Hey Lads,

I've got this posted in the commercial subwoofer forum too but not a single response 24 hours and 50 views later. I suspect that I'm more likely to run into HT enthusiasts that have tackled this problem on this board so here goes-

I'm currently running a pair of Paradigm Servo 15As as the .1 of my 5.1 Meridian Digital Theater. The subs are in the front corners of my room behind the mains. Subwoofer PEQ is currently courtesy of a Velo SMS-1 and Meridian's time domain based MRC is then applied to the entire system. I'd like to add another Servo 15 or two at the back of the room to both smooth out the lows and make sub-bass repoduction truly effortless. Meridian's approach to LFE does not allow for separate management of front and rear subs with my 861 so I have very real concerns as to just how I'll deal with the differing delays required to keep front and rear subs along with the 5 channels in sync.

Will the somewhat limited phase control facility on the SMS-1 be adequate if I just added a second SMS-1 for rear sub duty? Do I need to look at a pro/studio device from DBX or other to properly accomplish my goal? Pics of my system & 20x14x11' room below. Thanks!

http://i299.photobucket.com/albums/mm295/VinceHoffman/DSCN4257.jpg

http://i299.photobucket.com/albums/mm295/VinceHoffman/DSCN4264.jpg

http://i299.photobucket.com/albums/mm295/VinceHoffman/DSCN4261.jpg

Happy Trails!
Vince@Freewheelcycle.com

Vince, you can add another SMS-1 and daisy chain them and if I recall, it will calibrate the system as a whole treating / EQing the SMS-1's seperately. I considered doing this for my 4 subs but I rarely use my HT and I already get pretty flat response in my room with one SMS-1. I have a pair of subs co located at each of the front corners. My room is also similar in size (23 * 12 * 8). I believe many will recommend bass traps first before investing in more electronic EQ'ing.

Vince, you can add another SMS-1 and daisy chain them and if I recall, it will calibrate the system as a whole treating / EQing the SMS-1's seperately. I considered doing this for my 4 subs but I rarely use my HT and I already get pretty flat response in my room with one SMS-1. I have a pair of subs co located at each of the front corners. My room is also similar in size (23 * 12 * 8).

Thanks Eric,

Looks like I've got to go read the SMS-1 manual through again. My fundamental concern still remains though. With the rear pair of subs 5' from the listening position and front subs 15' away, all sharing the same ".1" source signal, will the two SMS-1's phase controls offer sufficient delays to time align the system as a whole?

I believe many will recommend bass traps first before investing in more electronic EQ'ing.

As my pics suggest, with the floor-to-ceiling stacks o' 20" and 16" Tube Traps in all the corners, I've kinda got that covered.

Happy Trails!
Vince@Freewheelcycle.com

Hi Vince,

Have you given any thought to parting with the Paradigms ?
You will be getting cramped for space with 4 Servo 15 in your room

Any thoughts on going to possibly a pair of JL F113 ?
By all accounts, they should be significantly superier ( trounce? ) the old Paradigms.
The JL's are very small in person and will give 1-band of variable EQ per speaker.
Plus you could still use your SMS-1 if need be.

I intend to pickup a pair of F113 when the right deal comes along.

- Andy

Vince: I have yet to finish but I have 4 subs as well and two SMS-1's. I have the back two subs almost ruler flat (the subs also have a single band PEQ facility) with the SMS. I adjusted the phase of the rear subs (the subs have phase control in addition to the SMS but used the subs phase knob) to line up with the mains at crossover point (in my case, 80Hz) and will do the same with the front two. And hopefully that will provide all of the benefit of the 4 subs. And while one could argue about the quality of your subs versus other, I still believe that you can end up with better results with 4 subs over 2.

I've been using a QSC DSP-30 for sub management. You could use one and run each pair of subs off one QSC channel, or, you could use two to control each sub independently. ( http://www.qscaudio.com/products/dsp/dsp30/dsp30.htm ) This has replaced the MRC in my 861 for the sub channel.

In my system there were two "problems" with multiple subs. First, the subs had to be time aligned with the mains. This actually turned out to be the lesser problem. Second, each sub had a different at the listening seat response profile, which caused images to not be as stable as they should, and, caused the sound field to "swim" a bit with frequency.

One additional complication in a Meridian setup is that the crossover slopes are different for Movie and Music modes (24 db symmetrical for the former, and 12db low pass 6db high pass for the latter.) Thus, you have to ensure you get good main to subs blending in both configurations.

I've been using a QSC DSP-30 for sub management. You could use one and run each pair of subs off one QSC channel, or, you could use two to control each sub independently. ( http://www.qscaudio.com/products/dsp/dsp30/dsp30.htm ) This has replaced the MRC in my 861 for the sub channel.

In my system there were two "problems" with multiple subs. First, the subs had to be time aligned with the mains. This actually turned out to be the lesser problem. Second, each sub had a different at the listening seat response profile, which caused images to not be as stable as they should, and, caused the sound field to "swim" a bit with frequency.

