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Where 2 sit audio quiz

Ok folks, don't take this too seriously now!

It's cold and cloudy here in Wisconsin and I'm bored out of my skull.

I've been messing around with different seating positions and trying to form a pattern between measured results and audible results.
I thought it might be interesting to put up measured results at 3 widely varying seating positions, and see if anyone could suggest ideas on a range of different issues. There's a $1 Million cash prize for whoever get's it right, redeemable 11/22/2064

First the setup:
Meter used is the RS digital set to slow response and C weighted.
Test tones from Rives CD 2
The Rives CD say's to use tracks 32 - 62 which are compensated for the non-linearity of the RS analogue meter. It doesn't say what to use for the digital meter, so I tried both, and the most consistent seemed to be tracks 1-31.
Anyway, the numbers are more indicative than they are absolute. If I need to re-do the test using tracks 32+ then so be it.
I used 3 different 'practical' seating locations at 12', 17' and 20.5' from the speakers.
The 20.5' position is up against the wall, which is central on a large un-draped window (a clue perhaps.. [14'x 4' approx window dimension]). I'm showing the 3 sets of results in tabular form (wasn't bored enough to bother making a graph).
Also, I'm not saying at this point which reading relates to which seating position....(perhaps the SPL level will provide the answer?)

Speakers are Maggie 3.6R's, amps are Cary V12 Mono's with ARC LS15.
I thought I would have to adjust the preamp gain at the farthest position, but it didn't require it, so all 3 positions are measured using the same volume setting on the LS15 preamp.
Questions that spring to mind....(add more if you wish).
From the results shown at http://thenaturalshopper.com/audiohell.htm

1 - which position would seem to suggest the best sonics
2 - what do the readings say about room layout and frequency response
3 - what do they indicate as far as equipment selection(speakers) for the particular room layout (example - insufficient bass response at any position, harsh treble response, or whatever?)
4 - which position do you thinks is the 12', 17' and 20.5' seating position
5 - given that the spl's are almost identical at higher frequencies, what does that say about the room layout. (given that there is a 8.5' difference between the closest and farthest seat position, shouldn't one of the columns show a consistent reduction in SPL?).
6 - what does all of this say about people from Wisconsin

What the heck!

Rooze
128x128rooze
sean
6,229 posts
 
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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rives
953 posts
 
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.
sean
6,229 posts
 
Rives: I'm sorry if i misinterpreted your comments, but i still don't agree with your clarification presented here. Due to the fact that all drivers "beam" or alter their radiation pattern as frequency is raised, one is bound to encounter varying frequency responses as speaker position and / or seated listening positions are altered. This can easily be measured outdoors where there are "minimal" room boundaries to cancel / reinforce / reflect the signals being produced and measured.

As further evidence, this can also be seen in just about any "decent" speaker review as the frequency response is altered as one changes the axis that one is listening on. Since distance changes the listening axis ( speakers don't rotate to accomodate seating distance ), you are bound to have quantifiable* differences in frequency response linearity. Sean
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* don't know if this is the most appropriate terminology, but it sure sounds impressive : )
rives
953 posts
 
Sean: You are right about being off axis, and I was not very clear in my comments--since we were talking about a distance from the speaker the angle of incidence doesn't change much, a highly directional speaker could have a modest difference. Now if you had a well absorbed boundary at one point (first reflection) and a highly reflected surface at another it would yield quantifiably different results, but otherwise they will be remarkably similar. Try it, Rooze did, and I'll bet you get the same or very similar results. Keep in mind--I measure a LOT of rooms under many conditions, and my dealers measure even more than I do and send in the results. I have measurements taken at a variety of locations--I do not do averaging (it masks real data).
sean
6,229 posts
 
Rives: I hope that you don't take this as a personal attack, only an open discussion of differing points of view.

I assume that Rooze basically took these readings walking away from the speakers in a straight line in what would be termed the "sweet spot". Then again, this is not mentioned but would be taken for granted as being the common sense approach by most readers.

As a side note, ALL speakers are directional and beam sound as frequency is raised. Obviously, some are worse than others in this regard, but they all do it. This happens not only horizontally, but also vertically. On top of this, the angle of incidence can vary quite a bit as distance is altered. Much of this will depend on whether the speakers are flat-faced or are toe'd ( sp ??? ) in.

If you look at any frequency response chart of a driver, off axis response becomes FAR less linear as one is moved further off axis. Going from 10* off axis to 30* off axis, which isn't that much, can make a huge difference in terms of frequency response linearity. Not only will this affect tonal balance, but also the soundstage, imaging and transient presentation of the system.

I have no idea what you or various dealers are using as a reference in terms of measuring frequency response and / or dispersion patterns. I would hope that it would be measurably more accurate than a stock Rat Shack meter. The non-linearities of this device itself, primarily in terms of frequency response and directionality, make the results very "questionable" under anything less than optimum conditions in skilled hands. As a generic tool used in the hands of civilians, it can be quite useful to study trends and average out results. As such, averaging is not a bad thing so long as the results are viewed in the right perspective. After all, Rooze verified that my observations, which were derived from averaging and following trends, were pretty consistent with what he was hearing.

Suffice it to say that we will probably end up agreeing to disagree here. Sean
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