Help interpreting my REW graphs

[Soundman2020]

Sent you a PM... not sure if you saw it?


- Stuart -

[wiz1der]

Sent you a PM... not sure if you saw it?


- Stuart -

Yes sir, I got it. I plan on loading and re-measuring this weekend. I'll get the new graphs right back to you!

Thanks for your help!

[wiz1der]

So, just an update to my post.

I have to say that my room sounds 1,000 times better than it did when I started this thread, and I want to publicly thank Stuart (soundman2020) for this!

He worked with me through PM's and we were able to get the room way past my expectations! A room the size of mine will never be perfect (and I knew that going in), partly because I have a ton of gear in it that I just cant part with right now and the arrangement of gear gives the room uneven symmetry, but I am now able to turn out product that is on par with the professional studios I have been working in for 28+ years!

I won't go into details with graphs, because I don't fully understand how to explain it all, but Stuart is more than welcome to post before and after if he'd like.

Here's to you Stuart!

[Soundman2020]

I have to say that my room sounds 1,000 times better than it did when I started this thread, and I want to publicly thank Stuart (soundman2020) for this!

He worked with me through PM's and we were able to get the room way past my expectations! A room the size of mine will never be perfect (and I knew that going in), partly because I have a ton of gear in it that I just cant part with right now and the arrangement of gear gives the room uneven symmetry, but I am now able to turn out product that is on par with the professional studios I have been working in for 28+ years!

Cool! Glad you liked the results! And thanks for the kind words.

I won't go into details with graphs, because I don't fully understand how to explain it all, but Stuart is more than welcome to post before and after if he'd like.

No problem!


Here's how your low-end frequency response looked before:

wiz1--FR--18-1500--1..24--ORIGINAL.png

And how it looks now:

wiz1--FR--18-1500--1..24--FINAL.png

Both show the entire low end and low-mid part of the spectrum: 18 Hz to 1500 Hz, smoothed to 1/24 octave for clarity. Originally, there was around 24 dB of variation (+/-12 dB), and that is now down to +/-7 dB, so I'd call that pretty good!

But of course, frequency response is not the only indicator of room acoustics: it's just a small part. Equally important (or maybe even more important) is the time-domain response: how the room behaves over time.

So here's the waterfall plots, for "before" and "after":

wiz1--WF--18-500--1..48--ORIGINAL.png

wiz1--WF--18-500--1..48--FINAL.png

In this case, the graphs cover just the low end, from 18Hz to500 Hz, which is the most important part of the spectrum for this. You can clearly see how much smoother and more even the decay times are. The "ringing" at 120 Hz in the second graph is not acoustic: it's a mains hum problem that Wiz1der is chasing down. So that's just electrical noise picked up by the mic, and is not actually in the room at all! It's a pity, because it gives the wrong impression: the graph is actually even smoother that what you see, because that problem is not really there at all.

Next up, the "before" and "after" for the spectrogram:

wiz1--SP--18-1500--.--ORIGINAL.png

wiz1--SP--18-1500--.--FINAL.png

Frequency range is 18 Hz to 1,500 Hz here as well.

Once again, you can see how much smoother the low end response is. And once again, the "glitch" at 120 Hz is not really there either: Just noise picked up in the mic cable. Probably a grounding issue.

So there you have it! Overall, a much, much better outcome! And very much audible! It makes the room totally usable for serious mixing, whereas before it wasn't. The low-end response (a key factor in any room) is now clean, smooth, and tight. Most of the worst artifacts have been dealt with, and there's clarity and depth that wasn't there before.


So what's the secret?

How did we accomplish this?

Well, first and foremost comes good acoustic treatment. That's the basis. Without that, nothing more can be done. So first get the bass trapping in, then deal with the first reflections, then smooth out some of the mid range issues, and a few other things.