One additional complication in a Meridian setup is that the crossover slopes are different for Movie and Music modes (24 db symmetrical for the former, and 12db low pass 6db high pass for the latter.) Thus, you have to ensure you get good main to subs blending in both configurations.

Thanks Bruce,

This is the sort of device I suspected I might need. I would imagine that the DSP30's ADC/DAC circuitry is up to the job of a sub's narrow bandwidth but I am somewhat surprised that it operates at 48K/24 bit rather than 96/24 that even Behringer uses. Speaking of which I used a BFD-Pro on my subs prior to the SMS-1 and found it a little flakey in its operation. Is the DSP30 consistently reliable? What measuring tools did you use with it to set up your system and how does it interface with your PC or Mac? I'm particularly interested in what measurement gear/software was required to determine the delays. I'm somewhat suspect of Meridian's delay settings when you are using DSP speakers with an analogue sub. Is there latency differences between the two output cards and DSP speaker signal chain which would invalidate the standardized measurements for a mixed DSP and Analogue speaker set-up? Thanks again.

Happy Trails!
Vince@Freewheelcycle.com

Happy Trails!
Vince@Freewheelcycle.com

Vince, the QSC has a terrific user interface. I use an XP laptop via a rs232/USB connection. The user interface is "drag and drop": delays, blends, high and low shelves, PEQ, gain, etc. What's nice is that you can change parameters on the fly when connected to the laptop.

I used to have a Behringer DEQ2496. It had a bit of a "tizzy" sound, sort of like the sound of overly compressed mp3 files. I have not noticed any of that with the QSC. But, I'm running it solely below 80hz to keep it out of the more processing critical frequencies.

I used Room EQ Wizzard and also ETF on my laptop to measure frequency response and time delays. Both work well. Room EQ Wizzard is free, and has an easier to understand user interface. (I've also found that I could temporarily insert a Denon receiver with Audyssey and use the Audyssey routine to measure distances.)

After pretty simple PEQ via Room EQ Wizzard MRC didn't "discover" any filters for the sub channel.

I had Mark Seaton spend a day configuring the QSC and subs. It was money very well spent.

You could also get the Audyssey EQ box, and run the subwoofers through that. If you tell it the input is for subwoofers, it will dedicate all the processing power to just the lower frequencies, and their EQ system is phenomenal.

A separate Audyssey Pro box dedicated to the subs, or, a pair of the announced but not yet released SVS Audyssey sub boxes would do a nice job. Each of the four subs could be independently PEQ'd. There might be a problem with the latency though: the Meridian doesn't give you that much room in the distance settings, and the Audyssey boxes can have pretty significant latency.

Alternatively, you could replace MRC all together with a single Audyssey Pro box, but, that would not allow you to PEQ each sub independently ... you could run your five main speakers and have three sub channels left, which would require that you run one pair of subs as a combined unit (not that big a problem, really.)

You could also get the Audyssey EQ box, and run the subwoofers through that. If you tell it the input is for subwoofers, it will dedicate all the processing power to just the lower frequencies, and their EQ system is phenomenal.

A separate Audyssey Pro box dedicated to the subs, or, a pair of the announced but not yet released SVS Audyssey sub boxes would do a nice job. Each of the four subs could be independently PEQ'd. There might be a problem with the latency though: the Meridian doesn't give you that much room in the distance settings, and the Audyssey boxes can have pretty significant latency.

Thanks for the additional input lads! The stand-alone Audyssey box approach hadn't occurred to me. I know absolutely nothing about the system but have noted that there appears to be as many detractors as champions of Audyssey EQ on AVS, particularly when it comes to the LFE channel. The DSP processing, buffering, and PLL in current gen Meridian pre-pro's already create pretty long latency times. To be on the safe side, I think an LFE processing/EQ unit suited to my needs must have very low latency. Yes/no?

Alternatively, you could replace MRC all together with a single Audyssey Pro box, but, that would not allow you to PEQ each sub independently ... you could run your five main speakers and have three sub channels left, which would require that you run one pair of subs as a combined unit (not that big a problem, really.)

My mains center and surrounds are all 96/24 Meridian DSP loudspeakers so any stand-alone PEQ/adjustable delay solution I go with will only be applicable to the LFE.

Happy Trails!
Vince@Freewheelcycle.com

I use two Velodyne SMS-1's. One for the front two subs and one for the rear two subs. They each have fairly granular phase adjustments (15 degrees) as well as a polarity switch (and of course an 8 band parametric equalizer). EQ each set of two subs, align the phase of each pair with the mains (very easy to do with the SMS by adjusting phase) and bingo, you will have amazing, powerful, and clean bass. It takes a while, but the results are nothing short of phenominal. The SMS has to be one of the best deals in audio.

Go with the QSC. I had Dennis Erskine / Adam Peltz set up my HT using the QSC along with an 861 and 4 Aerial Acoustics subs and the sound is amazing.
Ken