I want to build 2 subs. Have some questions for you.

[Djizasse]

I want to build 2 subs (for better integration and less peaks/dips). I've got a Behringer EP2500 amplifier, a Behringer DCX 2496 equalizer and one Infinity Kappa Perfect 12VQ driver (I can buy another).

My room is ~11x11x9 feet. Please check my signature for 2 pics of the room. I live in an apartment, so I'm not going to use them very loud. I don't want to shake the building.

Avaserfi's ported sub, at 22"x22"x25" is too big to put 2 in my room.

Goals:
- build two subs that together have the same linear response as Avaserfi's plan.

Questions:
- what would be the minimal dimensions of these two subs?
- If two subs together have the same volume that another bigger sub, will they have the same output and characteristics? If not, is there any relation between the two?
- is the shape important or what matters is the inner volume? Can I transform a cube into a rectangle or a L-shaped box, maintaining the same inner volume?

 

[annunaki]

I want to build 2 subs (for better integration and less peaks/dips). I've got a Behringer EP2500 amplifier, a Behringer DCX 2496 equalizer and one Infinity Kappa Perfect 12VQ driver (I can buy another).

My room is ~11x11x9 feet. Please check my signature for 2 pics of the room. I live in an apartment, so I'm not going to use them very loud. I don't want to shake the building.

Avaserfi's ported sub, at 22"x22"x25" is too big to put 2 in my room.

Goals:
- build two subs that together have the same linear response as Avaserfi's plan.

Questions:
- what would be the minimal dimensions of these two subs?
- If two subs together have the same volume that another bigger sub, will they have the same output and characteristics? If not, is there any relation between the two?
- is the shape important or what matters is the inner volume? Can I transform a cube into a rectangle or a L-shaped box, maintaining the same inner volume?

The shape of any enclosure will not matter much so long as the internal volume is correct and will accomodate the proper vent/port.

Are you thinking of two subs in the same enclosure or two seperate subs?

The dimensions of the sub listed above equate to 5.71 ft^3 gross internal volume (with .75" thick material). Figuring port displacement of 1.25 ft^3 (guess) and bracing and driver displacement of .25 ft^3 that would leave you with 4.21 net internal volume or so. I believe that to be somewhere near .7 ft^3 too much volume for the 12" Kappa Perfect VQ. I could be wrong but I thought the Kappa worked best with around 3.5 ft^3 net internal volume. I would check with Avaserfi there. He and WmAx have the most experience with said subs.

 

[Djizasse]

Thanks for your help Annunaki.

The shape of any enclosure will not matter much so long as the internal volume is correct and will accomodate the proper vent/port.

This means I can make two towers, which would let me use any corner of my room.


I want to built two separate subs as this will help me even the low frequency response.

I took those cabinet dimensions from Simple 12" Infinity Kappa VQ MidQ Plans
I just mentioned them because I would like my two subs to match the properties of Avaserfi's sub.

I'm thinking two subs, each with half the internal volume of Aversefi's unit, but with the double power avaiable would get me to the same low frequency output at 20Hz. Is this possible?

 

[WmAx]

Thanks for your help Annunaki.


This means I can make two towers, which would let me use any corner of my room.


I want to built two separate subs as this will help me even the low frequency response.

I took those cabinet dimensions from Simple 12" Infinity Kappa VQ MidQ Plans
I just mentioned them because I would like my two subs to match the properties of Avaserfi's sub.

I'm thinking two subs, each with half the internal volume of Aversefi's unit, but with the double power avaiable would get me to the same low frequency output at 20Hz. Is this possible?

Not quite. The smaller volume is not going to allow the low vent tuning frequency. The added output of the vent is what provides the enormous 20Hz output ability of avaserfi's sub. If you really want that kind of LF power with 2 small units, you have to move to drivers like JLW7 12 or equivalents(not many equivalents on this earth). 2x JLW7 12s with one EP2500 for each woofer would be comparable or superior at 30hz, and not too far down at 20hz, compared to a single Kappa Perfect 12 in the cabinet that avaserfi uses. Yes, much added cost is required to shrink the size and get the same performance! YOu should do some calcuations. You could do two towers that are roughly 14" w x 14" d x 48" H or so would take up little floor space and fit into the corners and allow the tuning that avaserfi's subs use. BTW, two of these? LOL. In smaller rooms, 125db at 20hz is easily possible. In moderate to larger size rooms, 120 is still going to be feasible to approach.

