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Advanced Room EQ, Acoustics and Optimization - Page 9

post #241 of 303
Quote:
Originally Posted by sdurani View Post

You need to measure a response equalized to sound flat and compare it to one that is flat. The parameters are up to you (and your resources, your patience, etc). But that, to answer your earlier question, is one way to define "perceptually flat".

Unfortunately it's not that easy. Even Allen touches the topic in "The X-Curve: Its Origins and History". Some more detailed explanations can be found in http://www.dirac.se/media/12044/on_room_correction.pdf

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post #242 of 303
Quote:
Originally Posted by markus767 View Post

Unfortunately it's not that easy.
So what? It won't be perfect either.

Those things didn't stop Fletcher & Munson from mapping equal loudness contours, nor did it stop Churcher & King from superceding them, or Robinson & Dadson from superceding them, or ISO from superceding them a decade ago.

Just because Fletcher & Munson didn't "fully understand" human hearing AND didn't get perfect results doesn't mean they were practicing Cargo Cult science.
post #243 of 303
^
That's not what I was talking about. It's not about "perfect" but a) about scientific research in (psycho)acoustics and b) how scientifc results are (mis)used in audio. Cargo cult.
post #244 of 303
Quote:
Originally Posted by markus767 View Post

^
That's not what I was talking about.
Then what are you talking about? You've already established that you believe "common room measuring/treatment practices" are cargo cult science. Are you trying to get others to believe the same in an attempt to convince them to stop measuring?
post #245 of 303
Quote:
Originally Posted by 3ll3d00d View Post

Does anyone else use PC based DRC here? I am now using acourate, with jriver to host the filters, and it is a lot of work to get it going but it is markedly better than anything I have used before. For music at any rate, I haven't had time to do the setup for 5.1 yet.
I use Audiolense and JRiver Media Center for my 7.1 system with two channels for subwoofers. I've also used just JRiver's extensive PEQ capabilities for other systems I've setup. I really like Audiolense's multi-channel/multi-measurement capability. I also use automatic filter switching by JRiver depending on content (music, DVD, Blu-rays, Concert Blu-rays, TV, interent).

I'm currently working on dlbeck's The Savoy theater which will start with 15 channels of output and might increase to 20+. JRiver will provide all the upmixing, channel routing, bass management, crossovers, parametric equalization,
Quote:
Originally Posted by kiwi2 View Post

I think I've discovered why Mini recommend to use negative PEQ only.

On some albums I would hear the occasional crackling sound when I had PEQ enable in JRiver. Turning PEQ off made the crackling go away. Then I found just disabling some of the boost I had in the midrange also fixed the problem. But tracks on other albums wouldn't have any distortion with all of my PEQ enabled.

I think what the problem is, is that some tracks are mastered at high levels already close to clipping and adding extra PEQ gain pushers things over the edge.

Have a look at the bottom left hand corner and note the percentage indicator. Any time that hit 100% I would hear the crackling.

The above is one of the tracks where I noticed the problem and it has a high average % level. Most other tracks have a much lower average level.
When you use the parametric equalizer in JRiver you need to first enter an "adjust the volume" filter for all channels to lower the signal so that any increase from PEQ never exceeds maximum signal level. You can use as much positive EQ you want as long as you have compensated for it in the overall level.
post #246 of 303
Quote:
Originally Posted by sdurani View Post

Then what are you talking about? You've already established that you believe "common room measuring/treatment practices" are cargo cult science. Are you trying to get others to believe the same in an attempt to convince them to stop measuring?

If anything I would want others to do more measuring. And more (thorough) reading...
post #247 of 303
Quote:
Originally Posted by markus767 View Post

If anything I would want others to do more measuring.
Then why not simply say that, rather than:
Quote:
Originally Posted by markus767 View Post

I do believe that common room measuring/treatment practices by and large are just cargo cult science. We don't know enough about our hearing.
post #248 of 303
My room is not nearly flat, but I'm trying to get it within 6-10 dB. I've been told that 0 to 3 db variances should be considered very good, 3-6 db acceptable.

The lowest note on an electric guitar is 40Hz, however there are harmonics that go lower than the fundamental and these bits and things like ambience, etc, lives in the lower bass regions, i.e. bass below 40Hz. Most systems miss this. Coupled with a decent subwoofer(s) and room treatments and you will be surprised how much content you are missing in this area when listening to your music.
post #249 of 303
Quote:
Originally Posted by sdurani View Post

Then why not simply say that, rather than:

Because measurements are only half the equation. The other one is relating measurements to perception. Not much knowledge there but lots of opinions and beliefs.
post #250 of 303
Quote:
Originally Posted by Heinrich S View Post

My room is not nearly flat, but I'm trying to get it within 6-10 dB. I've been told that 0 to 3 db variances should be considered very good, 3-6 db acceptable.

