Where 2 sit audio quiz

Rives, thanks, I've seen your site and tried the simulator, but I can't get my room dimensions keyed in, as the max width on your simulator is 10m and my room is 15m wide.

Newbee....my room is 45'X 28'. The speakers are 12' apart, 7.5' from the front wall and toed in slightly. I have some restrictions on where the speakers can go. They can't go closer than 18" to the front wall, and can come out into the room past 9' due to the proximity of a staircase. The closest possible listening position is at the 12' point, and the 20.5' position represents the farthest distance, being up against the back wall. The seat can go anywhere between the 12 and 20.5'....Though 12 is a little close due to the staircase and WAF.
There is an 'unreal' change in sound pressure as I walk between the 12 and 20'. At the 16-17' point, the spl just drops way down, and the low frequencies almost dissapear, then it just pops right back in there around the 19-20' area. I'm not really familiar with the term suck-out, though I guess that's what I'm experiencing in the 16-17' area.
To give some more information....the points ABC on the chart are actually A=12' B=17' and C=20.5'
I was amazed that the SPL could be significantly higher at 20.5' than at 17'.
As Sean stated, the best sonics would appear to be at the 20.5 position, given the apparent smoother low frequency extension. In practice, the sound is much better at point C (20') than at point B (17'). But at point A(12') the presentation is completely different than that at point C, even though the frequency/spl readings are quite similar.

There are obviously points in between the 3 positions that are possible, but only really at +/- 12" or so from the 12/17/20.5 points.

Anyway, it's been an interesting experiment for me. Right now I have the seat at the 20.5 position. I'm enjoying the
presentation of orchestral music and some big band stuff.
When I play more 'intimate' music like Diana Krall Live in Paris, or the Sting Live CD, I wish I were back at the 12' point for that enveloping soundfield effect!!...maybe I should install tram-tracks or something.

Anyway, when I moved to this bigger place and splurged on new 'bigger' sounding equipment, I never knew there was going to be so much involved. I wish I could afford to pay for the services of a pro installer who could perhaps get me at the 14-15' point by using acoustic treatments.

What do you think Rives?....I'm 12 miles from the Packer Stadium...I could get you tickets to watch some real Football, and you could fix up my room!...seems like a fair trade!

Rooze

Sean, sorry I just posted my last response as you were writing yours, so didn't see/comment on your last observations. What you say makes good sense, particularly that most of the issues concern higher frequency brightness and sibilance effects.
I'm intrigued to understand more as to what is causing the drop in SPL at the midway (17') point. Could it be that the 17' point is actually the more neutral place and therefore the 'best' place sonically?....perhaps what I'm hearing at the 12 and 20' points is 'boom' and 'refelections' for want of better terms. The sound is good at the 17 point, but just isn't warm enough with the absence of the lower frequencies...
Believe me when I say that as far as trial and error goes, I've worked bloody hard sliding those blasted marble slabs around!....I think where the speakers are now gives me the best low frequency extension and depending on the final choice of listening position, either a wide open soundstage (far position), or an envelopling, detailed and intimate sounding presentation (near Position).

Thanks again for helping me understand what is going on and help in exploring my options.

Rooze

Rooze, I'll have to admit that I have never worked with a room this size, let alone a room of this size with panel speakers. For what its worth I would opt for the best positioning for resolution and soundstage and supplement the bottom end with a fast pair of subs located in an area which will give you flat bass to 20 hz. How's that for a cop out! By the way have you checked out other room set up systems, such as Cardas. If not, you can read about this and others in the FAQ's at the Audio Asylum site. I'm not sure how you came by your listening seat positioning, but did you try the 14 to 15 ft area. I've often found some of my best bass reinforcement when the speakers and the listening position are around 25% of the room dimension (which in your case would be 7ft for speakers and seat). Have fun - good tuning takes a long time and you should take your time do it. Its a lot more than just good measured frequency response.

While i didn't present all of the figures involved in coming up with the conclusions that i did, C and A are quite close when looking at the big picture with B being off in left field ( no offense to left fielders : ) If going strictly by the figures though, C is the winner. Then again, facts & figures never factor in personal preference.

Newbee brings up some VERY valid points regarding low frequency response and output levels. With a room this large, you really should be looking at an active crossover and some subs. I would only go this route AFTER you feel comfortable that you've gotten everything dialed in with what you already have. Otherwise, you'll be running back and forth between the mains and the subs and it will only get more confusing. Sean
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Sean:

I didn't say rooms don't have an effect above 500 Hz--that would be REALLY wrong. I did say that positioning (both listener and speakers) has little effect above 500 Hz. Now that's not true in all rooms, but a room that is reasonably well balanced it is true. If high frequencies are tipped up, that will be true throughout most of the room--unless you are right up against one area that is heavily absorbing, but then this wouldn't be a well balanced room. In the bass region however there are peaks and nulls and they vary greatly by location.