Two subwoofers for two channel music listening

I got in touch with SVS and they suggested not mixing high level and line level. That we all can agree on:))

I will get a measurement mic in next couple of months or so and measure these things for my own learning and also for fun. I want to place the subs in their optimal location in the room - not necessarily symmetrically inside or outside of the main speakers. Nothing wrong with the symmetrical positioning though. Aesthetically they look really nice. Right now they are outside of the main speakers. 

I am also planning to do a DSP based crossover to distribute low frequency, say 50 - 60 Hz, to the dual subs. I used to have external 80 Hz high pass filter with my large bookshelf speakers and the dual sub crossover set appropriately. I really liked the sound. The imaging and soundstage were great. I had a pair of Maggies with the same set up. Now I have a pair of Thiel CS2.4 (and I am already looking for CS3.7 or 7.2 model ...... my never ending itch for upgrades - sigh) that go down to mid 30s, I guess. Adequate for most music I listen to. I still want the occasional 20 Hz bass if it is present in the music, as I like to feel that bass more than I hear it :)))  Heck at some point I will go for distributed bass array with 4 subwoofers! My room is a dedicated listening room, 17 X 24 ft in size. So I got space for that.

Before the mic and third party DSP ask SVS if one of their DSP/App equipped models could act as a master controller for your 1000 series. Remote control volume, customizable EQ presets, and the very useful adjustable Q = interactive low frequency.

I'm not sure if the SVS version is similar to the Velodyne Plus' Q which is a simple visual and audible drag and drop adjustment for individual bandwidth parametric filter frequency and level.
When used in conjunction with its discrete mutiband gain settings allow for a much higher crossover beginning with tone that closely matches the mains presentation from the crossover region on.



I'm in agreement with georgehifi and ieales descriptions. Comparisons with an owners REL $9K Studio III and two different amplifiers the low level inputs were our obvious preference. I wouldn't recommend the product.  

Richard Edmund Lord may have been the first to offer high level inputs intended as a connection of convenience for systems that lack low level outputs. Remarketing the same circuit for a different reason?
I would add that I've never encountered speaker level connectivity in any professional reinforcement or studio system.  

You want your subs to be the deepest, tightest and driest they can be, the last thing you want is an amp driving another amp, that’s just wrong and gives one note bass, that’s why line level drive the best for them.
The last thing you would want is to drive them from say a tube amps etc speaker output.
Probably the only amp driven output that could compete with line level, would come from an amp like a Krells or similar, that have absolutely no ? on bass performance.

Cheers George

Right. The only proper way to hook up subwoofers is with a dedicated two way subwoofer crossover preferably digital. The preamp outputs go to the crossover which will have dedicated main amp and sub amp outputs all line level. This rolls off the main speakers improving integration and lowering distortion in the main speakers. Good bass management systems will give you a wide choice of crossover point and slopes. The best will also automatically correct for phase and time and do room control.
Any other method is challenged one way or another. REL approach is just a cheap way to do it. Their insistence that is is the best is a rouge to sell more subwoofers. They know people who are buying their inexpensive subs do not want to spend more money and/or deal with more complexity. If they recommended the right way nobody would buy their subs. What you have here is a dysfunctional relationship between a manufacturer and it's clients destined to produce mediocrity, an interesting relationship common in the political world. The best subwoofer systems use passive subwoofers. You have to die laughing. You have all these audiophiles spending ridiculous money to keep their electronics isolated but they are fine jamming an amplifier into a earthquake replicating machine wherein the pressures vary from +- 30 PSI. So, why doesn't the industry produce passive subs? Passive subs in most cases are not much less expensive. Plate amps are dirt cheap and they make a lot of money selling them. People love all in one cheap solutions. It is the culture. JL Audio cuts it both ways. They make amplified subs with crossovers like everyone else but for people who want to do it right they make an analog subwoofer crossover to go between the preamp and amplifiers. The DEQX Premate has a wonderful bass management system with which you can set up a SOTA subwoofer system.

The only proper way to hook up subwoofers is with a dedicated two way subwoofer crossover preferably digital. The preamp outputs go to the crossover which will have dedicated main amp and sub amp outputs all line level. This rolls off the main speakers improving integration and lowering distortion in the main speakers.

I've had the best results using an external crossover as well. Back in my home theater days I purchased an Outlaw ICBM-1 for bass management in the analog domain, including integration of 2 subs. I kept only the ICBM-1 when I went back to 2-channel. It's been in/out of my systems for years and I still find it to be quite transparent and incredibly handy. OP .. these can still be found used on ebay in the $200-$250 range. Here's a review from back in the day if you'd like to know more about it.

http://www.soundstagenetwork.com/revequip/outlawaudio_icbm.htm