Dual opposed Scanspeak/HypexFa502 subwoofer

[Palmspar]

I have already build a Diy dual opposed subwoofer with 12 inch Scan Speak Discovery drivers and Hypex fa501 amp it sound very good.
The drivers share a 53 liter volume with a lot of wool to have a higher Qtc.
But now i have another pair of the same used Scanspeak drivers.
Im planning to build another Dos subwoofer with the bigger fa502 amp 2x500w@4ohm.
Its maybe better to give each woofer his one sealed enclosure with that amp?
In parallel conection with the fa501 amp that was not necessary.
Planning to build the subwoofer 48x50x40cm each woofer has then a seperate 28 liter volume, with a lot of wool the Qtc wil be arround 0.78
In that small box the driver can handle all the power from the Fa502 without over excursion i think.
Sombody advise of other thoughts about this project?

 

[Palmspar]

The box is almost ready its 48x42x50cm, each woofer has 30 liter with polyfill they behave like they in 36liter or so.

 

[Salt]

Any non-linearity of the two drivers would reflect to each other in a shared cabinet and not with single cabinets, independent of the amplifier, or, in other words: one channel that fits two parallel woofer, regarding minimum impedance, power and control, would not be worse than dual amplification.
Btw what's that little houses in the middle: the enclosure for the FA?

 

[Palmspar]

Yes its the box for the fa502

 

[Salt]

Would be interesting to see some FR and xover when You are finished (1 kW will rock not only one house )

 

[Palmspar]

Only sanding screw holes and the sub is primer ready.

 

[Palmspar]

The primer is done
And a picture of the drivers.

The first satin black layer, like Arendal speakers have.
Primer was already dry after 2 hours.

 

[Palmspar]

The third layer paint and the polyfill are ready.
I use sandpaper 320 between the last layers.

 

[Palmspar]

The sub is ready and i also make filters for the FA502 amp.
I wil finetune the dsp further.

Red line is the SVS SB2000 for comparison.
Green line is dual Scan Speak flat signal so it behave in the box without dsp
White line is dual Scan Speak with dsp tuned @ 22hz-6db and 15hz-10db
Its a beast, very nice project!

 

[sigbergaudio]

Nice. If the picture with the microphone is how you measured it, I am surprised that the "without DSP" is so uneven?

EDIT: If this is due to room resonances you should perhaps either measure it outside or measure it from the listening position to ensure you get an even sound where you are actually sitting.

 

[Palmspar]

@sigbergaudio Thanks for your input! maybe the uneven curve is because the woofers behave better in a bigger enclosure and the graph is to 150 hz it look worse.
Below 80 hz its not that bad without dsp.
The output with dsp is good but i want less dsp for the same curve.
With the mic 1 cm away from the cone i think the room is no part of the output but i wil test that further
For fun i test once with 1 woofer in 53 liter it was almost flat without dsp.
The room dsp itself is a job for the marantz avr

Edit the SVS SB2000 was once measured in the same spot in the same way and it has no big peaks and dips arround 45hz
Therefore i think room has no part in the peaks, its how the woofers itself behave.
In this old graph is green the SVS SB2000, purple single ScanSpeak in 53 liter with polyfill, and white the ScanSpeak with small dsp 22hz-3db and 16hz-6db it digs deep.