Reading waterfall graph

[teb76]

I've just finished doing room correction with REW, here are the waterfall and spectrogram graphs I get from the software, can anyone help me reading it?

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[teb76]

Here the same graphs of the actual measures with the correction in place, as a result of the vector average of the channel L and R.

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[AnotherJohnson]

I see that room EQ wizard is free … so that’s a good thing. At least it did not require a purchase.

In acoustics waterfall diagrams present the 2D spectral content with frequency on the horizontal axis and amplitude on the vertical … as it changes in time (the third dimension represented by the seeming depth of the offset series of 2D pictures).

So … if not much is changing, it suggests that you have a steady input that has caused the system to go into a steady state response. A perfect steady state would be represented by little change from slice to slice as the time domain marches forward.

Music is not a steady state input. You could do a waterfall diagram of Copeland’s Fanfare for the Common Man, or in Italy for a Paganini Caprice, and slices of it might be
stunning art.

If you’re using white or pink noise, you don’t even get stunning art.

I’d bin this as pretty useless in your quest to find audio nirvana. Focus on how it sounds while you listen to familiar music after you make changes.

[AnotherJohnson]

When waterfall graphs came out (not long after portable FFT capable analyzers became available) we used them to look at transient noise or vibration data during start up, shut down, throttling, etc. Before this you could look at amplitude vs time, or amplitude vs frequency at one time. Putting these graphs together for continuous slices of time gave visual clues to machine resonances and operating anomalies.

You could make something similar to study amplitude as a function of spatial coordinates but how to read the data gets complicated real fast unless you’re gifted to visualize in four, five, or more dimensions.

Looking at slices always presents us with something interesting to ponder. We can extend operations using linear algebra to as many dimensions (variables) as storage and patience allows. But it is hard to bring meaning to general abstract slices because they throw out thr related context.

[admin]

AJ describes what a waterfall graph is in REW.

As for my simple interpretation of the graph you posted: Your higher frequencies above 300 hz are falling off significantly before the lower frequencies and the lower frequencies are a little higher in amplitude to begin with. In other words, too much bass and not enough low end frequency absorption in the room.

This is consistent with the conversation we had in the other topic about your speakers and setup. The only other piece of information it adds is that the low end frequencies are "lasting longer" and not just too high.

[AnotherJohnson]

The only other piece of information it adds is that the low end frequencies are "lasting longer" and not just too high.

This is because of the room resonance and we do not need a waterfall diagram to know this. That is what standing waves do.

Think about the wave lengths. And then think about how thick the absorbers have to be it mitigate it.

[teb76]

I see that room EQ wizard is free … so that’s a good thing. At least it did not require a purchase.

In acoustics waterfall diagrams present the 2D spectral content with frequency on the horizontal axis and amplitude on the vertical … as it changes in time (the third dimension represented by the seeming depth of the offset series of 2D pictures).

So … if not much is changing, it suggests that you have a steady input that has caused the system to go into a steady state response. A perfect steady state would be represented by little change from slice to slice as the time domain marches forward.

Music is not a steady state input. You could do a waterfall diagram of Copeland’s Fanfare for the Common Man, or in Italy for a Paganini Caprice, and slices of it might be
stunning art.

If you’re using white or pink noise, you don’t even get stunning art.

I’d bin this as pretty useless in your quest to find audio nirvana. Focus on how it sounds while you listen to familiar music after you make changes.

Measures are taken with a frequency sweep up to 24 kHz (the sample rate being 48 kHz). If I have to just use my ears the bass are much more coherent with the rest of the music after the correction, I sometime perceive a kind of "radio" effect like something in the mid range is missing but it's hard to describe. In the frequency domain the measures are pretty consistent with the curve I used as target, the so called Harman curve.
Stereo image is not the widest but I have to deal with the room dimensions, vocals are precise and well defined, placed perfectly in the center of the stage. Overall I like it. What is totally unsatisfactory to me is listening to classic music, especially violin and strings

[admin]

Keep in mind you can mitigate the amplitude of the bass with an EQ but you CAN'T stop reverberations. That is a quality of the room and it's reflective surfaces. So you have to adjust speaker position and/or treat the room if you want to cut that down.

