Newbie needs help with D.I.Y. sub

[booberj]

Hello I'm new to the this forum and speaker building in general. The wife has given me the OK to move forward with designing my own sub for the house. I currently have an old Infinity 10in sub that came from Best Buy or Circuit City, it doesn't get the job done in our new house. The living room is an open floor plan with vaulted ceilings with the dining room open to the rear of where the TV is positioned. The living room is about 18x18 and the dining room is 11x12x8 flat ceiling, the kitchen is open but with an arch entryway and of course there is a entrance into a hall to the bedrooms. With all that being said I was trying to decide how much sub-woofer I was going to need to be satisfied. I thought about a TC Sounds LMS-R 12 but don't think I can get a box large enough for the wife to allow it so maybe two tens are in order outside dimensions that I can accommodate and not make the wife mad is 2 boxes no more than 20x30x18 inches all outside measurements. After a successful build of a sub I would like to continue (hopefully) with a new hobby of building my own speakers that I can be happy with.

What I'm looking for in a sub is for HT use primarily and listening to some music... I like to be able to feel the movies as much as I like to be able to hear them... loud is not my primary concern here... I know I'm missing some important details that you guys need but I've already written a book

Thanks,
Gary

 

[mpompey]

Welcome to Audioholics, you should find alot of helpful info on this site.

If I was trying to pressurize that room I would to buy/build 2 12" subs. Add in some transducers to your seating areas for those troublesome nulls and you should have a thunderous response.

SVS 12" box sub has a dimension of 18" wide x 21" high x 25" deep, which is a bit smaller than the dimensions you stated. Two should be fine. You do know how to do the subwoofer-crawl yes?

 

[booberj]

Welcome to Audioholics, you should find alot of helpful info on this site.

If I was trying to pressurize that room I would to buy/build 2 12" subs. Add in some transducers to your seating areas for those troublesome nulls and you should have a thunderous response.

SVS 12" box sub has a dimension of 18" wide x 21" high x 25" deep, which is a bit smaller than the dimensions you stated. Two should be fine. You do know how to do the subwoofer-crawl yes?

NO.. that is a new one on me
I really want to build my own so I'll try to find a driver that has similar specs as the SVS unless you can by thier drivers by themselves... I don't know... I'm just looking at my options... I figured it would take two 10/12s to get that much space pressurized. At the urging of some other forums I've been trying to run the numbers in WinISD and can't get a box smaller than the dimensions I listed above, not saying they are not out there I just haven't found them yet. Thanks for the input... if my searches continue to come up fruitless maybe I'll have to resign to a pre-manufactured sub... hopefully not.

Thanks,
Gary

 

[TLS Guy]

NO.. that is a new one on me
I really want to build my own so I'll try to find a driver that has similar specs as the SVS unless you can by thier drivers by themselves... I don't know... I'm just looking at my options... I figured it would take two 10/12s to get that much space pressurized. At the urging of some other forums I've been trying to run the numbers in WinISD and can't get a box smaller than the dimensions I listed above, not saying they are not out there I just haven't found them yet. Thanks for the input... if my searches continue to come up fruitless maybe I'll have to resign to a pre-manufactured sub... hopefully not.

Thanks,
Gary

Here is an assortment of subs people have asked about over the years.

 

[booberj]

Here is an assortment of subs people have asked about over the years.

After reading that article I'm kind of excited about maybe 2 JL Audio 8W7... the Infinity Kappa Perfect VQ I can't seem to find available for sale. Do you guys think that two 8s would be enough... they would be more aesthetically pleasing to my wife?...(smaller )

 

[TLS Guy]

After reading that article I'm kind of excited about maybe 2 JL Audio 8W7... the Infinity Kappa Perfect VQ I can't seem to find available for sale. Do you guys think that two 8s would be enough... they would be more aesthetically pleasing to my wife?...(smaller )

Excellent choice. Two of those will be perfect for you. Don't worry about them being 8", they are more capable than a lot of 15" inch speakers. That is the best answer for your situation.

The Kappas are NLA.

Article is too kind for that collection is subs in response to queries on these forums. It really needs sorting. May be this winter perhaps.

 

[booberj]

Excellent choice. Two of those will be perfect for you. Don't worry about them being 8", they are more capable than a lot of 15" inch speakers. That is the best answer for your situation.

The Kappas are NLA.

Article is too kind for that collection is subs in response to queries on these forums. It really needs sorting. May be this winter perhaps.

I'm going to go with the JL Audio 8W7s... any pointers in the box design?

 

[TLS Guy]

I'm going to go with the JL Audio 8W7s... any pointers in the box design?

Your box design is on the site, by clicking the hyperlink to that driver.

Here it is.

Now Vb is the volume of air in the box. So you need to get Vt, which is the size of box you will build.

The fill is allowed for. You need to cover 50% of the interior with mineral wool (like rockwool). Make sure you place some of that 50% behind the driver.

Now you must add the volume of the bracing (and brace well), a plate amp if you use them (an external two channel pro amp would be better), the volume of air displaced by the driver, and the volume of the port, this includes the material and air in the port. When you add all that up you get Vt, and it leaves Vb as the correct tuned air volume in the box.

