Im building this little fella to augment the subs Im using for HT,its purpose is to reproduce the middle bass from 50-80hz.For reasons of restricted placement options my main HT subs are located directly in the corners of my room.Corner loading means they will be exciting every room mode.
Because of this I have found that they sound best when crossed over at a rather low 50hz.These subs only handle the LFE signal (the LCR bass is not mixed in with it)but the LFE channel can contain info up to 120hz,so by rolling them off at 50hz means Im likely missing out on some parts of the bass track that can add some punch and impact.
Instead of comprimising the sound of my main subs by moving the crossover higher ,Im going to try adding a small box to handle the the upper part much like Hsu's MBM12. This box will be small enough to sit directly beside the listening chair.The fact that it will be in the near field of the listener and away from room boundries means it be less affected by response altering room modes.
I chose a 10" Infinity Kappa Series car subwoofer as it perfectly fit my reqirements.
It will work great in a small sealed box.
It has good sensitivity and power handling.
Price was right,got a great deal on ebay.
I will build a control unit for it that will have a 50hz hi pass filter to remove the low bass and match the crossover of the main subs.It will also incororate a 80hz low pass filter,level control and a 360 deg phase adjustment.The phase adjustment is essential to get the module to blend seamlessly with the other subs.
The pics show the tiny 11.75" square box with one side removed.It will get a skin of real wood veneer when assembled.