Revel C52 Speaker Review and Measurements

[lszomb]

This is again very impressive. I was lesser interested in Revel C52 center, keke...But this is an very important step on proving the testing methodology is actually working as a good simulation as getting test done in an anechoic chamber. Brilliant!

 

[Thomas Savage]

Not bad for a old bloke in a garage .

 

[Krunok]

As said, above than 600 Hz the perceived tonality almost fully depends on direct sound as our brain adapts to the room acoustics, thats why "George" still sounds to us like "George" and not "Keith", a nice example that Toole uses it that noone would ever get the idea to EQ live voices or instruments in according to some listening position measurements. Its all written in above posted links or in even more detail in Toole's book

I have read the book. However, you haven't provided any argument why a mild correction (1-2dB with Q 1-2) which serves only as a tone control to provide balance betwen LF and HF would sound "unnatural".

As an example, an linear omindirectional loudspeaker would create a flat listening FR if the room reverbation over the frequency is constant, same also any neutral loudspeaker in an anechoic room, trying to "correct" such response to a decreasing target curve would make them sound not tonally correct.

Not true - speaker that measures linearly in anechoic environment would have sloped down response in a typical roomand that is mentioned in a Tolle's book. Maybe you should give it one more read?

 

[jhaider]

Polars?

 

[Krunok]

Not bad for a old bloke in a garage .

C'mon, wife did the lifting and robot did the rest of the job - your bloke just published it and now is taking all the credits!

 

[Krunok]

Review looks qualify the new NFS is a good a investment to reference, thanks amirm share your delicious HT speakers.

"On axis" and "Sound power DI" overlaid on a 50dB scale, black=NFS, purple=Anechoic:

View attachment 46229

Wow, master of graphic overlays strikes again - really well done, as always!

 

[Thomas Savage]

C'mon, wife did the lifting and robot did the rest of the job - your bloke just published it and now is taking all the credits!

That's the Microsoft way.

 

[Krunok]

That's the Microsoft way.

Yep, indeed it is.

 

[thewas]

I have read the book. However, you haven't provided any argument why a mild correction (1-2dB with Q 1-2) which serves only as a tone control to provide balance betwen LF and HF would sound "unnatural".

If the speaker measures flat anechoically on axis, why would you need such a correction? Either its flat or not. If its not and its directivity is smooth, you can correct it by EQ also above 600 Hz (which I also do on my IN-8 and LS50) if the directivity is non smooth you can either make the direct sound neutral or the reflected sound, but it doens't sound as correct the one doesn't fully correlate to the other.

Not true - speaker that measures linearly in anechoic environment would have sloped down response in a typical roomand that is mentioned in a Tolle's book. Maybe you should give it one more read?

You misundestood what I wrote there, a linear speaker will have also a linear listening position measurement in an anechoic situation, like for example a huge field with fat grass.

 

[Krunok]

If the speaker measures flat anechoically on axis, why would you need such a correction?

I already answered that - to suit your personal preference. But you still didn't answer why would such mild correction sound "unnatural"?
Is a flat response your personal preference and everything else sounds "unnatural" to you?

You misundestood what I wrote there, a linear speaker will have also a linear listening position measurement in an anechoic situation, like for example a huge field with fat grass.

Because it is a huge field with fat grass where we usually listen our speakers, right?

 

[Krunok]

If the speaker measures flat anechoically on axis, why would you need such a correction? Either its flat or not. If its not and its directivity is smooth, you can correct it by EQ also above 600 Hz (which I also do on my IN-8 and LS50) if the directivity is non smooth you can either make the direct sound neutral or the reflected sound, but it doens't sound as correct the one doesn't fully correlate to the other.


You misundestood what I wrote there, a linear speaker will have also a linear listening position measurement in an anechoic situation, like for example a huge field with fat grass.

Here it is: measured at LP, 4m from the speaker, speakers have slight toe-in but they are not facing the LP directly thus the bigger HF roll-off.
Green is uncorrected and blue is corrected. Why would you say blue sounds "unnatural"?

 

[thewas]

I already answered that - to suit your personal preference. But you still didn't answer why would such mild correction sound "unnatural"?
Is a flat response your personal preference and everything else sounds "unnatural" to you?

Again, would you EQ your friends voice according to the different room (measurements)for you to sound more natural?

Because it is a huge field with fat grass where we usually listen our speakers, right?