-Chris

 

[Djizasse]

The smaller volume is not going to allow the low vent tuning frequency. The added output of the vent is what provides the enormous 20Hz output ability of avaserfi's sub.

Ah! I get it.

much added cost is required to shrink the size and get the same performance! YOu should do some calcuations. You could do two towers that are roughly 14" w x 14" d x 48" H or so would take up little floor space and fit into the corners and allow the tuning that avaserfi's subs use.

That might be doable.

BTW, two of these? LOL. In smaller rooms, 125db at 20hz is easily possible. In moderate to larger size rooms, 120 is still going to be feasible to approach.

LOL why? Is it overkill for my small room (1089cu feet)? I really have no idea. By "these" you mean avaserfi's or the 14" w x 14" d x 48" towers? I'm not reaching for 120db@20Hz, I'm just craving for the 20Hz at moderate levels.

 

[TLS Guy]

Low Q

You could build the low Q cabinet.

If you use a slot vent 3" X 8.75" X 48" you will reduce vent velocity to 12m/sec. The vent velocity with the tube vent is just acceptable. One member built it that way and was pleased with it.

 

[WmAx]

LOL why? Is it overkill for my small room (1089cu feet)? I really have no idea. By "these" you mean avaserfi's or the 14" w x 14" d x 48" towers? I'm not reaching for 120db@20Hz, I'm just craving for the 20Hz at moderate levels.

Well, that's exactly the kind of output you will get with these. Your room would also be classifed as small. 125db at 20 hz is very likely here. You need to realize, the sub driver at discussion is probably not like any sub driver you have ever used. It is of unusual motor quality/linearity; which results in unusual output levels with no distortion. The enclosure suggested, with the giant vent, is also for the same purpose. Most ported systems are highly compressed at the vent output. This is not. It's not overkill unless you turn the volume up that high. You control your gain levels.

The plus of this, is that even THX reference level at 20Hz is not going to strain the subs in the least bit.

-Chris

 

[Djizasse]

You could build the low Q cabinet.

If you use a slot vent 3" X 8.75" X 48" you will reduce vent velocity to 12m/sec. The vent velocity with the tube vent is just acceptable. One member built it that way and was pleased with it.

I've checked the plans and they refer 26m/s @14Hz, with a Vb=3.024 cu.ft and Vt=3.329cu.ft. If I were to enlarge the vent to reduce the air velocity that would decrease Vb. I would have to compensate for this. What would the new Vt be?

 

[Djizasse]

Well, that's exactly the kind of output you will get with these. Your room would also be classifed as small. 125db at 20 hz is very likely here. You need to realize, the sub driver at discussion is probably not like any sub driver you have ever used. It is of unusual motor quality/linearity; which results in unusual output levels with no distortion. The enclosure suggested, with the giant vent, is also for the same purpose. Most ported systems are highly compressed at the vent output. This is not. It's not overkill unless you turn the volume up that high. You control your gain levels.

The plus of this, is that even THX reference level at 20Hz is not going to strain the subs in the least bit.

-Chris

Chris, I'm sorry, but I'm having some trouble understanding your post.
Are you saying that using two 14" w x 14" d x 48" H towers in my room will probably get 125db at 20hz? That might be too much.
I can't quantify what is 125db, but according to the decibel scale, 110db is attributed to the front rows at a rock concert. For me, that starts being painful. I don't want to imagine what 125db would do to my ears.

I'm just trying to trade those extra decibels that I won't use by less volume.

I definitely want to harness the quality of the Kappa 12VQ, in particular it's linearity.