The port is a slot vent and max air velocity is 23 m/sec at full power. However with two subs you are unlikely to reach full power. The box is fairly small and I think it would be difficult to wind a longer slot vent round the cabinet. It is nearly 38". However if you think you can wind a longer vent round the inside of your cabinet then I can recalculate the vent to get max air velocity below 18 m/sec.

I personally don't like butt joints. You can see the type of joints I prefer here. And if you work it out right you can use pre veneered plywood or MDF, which makes finishing easy and looks a lot more professional. You can glue 1/4 round in the edges which also looks nice and tends to prevent damage.

 

[booberj]

Your box design is on the site, by clicking the hyperlink to that driver.

Here it is.

Now Vb is the volume of air in the box. So you need to get Vt, which is the size of box you will build.

The fill is allowed for. You need to cover 50% of the interior with mineral wool (like rockwool). Make sure you place some of that 50% behind the driver.

Now you must add the volume of the bracing (and brace well), a plate amp if you use them (an external two channel pro amp would be better), the volume of air displaced by the driver, and the volume of the port, this includes the material and air in the port. When you add all that up you get Vt, and it leaves Vb as the correct tuned air volume in the box.

The port is a slot vent and max air velocity is 23 m/sec at full power. However with two subs you are unlikely to reach full power. The box is fairly small and I think it would be difficult to wind a longer slot vent round the cabinet. It is nearly 38". However if you think you can wind a longer vent round the inside of your cabinet then I can recalculate the vent to get max air velocity below 18 m/sec.

I personally don't like butt joints. You can see the type of joints I prefer here. And if you work it out right you can use pre veneered plywood or MDF, which makes finishing easy and looks a lot more professional. You can glue 1/4 round in the edges which also looks nice and tends to prevent damage.

thanks for the advise on the box... I am going to be building 2 seperate boxes for the 8's, one on each side of the room... does this change the complexity or the amp that I need to get?

 

[TLS Guy]

thanks for the advise on the box... I am going to be building 2 seperate boxes for the 8's, one on each side of the room... does this change the complexity or the amp that I need to get?

No. You have two options, a good plate amp in each sub, like O Audio. Avoid cheap plate amps. Your other option, and probably the best, is a two channel pro amp.

 

[booberj]

No. You have two options, a good plate amp in each sub, like O Audio. Avoid cheap plate amps. Your other option, and probably the best, is a two channel pro amp.

OK... a plate amp is kind of a no brainer but a pro amp... never have dealt with one before... I have a feeling this answer is going to make me change my mind on which receiver I planned on purchasing (TX-SR608)

 

[TLS Guy]

OK... a plate amp is kind of a no brainer but a pro amp... never have dealt with one before... I have a feeling this answer is going to make me change my mind on which receiver I planned on purchasing (TX-SR608)

It should not change your receiver choice. Popular pro amp here are Behringer and Yamaha. Some use Crown and a variety of others. I use exclusively Quad amplification and have most of my life, but that is my preference. The crossover is in your receiver.

 

[booberj]

It should not change your receiver choice. Popular pro amp here are Behringer and Yamaha. Some use Crown and a variety of others. I use exclusively Quad amplification and have most of my life, but that is my preference. The crossover is in your receiver.

I want to thank all of you guys for your input... I'm going to start gathering the required components to do this build. If I go with a pro amp I'm positive that I will have more questions on how to get the most out of it and which model to go with

-Gary

 

[leousm]

Those JLs are awesome subs, I think you are going to be extremely pleased and very surprised!

 

[booberj]

Attached is an image of a Google Sketch I made of the enclosure... still need to add some bracing... currently it's at 1.5581054 Cubic Ft... I just looks odd to me... If some of you guys have a design idea, please lay it on me.

 

[TLS Guy]

Attached is an image of a Google Sketch I made of the enclosure... still need to add some bracing... currently it's at 1.5581054 Cubic Ft... I just looks odd to me... If some of you guys have a design idea, please lay it on me.

What is odd about it? It looks fine to me.

 

[booberj]

What is odd about it? It looks fine to me.

I think what it is that I'm just used to those typical square subs that you get already manufactured... showed the sketch up to the wife, she approves, I just have to finish it in a veneer that goes with her furniture.

Thanks again for the help and advice.

-Gary

 

[miniSQ]

Do you have your amp picked out yet?

 

[booberj]

Do you have your amp picked out yet?

TLS Guy suggested that I go with a pro amp but with limited space available on the entertainment center I'll probably go with OAudio plate amps.

 

[miniSQ]

TLS Guy suggested that I go with a pro amp but with limited space available on the entertainment center I'll probably go with OAudio plate amps.

the reason i asked is that the Jl 8w7 is a 3 ohm sub i believe...most plate amps are not 3 ohm stable so you might want to nail down the amplifier before spending the 8 bills on a pair of 8w7's. You can do a single plate amp and wire the subs in series...but if you do that you will want a huge plate amp. 1000wats maybe at 8ohm.

Not trying to steer you away from the 8w7...but i am concerned that it is going to be a little tricky to be able to drive 2 of them to there fullest potential in a HT environment.