[mlundy57]

What are the differences and considerations between the design for two 12" servo sub drivers used in the super V (H frame) and the OB sub design that is linked to the driver page of the GR-research website (W frame I think)?

It looks like the W frame would result in a speaker 2.5" shorter than the H frame but what about performance differences? Pors/cons?

Mike

[Danny Richie]

What are the differences and considerations between the design for two 12" servo sub drivers used in the super V (H frame) and the OB sub design that is linked to the driver page of the GR-research website (W frame I think)?

It looks like the W frame would result in a speaker 2.5" shorter than the H frame but what about performance differences? Pors/cons?

Mike

The advantage of the W frame is only that it makes the whole thing shorter. The front facing V area leaves a larger un-braced panel area though. So side walls really need to be thicker and heavier to minimize that panel resonance.

The H frame divides the panels better and keeps side wall panel area smaller and less resonant.

And even though the box is open tot he front and the back, the woofers still put a lot of force on those side panels.

[mlundy57]

If i understand correctly, as long as the size of the H frame will work, it will be the better choice.

[Captainhemo]

I jump in here with a coupole  questions too...

1.  Is staggering the 2 baffle braces in the H Frame important ?  Can they just be aligned to make the  front/back of the boxes equal in height ?

2. If it is ok to align the  bracs,  I notice  the internal width is 11.5", can the  height be adjusted to match ?

3. With that 11.5" width,  I assume the no res must overlap the  driver a bit,   would it be better to make   the internal dimension a bit  bigger ?

-jay

[Danny Richie]

In everything that I have used the H frame with the baffle that the drivers are mounted to are common. So just one baffle and not two.

Also, the frame of the woofers (with rubber gasket) is 12.625" across. So you need 13" of space for each woofer to mount in.

And when applying No Rez you do have to allow for the surround and woofer travel. So you have to come off of it about 1.5" from the baffle.

[Captainhemo]

Hi danny.
I understand the baffle is one piece, I was referring to the  2 braces , one front and one  rear being staggered.  In the plan I have, they appeear to be   offset .75"  and also the plan (front view sub box)  shows  the internal width  of the H Frame at only 11.5  ,  maybe I have the  wrong  plans  (supervbox.pdf) ?

So internal  dimensions should be 13 x 13 x 6.5  front and back for each  woofer, correct ?

-jay

[Danny Richie]

Hi danny.
I understand the baffle is one piece, I was referring to the  2 braces , one front and one  rear being staggered.  In the plan I have, they appeear to be   offset .75"  and also the plan (front view sub box)  shows  the internal width  of the H Frame at only 11.5  ,  maybe I have the  wrong  plans  (supervbox.pdf) ?

So internal  dimensions should be 13 x 13 x 6.5  front and back for each  woofer, correct ?

-jay

Oh, I got it now...

The braces are staggered because of how close the woofers are together. The frames are practically edge to edge if you look at them from the side. And the 11.5" box on the back side means each woofer is centered in that box. The back side box is actually under the woofer frame on four sides.



Then there is a common side panel.

The reason for this is to keep the baffle width of the upper panel as small as possible. So the side panels on the subs are also the support for the upper section.

You don't have to build the H frame that way. You can give it 13" of space on all four sides front and back.

[bdp24]

A good idea for both the W and H frame is to double the thickness of the baffle by using two layers of 3/4" MDF glued (Green Glue? That's what Ric Shultz uses between the three layers of MDF in his flat baffle design) and screwed together. And for the W frame, put a 1-1/2" dowel from side panel to side panel, spanning the open V side (the front) of the frame, connecting and stiffening the large, unsupported side panel areas. You can countersink a flat-head screw through each side panel into each end of the dowel, and the second layer of MDF side panels will cover the head of the screw. If you want to adapt Danny's Sand Box design for sealed Servo woofers into an OB W or H frame sub, put spacers (I used 1/2", but it can be any depth you want. The greater the depth, the more sand it will take to fill it, and the heavier the frame will be, of course. Silica sand is best, clean and cheap; you can find it in different grades---the higher the number, the smaller the size of the grains---at building supply yards, $7-$8 for a 50 lb. bag) between the inner and outer layers of the side panels, and fill the gap with the sand. Cheap and VERY effective!