EQ in stead of acoustic treatment?
Joniverse
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#1
23rd December 2012
Old 23rd December 2012
  #1
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EQ in stead of acoustic treatment?

I just had a thought. The hardest thing to get rid of when treating a room is resonating waves in the bass frequency. If i have a resonating wave at, say 55hz, coudn't i just use an eq to take away 55hz while i mix, and then remove the eq before i print?
#2
23rd December 2012
Old 23rd December 2012
  #2
Quote:
Originally Posted by Joniverse View Post
I just had a thought. The hardest thing to get rid of when treating a room is resonating waves in the bass frequency. If i have a resonating wave at, say 55hz, coudn't i just use an eq to take away 55hz while i mix, and then remove the eq before i print?
no. detailed explanation check the internet.

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#3
24th December 2012
Old 24th December 2012
  #3
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avare's Avatar
 

Quote:
Originally Posted by Joniverse View Post
I just had a thought. The hardest thing to get rid of when treating a room is resonating waves in the bass frequency. If i have a resonating wave at, say 55hz, coudn't i just use an eq to take away 55hz while i mix, and then remove the eq before i print?
The eq does nothing to correct the longer decay time. You will still have the mode, just at a lower level.

With no decay,
Andre
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#4
24th December 2012
Old 24th December 2012
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Ethan Winer's Avatar
 

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Quote:
Originally Posted by Joniverse View Post
If i have a resonating wave at, say 55hz, coudn't i just use an eq to take away 55hz while i mix, and then remove the eq before i print?
You already got some good answers, and a highly detailed explanation of why EQ cannot replace bass traps is in this article:

Audyssey Report

--Ethan

The Acoustic Treatment Experts
#5
26th December 2012
Old 26th December 2012
  #5
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DanDan's Avatar
EQ

I am afraid I have to disagree here.
Eq can and does shorten some modal decays. Luckily it is usually the lowest most difficult to treat ones which are amenable to such treatment.

The decay shortening can be fairly localised, and frequency response much more so. However within a reasonable sized sweet spot, modern Eq systems can work well.

Some surveys have been carried out in this regard.

One found that some Eq products didn't work at all, while others were well received. This may explain that old Audessey Report. But more recent implementations of Audessy in other products seem to work well.
ARC 2 Advanced Room Correction System is now available from IK Multimedia

Another survey, in professional studios, found Eq to be very beneficial in poorly performing rooms, but of little effect in the better rooms.

DD
#6
27th December 2012
Old 27th December 2012
  #6
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Glenn Kuras's Avatar
 

Quote:
Originally Posted by avare View Post
The eq does nothing to correct the longer decay time. You will still have the mode, just at a lower level.

With no decay,
Andre
Plus 1.
#7
27th December 2012
Old 27th December 2012
  #7
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Tests

#8
27th December 2012
Old 27th December 2012
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That article most certainly does not prove what it claims. It shows an impulse reduction at a location. Very bad science!! You can reduce the level of excitement but not remove the time domain effects. That is all that has been demonstrated.

The graph does not show a reduced time domain response - it shows a lower excitement. This is likely okay for a cinema room but is NOT okay for making translatable decisions.

Secondly proof requires maths and not conjecture or empirical evidence based on one condition. Evidence forms an hypothesis not proves it. Very very bad science ( although if ypuvrerrad it does not claim to remove the time domain issues)
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#9
27th December 2012
Old 27th December 2012
  #9
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True that, Nyal's article is only a small part of the thread though. Your point has been made elsewhere also, by Ethan I think. Nyal claims that he actually tested over multiple locations. I have no reason to disbelieve him but it has not been presented. My own very quick test in the same linked thread shows a higher stimulus level followed by a steeper slope, post EQ. The decay is certainly shortened. Flatten Monitors Response - Recommended Software?! Filter Impulse Response?
Again the point can be made that this is position dependent. I intend to do a test of my current system, Dirac soon. i.e. Test at the nine locations which define it's target sweet spot. Which is quite small.
I will say though, as a Mix and Mastering engineer, I would now find it difficult to work without that extra 10% of clarity and fidelity which I am experiencing.

DD
#10
27th December 2012
Old 27th December 2012
  #10
Gear addict
 

that blog post by Nyal is actually one of my design jobs. I brought Nyal in to measure and assist in calibration as the space is in the Bay Area...just made more sense for him to do that than pay for my travel. He did in fact test at every seating location. I've got all the data. This was all anchored by my studies and design for sub placements that by far gave the most spatially consistentent LF response modeled...and the reality proved similar. In my design report I specified to the integrator that one or two bands of PEQ should be expected...that's exactly what happened. As for improvements in other locations, every location but one had similar improvements to that shown location. One location as a different shade of the same...but not worse.

