# What do you think of the waterfall and RT60?



## Big Red Machine (Jan 29, 2010)

Fairly flat response of my stereo set-up (no sub). I see plenty of decay in the waterfall which says absorption needed. I have plenty of diffusion going on and very little room for absorption with my layout.

What do you think?


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## Big Red Machine (Jan 29, 2010)

I put the Waterfall on a log scale at 800ms to try and see where it would drop off. There is a 6k issue on the RT60 that is noticeable on the waterfall (it drops to a second plateau for some time before dropping down again which seems to be captured in the RT60). Probably just too much diffusion.


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## ajinfla (May 10, 2009)

Big Red Machine said:


> Fairly flat response of my stereo set-up (no sub).


Indeed. Not "seeing" any amplitude problems there.



Big Red Machine said:


> I see plenty of decay in the waterfall which says absorption needed.


I see pretty pics and sliding frequency scaling. 
What happened between the first and second graphs in the frequency domain?
What are your ears telling you problems and preference wise?



Big Red Machine said:


> I have plenty of diffusion going on and very little room for absorption with my layout.
> What do you think?


I think that unless you want to make a fashion statement, you should trust what your ears are telling you.
I know, I know, what subjectivist entity has possessed ultra-objectionist-deaf-eared-graph-staring AJ?

You applying any EQ?

cheers


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## Wayne A. Pflughaupt (Apr 13, 2006)

Big Red Machine said:


> Fairly flat response of my stereo set-up (no sub).


Assuming the measurement was made with a calibrated mic pointed at the speaker - yes it’s an excellent graph. Pretty impressive low-end extension not to have a sub! :T




> I see plenty of decay in the waterfall which says absorption needed.


Waterfalls are only relevant below 3-400 Hz. However, it does look like you have rather high background noise levels in your room.




ajinfla said:


> What happened between the first and second graphs in the frequency domain?


1/6-octave vs. 1/24-octave smoothing. :T

Regards, 
Wayne


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## Big Red Machine (Jan 29, 2010)

ajinfla said:


> Indeed. Not "seeing" any amplitude problems there.
> 
> 
> What are your ears telling you problems and preference wise?
> ...


I don't hear any problems. I will go back to some music listening to make sure I don't have any overhang of notes. No EQ at all, this is straight through the Lampizator dac and Dude preamp. No processors in my stereo setup!!

I like the way it sounds. I will move some side diffusion out and replace with some absorption and re-run. I have some leftover 2 inch panels from my last house.


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## Big Red Machine (Jan 29, 2010)

Wayne A. Pflughaupt said:


> Assuming the measurement was made with a calibrated mic pointed at the speaker - yes it’s an excellent graph. Pretty impressive low-end extension not to have a sub! :T
> 
> 
> Waterfalls are only relevant below 3-400 Hz. However, it does look like you have rather high background noise levels in your room.
> ...


Big time background noise in this rental house Wayne. I stuffed all kinds of 703 in the furnace room walls to reduce that noise which is off to my right rear. And those lousy fluorescent lights stay off most of the time!!

I am using the EMM6 mic with the cal file. I had it at 45 degrees off the back of my seat.

My original feeling was this is pretty good, but when you look at the Waterfall and I have it out to 800ms and it still is pushing up against the window glass, that says a lot of time is needed to expend energy of the sound.


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## Big Red Machine (Jan 29, 2010)

What do you make of the RT60 at 6000 hz? Is that weird?


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## Big Red Machine (Jan 29, 2010)

I crudely covered up the diffusors on the side walls with 2 inch thick 703. You can see how the decay in the upper registers, where 2 inches is going to be effective, eliminates the ringing after 1500 hz. I don't particularly like the resultant sweep with the 703 but I will give it a listen to see how I like it.

For those wanting to believe in bass trapping, you can see that I essentially have none, and that is true, and the waterfall shows that. Also, you can see how simple 2 inch 703 material can eliminate upper frequency long delay times.


