You are ignoring the fact that I am suggesting to EQ individually 1st, then overall 2nd. Not just individually.

And SVS told me over the weekend that either way can work. And they *have* tested in a bunch of real rooms. And that's one reason why they offer the capability in the AS-EQ1.

I can't speak for Sanjay, but I for one fully understood what you were suggesting in your previous posts. By all means go for it, if it will make you happy.

It's important to point out, though, that you will have difficulty finding anyone to suggest that what you are doing confers any advantage whatsoever, other than someone who gets to sell you an expensive piece of equipment by doing so.

Not ignoring it at all, just pointing out that it makes no sense, since the second round of equalization changes the settings that originally made the response of each sub flat, thereby rendering the first round of equalization pointless.

Whether you want them to not, the two subwoofers will interact with each other. Rather than take my word for it, anyone reading this thread can try it at home. Equalize two subs so that each one is flat at the listening position. Without moving the measuring mic, turn on both subwoofers. Notice that the response from two flat subs now looks like a roller coaster, because their interaction wasn't taken into consideration. I suppose you could then do a second round of equalization, but now you've just changed the original EQ settings to what they should have been from the begining.

A better, simpler, easier and cleaner approach would be to measure the interaction between the two subs, since that's what you're going to hear anyway. IF it is possible, move one or both subs around to see if you can improve the frequency response, in which case you'll minimize the amount of correction that the EQ has to do (always a good thing). The box was designed and built by Audyssey. They allowed the option of EQing each subwoofer independently because the box can take in a stereo input signal. Two separate signals require two separate equalizations, since their interaction can change based on content. At the time, Audyssey used to EQ each subwoofer channel independently, like the 3 subwoofer outputs on the Denon AVP1 (again, because each output could carry a different signal). They have since wisened up and now send the same mono signal to each AND globally equalize their interaction.

If the above doesn't convince you, Kevin, so be it. I'm done.

One sub. The ongoing wisdom has been that if you have a dedicated means of EQ'ing the sub: SMS, Velodyne DD, AS-EQ1, RABOS, etc; use that first, then use Audyssey over top of that. A lot of people have expressed that they get better results that way than just with Audyssey alone.

So now with two subs, Audyssey can do a better job alone w/o first EQ'ing each sub individually? When EQ'ing two subs together is a lot more difficult than one sub by itself ... specifically due to their interaction?

If each sub is EQ'ed individually first, Audyssey is given a more uniform response to start with, to then EQ the combined response.

I always understood that the rationale behind using dedicated subwoofer EQ tools (SMS-1, AS-EQ1, RDES, etc.) prior to using overall room correction tools like Audyssey was that it was the only practical way to merge the two forms of EQ. The dedicated tools frequently had more available bands of EQ available specifically for the sub and could do a better job of getting subwoofer response flat, then the room correction addressed the full-range speakers and did whatever it could with the subwoofer. (In early room correction and even some current models, their sub EQ was of limited capability, which just reinforced this idea.) The SMS-1 is the only such sub EQ I've used, and while it has multiple sub outputs it operates with a mono output and applies the same EQ to all of the subs.

Despite my promise not to, I feel compelled to stick my nose in here again to take issue with the quoted statement. It is patently false, and makes me suspect you have to completely rethink your concept of what happens when two transducers interact.

Audyssey has no more difficulty EQing a pair of subs reproducing the same signal (which it sees as a single virtual sub) than it does EQing a single physical sub.

That scenario works because the response of the subwoofer doesn't change due to interacting with another subwoofer. Not a question of better or worse, but what is being EQ'd. If you EQ each subwoofer independently, when they'll never be heard that way, then you're EQing the wrong thing (and wasting your time). That would be like EQing a subwoofer in the middle of the room, where it is easier to get a flatter response, then placing it in the corner where it is going to reside before EQing it again. Why bother with the first round of EQing when no one is going to hear the sub from the middle of the room? Likewise, why EQ each sub independently when no one will ever hear it that way. Why is it more difficult? You measure the bass response, and minimize the peaks and dips as best you can. What difference does it make how many subs are physically connected to the EQ? That uniformity disappears the moment you turn on both subwoofers. Try it for yourself and see.

In case there's still some doubt after Sanjay's excellent post, I'm tempted to revisit my "virtual sub" analogy. Turning on the second sub does not actually change the response of the first sub (or vice versa); rather their combined output is now heard as a new virtual sub whose response is different from either physical sub heard individually, and whose raw response can then be equalized to achieve the desired response.

Equalizing the 2 single physical subs independently before equalizing them together will certainly change the response of the virtual sub, but in a completely unpredictable and not necessarily favorable way. In addition, it wastes time and money and adds unnecessary complexity. It's simply a bad idea.

I don't see it. If you individually EQ each sub so that the phase, distance, amplitude, and freq spectra is what you want at the main listening positioning, and then you add them together, their responses should just add together. Where's the interaction? The 2 subs' physical locations are different. But what EQ'ing is supposed to be doing, is to make it so that they sound the *same* at the main listening position. (Or as much as possible the same, given their different physical locations.) Essentially, you're just co-locating 2 different sound fields over top of each other. (Hard to explain.) As if you had one speaker exactly where you're located, and then you add another one in the same exact spot. All you're doing is doubling the volume of something that should be "correct" in the 1st place: the soundfield of each sub at the main listening spot.

Gary- with your virtual sub idea: if each individal EQ system is doing what it's supposed to, the new virtual sub created from one plus another would simply be the two fields added together. No interaction. The only way *interactions* occur is if things *aren't* in phase so they don't add together properly. And let's say that there are some phase issues introduced by EQ'ing those 2 subs individually. The responses of each sub are still smoother than w/o 1st individually EQ'ing then, and yet still, that's why you run Audyssey over top of their combined response to deal with that.

And if it was such a "bad idea", why are there solutions out there in the market?

And why would SVS have told me that it can work both ways?

Does Velodyne say in their manuals, for example, that if you have two Digital Drive subwoofers not co-located, *not* to use the EQ system because it's a "bad idea"?