It was just an example (like also the omidirectional speaker in a normal room which you ignored) to show that there ain't such thing as a universal target curve.

Here it is: measured at LP, 4m from the speaker, speakers have slight toe-in but they are not facing the LP directly thus the bigger HF roll-off.
Green is uncorrected and blue is corrected. Why would you say blue sounds "unnatural"?

Without knowing the anechoic measurements noone can judge from such curves as I quoted Toole before:
When we talk about a "flat" frequency response, we should be talking about anechoic on-axis or listening window data, not steady-state room curves

The rest is personal taste and circle of confusion from flawed recordings (also from users that try to "correct" their speakers to some predefined curves)
http://seanolive.blogspot.com/2009/10/audios-circle-of-confusion.html

 

[Blumlein 88]

Review looks qualify the new NFS is a good investment to reference, thanks amirm share your delicious HT speakers.

"On axis" and "Sound power DI" overlaid on a 50dB scale, black=NFS, purple=Anechoic:

View attachment 46229

Thanks for this. Viewing on a phone at the moment. So am I seeing this right, the slightly more squiggly line is the Klippel?

 

[Blumlein 88]

A max of 9 would mean LFX cut-off for best score would be ~25Hz, so I don't think that's correct. Unless it's not programed for 0 for NBD and 1 for SM to exist.

So what is the max score possible?

 

[mhardy6647]

Two comments:
1) I thought you were in the Pacific Northwest? Freezing garage?
2) Two words: heated garage.



In seriousness, great information -- keep 'em coming!
(and, yeah, looking forward to the impedance and phase curves)

EDIT: PS -- 2 degrees F outside at our house today. ... and, yes, the garage is heated (since the hifi room is above it, it has to be).

 

[Krunok]

Again, would you EQ your friends voice according to the different room (measurements)for you to sound more natural?

If I had to listen to him every day, sure I would. But that is really a lousy analogy.

Without knowing the anechoic measurements noone can judge from such curves as I quoted Toole before:
When we talk about a "flat" frequency response, we should be talking about anechoic on-axis or listening window data, not steady-state room curves

The rest is personal taste and circle of confusion from flawed recordings (also from users that try to "correct" their speakers to some predefined curves)
http://seanolive.blogspot.com/2009/10/audios-circle-of-confusion.html

Exactly, I adjusted the 600-20000 range to my personal taste. It simply sounds better to me than when I left it untouched. My opinion is that it has to do with my room which has heavy rug on a 5cm thick wood floor while all walls and ceiling are covered with plaster panels with thermal and acoustic isolation behind them.

But again, why do you think it would sound "unnatural" to you if you would to listen music in my room? How comes you even have an opinion how it would sound to you as you've never been to my room?

Btw, are you one of those guys who think music sounds best when listened in anechoic room with totally flat FR?

 

[thewas]

I won't repeat again what is written above, you confuse the science of perception (where the direct sound is dentrimental at higher frequencies) with personal taste at listening flawed recordings from flawed loudspeakers and in flawed acoustics. Please don't take that personally, my speakers and acoustics aren't by far perfect either, but I wouldn't think of using them as an argument to oppose what the research of Toole has shown.

 

[MZKM]

So what is the max score possible?

Well, with a -6dB of 1Hz it would be 15.1, so it's been discussed that maybe it's supposed to be capped at 10 and thus a -6dB of ~14.5Hz is set as the ideal.
Amir should contact Sean Olive again for clarification.

 

[Krunok]

I won't repeat again what is written above, you confuse the science of perception (where the direct sound is dentrimental at higher frequencies) with personal taste at listening flawed recordings from flawed loudspeakers and in flawed acoustics. Please don't take that personally, my speakers and acoustics aren't by far perfect either, but I wouldn't think of using them as an argument to oppose what the research of Toole has shown.

I am very well aware of it and I am not confusing it, I simply don't see it as a reason not to slightly adjust FR above transition frequency to my liking.

What exactly is your attitude? That room EQ shouldnt' be done above Schroeder? Not even a mild corrections in the transition range? Do you see Schroeder frequency as a hard barrier after which forbidden land lies?

So you think my recordings are flawed, as well as my speakers and acoustics of my room? This really sounds like you are an old friend of mine who has listened to my recordings played by my speakers in my room many times. But you aren't, so how can you judge?

 

[Krunok]

@Thomas savage Can you pls move these room EQ related posts/discussion to a sepearate thread as it doesn't belong here.