200 Hz spike might be a wall reflection reinforcement from your main speakers. If your main speaker baffle is 43 CM from the rear or 43 cm from the corner wall ( measured to furthest edge of speaker from wall ) then this would explain a boost at 200 HZ.
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My last post is the speaker to wall distance for a downward cancellation spike at 200HZ (not reinforcement...oops).
If you are seeing an upward spike or reinforcement at 200 HZ then the distance from the rear wall to the front baffle of your main speakers would need to be about 60 CM to cause this.
Sorry for the error on last post.
thats what i am not sure of. How to locate where the spike is. I charted the frequencys on the graph to find the spikes and i did a map of the room, however i am not sure how to actually find where the spikes are......
I am using def tech 7004 towers which are bipoles. I have played with speaker position as far as the mains are concerned and have found no change. Any ideas?
Dzigon, Are you taking the measurements from the listening seat (sweet spot)? For the most part that is the most important location. Also, it appears that you have a multi channel set up. Assuming that you have taken the measurements from the sweet spot, have you tried doing the measurement proceedure with only the two stereo channels operating, and then adding the additional channels one at a time to see if there are variances. Perhaps the spikes you mention are aas a result of the placement of the extra channels. How big are the spikes you are finding?
Placed spl on tripod in "MY SEAT"(sweetspot). Actually, you must have been reading my mind. Initially, i had the tones playing from the mains, then measured again playing tones through 7 ch. stereo.. The 200hz spike is about 10db higher, the other approx 8db higher. I am not sure how i can add the other ch. one at a time but will give it a shot tonight.
My system is a Yamaha rx1500(using as a pre/pro) with an Adcom 7ch amp, 7.2 ch system. I know its not considered "audiophile" equiptment but I'll tell you what, each time i have experimented with a "cheap tweak" that i have learned about through this site and others, there has been a "nice" improvement every time. Soundstage, etc. are like night and day from my initial set up. I have had this set up about a year now and i think once i am finished with room treatments i am going to be done.,.I'll let you know what happens.....thanks for the advice..dz
Is your room 27 by 15 with 9 foot ceilings?
If it is you will get a response bump between 190 Hz and 230 Hz (roughly).
You can see this on a mode plot.
To get the excel file for this calculation, click this link