I really don't understand there is any question that EQ is a tool. It is most effective below 50Hz and does reduce resonance. And, it is decreasingly effective as you approach the modal transition. Sure it's possible to make a singular improvement and make a global worsening...that's just bad use of the tool. Certain DRC algorithms make poor decisions and will in fact extend resonances while flattening the pressure amplitude response.

Get the best room possible, get the best speaker possible, put the speakers in the best possible location, treat the room consistent to the use (if it's a pro room...treat to pro level), tweak all of the above and then it's time for PEQ or a good DRC (if needed).

I suggest that we are just coming in to the age of really exceptional DRC options.
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#11
27th December 2012
Old 27th December 2012
  #11
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Certainly I wouldnt advocate any version or type of EQ until all other treatments have been exhausted.

But lets consider another factor.

Bi-Amplification:

If your running a bi-amplified system, that is separate power amps for subs and satellites, or a full range speaker that has bi-amp capability and one is using it as such.
In this scenario, you can EQ just the sub/woofer amp without electronic degradation to the mid/high frequencies. Ok maybe.

Single Amplification:

Basically, one amp feeding a full range speaker. In this case, there is no getting around the EQ being in the signal path of the entire freq range. In this case, what you gain in bass smoothness you may lose in more compression, added distortion, and a less open soundstage (just all the typical things that happen when adding another component to the signal path).
#12
29th December 2012
Old 29th December 2012
  #12
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DanDan's Avatar
Practical

I guess it is fairly obvious that Eq cannot be used as a replacement or substitute for acoustic treatment. No Eq will kill side or overhead reflections or flutter echo.
On the other fully effective treatment below 100Hz, requires enormous space, cost, and effort. So much that it is rarely achieved in my experience.

Viewed in that light, the two techniques should work together not be asked to spar.

jim, I would be just as reluctant to introduce poor quality electronics into a high end chain. I certainly won't be using any Behringers anytime soon.
But many of us have primarily digital systems, typically a DAW, or streamed or HD based HiFi. I have found Digital Equalisers to be amazingly good.
I prefer the software MDW to Massenburg's Hardware Eq.
Even with much cheaper Dig Eq's, I have never heard distortion, and certainly not compression.

There are other factors at play. Speakers are imperfect. A little touch up with a transparent Eq can straighten things out without any downside. Many manufacturers are now using DSP for this reason, plus the crossovers can be made more transparent.
Similarly one can chose a Target or Preferred Listening Curve using DRC. This is much more sophisticated than attempts using on board speaker eq, and is a no brainer with passive speakers.

The Hi Fi world often uses language foreign to the practicing pro. Reading some of the more far fetched PR for the product I use, I could become sceptical.
However, switching in DRC has a dramatic effect on stereo image, width and depth perception. It may be doing this by removing some midrange peaks in the speaker, or the room. But it certainly is better. I have a simple A/B path switch at the listen position. Engineer and Hi Fi friends, visiting my White Room, have universally chosen the DRC sound over non.

DD
#13
29th December 2012
Old 29th December 2012
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Quote:
Originally Posted by DanDan View Post

jim, I would be just as reluctant to introduce poor quality electronics into a high end chain. I certainly won't be using any Behringers anytime soon.
But many of us have primarily digital systems, typically a DAW, or streamed or HD based HiFi. I have found Digital Equalisers to be amazingly good.
I prefer the software MDW to Massenburg's Hardware Eq.
Even with much cheaper Dig Eq's, I have never heard distortion, and certainly not compression.

There are other factors at play. Speakers are imperfect. A little touch up with a transparent Eq can straighten things out without any downside.

DD
In a primarily digital rig, there maybe no audible downside to EQ in the sense of signal degradation, although id like to see the phase characteristics of this before I would embrace it totally.

I am old fashioned I guess in the sense that my rig is all discrete, except for the source (Rega - Apollo CD Player). The case I made in the previous post is addressed to this type of set up primarily.
#14
29th December 2012
Old 29th December 2012
  #14
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Glenn Kuras's Avatar
 

Quote:
On the other fully effective treatment below 100Hz, requires enormous space, cost, and effort. So much that it is rarely achieved in my experience.
Glad you said YOUR experience, because that is not my experience on a daily bases.
#15
29th December 2012
Old 29th December 2012
  #15
It's a substantial fallacy to assume that reflective surfaces have effects at only specific localised frequencies, and one would be equally mistaken to install Helmholtz traps to suck out just those "modal" frequencies as one would be to chase the issue with EQ. In the real world it's much more complicated, and it's the reflections that you want to mitigate the effects of, the usual and direct solution is to change the properties of the boundaries.

Headphones is the easy solution.

You could also get clever with placing subwoofers, controlling the sound field at multiple boundaries.
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