Where 2 sit audio quiz

I'm not responding until Rives posts his answers. Then i'll let him know if he is right : )

The rankings below are rated from best to worst in descending order.

Broadband frequency response linearity

1) C
2) A
3) B ( WAY behind the others )

Most solid, even & extended low frequency response ( hardest to achieve )

1) C
2) A
3) B ( WAY behind the others )

Highest average broadband spl*

1) C
2) A
3) B

Obviously, the one to go with is "C" as it offers the most linear frequency response, smoothest and most extended bass response and the highest broadband sensitity.

As to your other questions, i know nothing about everything : )

The one suggestion / comment that i would make is that you need to work on your room acoustics. My thoughts are that the first place to start would be with damping ( NOT diffracting ) the primary points of reflection. Since the frequencies that seem to be the most troublesome here are relatively high in nature, you don't really need anything that is real thick or offers extended low frequency coverage. You can probably get by with using some relatively thin "acoustic foam" that is properly placed. This should tame the "hot" upper mids and treble response that you are experiencing without really toying with any other part of the audible spectrum. This would improve linearity even further and help to level out the otherwise "hot" and potentially highly sibilant upper mids / lower treble that you are probably dealing with. Sean
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* If we limit bandwidth from 40 Hz and up, "A" offers the highest average spl of the three. Even with bandwidth limiting though, "A" does not offer the solidity or evenness in low frequency response that "C" does. As such, "C" is still the clear winner even after trying to compensate for the lack of extension in "A" and "B".

Rooze: I would not insert a resistor into the tweeter section until you address the primary points of reflection. If you do that and things are still too "hot" sounding, then go the resistor approach.

As far as bass goes, Newbee has a point. That is, you need to configure the speakers AND your seated listening position taking room nodes into account. Getting the speakers positioned is one thing but then throwing that away with a poor listening position is all too common. Anybody that thinks that you can't take the room into account and obtain optimum results is fooling themselves.

Having said that, diffusion / diffraction is typically only good at mid to higher frequencies. Bass is a completely different animal and far trickier to work with. I can't really make suggestions based on the information that i have here. The one suggestion that i would make would be to pick up some books on acoustics and read, read, read.

Newbee: Your comments about room nodes is kind of "there, but not there". Everything that you hear is a combo of directly radiated sound and reflections / room nodes. There is no way to avoid this so the smart people learn how to tame and / or incorporate them into the response that you hear at the seated listening position. It is impossible to achieve linear response at multiple positions spread over a wide area.

Rives: I can't agree with your comments regarding rooms not really affecting anything above appr 500 Hz or so. The measurements that Rooze provided support my beliefs and experiences. While a lot of this will vary from room to room and speaker to speaker, making such a "generic" statement put you out on a limb. Luckily, i have a saw and a ladder and i'm going to get you down from there : )

Let's look at the variances above the cut-off frequency that you mentioned i.e. 500 Hz. Cutting you some slack, we'll double that and look at 1 KHz and above. I'll list the center frequency and the amount of variance from the highest reading to the lowest reading. This will demonstrate how much room loading can affect the sonic perspective at these frequencies.

1KHz - 13 dB's variance

1.25 KHZ - 9 dB's variance

1.6 KHz - 11 dB's

2 KHz - 6 dB's

2.5 KHz - 5 dB's

3.15 KHz - 5 dB's

4 KHz - 5 dB's

5 KHz - 10 dB's

6.3 KHz - 5 dB's

8 KHz - 10 dB's

10 KHz - 7 dB's

12.5 KHz - 6 dB's

As one can see, there are major divergences depending on room nodes / reflections regardless of frequency. To be fair to Rives, much of this has to do with the type of speakers being used. While Maggie's are not "oddball" or uncommon speakers, they do present a very different type of installation challenge than what most "front firing boxes" would. As such, one can not make sweeping generalizations without expecting some type of variance from installation to installation. Since i have every type of speaker known to man ( large towers, dipole's, omni's, mini-monitors and horns ), it is easy to see why i might have the outlook that i do whereas Rives has probably worked with more conventional designs most of the time.

As a side note, this is the reason that i don't respond to a lot of threads i.e. too much room for interpretation due to variables and not enough information presented. On top of that, i hope that some folks realize that "spec's" can be interpreted usefully. That is, IF one knows how to understand the data provided and that data was obtained in an accurate manner.

Having said that, i worked with the information presented here. I took into into consideration that the speakers are where they are and that Rooze has ( hopefully ) done his best to get them in the right spot. If such is not the case, then speaker placement should be done first and then one can calculate proper placement for room treatments from there. Not all rooms should be treated identically or following set formulas as the radiation pattern of the speakers to be used will alter what is required. As such, you can set up a room for one set of speakers and end up requiring a different configuration when you change speakers. Sean
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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: 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: 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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This is strictly a guess, so take it for what it is worth.

My "guess" is that the reflection from the back wave of your Maggies is "colliding" with the front wave at these distances. As such, you're experiencing out of phase cancellation, reducing the spl. The reason that this takes place over a specific area is that sound waves are all different lengths. One batch of frequencies is nulled at 16', another batch at 18' and the frequencies between those points at 17'. As such, you have a noticeable broad band dip at this specific distance.

In front and behind those distances, you'll experience reinforcement of those frequencies ( to varying degrees ) but cancellation of other frequencies. The key is to find the point that allows the most neutral tonal balance while still allowing good to optimum soundstaging / imaging. Since a microphone and test gear don't hear or process information the same as our brain does, using equipment and tools to get you in the area is fine, but trust your ears.

As far as doing the math to figure out the wavelengths and reflected paths, a room with irregular shapes, sizes and / or irregular non-solid objects that break up reflections can cause pretty erratic results. This is the reason that the acoustic modeling program called C.A.R.A. wants to know as much as possible about your room, it's shape and size, what you have in it, the speakers radiation pattern, etc... The more info that one can provide an acoustician or a program similar to CARA with, the more likely the results are to be accurate.

As far as "boosting" the spl's and linearizing the frequency response at that distance, this can be done. It will take a lot of work and will completely change the presentation that you hear at any given distance. This is because you'll be "squashing" the back wave to minimize cancellations and reflections. In effect, you will probably end up losing many of the desirable attributes of the Maggies that attracted you to them to begin with.

As a side note, with Maggies at 12' apart with a very mild amount of toe-in, 16' - 18' is too far back in my opinion. Then again, i don't know the specifics of the room or anything else about this installation, so keep experimenting and learning as you go. This can be a very educational and beneficial time for you in terms of learning via first hand experience. If you really get serious and start doing a lot of experimenting, keep a notebook. I would also make cohesive notes, not just jot down things at random. You might not look at these notes for a while and by that time, you may have forgotten some of the specifics of your "abbreviated" notes. Sean
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I did a post not that long ago giving a brief run-down on the method that i generally use for setting up speakers. It is somewhat of a universal approach that works regardless of room or speaker size and takes into account tonal balance and soundstage / imaging. Only problem is, i can't remember what thread it was in and it's too long to type out again. I'll see if i can find it or hopefully, someone else will point us to it. Sean
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PS... As a general rule, i prefer little to no toe in. Then again, that is with using the approach that i mentioned above.

Aargon: Found the thread that i posted a basic and relatively universal speaker set up method in. It it just so happens that Rooze started that one too : )

Look for a thread of his entitled "problems with Maggie 3.6's" or something to that effect. This should answer your questions and then some. Sean
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