[bjb]

I want to try making my own sub. So far I have been doing a lot of reading, and I have a few ideas.

My room is 3100 cu.ft. and opens up to two other rooms (one 4'x9' opening and one 6'x7' opening). I can attach a diagram if that will help.

I can fit a ~4 cu.ft. enclosure slightly behind and to the side of the couch, but that is about as large as I can go for that spot. I was looking at the CSS SD12 ported design which is that size. Any other spot in the room will have to be smaller and closer to the 1-2 cu.ft. size (WAF).

I did some modeling with winisd, and the CSS SD12 ported design looks pretty good to me. What I am having trouble with is what I can expect from various designs in my room and my placement restrictions. The CSS SD12 design goes low enough based on what I see in Winisd, but will that translate well to my room?

I was also looking at the Mach5 IXL 12.2.2 and 15.2.2, and those seem to offer pretty good results for me as well.

I really would like to improve the low frequency output that I get with movies which is what started all of this.

Can someone help me out with some real world expectations and some better direction? Am I better off with a different design? Should I go sealed due to my size restrictions?

Thanks,
Brian

 

[Mike P.]

I can fit a ~4 cu.ft. enclosure........

That's net internal volume after displacement of the sub, port and bracing have been deducted, correct?

 

[Ricci]

That's net internal volume after displacement of the sub, port and bracing have been deducted, correct?

+1

Plus, does it matter what shape the box is? Does it need to be limited dimensionally in one way, or the other?

 

[bjb]

Yes, that is the internal net volume. I can go as large as 24x24x21, but only in the "SubOpt1" location. I would prefer to go smaller, since that would allow me more placement options if it doesn't work well in that location. I know the location "SubOpt2" would probably work best, since it will likely blend better with my speakers. The problem with location 2 and 3 is that it will be more difficult to get WAF approval especially if it isn't tiny (e.g. 16-18" cube).

I modeled a 21" cube with a CSS SD12 and two CSS 15" PRs that looked pretty good. I also modeled it with one PR in a 17" or 18" cube and that looked pretty decent as well. A size like that would get easier wife approval in other spots of the room.

The shape is somewhat flexible, but how flexible will depend on placement.

 

[Ricci]

Thanks for posting the room layout. That helps a lot. Your room is fairly large considering the openings to other areas, but sw placement #1 puts it really close to the listening position, which should help you get some extra output. The sw position 2 might be good also. #3 probably will have more FR problems than the other 2 spots so I'd not worry about putting it there. Did you have a budget planned for the SW? Do you want a plate amplifier or an external one?

A nice 12" with dual PR's will probably work out well. Sealed could work too. It depends on your tastes, budget and priorities, which is a better fit. If you would, post up the parameters for the SD12 PR build you were modeling.

 

[bjb]

Thanks for posting the room layout. That helps a lot. Your room is fairly large considering the openings to other areas, but sw placement #1 puts it really close to the listening position, which should help you get some extra output. The sw position 2 might be good also. #3 probably will have more FR problems than the other 2 spots so I'd not worry about putting it there. Did you have a budget planned for the SW? Do you want a plate amplifier or an external one?

A nice 12" with dual PR's will probably work out well. Sealed could work too. It depends on your tastes, budget and priorities, which is a better fit. If you would, post up the parameters for the SD12 PR build you were modeling.

Do you think placement #1 will cause localization issues?

I modeled 2 new designs that I think I prefer over the other stuff I did. One is vented, the other is a PR.

PR
2.8 cu.ft.
1 Fi. BTL15D2
1 CSS PR1821

If I crossover at 60hz, it seemed relatively flat from 20-80hz.

Vented
1 Fi. BTL15D2
3 3" Ports at a length of 18" each
3.0 cu.ft.

They seem pretty similar to my eye, so I guess it will depend on cost and opinions.

