somebody help me out here..

who knows more about this then me. after getting my room correction system, i got curious to know what it was correcting and how much. so i downloaded a buncha test tones and got a ratshack sound meter. the results were suprising and also somewhat confusing. (i tried uploading pix but it almost always fails with flickr, so sorry about the clicking. also i apologize for the crappy cell fone pix, but you'll get the idea).

http://www.flickr.com/photos/38854667@N00/3443165546/

well the first thing is that wow, it's almost ruler flat for most of it! and yes, that's useable bass at 32hz, less then 3dB down (vantages)! but what is going on at the top? close up:

http://www.flickr.com/photos/38854667@N00/3443165498/in/photostream/

so if you can't read the blurry numbers, it drops off at 4khz, down some more at 5khz, jumps up at 6.5khz, up more at 8khz, then rolls off at 10, 12.5, 16 khz. the same thing happens with the room correction off, so it's not the processor doing it. i haven't really seen a frequency response graph like this ever! most of them jump around down low and early mid, then flatten out. i would think a suck out at 4-5khz would be caused by a lot of absorptive stuff like carpet and furniture. but i have all hardwood, only a few pieces of furniture, reflective walls, vaulted ceiling? i have curtains behind and to the sides of the speakers, but i wouldn't think that would cause it? and i've never thought of ML's as being 'rolled off', their known for their mids/highs, right? down 10dB above 10khz? does this make sense to anyone?

Hi Ratso,

Does your system sound dull as the numbers would suggest?

GG

actually gordon, my system sounds great in comparison as to how it sounded before! i have already gone through numerous speakers and equipment trying to get a halfway decent sound out of my crappy (acoustically that is) room. the room correction has been a blessing to me, and has easily made i would say a 50% improvement subjectively. but now i'm wondering if i could still make some more strides. the problem is i would think that this is still all related to my room, and i'm not willing to hang weird panels all over the place. (and yes, even if they're pretty colored weird panels).

Gordon Gray said:

Hi Ratso,

Does your system sound dull as the numbers would suggest?

GG

Click to expand...

Does your room have a wood floor? Those numbers are typical of a wood floor around it's point of resonance. Try a throw rug in front of your speakers and centered between them.

ratso said:

wow, it's almost ruler flat for most of it!

Click to expand...

I can't see the data clearly, especially the vertical deviation. Regardless, I'll try to let you down easy.

The best way to measure the response at low frequencies is at a very high resolution. Like 1/24 octave or even higher. Spot checking the response at 1/3 octave frequencies hides the true extent of the peaks and nulls, especially the nulls. As an example, the graph below shows the very same data expressed at 1/3 and 1/12 octave resolution. Even 1/12 octave is not fine enough to see the true response. If you're serious about this stuff, you might consider getting software to measure more accurately. The Room EQ Wizard program is free, and is much better than using simple test tones.

--Ethan

DrJRapp said:

Does your room have a wood floor? Those numbers are typical of a wood floor around it's point of resonance. Try a throw rug in front of your speakers and centered between them.

Click to expand...

thanx to both of you for that! i will go get a throw rug ASAP and see if that helps some, i think i could improvise something to test it out beforehand. as for the program, i've looked at it before but my cheapo dell with it's built in soundcard won't support it. i know i can work around that, but to be honest, it's a few more hoops then i want to jump through. i have heard good things about it though, so very good advice indeed.

Ratso, the RatShack meter is pretty inaccurate at both ends of the spectrum, so unless your graph included corrections for it, don't be too surprised.

And as Ethan notes, a single point sample can be pretty misleading as well.

In another thread here we are talking about measurement tools, you might want to join that discussion as well.

thanx jon! i should point out that i pretty much realized what you guys have stated about the accuracy of my testing methods and equipment. i was really just looking for a quick 'thumbnail' sketch of what was going on with my system. i have played with some of the ratshack correction tables.

But the real reason i wanted to come on today, is i had an unexpected day off from work today (damn economy) so i spent the day playing with my stereo. tried the rug in front of the speakers, didn't seem to make a diff one way or the other, either to my meter or my ear. ditto with curtains open or closed behind the speakers. but to my surprise i quickly and cleanly cleared up that 4k-10k suckout/spike with one of our favorite 'tweaks' - the ol' tilt the ML's forward! put the rear spikes on, took out the front ones and ta-da! no more upper-mid weirdness. sounds great too! no wonder why we all like that tweak so much, i'm not sure exactly why i stopped doing it.

JonFo said:

Ratso, the RatShack meter is pretty inaccurate at both ends of the spectrum, so unless your graph included corrections for it, don't be too surprised.

And as Ethan notes, a single point sample can be pretty misleading as well.

In another thread here we are talking about measurement tools, you might want to join that discussion as well.

Click to expand...