Push pull cabinet designs?

Could someone fill me in on a few things about stated designs? I have tried inquiring on the other side, but the response was not friendly. I know they offer less distortion, but how are they wired? And also how does one sim in winisd or hornresp? Thanks guys,
Mike

depends how do you mount the drivers....if the cone faces other driver's magnet they are wired in parallel, like in 12pi horn.

on a push pull design like the lab sub, one speaker is wired positive to positive, neg to neg. the other speaker is wired pos to neg and neg to pos. This makes them work with one speaker in phase and one working outa phase. Both drivers normally fire in to a small chamber and out into a horn. In theory they create a higher pressure wired like this in the chamber. If both were wired normally then both drivers would be working against each other i.e. both would be pushing and pulling at the same time....... hope this helps.....

Ok Very Crude drawing, but i want top make sure i have the understanding. My thoughts were that wired like this, one speaker was effectively cancelling the other one? but I must be wrong.
How are these simmed?

pic b is how they are wired up....... from what i know about this type of design the chamber they fire into is critical to how it works...... there is alot of info out there in regards to the lab sub, this is a good referance (starting point) to this type of design......

Bitzo this is also true, ive not seen many good designs were the one driver sits behind the other (re pic a)......

Typically both of those designs are used alot in car audio. They are called isobaric boxes. I use to build competition car audio systems and did a few with that design. Not to impressive in regular boxes. However the LAB company has perfected that push-pull design.

What sparked my interest was DJK's push pull designs. Not so much horn loaded pp designs. If i remember right my old servodrives were push pull (same thing as labsubs with servomotors instead), and they sounded great, NO distortion. I m just trying to figure out how to sim in winisd,
Mike

To me the main trouble to design this type of cab is modeling exactly the same compression chamber and rear chamber for both drivers just because the drivers volume isn't known.

bitzo wrote: To me the main trouble to design this type of cab is modeling exactly the same compression chamber and rear chamber for both drivers just because the drivers volume isn't known.

the DJK style cabs have one rear chamber and a manifold style opening, from what i have gathered, the closer you can mount the drivers the better. My question is how does one determine the rear chamber and porting info. as a double driver reflex or something else. the one PM i got sent from DJK said that they ARE NOT isobaric, leaving me puzzled smiley29

MAutopsy wrote:

bitzo wrote: To me the main trouble to design this type of cab is modeling exactly the same compression chamber and rear chamber for both drivers just because the drivers volume isn't known.

the DJK style cabs have one rear chamber and a manifold style opening, from what i have gathered, the closer you can mount the drivers the better. My question is how does one determine the rear chamber and porting info. as a double driver reflex or something else. the one PM i got sent from DJK said that they ARE NOT isobaric, leaving me puzzled smiley29

They are reflex boxes. Rear chamber and porting is calculated just like in normal 6th order reflex box. Manifold is non resonant in operating range.

Isobaric mounting means drivers mounted on different sides of plywood to same hole cones facing each other. This leaves a small airtight gap between drivers and only 1 driver is basicly creating all the sound you hear and other is helping to create better environment to this driver. This halves the Vas and box size for example.

Push pull configuration is where drivers are mounted separately like in normal 218 sub. Difference is that other driver is mounted cone outwards and the other is mounted cone inwards showing magnet outside the box. Benefit of this arrangement is cancellation of nonlinear behaviour of suspension and spider.

Both configurations are wired same way, in opposite polarities. Like name indicates in push pull configuration for example, when the driver which has magnet inside the box is puhing cone outwards the other driver which has magnet outside the box is pulling it outwards thus being in same phase.

Hope this helps.

I'll try to be more around now and answer any questions rised. Best way to get my attention is either PM or post to Ohm area.

Best regards,

Pasi