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Author Topic: Free EQ room correction in a small room, Room EQ Wizard Rocks!  (Read 13346 times)

martindale

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #15 on: August 30, 2010, 07:44:42 pm »

This thread seems to be about "external eq vs. proper acoustic design" and IMO, everyone's points are good and correct and valid.
However, I would take some exception to the thread's seeming "slant" towards external eq in the monitor chain being "evil".
I do totally agree (and really like the phrase) that the goal in acoustic design should be to build (or fix) rooms to be "quasi isotropic."
But it is a fact that most of the studio designers and room tuning gurus ( at least in the US) use some external eq to fine tune the room---not to correct large modal problems, but sometimes to make small corrections and/ or achieve a certain "curve", which can be VERY important to some engineers in some facets of studio monitoring.
I've spent 100's of hours listening to and working with various external eq's, in a very wide range of rooms--and some hardware does clearly sound bad. However, some products are very close to transparent, but I've never heard anything utterly invisible. As always, the use of any gear in the signal path has compromises.
Without external eq, some music production operations would be impossible. Try talking to Dolby about a film mix room that does not conform to an "X" curve....you won't get very far.  I don't think any designer could build a room and install speakers that conformed to an "X" curve without any eq. Having worked on a lot of film rooms, in close cooperation with Dolby, I understand the powerful need for standardization of monitor curves.
You may say, "but we're talking about music studios, not film rooms", but I would ask what about the many "music guys" who are more and more starting to add TV and indie film mixing to their scope, in order to open up additional income streams and get hip to the changing definition of "recorded sound media."  ...should these people tune their speakers to a small room "X"; or have multiple eq settings (shudder)?....these are additional thread topics, food for thought, but speak to the necessary use of external eq's.
As always, "buyer beware" and yes, some of the gizmo's being hawked out there are crap. I'd love to elaborate on that, but would get in trouble with some manufacturers. Some of the available external processors are amazingly powerful, if used judiciously. They can be very cost effective as well, compared to re-building walls in a room that has small issues; or, as an alternative to other filters and crossovers built as part of a speaker system. The use of any external eq in the monitor chain can be used wisely and with great positive effect, in different applications, but it won't replace good room design and acoustics. Brett's approach to first "deal with the room" was certainly good practice.
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brett

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #16 on: August 31, 2010, 12:36:32 am »

This thread was sort of about external eq vs internal eq and doing it for free. However, it was not about using it in place of acoustic design and I don't know how many times I need to repeat that.

That is what the scientists started in on. This thread was for those on a budget in project studios with less then perfect rooms who didn't want to insert a cheap piece of kit into the chain and have no control over how it does what it is doing. Dialing in eq manually is the only way to go and only after you have taken the room as far as you can.  

You don't put Nu Finish on new car. You may use it on an old piece of junk and it may shine up the appearance of the paint but it wont work it there is body work to do too.  

Most studios on the project level don't design the room. We treat it. What happens when you have gone as far as you can with panels or space?

And you are right about curves. in a well balanced room a house curve is always dialed in for theaters and film mixing studios. I know engineers that have tweaked their mains as well to achieve a preferred curve. Why do you think my ADAM's have eq adjustments on the back or focals or any other studio monitor with eq or dip switches for that matter.   This was an experiment to see if it could help me with my problem mode between 100-200 without using an external device that would degrade the signal and cost money that I would rather put toward additional acoustic treatment.

The answer, and all of the science can't argue that it worked. Say what you want...It did.  And not just in a little space micro space between the monitors. With the eq on and off I can hear the same issue and same problem mode solved even if I slide side to side doing things.

I also have 12 panels up and the room has some advantages... a large window on the front wall. A stepped rear wall with 3 offsets which break up modes and it is open to other rooms partially on two walls the full length of the room and the rear wall. Its a loft. A lot of low end energy already goes out on its own.  

