Axiom Home Page Forums General Discussion Home Theater Speaker matching/imaging question

Hey, I finally got my system set up (pics will follow when i get the place cleaned up). My question is about speaker matching. I have a VP150, and 2 M60s as fronts. When the sound pans from front to left or visa versa, there is a noticable disconnect between speakers. I have somewhat calibrated my system (using the auto calibration with the Onkyo 605) so my speaker levels arent off, and my stereo imaging is pretty much smack dab in the middle. I have thought these might be sources of the problem

-My fronts are too far apart (about 11 ft apart, i sit 9 or so feet from screen)
-The levels arent really calibrated. I dont have an SPL meter
-There is more open space around the Front left, rather than the Right
-my center channel is on top of my tv (about 50 inches) and pointed down at me, whereas the M60s are on the floor
-my toe in is either too great, or not great enough

Any help would be great,

Thanks

Please don't take the following the wrong way: did you triple check that your speakers are all in phase (+/- connectors)? It sounds silly, but it happened to me once (bad movement between speakers) and after wasting 2-3 hours of toeing-in, distance and levels... I decided to go back to basics and... ta da! The day before I had changed connectors on a cable; I had dropped the cable then picked it up; and then I properly connected +/- (based on the writing on the cable).... It turned out that the cable (not done by me) was inverted! So, as long as it was inverted to both ends, I was OK. As soon as I accidentally "repaired it", I was screwed!

So, this is probably not your case, but you may want to have another look to make sure.

I can't say for certain but, after trying the remedy suggested above, you may want to try calibrating with a SPL meter. Many around here will mention that the auto calibration leaves something to be desired. I'm always amazed at how poorly I do it by ear and swear by my SPL meter.

If I understand correctly, it is also ideas to make a equilateral triangle with yourself and the front mains. So, perhaps try sitting ~ 9 ft from each of the mains with ~ 9 ft separation between them.

Good luck mate.

Try all of the following in the following order:

1. For a perfect equilateral triangle, you should be 5.5*tan60=9.5 feet away from your monitor. Half a foot makes a big difference. If you can't move back, then place your speakers 2*9/tan60 apart or 10.4 feet.

2. Toe them in so that the tweeters are aiming about a foot behind your head. To ensure the perfect toe-in, some use a laser interferometer .

3. Calibrate with an SPL meter as suggested above.

4. Then, re-calibrate using your ears. If there is more open space around the front left, you will have to decrease the front right and increase the front left gains. I have the exact same issue (see picture below) and had to do the same thing. Keep tweaking with the channel levels until the image is in the centre. The pink noise calibration doesn't work well when you don't have symmetrical reflective surfaces.

5. Find the correct setting for your 500's phase switch. Here's how. Set your receiver's main volume control to your normal listening level (mine is -20dB). Turn off all your speakers and leave just the sub on. Set up the SPL meter right at your sweet spot on dBC, slow. Play a test tone that exactly matches your receiver's cut-off frequency. So if it's 80Hz, play an 80Hz tone. Flip the phase switch one way and then the other. Keep the setting that results in the highest SPL. In my room, there is as much as a 15dB difference between the two settings.

6. Make sure your front speakers and your sub are matched at the cross-over frequency. With your front speakers still off, record the SPL. Now turn the sub off and turn your mains on. Record the SPL. Now turn the mains off and turn the sub on. Using your receiver's sub level control, adjust the volume of the sub channel to match the mains SPL.

5 & 6 above sound complicated but they really aren't. I'll be posting separately to explain more about this.

The fact that your M80 tweeters and centre tweeters are not aligned horizontally is not good for panning especially since you are sitting somewhat close. Sorry, I don't know what to suggest about this. Maybe someone that has more experience with this can help.

Hi aouimet,

Your fronts are too far apart. On initial setup, I generally advise separation of no more than about half the seating distance or a bit more--try 6 or 7 feet maximum between your front left and right. That way you'll avoid the potential hole-in-the-middle effect that may occur with too much separation. I've never endorsed the equilateral triangle approach--it may work fine in some rooms but certainly not all, and it's better to start with much less separation.

The out-of-phase advice is excellent. That might be the problem, but reduce the separation of your fronts anyway.

Is there any way to try the VP150 below the TV angled upwards? That might help.

If the right front speaker is in a corner, move it away. Corners are almost never good places for any speakers because of the undesirable bass coloration and unwanted reflections.

Be sure you don't use the ONkyo's auto-EQ, which may do nasty things to good, linear loudspeakers like Axioms. You can use the auto-setup until you get an SPL meter and do it manually.

Regards,

Randy,

That's a very good point and I agree that it's nothing to worry about. Going through all those steps though would still be good due diligence.

Adam, it isn't entirely clear how you're defining "disconnect" and you're getting varying responses. Are you experiencing a substantial variation in output level or is it instead a variation in tonality? If it's the latter, as Randy pointed out, you have to keep in mind that the center speaker is of significantly different design and will sound different; this is one of the reasons why the ideal would be to have a center speaker identical in orientation and as identical as possible to the mains in frequency response.

The several points that you list don't appear to be major problems: the separation is just slightly wider than usually suggested, but should be okay if you have enough toe-in so that the tweeters point at your ears; the level calibration that Audyssey did should be reliable if the instructions were followed and it's unlikely that adding human error by way of a manual calibration with an SPL meter would result in higher accuracy.