I would like to share my experimentation and realization of an active SUB based on the force cancelling principals, also called dual opposing driver configuration, based on an “exotic” setup:
The Sub:
For the sub I used 2 speakers from Dayton Audio : EPIQUE E180HE-44 200W – 2 x 4 Ohm 84dB 25Hz. They have a dual coil, and an impressive Xmax of 14 mm for such small speakers. In a sealed box, the volume for the 2 speakers is only 16 Liters, so quite small, for a big sound !
The box finalized:
The AMP:
To drive the speakers, I used a very interesting and rather cheap Amp with integrated DSP: the T.Rack DSP 4x4 Mini AMP, not used in a usual way I would say.
I used in particular the DSP filters section in order to:
For the power amp section, I also selected the T.Rack Mini Amp because it has 4 outputs of 60 Watts each, which matches the 4 coils of the 2 sub speakers !
Some will argue that it would be simpler to use a DSP and an amp of 200 W. Indeed , but for the price of the T Rack, I didn’t find such good combination.
The overall picture of the full system:
The Sub:
For the sub I used 2 speakers from Dayton Audio : EPIQUE E180HE-44 200W – 2 x 4 Ohm 84dB 25Hz. They have a dual coil, and an impressive Xmax of 14 mm for such small speakers. In a sealed box, the volume for the 2 speakers is only 16 Liters, so quite small, for a big sound !
The box finalized:
The AMP:
To drive the speakers, I used a very interesting and rather cheap Amp with integrated DSP: the T.Rack DSP 4x4 Mini AMP, not used in a usual way I would say.
I used in particular the DSP filters section in order to:
- Cut high frequencies >100 Hz
- Cut Low frequencies < 25 Hz
- Compensate the loss of efficiency of the sub bellow 60 Hz in a closed box, by a regular increase of the gain.
For the power amp section, I also selected the T.Rack Mini Amp because it has 4 outputs of 60 Watts each, which matches the 4 coils of the 2 sub speakers !
Some will argue that it would be simpler to use a DSP and an amp of 200 W. Indeed , but for the price of the T Rack, I didn’t find such good combination.
The overall picture of the full system:
8 posts for 2 drivers? Each coil of the dual coils is feed outside?
(not a fan of posts with that much metal)
Reminds me a lot of the ApexJr Super8 push-push woofer we built out of scraps a sander and black paint was th finish as well. Given it is push-push the issues with the choice of MDF will be minimized.
Good job.
dave
(not a fan of posts with that much metal)
Reminds me a lot of the ApexJr Super8 push-push woofer we built out of scraps a sander and black paint was th finish as well. Given it is push-push the issues with the choice of MDF will be minimized.
Good job.
dave
the description mentions « 6db less when we consider one side » which I don’t understand: if the amp power is multiplied by 2 (ie: 3db) with 2 speakers, how can the global speakers volume by multiplied by 4 (6db)?
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If we consider only one side (ie one woofer), output falls 6 dB on axis as the transition for 2∏ to 4∏ stereiradians. Standard baffle step diffraction theory).
When you add the 2nd woofer, you get 3 dB more from the second woofer, and (typically) ∓3 dB depending on whether you wire parallel or series.
In a woofer as small as yours there would be no 2∏ radiation, the baffle is too small.
dave
When you add the 2nd woofer, you get 3 dB more from the second woofer, and (typically) ∓3 dB depending on whether you wire parallel or series.
In a woofer as small as yours there would be no 2∏ radiation, the baffle is too small.
dave