long ago when I performed the "sub crawl" I found one of the primo locations to be where I now have them placed. when I run audyssey, I set the gain on both subs to 80-81 db individually, then run both as one from a single sub out. this sets the subs gain knobs at 9 o'clock. audyssey on my Marantz av8801 then sets subs to -12, which I bump 6db so i'm at -6. all sounds great!!
as most here are aware, Mike Thomas has written an excellent guide to subwoofer setup. he states two things that have me wondering if my setup could be improved even more...
1 when audyssey sets my subs to -12, they actually could be even lower (-16 for example, which in this case a 6db bump would only be actually taking them to -10)
2 Mike and others agree that the gain on the sub amp should be set higher to maximize the subs potential...setting so that audyssey sets subs at -9 to -11.5 then to bump 6db to -3 to -5.5 or so.
so then, contrary to my prior thinking, would it be advantageous to move the subs to a LESS primo spot so points 1 and 2 are addressed? my room is 24x14x8 and is NOT sealed.
does this make any sense or should I quit thinkin so much
Thanks for the compliment! My first thought was whether it was thinking or drinking so much?
I assume from what you said that you have the two subs stacked. Is that correct? If so, I am curious whether you have also tried separating the subwoofers, perhaps on opposing walls? If you like your current subwoofer location, with the subs mutually-coupling, there is probably nothing wrong with the procedure you have described. Do you have REW, and have you measured your frequency response with both subs together versus separated? I'm guessing not, but I thought I would ask anyway.
As far as increasing the gain control on the subs, the advantage in using the subwoofer gain to produce more of the voltage going to the subs really only comes in if you are pushing your subs a little harder than you are. It sounds to me as if you have abundant headroom available to you.
As far as whether it is okay to be at -12, when you might really need to be at -16 if the trim settings went that low, that is sort of a numbers game in this case. I would always prefer to start at -11.5, so that I know where I am with respect to how low the trim levels can go, but I don't know whether it needs to be an ironclad rule. Since you are already at 9:00 on the gain dials, I'm not sure that you can lower the gain enough to get to -11.5 in trim level anyway, with the way that your subs are currently wired.
Separating the two subs into separate sub outs, and setting them to a little less than 80db individually, might allow you to reach -11.5 in trim without having to go much lower than 9:00 in gain, but I'm not sure. You could try it if you are really curious.
As far as adding +6db to your trim is concerned, I think that the +6 would still be a 6db increase in either case, regardless of your starting point. You could always use your SPL meter, if you have one, to do a before-and-after measurement of the subs, with the same content. That would tell you whether your trim adjustment were actually netting you 6db or not. But again, I'm not really sure it would matter. After all, I assume you are just adding the amount of subwoofer boost that sounds appropriate to you. So, does it really matter whether you are adding 3db, or 6db, or some other number? I could see it mattering if you were concerned about sufficient headroom, but that clearly isn't an issue in this case.
What I would not
do is to move both of the subs to a less suitable spot in the room, simply to hit -11.5 trim levels. I would definitely experiment to see if separating the subs, by moving one of them to another good location, gave me better overall sound (or measurements). And, since you have dual sub outs in your AVR, I might try recalibrating the subs with separate sub outs, just to see what that would do to my gain/trim levels, with them where they are now. But, if the subs are in the best spot in the room, and you like running them stacked, then I wouldn't change that part for the reasons you describe.
I hope this helps!