Axiom Home Page Forums General Discussion Home Theater Sub level- adjust at sub vs let Denon/Audyssey1909

Simple way top find out for sure, try them out and see if they distort/chuff etc. If they do then turn them down and if you feel they are not adding anything get rid of them and buy a second good sub.

Dave, if your subs are calibrated to 75dB's like the other speakers, and not adjusted to be to "hot" as many set their subs, you should be fine. The combined amount will be about 5-6 dBs higher in what we can hear. Keep in mind the RS meter is not as accurate below 50hz.

Here is Ian's video on setting up Multiple Subs

But apparently rather expensive. The least of your subs costs about twice what all 3 of mine cost. Geddes bills his approach as an economical way to achieve even bass response.

The fact Sirquack spent more money than you has nothing to do with it. From what I can make of the GedLee study, he randomly located the 4 subs in his room with no corner loading and took some readings, big deal, it is well known to keep your subs out of the corners for best response and having four in the room will even out the frequency response, multiple sub placement basics these days.

The economical part I suspect is in reference to the lack of buying seperate EQing equipment and room treatments, not in that it works better for cheaper subs.

You pay for better overall performance when you are talking about subs and in particular low end extension.

You're mistaken. See for example:
Are three inexpensive subs better than one expensive sub-Dr. Earl Geddes Approach

From Mr. Geddes in the linked thread "In my setup the room is special, its designed to be a listening room and it has extensive LF damping" so the question is will his theory still work in an undamped room as well as his with "extensive LF damping". SO he has spent the equivalent of a good sub on room treatments, how is this cheaper?

He has also chosen 3 subs using different crossover regions with each sub, this sounds like a pretty extensive DIY project or at the very least a lot of research to get the correct subs so they will play nicely together.

I think the majority of us are just looking to plop something down and have it play smooth with very little effort. An hour or so of level adjusting good subs to achieve smooth bass qualifies for plop down smooth bass.

I will and have always ascertained that multiple subs of the same are not necessary but there will most likely be a draw back or two.

I have tried a set up similar to what he is suggesting with out any more expense to my self. I ran my old sub with my PB13 and I couldn't even tell my old sub was turned on, it couldn't compete with the PB13. I did try the PB13 at 40hz and the cross over on my old sub was set to work from 60hz down and my M80s XO set at 60. I could not hear any difference except what I felt was a lack in the mid bass that my old sub was supposed to be producing even though it was level matched, so Mr. Geddes theory isn't as simple or easy or guarranteed to work with 3 subs you pick up cheap, IMO.

I think that the bigger point is that multiple subs DO smooth out your bass response through out the room and that there are multiple ways of adjusting the subs for the smoothest response.

Forgot to bring up the point that he is still running one good sub down low for LFE, 50hz and lower which is the majority of what we hear/feel as bass and then using smaller cheaper subs for the mid bass region much like the Hsu MBM, so in effect still a one sub configuration in my books.

"But apparently rather expensive"??? Who said that?

Dr Toole and Weltis methods at Harmon International don't require expensive subs, it is about balancing out the frequency response in your room by placing them on opposite walls. Dr. Geddes has commented on how similar the two approaches are, I've read the thread.

For me it is about flat, powerful, non-distorted LFE at any levels. You can't get that with mediocre non DSP subs following this plan. Enjoy your GedLee approach.

Those are good points (among others you make). I don't know exactly how Dr. Geddes makes his living, but I get the impression he is a pro at speaker building and room setup. When he says his subs are inexpensive, he seems to be counting up only the costs of materials, because he makes them. They might seem pretty expensive, to me.

And I agree that his methods take more equipment, time, and expertise than I, or many of us, could muster.

I just now said that, in reference to the cost of the three Axiom subs you said you had, and whose response curve you gave in support of your point.