If by using less volume means that I'll be building something that's not optimal for this driver, then I'll just build the big cube and try to live with it. The problem is that the only place where I can put avaserfi's cube generates a dip at my listening position. But I've just measured some free space I have in my room's closet. I'll test it tomorrow to see if it rattles and has a different room response.


Thank you all for assisting me

 

[WmAx]

Chris, I'm sorry, but I'm having some trouble understanding your post.
Are you saying that using two 14" w x 14" d x 48" H towers in my room will probably get 125db at 20hz? That might be too much.
I can't quantify what is 125db, but according to the decibel scale, 110db is attributed to the front rows at a rock concert. For me, that starts being painful. I don't want to imagine what 125db would do to my ears.

Well, bass sounds far less loud as compared to mid-range of the same SPL. But you are the one that controls the volume knobs. They will never go over 60 db if you keep the gain down low enough; the point is just that you will have the dynamic headroom available that is virtually unlimited for any purpose you may have; that these will have outpout superior in both quality and quantity to pretty much most commercial subs at any price.

I'm just trying to trade those extra decibels that I won't use by less volume.

There is the problem. You can trade volume but the volume trade will be with extension, not SPL. If you use ported cabinets half the size, you are looking at a cut off around 30Hz or so roughly.


I

f by using less volume means that I'll be building something that's not optimal for this driver, then I'll just build the big cube and try to live with it. The problem is that the only place where I can put avaserfi's cube generates a dip at my listening position. But I've just measured some free space I have in my room's closet. I'll test it tomorrow to see if it rattles and has a different room response.

What's wrong with the 14W x 14D x 48H tower pair? That can be done and get identical tuning to avaserfi's huge cube. It results in the same volume; you are just pushing the width/depth up into the height instead; there by reducing the floor space use. One of these in each front corner, using the DCX for smoothing FR would be ideal in all ways.

-Chris

 

[Djizasse]

Ok. I'm slowly getting it. Nothing like internal volume to drive the low frequency.
I'll keep to the calculated volumes and will decide on the shape according to the best place to put 2 subwoofers. I'll need some help later to design the box

My next question is how am I going to determine the best location for the 2 subs?
Both should be at the same distance from the listening position, which in my room means front corners or back corners. Is this correct?

 

[Alex2507]

In an 11'x11' room your options are going to be limited but from what I understand keeping the subs close to the mains is a good idea for integration of bass. So my pick would be along the front wall but pulled in toward the center by a couple of feet or whatever you can swing. No matter where you put them, you will move them.

Having said that there is an article around here somewhere called Crawling For Bass but you seem to have multiple seating positions. Here is an article that I was able to track down:

http://www.audioholics.com/tweaks/get-good-bass/subwoofer-connection-guide

 

[Djizasse]

Thanks

From the alternatives presented on the article
- mid side wall subs is not possible
- mid front/back is only possible if I hang them on the ceiling, not likely

I'll have to choose between
- opposed corners
- front walls

Either of these will not permit 2 aversefi's cubes (22 x 22 x 25).
I'm going to make a 14 x 14 x 48 tower in carton and convince the wife that it will look good and that's the only way I can get quality bass.

Wish me luck

 

[WmAx]

Thanks

From the alternatives presented on the article
- mid side wall subs is not possible
- mid front/back is only possible if I hang them on the ceiling, not likely

I'll have to choose between
- opposed corners
- front walls

Either of these will not permit 2 aversefi's cubes (22 x 22 x 25).
I'm going to make a 14 x 14 x 48 tower in carton and convince the wife that it will look good and that's the only way I can get quality bass.

Wish me luck

Hey. Please point out to her that you can put nice veneer on them, and use large designer molding on the tops and bottoms of the cabinets and put some fancy sculpted furniture legs on them and they will make beautiful plant stands or art/vace stands, etc.(You only need to use a little blue-tack on the bottom of stuff and it will stay put). Seriously. Point the driver/port to the back facing the front wall so they are not seen, and space it 12" or so from the wall so they have clearance, it will be perfect.

