wasn't about to spend $30 per clamp and only use it one time.
The sub is hooked up and working. My fist impression of sealed enclosures is that there is no port noise but the roll off is high. I added about 4 lbs. of Poly-Fill and unfortunately without testing equipment I can't be sure it even makes a difference. If I boost the equalizer's 20Hz setting I can get it to about 25 Hz. Room gain is giving me a huge boost at 40-50Hz so I might cut that frequency out rather than boost the 25Hz region.
I'm sure the placement of the sub is bad. Right now it's positioned on the long wall about halfway. I'm going to try it in the corner next. This was just a power test basically.

Some reviewers say this enclosure doesn't need Poly-Fill, but other reviewers say the enclosure is a bit too small for the parameters. (4 cu. Ft sealed...10 cu. Ft. ported!!?)

My live-and-learn mistake was thinking I could make this a down-firing sub with only 4" of clearance. Little did I know that there would not be not enough room between the sub and the floor given the cone area. The cone area is 855 In Sq. but the area of the space around the bottom when on it's legs is only 264, with all four sides taken into consideration.

The calculations determined I need about 12" height for proper air displacement. Unless I attach 12" long 4" PVC pipe to the feet this may have to remain a front firing, or top firing sub woofer.

Figured as much on the clamps, lol. While I bought clamps first for diy subs, I had other uses in mind down the line in wood working, but I didn't buy Bessey either...paid around $120 for a set of 30 Denali clamps in assorted sizes.

What size box is it and who sells the baltic birch flatpacks?

Whose and what formula are you using re the air space needed for the downfiring configuration? Seems excessive. Did you also check the driver parameters to make sure it was suitable for a downfiring configuration? IIRC the SI drivers are okay, but that was gen 1 like I have.

 

[aweir]

It is a 4 Cu. Ft. enclosure sold by DIY Audio Group.

The calculation was just an opinion from someone else that i asked. Also when it comes to subwoofers being OK to downfire a lot of it has to do with how tight the suspension is and how much is sags. The Stereo Integrity sub has a pretty tight suspension, and the high excursion of it should mean sag should not be an issue.

 

[lovinthehd]

Here's a formula for downfiring suitability for a driver's sag https://www.parts-express.com/resources-woofer-mount-up-down

I think you're fine with the 4" clearance on the df configuration, tho.

PS Thanks for the info on the bb box, didn't know diysg offered such.

 

[aweir]

After moving the sub into the corner and tweaking the EQ (had to cut the 35-40Hz way down, it sounds freakin awesome. Usable bass down to about 18 Hz. I even feel output down till about 12 Hz. Only issue is things vibrating in the room.

This sub is awesome. I suppose the polyfill works (1 Lb. per Sq Ft.) to lower the response. Only time will tell if this holds up. But it's nice to know you'll have a sub that that can handle the deepest of bass with ease.

I tried to figure out the sag and ended up with 0.445. Not sure what that means.
I'm pretty bad at math but here's what I plugged in for the formula.

Percentage of Sag = 981,000 / (Xmax * (2 * Pi * Fs)²)
Sag= 981,000 / (22.5 * (2 * 3.14159 * 21)Sq.)
Sag = 981,000 / 22.5 * (131 Sq.)
Sag = 981,000 / 22.5 *17,285
Sag = 981,000 / 388,913
Sag= 2.52241

 

[lovinthehd]

LOL now to spend some time getting rid of those sympathetic vibration noises....some museum putty to put behind pictures, on bottoms of some things, I find is a very useful tool.

An article on the effects of filling/lining subs here if you haven't already seen it http://www.data-bass.com/data?page=content&id=79

Didn't check your math but 2.5% should be fine.

Good job. I built my own boxes but have built three, using the v.1 drivers (slightly larger volume boxes, tho)...still have two to go.

 

[aweir]

I tried to EQ the 30-40 Hz range down all the way (-14.5Db )but the peak still persists. Looking to add a
Behringer iNUKE NU3000 to my setup to equalize those frequencies out further. The parametric EQ in my Dayton amp just isn't cutting it no pun intended. It's not horrible but it is really hampering the ability to play the 18-30Hz movie content loud enough without the peak at 30-40Hz being too loud.

 

[lovinthehd]

What avr and amp are you using now? You can tolerate the fan noise with the iNuke?

 

[aweir]

I'm using a Dayton Audio SA1000 external amp (the old model) and a Yamaha HTR 5.1 receiver. The fan on the iNuke can get pretty loud but if you watch movies at THX levels you probably won't even hear it. I don't know if the iNuke would be better than the Dayton amps though it's not really a subwoofer amp, and requires you to bridge the left and right channels together to get you the highest wattage it's rated for.

 

[lovinthehd]

Subwoofer specific amp may have certain features like phase adjustment and built in low pass filter/high pass filter, etc.... this is closest I came to finding 3rd party measurement on the SA1000.

iNuke may offer a little more power, but do you need it? The iNuke NU3000DSP model does have decent dsp, but the plain ol' iNuke NU3000 you mention doesn't. You could consider a minidsp to use with your current amp instead? I didn't want fan noise so went Crown XLS route for amp.

 

[roadrune]

I would rather put a Minidsp 2x4 in there, then you can add a Linkwitz transform and get flat responce down as low as you want using a single filter.

 

[aweir]

Subwoofer specific amp may have certain features like phase adjustment and built in low pass filter/high pass filter, etc.... this is closest I came to finding 3rd party measurement on the SA1000.

iNuke may offer a little more power, but do you need it? The iNuke NU3000DSP model does have decent dsp, but the plain ol' iNuke NU3000 you mention doesn't. You could consider a minidsp to use with your current amp instead? I didn't want fan noise so went Crown XLS route for amp.

It's interesting. Once you cross that line from consumer grade equipment to "pro audio" it's like a large oppressive weight has been removed from your shoulders.

 

[aweir]

I would rather put a Minidsp 2x4 in there, then you can add a Linkwitz transform and get flat response down as low as you want using a single filter.

Which plugin would you recommend for just equalizing a sub?

 

[roadrune]

I am only familiar with 2x4HD and 4x10HD, but you need a plugin with biquad filters to use the Linkwitz transform.

 

[lovinthehd]

Which minidsp 2x4 are you looking to get? I'd go for the 2x4HD these days....

 

[roadrune]

Just for sub-duties i dont think you will benefit from the HD.