Axiom Home Page Forums General Discussion Advice from Axiom Owners Advice on Freq. Resp. (Wide Photo!!)

OK… now you'll all realize why I'm taking so long to post my big "impressions" article! Sorry about the scrolling, if I resize it to fit in the BBS, no one could read the text!

Below is a frequency response plot that I took a few hours ago. I wanted to see if I could actually chart the different responses from an M60 up against the wall, 12" out and 18" out. In this case, I also added a plot for 18" out with a sound blanket on the floor and wall alongside the speaker. This plot is for the M60 by itself; receiver set to "large" and sub off.

I've been mentioning in this forum for awhile how problematic my room is, and I've been doing some free-hand drawn plotting here and there with my RS meter and a disc of test tones that I made…. I probably have 30 of them at this point! Looking at this one though, I decided to draw it in Photoshop (instead of scanning a hand drawn one) and post it here for opinions.



This shows the enormous peaks and valleys that I'm dealing with…one of which is a 25db swing! The area where that valley is centered (60Hz) also reflects in plots from my Left speaker AND the sub… i.e., it's the room, not the M60.

There's a photo positioned in the upper-right corner of the graph to demonstrate the setup as far as where the speaker is located. Here's a photo showing the setup with the sound blanket:



FWIW, I've plotted the sub out of the corner position as well and find it plots close to the same for all locations, so I figure I might as well leave it in the corner for aesthetics and gain.

I tried the blanket because I thought many of the problems were reflections from the floor and wall to the right. As you can tell, the plot with the sound blanket helps a bit, but not much. Now I know that room plots are always a bit scary looking- they never are as smooth as one would hope. But this chart really looks to be off the…ummm…charts! In all honest, I'm not unhappy with the way things sound in comparison to my old speakers, but I have to believe it would be much better if I can smooth some of this out!

As I've mentioned here, I'm considering a BFD to help with my bass situation. If I change my M60s to "small" from my current "large" setting and enable the sub (with BFD) handle all the bass, maybe I can at least tame the peaks.

Any thoughts? Burn the house down and start again?

/runs away screaming!

I'm not seeing this! I don't even want to know what my room response is!

I'm not seeing the image, for some reason... ?

I added a couple of sentences...i.e. was editing the post. Try reloading the page?

Nope. Maybe my work firewall is the culprit. I'll look later. But if it makes you feel at all better, Mark, I spent several hours last night trying to tame my freq. curves. My sub went from 77 dB SPL to 113 db SPL between 25 Hz and 50 Hz!!!

With the Behringer Feedback Destroyer, I've been able to tame it a bit - now it's more like 80 dB to 95 dB. So it's going to be an ongoing project. But without seeing your frequency problems, I bet they're treatable with some EQing, if nothing else works.

The BFD is recommended for taming peaks rather thatn filling in holes, right? That 60Hz hole is going to be a b**** remedy.

Filling holes is hard. You hit a ceiling after a point and then you'll lose all headroom and bad things happen.

Of course, in theory, I suppose you could turn the levels on the sub way up (such as a doubling it, which I know the 3910 will let you do) so that the lower part of your valleys are near the ideal level and everything else is outrageously loud... then you could cut all that other stuff down.

Don't know if I'd recommend such a couse, or what attendant problems that might bring, though...

Well, maybe I should ask:
Is this really that unusual a plot? I know that many people get scary plots in their rooms.... maybe I should stop banging my head against the wall?

I EQ'd my QS-8s last night based on their plots and planned on doing the same for the M60s anyway. I guess I'm just concerned that trying to correct huge swings like these via EQ will introduce some funky phase problems, etc....

Considering I do like them anyway, I'd love to hear them in a good room!

I remember reading something a while ago that about how our brains do a good job of filtering out the specific signature a room gives to sound. I think Dr. Hsu said it.

To make an analogy, it's akin to wearing ski goggles. When you first put them on, everything looks decidely tinted. But then your eyes adjust over the period of a few minutes and everything looks normal again. When you take the goggles off at the end of the day, all the colors seem off again.

Have you tried to plot a graph with both speakers + sub? The sub might help smooth out some of the low frequencies.

I do mine with both mains + sub using the Rives Audio Test CD 2 (corrected for RS meter). All frequencies from 20Hz-10Khz are within +/- 6db at the main listening position. I do have some diy room treatments plus lots of plushy stuff in the room.

BTW, the RS meter is not designed for frequencies above 10KHz.