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## jtalden (Mar 12, 2009)

It appears your charts may represent the left and right channels playing together? If so, then the higher freq results are potentially contaminated by comb filtering depending on the exact position of the mic. 

To get the clearest picture of the impact of any changes at those freqs, it is best to measure only one channel at a time.


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## Big Red Machine (Jan 29, 2010)

independent measurements


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## Wayne A. Pflughaupt (Apr 13, 2006)

Big Red Machine said:


> I am using the EMM6 mic with the cal file. I had it at 45 degrees off the back of my seat.


If that’s our generic calibration file you’re using, it’s a 0-degree file. A generic file is perfectly adequate for acoustic measurements (actually, no file is needed for that), but only gives you a “guesstimate” of frequency response.




Big Red Machine said:


> ... but when you look at the Waterfall and I have it out to 800ms and it still is pushing up against the window glass...


That “pushing up against the glass” stuff is the background noise. You can tell that because it isn’t decaying like the signal “behind” it, but stays at a constant level - which is what background noise does.

Regards, 
Wayne


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## ajinfla (May 10, 2009)

Wayne A. Pflughaupt said:


> 1/6-octave vs. 1/24-octave smoothing. :T


Hi Wayne, sorry for not being clear, I'm referring to the frequency scale. Look at graph 1 & 2

cheers


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## ajinfla (May 10, 2009)

Big Red Machine said:


> I don't hear any problems. I will go back to some music listening to make sure I don't have any overhang of notes.


You should never do that after measuring. You may be inclined to "hear" what you saw! 



Big Red Machine said:


> No EQ at all, this is straight through the Lampizator dac and Dude preamp. No processors in my stereo setup!!
> 
> I like the way it sounds.


Interesting. That's pretty good LP response, though would (personally) prefer a slightly more downward slope tapering towards HF if you're in the >9' away range. The RAALs must put a lot of sound power up high. May we explain why so many like them (That includes me btw).

Good!



Big Red Machine said:


> I will move some side diffusion out and replace with some absorption and re-run. I have some leftover 2 inch panels from my last house.


Noooo...
Hey, if you prefer it, so be it. I'm more of a classical/acoustic/real spaces type guy, so that's a big no, no.
However, I know most audiophiles prefer that studio artificial pan pot precision stereo construct thing. You may too. We'll see.
I'm with you on the diffusion thing though, especially at rear of room.

cheers


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## Wayne A. Pflughaupt (Apr 13, 2006)

ajinfla said:


> ...though would (personally) prefer a slightly more downward slope tapering towards HF if you're in the >9' away range.


He’s using a generic calibration file, so the high-freq range of his measurement isn’t especially trustworthy.










Regards, 
Wayne


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## Big Red Machine (Jan 29, 2010)

I'm using the cal file from here. Is there another I am supposed to be using?


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## Wayne A. Pflughaupt (Apr 13, 2006)

It's the only one we have.

Regards,
Wayne


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## Big Red Machine (Jan 29, 2010)

So is it trustworthy? YOu implied otherwise so I want to make sure I am not foobaring this somewhere.


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## EarlK (Jan 1, 2010)

Big Red Machine said:


> So is it trustworthy? YOu implied otherwise so I want to make sure I am not foobaring this somewhere.



I'd say that it ( the generic mic calibration ) is trustworthy enough for your purposes .

BTW, I really enjoyed this thread for various reasons ( which is why I'm back looking at it ) .

One of those reasons is I don't see many REW users pursuing room treatments through the application of diffusion techniques .

What I didn't "get" was your motivation ( post-all-this-success ) to swap-out some of those diffusion panels, for absorbing batting . 

( You did state that you liked what you heard . ) 

By chance do you still have these measurements & ( if so ) could you attach the .mdat file ? 

Thanks !

:sn:


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## jtalden (Mar 12, 2009)

Yes, the .mdat would be interesting. 

Looking at this again I am curious if there is a measurement loaded as a soundcard cal file. The measurements appeared suspect to me from the start and now it finally dawned on me that an erroneous SC cal may be the issue. At least, we would be able to rule that out.


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