Who told you that? Was he talking about steady-state or only a certain time frame?
Quote:
Originally Posted by Heinrich S View Post

The lowest note on an electric guitar is 40Hz, however there are harmonics that go lower than the fundamental

There are no harmonics that go lower than the fundamental. The lowest partial IS the fundamental.
post #251 of 303
Thread Starter 
Been busy for the past few days and trying to catch up here, so I'll try to address a few topics in the thread.


Max
post #252 of 303
Thread Starter 
Quote:
Originally Posted by mtbdudex View Post

OP - djbluemax1;

I brought up basics/fundamentals in post 162 and now see 2 distinct conversations happening.

How do you feel, as this is "your" thread.

Shall they both stay in your thread, or would you like me to create a specific thread to discuss the topic I introduced, copy/past the posts there so not to clutter your thread and it's discussion?
Now is the time to split them if we will, before too much more dialogue happens.
That might be a good idea. There are already a few threads that go a little more into the specifics of acoustic theory.

While I originally intended this thread to allow a fairly broad scope, I guess the thread title wasn't quite clear/precise enough to indicate that the intent of the thread is primarily geared to tweaking/optimization that goes beyond the standard plug-in automated Room EQ solutions, and could include acoustics as they pertain to such optimization.


Max
post #253 of 303
Thread Starter 
Markus,

although there may be areas of neurosicence and psychoacoustic relation still to explore, there are some common measurements used that I personally (as well as many others) can and do find to provide beneficial data. For instance, I DO find it possible to hear differences between a smooth frequency response vs an very uneven frequency response. I can also hear the difference between a setup with waterfalls that show well-controlled bass ringing vs a setup that has uncontrolled and extensive bass ringing. I'm also beginning to understand how the differences in acoustic dispersion between speakers can affect how they sound in untreated vs heavily treated rooms, and I see how Jim's posts about sliced ETC's and even attenuation of reflections across the frequency spectrum can affect those things.

So while it may be true that we don't know everything there is to know, we still have a base to explore from. I do agree that the more we explore and measure, the better we may be able to relate the measurements to the perceptions.


Max
post #254 of 303
^
Yes, keep exploring and try not to fool yourself. Something isn't necessarily "better" just because there is an audible difference. Don't fall for cargo cult medicine men that only conduct and report experiments that support their beliefs.
Edited by markus767 - 2/21/14 at 5:11am
post #255 of 303
Quote:
Originally Posted by Heinrich S View Post

My room is not nearly flat, but I'm trying to get it within 6-10 dB. I've been told that 0 to 3 db variances should be considered very good, 3-6 db acceptable.

The lowest note on an electric guitar is 40Hz,

Not a global truth. Electric guitars can be tuned by the user to suit, and generally 5 string basses go significantly deeper. I think it is reasonable to set the desired bass extension point for a music-only system at 32 Hz.

Quote:
however there are harmonics that go lower than the fundamental


By definition there is no such thing. If there is a tone that is lower than the fundamental then it is properly called a subharmonic. Musical instruments that generate these are few and far between. Most involve very large diaphragms. There are also electronic devices that perform the function of subharmonic generation, and they are more likely to be encountered.
Quote:
and these bits and things like ambience, etc, lives in the lower bass regions, i.e. bass below 40Hz.

Ambience generally rolls off both the bass and treble.
Quote:
Most systems miss this. Coupled with a decent subwoofer(s) and room treatments and you will be surprised how much content you are missing in this area when listening to your music.

Agreed.

The guidelines that I am working with is that a music system needs to extend down to no higher than 32 Hz, and a HT system needs to extend down to no higher than 20 Hz. There are a goodly number of subs that can be clean and loud down to 32 Hz, but 20 Hz is far more challenging.

Often more than one sub is required to get bass that is evenly enough distributed across the preferred listening location. For example I have a friend with a massive IB subwoofer (4 x 18" driven by 4x 2500 watt amplifiers) and it turns out that his room has a natural null at 60 Hz right where his preferred sitting location is.
post #256 of 303
The lowest note on a five- or six-string bass guitar is about 31 Hz (low B, B0). Some players like a low D0 and so drop a hair lower. A four-string bass, or regular guitar, goes to about 41 Hz (low E, E1). If it is close-mic'd there will be percussive content well below that from fingers striking the strings. It is that sort of percussive stuff, from kettle drums to pianos and guitars, that I tend to miss in systems without a sub or sufficient low-end extension.

IME subs, and just speakers in general, distort "ambience" and decay by ringing after a pulse. The ringing can be electrical, mechanical, or both (in reality it is an electromechanical device so you cannot really separate them). The ring frequency may not be related to the tone that started it. That is one of the reasons I have for decades preferred servo subs, or well-designed regular subs, with big amplifiers (low output impedance) tightly coupled to the driver.
post #257 of 303
Quote:
Originally Posted by markus767 View Post

....Don't fall for cargo cult medicine men that only conduct and report experiments that support their beliefs.
Hi Markus,

For myself, at least, it would be helpful if you could provide one or more specific examples of the sort of "cargo cult medicine" you'd like us to avoid.