I plan on building 2' thick broad band traps in the offsets along the back wall and using the panels elsewhere. Hopefully at some point I won't need the eq to fix the room mode. I say "the" room mode as there was only one mode to deal with. But right now its a blessing to have figured out how to use digital plug-in eq  as a solution. The plug-ins I am using aren't degrading the sound ... to my ears they are correcting the problem and making things sound better at the mix position.... and that is all that matters in my room!

Cheers
-Brett    
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Thomas Jouanjean

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #17 on: August 31, 2010, 09:29:48 am »

brett wrote on Mon, 30 August 2010 23:36

This thread was sort of about external eq vs internal eq and doing it for free. However, it was not about using it in place of acoustic design and I don't know how many times I need to repeat that.


I thought it was clear and a good way to do it all.

martindale wrote on Mon, 30 August 2010 23:36


However, I would take some exception to the thread's seeming "slant" towards external eq in the monitor chain being "evil".
I do totally agree (and really like the phrase) that the goal in acoustic design should be to build (or fix) rooms to be "quasi isotropic."
But it is a fact that most of the studio designers and room tuning gurus ( at least in the US) use some external eq to fine tune the room---not to correct large modal problems, but sometimes to make small corrections and/ or achieve a certain "curve", which can be VERY important to some engineers in some facets of studio monitoring.


I've seen guys correct for speaker response with EQ. Giving them a shape or correcting a bit of boxiness etc. I don't have a problem with it at all, but I really leave this decision to the client. I don't feel I should get my hands into this as it is in fine a question of taste. One should try (and that's not always easy) to pick a speaker / mains system that already has features that fits one's tastes.

But I have seen White EQs on mains in the US with rollercoaster like 6dB boosts and cuts, and I can't help but wonder...

From discussions I had with engineers there I could not extract a general trend though. Some like it, some press the bypass as soon as they walk in.

martindale wrote on Mon, 30 August 2010 23:36

Try talking to Dolby about a film mix room that does not conform to an "X" curve....you won't get very far. I don't think any designer could build a room and install speakers that conformed to an "X" curve without any eq. Having worked on a lot of film rooms, in close cooperation with Dolby, I understand the powerful need for standardization of monitor curves.
You may say, "but we're talking about music studios, not film rooms", but I would ask what about the many "music guys" who are more and more starting to add TV and indie film mixing to their scope, in order to open up additional income streams and get hip to the changing definition of "recorded sound media." ...should these people tune their speakers to a small room "X"; or have multiple eq settings (shudder)?....these are additional thread topics, food for thought, but speak to the necessary use of external eq's.


This is a very good point.

Am-I the only on here that finds it difficult every now and then to understand some of those standards? Some you can clearely see where they're headed. Some, it feels a bit like non-sense. I've done a few post-prod suites and movie venues and hence worked with companies specialized in installing these large systems. It's always been near impossible to get a proper answer to many questions I had for them. Dodgeball game.
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Ethan Winer

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #18 on: August 31, 2010, 01:25:22 pm »

brett wrote on Mon, 30 August 2010 19:30

not in this case.


Understood. That's why I qualified my comment by mentioning rooms where large modal peaks dominate. But it's important to understand that even at very low frequencies the response can change greatly over very small distances. The graphs below show the response I measured at two location only four inches apart! (SOURCE)

--Ethan

http://www.ethanwiner.com/believe-lf.gif

http://www.ethanwiner.com/believe-hf.gif

brett

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #19 on: September 01, 2010, 01:24:26 am »

Yes Ethan, but that room appears to have serious modal and null issues. Is there even any treatment being used in those tests?
-Brett
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Ethan Winer

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #20 on: September 01, 2010, 03:16:38 pm »

^^^ That room is 16 by 11.5 by 8 feet, which is typical for a lot of home studios. Of course it has "serious modal and null issues." All such rooms do! Those graphs are absolutely typical. In any event, those graphs were taken with the room empty as part of this exhaustive comparison:

EQ Versus Bass Traps

--Ethan

brett

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #21 on: September 01, 2010, 07:44:19 pm »

Ethan Winer wrote on Wed, 01 September 2010 20:16

^^^ That room is 16 by 11.5 by 8 feet, which is typical for a lot of home studios. Of course it has "serious modal and null issues." All such rooms do! Those graphs are absolutely typical. In any event, those graphs were taken with the room empty as part of this exhaustive comparison:

