Two subwoofers

When you match the output level of a sub to the main speakers in a system, you do so at a given SPL (75db in the latest Audyssey set-up regimen IIRC). I think the OP may be asking what happens as that SPL changes. Might two different sub models behave differently as SPL rises.

Theoretically, at least, I believe that the the answer should be "yes". In every sub (and speaker, for that matter) some amplifier output is converted to acoustic output and some is lost to heat - thermal compression. The ratio of the two may differer between different designs.

In practical use, I doubt that it's likely to be meaningful (or even audible). Since most dual sub set-ups aren't stereo, the theoretical mismatch wouldn't affect stereo balance (the subs are operating in mono, anyway). The bigger theoretical issue is how thermal compression impacts the combined output of the subs vs the combined output of the main speakers as the SPL increases. This is as true with identical model subs as it is with differing subs.

It may vary case by case, but I've measured the response of my system (with identical twin Rythmik subs) at 75db and at 95db and the difference is negligible. FWIW.

Thanks all. Wow 5 subs in a single HT system. Whoa and I thought two was more than most. Yes that can be quite tricky. Bob what I meant by out of synch is that perhaps the two different subs were not in exact phase. Perhaps the drivers could be out of the exact timing being of different types of amps (class B and Class D) and one having a larger enclosure. So here's what I ended up doing. I took home a 2nd ASW610 brand new from my dealer and removed the ASW600.

After many hours of listening and trials, I became convinced this was the right move. I purchased the new ASW610 and redeployed my older ASW600 as a sub for my Dell desktop PC in another room. The two ASW610s work extremely well together being very compatible. The LFE and bass extension is far more tight and focused on the sweet spot. I realized that the older ASW610 produces more rattle and actually more vibrations in other rooms. Now those vibrations have greatly reduced which was also my interest in upgrading. So far, mission accomplished !!

I am assuming when you mean out of synch, you are referring to out of phase? I am guessing one sub set at 180 and the other 0. I pondered similar issues a few years ago. My old 15" sealed 1000 watt sub watt (B&W Nautilus ASW 850) has been a workhorse in my system. I wanted to get a replacement but of course they are not made anymore. After researching and doing comparative analysis (Internet sources and manufacturer products), I opted to get another 15" 1000 watt sealed sub, from HSU. It had all of the basic functionality of the B&W in terms of specs and controls. It was easy to blend both of these subs with a Velodyne SMS1 sub eq. Excellent room response. I have them configured directly to the right and left of the main speakers. You will need to level match them first in order to ensure that the volume is the same for a given output.

Good luck,
Audioquest4life

I use a pair of Velodyne HGS-15s controlled by an SMS-1. I recently bought a pair of SMS-1s with the thought that I might try an SMS-1 for each HGS-15 and use the third SMS-1 in another setup with an HGS-10. I can't quite get my head around the efficacy of a separate SMS-1 for each HGS-15, because it seems that it's the combined output of the subs that one wants to equalize. Nevertheless, the Manual for the SMS-1 covers using them in tandem, so I plan to try it.

db

Where you get the SMS 1's? It is not for sale on the Velodyne website anymore. I want to use two for my setup.
Thx.
Audioquest4life