-Chris

 

[Djizasse]

I took some time but my wife and I started the negotiations for two sub towers in my room We're taking some measurements and making some tests.

Before submitting the measurements for you to (hopefully) correct or approve I, or should I say WE, have a question:

How much space do I have to leave between the rear of the driver and the back wall? Is there a minimum space needed? Can I leave just an inch or two?

 

[WmAx]

I took some time but my wife and I started the negotiations for two sub towers in my room We're taking some measurements and making some tests.

Did you suggest what I said above, about making them in beautiful stands with accented legs and trim and fancy veneer? Just curious what got her to agree....

Before submitting the measurements for you to (hopefully) correct or approve I, or should I say WE, have a question:

How much space do I have to leave between the rear of the driver and the back wall? Is there a minimum space needed? Can I leave just an inch or two?

6-7" will be sufficient. 2" may cause problems at high SPLs when substantial air is being moved. It may even effect the vent tuning if too close to the wall.

Note: If you prefer a simpler sealed system, I have very recently given my approval for another subwoofer, which is especially suited to sealed cabinets. Ideal volume would be about 5-6 cubic feet; about the same as the gross volume of the Kappa Pefect ported system. You can use in as little at 3 cubic feet, but extension will be not as good, and you will of course need to use parametric EQ to smooth the peak caused by the less than optimal smaller box volume. The output from 20-30hz would be about 3-4dB less with this particular sealed system with 6 cubic feet, but you would have even deeper response overall, and it is simpler to build if that matters. You would not lose any SQ, even at high amplitudes at LF, because this new driver has extraordinary linearity at extreme excursions. But it will have about 50 percent less output(3dB) at the lowest octave compared to the Kappa Perfect ported system.

-Chris

 

[Djizasse]

Did you suggest what I said above, about making them in beautiful stands with accented legs and trim and fancy veneer? Just curious what got her to agree....

I made a full scale cardboard model of the simple kappa build, she freaked out with the size of the thing. The look on her face was like this:
At least understood I'm serious with this.

Although there's no way I'm putting one of avaserfi's monsters in this room, at least she's open to two towers, providing that they follow some size constraints.

6-7" will be sufficient...

... If you prefer a simpler sealed system ...
...5-6 cubic feet....
-Chris

Thanks Chris. My problem is not the build, or the finish. She know I can make it nice looking. The problem is just one of dimensions and layout esthetics.
I'm gonna take a look at how deep the Kappa is, add it 7" and check that with her.

I have another question. Can I point the driver to the ground and leave 2", or will I also have problem with that?

 

[WmAx]

I made a full scale cardboard model of the simple kappa build, she freaked out with the size of the thing. The look on her face was like this:
At least understood I'm serious with this.

Although there's no way I'm putting one of avaserfi's monsters in this room, at least she's open to two towers, providing that they follow some size constraints.



Thanks Chris. My problem is not the build, or the finish. She know I can make it nice looking. The problem is just one of dimensions and layout esthetics.
I'm gonna take a look at how deep the Kappa is, add it 7" and check that with her.

I have another question. Can I point the driver to the ground and leave 2", or will I also have problem with that?

I would not have the port any closer than 5 or 6". The driver itself could be 3" no problem. But more complications are at issue with the port, as well as higher pressure front.

If the size thing becomes a real blockade to the project, then at increased cost, you can use much smaller cabinets and go with drivers suited to small sealed cabinets such as JL W7 12", which would work well in 1.5-2 cubic feet in combination with DCX2496 and at least 1000 watts per channel.

-Chris

 

[Djizasse]

Thanks for the help Chris.
I'll be back with some WADs (Wife Approved Designs)

 

[mike c]

I'm gonna take a look at how deep the Kappa is, add it 7" and check that with her.

I have another question. Can I point the driver to the ground and leave 2", or will I also have problem with that?

when chris said 6-7" he meant if the PORT was pointing to the rear wall (distance of the driver outside the enclosure to the room wall). i think the rear of the driver inside the enclosure can be much smaller - a few inches will do in distance to the rear enclosure wall