Ken
post #258 of 303
Quote:
Originally Posted by markus767 View Post

There are no harmonics that go lower than the fundamental. The lowest partial IS the fundamental.

What I was trying to imply : if you have the bass sorted then you should not hear one note bass, i.e. the fundamental is clearly seperated from the harmonic(s) and when heard this way the latter sounds lower.
post #259 of 303
Quote:
Originally Posted by Heinrich S View Post

What I was trying to imply : if you have the bass sorted then you should not hear one note bass, i.e. the fundamental is clearly seperated from the harmonic(s) and when heard this way the latter sounds lower.

The harmonics sound lower when one has "the bass sorted"??
post #260 of 303
Quote:
Originally Posted by markus767 View Post

The harmonics sound lower when one has "the bass sorted"??

Or how about the way instruments energise the room they are in and then that room reverberates a lower frequency.

I like to listen to a lot of live recorded music from clubs and bars and such and getting a sense of what the room was doing is just as important to me as the musical instruments themselves. I even have one jazz track that I swear must have been recorded in the lounge of a hotel on the top floor of a high-rise, as you can sense the reverberation of the room that is just like being in a high-rise on a windy day. Or listening to a choir inside a church and you can hear and even feel traffic going past the church.

My system extends down to around 25hz. I once changed my configuration slightly and only ended up getting down to 35hz. I very quickly started to miss that last 10hz.
post #261 of 303
Quote:
Originally Posted by desertdome View Post

When you use the parametric equalizer in JRiver you need to first enter an "adjust the volume" filter for all channels to lower the signal so that any increase from PEQ never exceeds maximum signal level. You can use as much positive EQ you want as long as you have compensated for it in the overall level.

Thanks, great tip! This has helped my EQ problem and also made the volume between different albums more even. Thanks.
post #262 of 303
Quote:
Originally Posted by kiwi2 View Post



Or how about the way instruments energise the room they are in and then that room reverberates a lower frequency.

No reverberation without excitation.
post #263 of 303
Quote:
Originally Posted by markus767 View Post

No reverberation without excitation.

What..???

A room will have its resonant frequency which is usually very low. With my live recordings I not only want to hear the instruments, but I also want to hear the space they were in as well. It's all part of the atmosphere.
post #264 of 303
Quote:
Originally Posted by kiwi2 View Post

What..???

A room will have its resonant frequency which is usually very low. With my live recordings I not only want to hear the instruments, but I also want to hear the space they were in as well. It's all part of the atmosphere.

A room has thousends of "resonant frequencies". So I'm not sure what you're trying to say?
post #265 of 303
If you want to hear the space the instruments are in wouldn't you need a deadened room? That would allow the system to reproduce only the ambiance in the recording. Nothing wrong with that, and my room takes that approach (for different reasons). If you want to hear your room you must be aware that the reflections and reverberations it adds, while they may be pleasing, are not the same as when the recording was made.

A lot of audiophiles would be shocked, stunned, and dismayed at the amount of processing that happens in the studio...
post #266 of 303
Quote:
Originally Posted by DonH50 View Post

If you want to hear the space the instruments are in wouldn't you need a deadened room? That would allow the system to reproduce only the ambiance in the recording. Nothing wrong with that, and my room takes that approach (for different reasons). If you want to hear your room you must be aware that the reflections and reverberations it adds, while they may be pleasing, are not the same as when the recording was made.

A lot of audiophiles would be shocked, stunned, and dismayed at the amount of processing that happens in the studio...

Not necessarily. If the ITD of your room is greater than that of the studio it was recorded in, it is possible to have later arriving reflections (non-dead room) and also preserve the full content of the recording.

Having an anechoic room response (-30db) for the first 25ms, and then introducing reflections after that is the approach I have taken.
post #267 of 303
Sorry, should have said "very dead" or "very big"... 25 ms implies about 25 feet.

Good catch!
post #268 of 303
Quote:
Originally Posted by DonH50 View Post

Sorry, should have said "very dead" or "very big"... 25 ms implies about 25 feet.

Good catch!

28 feet actually wink.gif
post #269 of 303
Yeah, yeah, yeah, depends on temperature, altitude (density), humidity, etc. 1127'/s is pretty close to 1000'/s, is what I was thinking so I use 1'/ms as a rough rule of thumb, but you're right again.

2 + 2 = 5 for very large values of 2. smile.gif

Thanks Mr. Spock. biggrin.gif
Edited by DonH50 - 2/21/14 at 11:38am
post #270 of 303
Quote:
Originally Posted by DonH50 View Post

Yeah, yeah, yeah, depends on temperature, altitude (density), humidity, etc. 1127'/s is pretty close to 1000'/s, is what I was thinking so I use 1'/ms as a rough rule of thumb, but you're right again.

2 + 2 = 5 for very large values of 2. smile.gif

Thanks Mr. Spock. biggrin.gif

28.133202 feet then tongue.gif
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