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fine tuning speaker placement

Just moved to a new home with a 22Lx14Wx10H ft room and trying to fine tune the speaker placement. Room is untreated. Speakers are Avalon Diamonds.

I first use a velodyne subwoofer test tone analyzer (only up to 200Hz). I moved the speakers around as I watch the frequency graph changes. Then I position the MIC in several possible seating posistion to find a seating position. Speakers ended up at 4ft 6inches from the front wall & 3ft 4inchnes from the side. I am sitting 3 ft from the rear wall

Next, i use a PAAA3 spectral analzer to check the 20-20Khz response and ended up with >10db narrow band suckout at 3.6Khz, the rest of the spectrum is resonable flat.

My questions:
1. Is there a spectral analyzer that generates a curve repeatedly on a screen similar to the velodyne unit but do the full spectrum? I find this more convenient as I can see the chnages on a graph while moving the speakers around.

2. Is it time to play with toe in to minimize the 3.6Khz null or should I treat the room? I am new to room treatments and is GIK package 3 a good place to start?

3. My measurements correlate well with the Cara simulation on Rives audio website. According to the simulation, another good location would be putting the speakers halfway into room. This is PITA because my speaker cables are not long enough and that means moving the rack, too. I am missing some midrange clarity and soundstage depth in comparing to putting the speakers 7ft from the front wall. However, the bass is very uneven.

4. The frequency response changes tremendously with tiny variation of head position (dist to rear wall). what do u use to position the mic precisely. Would the average of two meaurements ( one for each ear) be more accurate than one measurement betw the ears?

Many thanks
128x128glai
pacific_island_audio
49 posts
 
Frequency variation with small changes in position is normal in the high frequencies. If all you have is the 3.6 kHz dip, you're doing very well. The front and side wall spacing you've calculated should be working nicely for you. I doubt half way into the room will improve much. It will change your measurements, but will it improve? Only your ears can tell you that.

Unless I've done my math wrong, you're sitting 10' 8" from the speakers. You might try moving your listening position up 1 or 2 feet from the back wall (2' would put you at about the equilateral triangle position). This will increase the direct to reflected sound ratio and should improve both transients and clarity—not dramatically, but noticeably. You can experiment with toe-in from there. Sometimes a very slight toe-in is all it takes. Give yourself plenty of listening time with many different recordings. It may take some days or weeks before you get it settled.
glai's avatar
glai OP
446 posts
 
By moving either the speakers into the room or the listening chair into the room, there will be a 10db suckout at 40-50Hz. However, the midrange and depth perception are better.

If I move to speakers with 13 inch woofers, would that allow me to move the speakers further into the room and fill in the 40-50Hz area?
peter_s
1,348 posts
 
I agree with all the trial and error suggestions above. I need to do the same with my Avalon Indras, which I recently purchased. If you do want to visualize your results though, and have a computer available, consider purchasing "TrueRTA" on the web and a behringer mic made for calibration (around $60 from Musician's Friend). You can use it to continuously generate pink noise and view your frequency response.
newbee
4,767 posts
 
Size of the woofer shouldn't make a difference - it's the room & location that count. BTW I have a 40 and 50 hz suck out of 6db at 50hz, 5db at 40hz, but I'm flat at 60hz and 32hz and I had to fine tune speaker/chair locations to get it down this low. I started off at about 10db too. I think this was primarily due to my chairs location but I did have to move the speakers a bit too. This has existed in my room regardless of speakers, including electrostats and planers. That is a trade off that disturbes me not! The width, depth, and clarity issues (pin point imaging) that I get are just excellent. I see the suck out more on my graphs than I actually hear the result of it. :-)
blindjim
3,092 posts
 
Newbee

What else could overcome a suck out at lower HZ? Is a suck out the same as a null?

Before renovating my room my hump, bump, or issue in bass was noticed between 50 & 60hz, which I understand that at that point, it is a reflection of an issue at still lower hz, and continues on at double the freq... ie., 110, 220, etc. The on paper (theoretical or supposed) trouble spot is 52.3hz as I recall... based again, slely on physical dimensions only.

I ask as, well, this is my problem, but was wondering, perhaps what is happening with this threads posters room isn't the result of another problem taht began at a lower Freq, and culminates or is realized, further up the bandwidth?
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