The Truth Hurts - REW and my room...

[losthighway]

^ It was radical.

Also means that next time I ask for notes on a mastering job you hopefully won't have to explain how you needed a lot of dynamic eq to tame some wild lows on the bass guitar..... Hopefully.

[Dok]

Anyway, no amount of treatment is gonna get rid of that null

???

That's exactly what proper room treatment does.

I don't feel like arguing so I'll just say that going from a 15db null at 80 to half that at 95 is a HUGE improvement and losthighway I hope you did a little celebration dance.

I'd argue that putting the speakers against the wall did much more to fix that null than the extra treatment. Unless you can explain how more absorption can fix a null? Really not trying to be cheeky, but I don't understand how that principle works. There'd be a pretty easy way for losthighway to test which change did more of the heavy lifting.

[MoreSpaceEcho]

He didn't add any extra treatment, he just moved the speakers.

Obviously finding the best spot for the speakers/listening position is step one.

If someone has a huge null at 80, it's not because there isn't enough 80 in the room, it's because that freq is getting cancelled at the listening position. Change the listening position or the position of the speakers and the null will change/move. Anyone can test this for themselves in 2 seconds by just playing some tones and moving around the room.

Put a pair of speakers in an empty room. Measure the response. It's likely to be very bad, with big peaks and nulls. Add appropriate treatment and measure again, the peaks and nulls will have improved. This is rudimentary stuff.

Trying to fix a big null at 80 with a sub, I just don't get it. You can't tell a sub to put out just a half octave either side of 80hz to fill up your null. They're going to put out everything under whatever you have the low pass filter set at. So you set the filter as high as it'll go and crank the output of the sub to try and fill up the 80hz hole and now you have a whole other problem because with the sub cranked there's now a ton of40hz shaking the building. And this is a much worse problem.

[losthighway]

^ Yes.

To put it another way, think of the geometry of the following variables: sound source, wavelength of any specific frequency, distance to a wall.

I can almost imagine putting the speakers on a moving walkway and playing the room modes like a wah pedal.

[The Scum]

Room modes and SBIR are both phenomena caused by sound bouncing around inside a room.

If you attenuate (absorb) the energy of the bounces, those phenomena are reduced. There is less energy in the reflected waves to cancel/reinforce vs the initial wave.

A totally free field (and an anechoic chamber) won't exhibit either of them.

[MoreSpaceEcho]

Right.

I should've mentioned before that you can't just look at the freq response, you need to look at the decay time as well. In an untreated room, the decay time will be really long, especially at low frequencies. All that ringing is what causes the peaks/nulls. The only way to shorten the decay time is to absorb the freqs, or be outside.

[Dok]

He didn't add any extra treatment, he just moved the speakers.

Trying to fix a big null at 80 with a sub, I just don't get it. You can't tell a sub to put out just a half octave either side of 80hz to fill up your null. They're going to put out everything under whatever you have the low pass filter set at. So you set the filter as high as it'll go and crank the output of the sub to try and fill up the 80hz hole and now you have a whole other problem because with the sub cranked there's now a ton of40hz shaking the building. And this is a much worse problem.

With some added corner trap action I went from a 15 db hole at 80 hz to a 5-10 db hole around 95.

I guess I'm confused then because this seems like it's attributing fixing the null to the added absorption. I'm certainly not saying acoustic treatment isn't necessary but you cannot trap a null away.

As for the principle behind using subs activating room modes to fill out nulls in the listening position, I would again point you to the two articles I posted as well as my previous comment. You're not trying to throw 80Hz from the sub (to use your example) back into the room, you're only trying to excite the room modes to add to where the physics dictate there must be a null according to the dimensions of your room and the positions of the components of your listening system, nor do your sub(s) have to be particularly loud. But you can't just put a subwoofer anywhere in the room and expect it to work - you still have to put it in the right spot, measure the results, and make adjustments accordingly, just like with your main monitors and listening position. It absolutely feels counterintuitive but you don't have to "get it" for it to be true. Anybody can test it, anybody can measure the results and see for themselves. It works and is reproducible in every single room I've ever tried it in. And it sure beats fumbling around in the dark and trying to guess where to put more expensive absorption than may be necessary while pulling your hair out wondering why your low end never seems to translate.

Anyway, I appreciate your comments - I'm also not trying to have an argument, just to add helpful information that took me a long time to understand after reading many years of unhelpful forum posts that took me further away from my goals. If people don't want to try subs and they're happy with how things are sounding, great, but this understanding was a huge milestone for me in being able to quickly set up my rooms and get to making music.

[losthighway]

^ Yes, to clarify. I made two changes this week. Step one: move speakers, big improvement. Step two: add trapping, small improvement.

Next is step three: more trapping. I hope for another small improvement.

[digitaldrummer]

sounds familiar. if I recall, I ended up moving my monitors a bit closer to the wall, which also had more trapping behind/around it. My room will never be perfect. I have shelves full of snare drums (as well as a drum kit always setup) that will ring and buzz depending on the frequencies. I turn off the snares and can throw towels on the drums if needed (like when making measurements), but otherwise its what my room sounds like...

[losthighway]

My room will never be perfect.

Yeah, I feel that.

At least with measurement we know our rooms' weak points. This way I won't go crazy boosting underrepresented frequencies with eq when mixing. Kind of suspension of disbelief, but at least based on data.

The other thing I realized when I started measuring is the nulls can fill in, or at least move when I moved the measurement mic back 5 feet. I'll check now that I've altered things, but I figure if I have to step back to get perspective on the bass in the middle of mixing that's not terrible.

[MoreSpaceEcho]

you cannot trap a null away.

You absolutely can.

I give up!

[Scodiddly]

Trying to fix a big null at 80 with a sub, I just don't get it. You can't tell a sub to put out just a half octave either side of 80hz to fill up your null.

Sure you can. It's called a speaker processor. They're de rigeur in the concert sound world.

[MoreSpaceEcho]

I didn't know that! Do you know of anyone doing that in a studio setting though?

[Scodiddly]

I didn't know that! Do you know of anyone doing that in a studio setting though?

Did one for a guy a few years ago. I don't know how common it is, though - customer was a friend of the boss. I would guess that most people either don't think about it, or it's a hidden part of the complete system from one manufacturer.

[vvv]

I know nothing.

Just my uninformed opinion on this:

I frequently read that EQ, and digital processing including but not limited to digital EQ, affects phase.

But I'm a guy who tries to avoiding using modeling because I find it ultimately un-satisfying.

For me, there'll be no digital modeling or processed speakers at Fetacentral DDL.