EQ Versus Bass Traps

--Ethan

I thought so, but the point of this discussion is using eq in a room that is treated. The graphs in a treated room are going to much more uniform over small distances and so will eq changes. Also some monitors exibit a much smaller sweet spot then others and the center ghost image can tilt  over short distances. Especially in a near field application.  
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AndreasN

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #22 on: September 07, 2010, 09:30:25 am »

bruno putzeys wrote on Mon, 30 August 2010 13:30

If the EQ is a full FIR correction you can, in principle, correct everything...

BUT ONLY...

...in one spot in the room. Or n spots if you have n speakers. The issue has nothing to do with time vs frequency domain but with the fact that the room is a space and you have only two points (a pair of speakers) to control it by. If you have a dip at a certain frequency / spot, you will have a bump at the same frequency elsewhere. Correct the dip and the bump elsewhere gets worse. Room correction restricts you to sitting in one exact spot. That is why it doesn't work practically. However, if you are happy to have your head nailed down in one precise location you can remove everything. Echos, everything. Just don't move your head.


Is it really that easy? The ears are not a single omnidirectional observer in a close to point like existence in the room. They're 3D sensors with ability to discriminate time and intensity differences between the ears, and the sound is filtered (HRTFs) to have different frequency response depending on incoming angle. What may look like a good cancellation in a measurement mic doesn't translate to a good cancellation in the ears.

Given this starting point, I think it's safe to assume that room correction can never be successful to arbitrary degree, even assuming a listener stuck in a head vice.
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bruno putzeys

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #23 on: September 07, 2010, 11:09:01 am »

Yes, to make this true for a human listener instead of just a measurement mic you would need to put the listener's head there during the measurement as well. This strengthens my point: the more you want to get done from DSP based room correction, the narrower the range of conditions in which it remains valid.
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Bogic Petrovic

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #24 on: September 24, 2010, 06:15:44 pm »

bruno putzeys wrote on Mon, 30 August 2010 13:30

.......................
If the EQ is a full FIR correction you can, in principle, correct everything...
.......


I agree, and I think that we may add "at the expense of longer overall delay of corrected signal".

AFAIK 3ms is some maximum of latency that audio production people cannot easily perceive, and 3ms is only about 1m distance in acoustics Smile

For "off-line", audiophile like, listening of music, movie, etc I think that FIR correction introduced delay can be easily tolerated...

However, for audio production... i think not. Smile

bruno putzeys wrote on Mon, 30 August 2010 13:30


With all other
BUT ONLY...

...in one spot in the room. Or n spots if you have n speakers. The issue has nothing to do with time vs frequency domain but with the fact that the room is a space and you have only two points (a pair of speakers) to control it by. If you have a dip at a certain frequency / spot, you will have a bump at the same frequency elsewhere. Correct the dip and the bump elsewhere gets worse. Room correction restricts you to sitting in one exact spot. That is why it doesn't work practically. However, if you are happy to have your head nailed down in one precise location you can remove everything. Echos, everything. Just don't move your head.

I agree

franman

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #25 on: February 18, 2011, 11:20:48 pm »

Sorry I missed this one while it was hot.. great topic and good conversation.. good one guys!!
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martindale

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #26 on: February 19, 2011, 10:20:32 am »

Just an interesting/ funny add on this: recently visited a music venue installation, Meyer main system, with their Galileo DSP processors....but with old school White 1/3 octave eq's before the input of the DSP.  I asked someone on the install crew---not the system designer, unfortunately couldn't speak with him---what the White's were for if the extensive DSP was in line. The reply was, "to warm up the sound."
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franman

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Re: Free EQ room correction in a small room, Room EQ Wizard Rocks!
« Reply #27 on: February 20, 2011, 10:39:22 pm »

Did you get an impression of the Galileo?? I've got one going in on that Acheron system that we spoke about.. wondering what it's like... (do I need to "warm it up").. lol... Confused
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