Now comes the part that I don't like talking about much, but it can help to put the "icing on the cake" so to speak: It's the final touch, once the acoustic treatment is in place. I call it "digital tuning". Some people call it "room correction", but that's actually a terrible name, because it does NOT "correct" the "room" at all! It gives totally the wrong impression, because people think that if they buy a "room correction" plug-in, or a "room correction" hardware box, or "room correcting" speakers, then everything will be great, and they'll get fantastic sound in any room, with razor flat response! Garbage. Pure trash. Absolute lie. Nothing could be further from the truth. That's pure hype put out by some manufacturers, and this is the reason I do not like talking about it, because it looks like I'm saying that room correction is a good thing: it is NOT a good thing when used in ignorance, without a clear and deep understanding of what it does, and how to use it.

Here's the problem: room correction software and hardware is ONLY useful IF the room is already well treated, acoustically. Period. If the room is not fully treated already, then room correction will likely make things worse, not better. It might sound flatter at the mix position, but at the expense of something else. There's no free lunch here: if you adjust one parameter to make it better, then it MUST make another parameter worse. Simple math. You might manage to fill in a dip in the frequency response, but at the expense of the time response, or the phase. In other words, the frequency response graph might look flatter, but the phase will shift wildly, and that frequency will now "ring", almost like it was a room mode. You can't get something for nothing in an untreated room. It does not work.

Some unscrupulous manufacturers of "room correction" products want you to believe that you just plug in your speakers, plug in a mic, press the magic button, and the system will figure it all out, spread some pixie dust, and make the room perfectly flat, smooth, and even. Not so. Snake oil.

That's why I do NOT call what I did here "room correction", because it does not correct the room, and can only work under a specific set of circumstances. That's why I call it "digital tuning". Perhaps a better term would be "electronic tuning", because it does not have to be done digitally, but that's the best way to do it, and that's the way I do it, so I'm sticking with "digital tuning".

I'm not going to go into all the details, as it gets rather complex and technical, but as you can see, when done PROPERLY, it does work.... provided that the room has already been treated well!

So basically, what I'm saying is: "Don't try this at home, kids. You might hurt yourself!" It's hard to do right, and easy to do wrong. When done wrong, it makes things worse, not better.

Just think that, as Wiz1der mentioned, he's been mixing in pro studios for over 28 years, and has a really good understanding of rooms, acoustics, sound, treatment, equipment, speakers, layouts, digital gear, mics, and etc., etc. But he was smart enough to not attempt it himself! He knows how a room should sound in order to be usable, realized his was not sounding that way at all, and got the help he needed, instead of trying to do it himself.

That's the smart way to do it, but I'm betting that many folks who read this will try it any way, and think they have done something wonderful for their room, as they see a flatter frequency response graph... not realizing what a mess they have made of the phase, ETC, and decay...

Which takes us back to the reason why I don't like talking about it...

So, what we did here was FIRST install suitable acoustic treatment, and THEN do some gentle digital tuning for those parts of the spectrum where it could help, carefully crafted to NOT do any harm, and without any attempt to fix things that cannot be fixed like this. That's why there's still some unevenness in a few places that looks like it would be "easy" to fix with digital tuning, but in fact cannot be touched in reality, as it would create artifacts that aren't there currently, and would be worse than the problem they "fix". Some of those could still be improved with additional acoustic treatment, yes, and that treatment might then allow further digital tuning, but Wiz1der is happy with the way his room is working right now (since it is now as good as any pro room he has worked in!), and understands that although the additional improvements might flatten the graphs more, the result would not necessarily be audible enough to be worthwhile. The room already meets his goals of being plenty good enough to do the same level of mixing that he's done for decades in high-end pro rooms, so there's probably not much need to go further, at this stage. (Maybe one day... )

By the way Wiz1der: Congratulations on the outcome of your room! The room looks great, the acoustic graphs look great, the room sounds great, you are mixing cleanly like never before, and making money, so ... mission accomplished!

- Stuart -