I am undecided on the amp. I like the simplicity of a plate amp, but it wouldn't take much arm twisting to go with a separate amp either especially if the value is considerably higher. I don't have room in my rack for it, but I was thinking about mounting it in the basement, running the cables under the floor, and putting a wall jack in next to the amp. The only caveat to that is I would have to run down to the basement to make adjustments.

I don't really have a preference on ported vs sealed vs pr. I will play about 50/50 music/ht through it. My listening levels are moderate 90% of the time, but I will crank it up the other 10% when no one is home. My concern with sealed is that I won't be happy with it for HT use.

Whatever I get will be a huge upgrade from what I have now which is almost nothing. My mains have 8" subs built into the cabinets with a 225watt amp driving them, and they only go down to 30hz. I have always been satisfied with them for music, but they don't go deep enough for HT.

Thanks for the help.

 

[salvasol]

Have you checked for the best placement where you get best response???

Because WAF is important in your case, you can build a sub and use it as a end/cofee table or something that blend with the rest of room :yes:

 

[bjb]

Have you checked for the best placement where you get best response???

Because WAF is important in your case, you can build a sub and use it as a end/cofee table or something that blend with the rest of room :yes:

I have thought about that, but I would like to go with something a little more simple for my first build. I have pretty basic wood construction skills, and my confidence level in building something furniture grade that my wife would be happy with is not real high. The idea is definitely appealing if I can develop my skills a little.

 

[salvasol]

I have pretty basic wood construction skills, and my confidence level in building something furniture grade that my wife would be happy with is not real high. The idea is definitely appealing if I can develop my skills a little.

I don't think you need a lot of skill (just the basic :yes, maybe you can build the sub as a box then add a piece of granite on the top and there's your table ...some molding and legs and ready :bigsmile:

 

[bjb]

I don't think you need a lot of skill (just the basic :yes, maybe you can build the sub as a box then add a piece of granite on the top and there's your table ...some molding and legs and ready :bigsmile:

The granite is an interesting idea that I hadn't thought of. Have you done this, or know of any examples that you have seen?

 

[fredk]

If you put fake sliders or doors on one side of the table to make it look like storage space I think it would make a very convincing coffee table.

 

[salvasol]

I couldn't find anything with granite (just glass) ...here is some ideas

 

[fredk]

Nice selection of pictures salvasol. I like the Rubix cube.

 

[bjb]

The wife put an end to the end table sub. She doesn't want her furniture choices restricted by what I build. As a result, I am back to looking at a box. I got the ok from her to go as large as 18x21x35 (HxWxD) inches. My budget is about $1k with all expenses included.

I modeled the Fi BTL15 and SoundSplinter RL-15p in a 4.6-5 enclosure, and they seemed to do pretty well. The only issue with both of these was port length. I was looking at doing a slot port that would wrap around the outside of the enclosure. I think I saw a end table that had a similar approach. Are there any issues in doing so? How close can I get to the back of the driver if it starts coming back across the top?

I have modeled so many different options that paralysis has started to set in, so I would really appreciate any opinions/feedback.

Thanks,
Brian

 

[Mike P.]

Do you mean the port would physically be on the exterior of the cabinet?

 

[bjb]

Do you mean the port would physically be on the exterior of the cabinet?

No, on the inside. It would be something like this (http://www.avsforum.com/avs-vb/showthread.php?t=1018171), but smaller. I would also use a 15" driver instead of an 18.

 

[Mike P.]

The internal volume is 6.2 cu.ft. Try modeling a SDX15 in 5.5 cu.ft. with with a 6 inch diameter port and 1000 watts input.

 

[bjb]

The internal volume is 6.2 cu.ft. Try modeling a SDX15 in 5.5 cu.ft. with with a 6 inch diameter port and 1000 watts input.

With the SDX15 @ 5.5 cu.ft. the port air velocity is estimated at 33.5m/s. I read that it should stay under 25m/s. Is that correct?

Some of the other drivers like the SS and Fi model flatter. Wouldn't that be preferred, or is it better to have a more gradual slope because room gain flattens it out?

Thanks,
Brian