[AnotherJohnson]

With classical music you are trying to reproduce something from a significantly bigger performance venue than would fit in your room.

Maybe headphones would help.

Strings are classically difficult to get right. People with €100000 systems can have trouble with this, especially in small rooms.

[teb76]

Keep in mind you can mitigate the amplitude of the bass with an EQ but you CAN'T stop reverberations. That is a quality of the room and it's reflective surfaces. So you have to adjust speaker position and/or treat the room if you want to cut that down.

Yeah, that's I think is what I understood experimenting with room correction!

[teb76]

With classical music you are trying to reproduce something from a significantly bigger performance venue than would fit in your room.

Maybe headphones would help.

Strings are classically difficult to get right. People with €100000 systems can have trouble with this, especially in small rooms.

Same conclusion, I think I will enjoy classic music with headphones! I've ordered a Verum 1, waiting for delivery since 2 months, hopefully the guy will be able to survive the winter and ship...

[AnotherJohnson]

A friend of mine from the music industry fought this battle in his smallish listening room for years.

He finally threw up his hands in disgust. Rather than throw good money after bad by trying to recreate a large live experience with a proverbial acoustic shoe horn, he pronounced that

“I should have bought a Krell integrated with a pair of Dynaudio stand mounters and just enjoyed the music that was enjoyable.”

He quit in frustration at the amount of time and money he’d wasted instead. On the bright side (for me), he was also unhappy with the offers from resellers for much of his hard media. He said he’d rather “give it away” than let them have it for a dollar a disk. Lucky me … I was right there and handy. I have given him many “gifts” too, so it is a mutually beneficial relationship.

I put together a vintage/modern system for a decent sized room that blew him away. He still talks about that. I had about $3500 in the whole thing, but it’s been several years since.

[teb76]

Are you suggesting to go for a smaller bookshelf speakers with standmount?
Because I'm thinking on it...

[admin]

Are you suggesting to go for a smaller bookshelf speakers with standmount?
Because I'm thinking on it...

What's the budget? Are you looking for new or used?

[teb76]

Are you suggesting to go for a smaller bookshelf speakers with standmount?
Because I'm thinking on it...

What's the budget? Are you looking for new or used?

Second hand, I'm looking what I could take, for now I've found a pair of revel Concerta2 M16 at about 800 euros

[admin]

Used market you probably have to see what's available, especially in your area.

If looking for new at that budget, I would suggest looking at the Hsu Research CCB-8 bookshelf speaker.

[AnotherJohnson]

I had to look Dr. Hsu up. Those speakers (from price point to concentric Chinese drivers) remind me of old time car audio. The drivers are like door speakers, or the speakers we used to mount on the back deck firing into the back window.

They may be great, but I’d sure want to listen to them before buying.

[admin]

I had to look Dr. Hsu up. Those speakers (from price point to concentric Chinese drivers) remind me of old time car audio. The drivers are like door speakers, or the speakers we used to mount on the back deck firing into the back window.

They may be great, but I’d sure want to listen to them before buying.

I have a Hsu sub in my home theater system and my brother owns the bookshelf speakers. They are no going to compete with some Sonus Faber bookshelfs, but for an $800 budget they offer a lot of bang for your buck. There are limited high quality options at this price point (at least on the new market).

AJ, these speakers are not for you.

[AnotherJohnson]

Maybe for my car …

If the OP buys used, he may lose nothing on resale.

I wonder how the Hsu speakers fare on the resale market. That might be the way to buy them.

[teb76]

I've seen here https://www.audioholics.com/bookshelf-s ... -bookshelf they suggest to place 15 degrees off-axis. I'd like to find the same information for my current speakers... Is there a way to understand how to angle the speaker with respect to the listening point?
Also I'm surprised to see they are rotated toward the inner, I would expect to be rotate outward. Mine are currently slightly rotated outward with respect to the conjunction speaker-LP