Help Me Interpret a Few Waterfalls

[DaFuente]

I've just finished the first phase of treating my room and I'm unsure of how to interpret the resulting waterfall graphs. The room is small (10x12x8), so I basically had to treat every single surface (4" 703 straddling the corners, 4" around the RFZ, 2" around the back. The result is a dead room that is great for mixing and mastering. Modal issues are still there, but nowhere near the magnitude they once were. I'm hoping to install some panel traps soon to target them.

Anyway, Fuzzmeasure defaults to -102 db as the baseline, but my signal seems to be around -15 at the max. Do I really need to worry about an 87db drop, or should I focus more on a drop of around 60 (putting it at -75 db)?

Here's some charts showing what I mean. For the untreated room you have to bring it out to about 4000ms to see the end of the mountain. This are all with 1/12 octave smoothing.

Default Fuzzmeasure graph of untreated room:


Fuzzmeasure graph of untreated room at -75db:


Default Fuzzmeasure graph of TREATED room:


Fuzzmeasure graph of treated room at -75db:


Hope all this makes sense. Looking forward to your suggestions.

[Ethan Winer]

Clearly, the treated version is much better.

I usually display waterfalls up to 300 Hz or maybe 400 Hz max, and set the vertical range to 30 dB or maybe 40 dB max. This makes it easier to see the important part of the decays.

--Ethan

[Weasel9992]

Holy cow...that's a big difference. That room is looking pretty good!

Frank

[DaFuente]

It's great so far! I actually did the project as my master's thesis, so I pulled out all the stops. AND it gave me an excuse to build a room that works as a studio.

As soon as I'm done (defending on Dec 17), I will post a thread on the build.

Oooh, quick question. The literature would suggest that for a small room, RT60 is rather worthless. Fuzzmeasure will give you T20, T30, and EDT...are any of those viable for small rooms?

Thanks for the responses, guys.

[jhbrandt]

Originally Posted by DaFuente

Oooh, quick question. The literature would suggest that for a small room, RT60 is rather worthless. Fuzzmeasure will give you T20, T30, and EDT...are any of those viable for small rooms?

Yes RTanything is rather worthless in small rooms. True.

What you are looking for is decay slope. You see the decay response of your treated room is very much better in the mid-rang and high, but there is still a long tail to the decay of the LF.

Of course it is caused by modal ringing, and I would suggest more bass trapping and maybe a little less absorption in the mids and highs to balance the decay. Your room then will not be so 'dead'. You could also add some diffusion elements to help the room sound larger and more natural.

Dead rooms really are not the best - they are only the best that some can do with given their circumstances.

Here is an interesting little paper I have just finished on the topic of modal decay. - comments are welcomed.

Cheers,
- John