Short list of musical subwoofers

@lanx0003 --

"It is interesting that you disapprove the high level connection. May I know your reason why."

Can’t speak for poster @mijostyn, but maybe it’s at least partially due to the simple fact that using the high level output from the main speaker amp to feed the corresponding high level speaker input of the sub requires for the signal to be full range, and not high-passed - which would of course defeat the purpose. Some prefer running the main speakers full range when augmenting with subs, while others - like @mijostyn and also myself - prefer high-passing the mains here to relieve them of LF, which usually means using a higher cross-over frequency to the subs. Configured this way (i.e.: high-passing the mains with a XO point to the subs, say, no lower than 80Hz) the mains will have lower distortion and a cleaner reproduction in the audio band taking over from the sub, while also adding more headroom.

@lanx0003 , phusis hit the nail on the head. The benefit of using a two way crossover increases the wider the frequency response of the main speaker's woofer. Speakers with a large woofer that only covers the bottom 250 Hz are not going to benefit as much as speakers with smaller woofers that cover the bottom 1000 Hz. This includes a big chunk of the midrange where the decrease in distortion is very noticeable. With full range loudspeakers like my Sound Labs IMHO it is mandatory. You turn a polite speaker into a disco rocker. There are other advantages. If you are using digital bass management which includes the crossover you can place the subwoofers where they work best and are most efficient (in corners and against a wall) and correct them so they match the mains speakers in time and phase. If you like to feel the kick of a bass drum you can consider this mandatory. If you have a low power main amplifier like a SET this is also mandatory IMHO. You will increase your headroom and keep the SET away from clipping. 

The manufacturers know that most people are cost and complexity sensitive. Using just a low pass filter and pulling the sub in under the main speakers is an inexpensive, easy way of running a sub. If you have to start out this way as a temporary measure to get yourself into the game, go for it. Down the line get a preamp with bass management or a crossover like the MiniDSP and you are really in business. There is a tendency to dis digital equipment but IMHO the benefits far outweigh the disadvantages. There is so much you can do in the digital world that is impossible in the analog world. My days of being a purist are long over and I never plan to look back. Being able to tune your system exactly the way you want it is a huge advantage. The trick is to keep everything digital until the DACs before the amplifiers. This means you have to digitize your phono stage but if you do it in 24/192 the conversion is invisible. 

@phusis, Thank you.

@mijostyn, I get it now. I am convinced that is the way to go and seems not a costly and difficult thing to do. So correct me if I were wrong. I will go buy a miniDSP 2x4 HD (assuming HD version is better) and miniDSP 2x4 HD1 plug-in and make the following connection to integrate the main speakers with the SW:

source -> DAC/preamp -> MiniDSP HD -> main speakers/SW

I am not sure how good is the DAC inside the miniDSP so I feed the digital source to my DAC first and let the miniDSP process the analogue signal before distributing to main/SW, right? On the active SW side, I will by-pass the Xover (or set it to the highest frequency). Anything else I should pay due attention to please let me know.

@kiterlux

Thanks for the post.  I started another tread regarding REL Subs and Corner Horns and your video explained the REL issue.

Thanks

If I vacuum does it make me a robot?

Stacked Open-baffle GR Research 12” Paper cone drivers with the Rythmik plate amps specific to this application. 
 

Incredibly quick and detailed. Easy to tell if a drum is out of tune, 

there’s a bit of DIY involved 

contact Danny at GR Research.