The music playback EQ adjustment based on sound pressure

[jinkemao]

Hello, everyone,
my English is not good, I have a question?

Equal loudness curve, has been more contradictory, music playback, the environment is very perfect, adjust the EQ loudness, 85dB, smaart test a straight line (fiat) sounds good point 100dB something noisy, 120dB as straight, the 2500HZ is very noisy, whether according -6dB.,to the bookP1010040.JPG

thinaks

[Kip Conner]

Are these your measurements in the attached image?

Are you saying that your systems sounds good at the 85dB mark and as you increase the SPL to 100dB it gets noisy in the 2500kHz range?

Or is this a general question to how manufacturers set their EQ to produce loudness contouring?

[Dr. J]

Yeah -- I am not sure exactly either but IF this is what you are getting at great. If not -- sorry for my post.

I know the Coherence trace only needs to be so high for the data to be considered valid (I guess) and this doesn't mean the system has to be at concert level. This is what I am told. However, I am forced to think otherwise by my results.

In fact -- I have never really cranked the system up for measuring due to neighbors. With that said -- my results have been very similar to yours (in your graphs) at least from a harshness standpoint in the upper frequencies through listening at higer volume levels during shows. I have only measured at shows a few times and it simply is too hectic because I am in the Club / Bar scene where the management don't get this. Great sound is a given (as it should be) and I am lucky if we even get a quality sound check in.

I am convinced that through all the trial and error I have gone through that the system needs to be tuned at the volume you are going to be playing at. Some will disagree but until I get to be as good as they are at this stuff -- this is where I am at.

An easy way to check yourself is by recording your MAIN out on your console BEFORE it gets to your system EQ. If your board mix is DULL -- then your System EQ is set too bright. If your board mix is too bright -- then your system EQ is too Dull. This is REGARDLESS if your trace is flat or not.

For me -- tuning at low volumes translated into an overshoot once the system was roaring at show levels and the harshness and brightness manifested itself something fierce. I knew I couldn't accept the FLAT trace at low levels. This is of course outdoors. Inside -- alot of those levels once again changed due to the heavy buildup of certain frequencies.

I began recording the main out and listening with a known flat response set of headphones. If my headphone sound was DULL and I took them off to hear the system screaming in the high frequencies -- I would make a cut on the system EQ. I would go back and forth until I knew I thoroughly messed up my perfect FLAT trace.

At some point where the system was more tamed to match the headphones -- I would stop. The next opportunity -- I would do another outdoor tuning and fire up the system AS IS from the gig only to discover YES my flat trace is no longer there and my high frequencies are much lower (-6 dB) than the mid area. Interestingly -- the phase response still looked like it did before. I see many on here say the phase response is what matters not the frequency response. Bob McCarthy says the flatter the magnitude response the flatter the phase response. Hmmm -- I may not be doing it correctly then. He also states that the magnitude response need not be flat in order to be smooth. A tilted spectrum (that is essentially flat but tilted) is just as good as a perfectly flat system.

In any case -- I would go ahead and smooth out the new trace that isn't FLAT anymore to its new shape and go out to the gig and repeat. I would then EQ instruments on the board to sound correct in the headphones which then again made the system sound bright -- this would make me get back into the system EQ and make more cuts UNTIL the sound off the console was more in alignment with the sound coming out of the speakers.

The trace I have now is anything but FLAT. It is more like a slope of a roller coaster with a buildup heavy in the low end with a series of dips and hills down to the high end of the spectrum. At my next opportunity -- I will post a snapshot.

I own my system and I use the same mics - same everything - everytime, so I think I can get away with this. It brings up the discussion of should the system be neutral or should the board be neutral. I personally think the board mix should sound accurate without speakers even hooked up to it but that is just my opinion. I know if done accurately -- that is what Smaart is all about but Smaart has operator errors. ie. ME

The flat response headphones (Ultrasone HFI 680's) have pointed out to me that my outdoor low level tuning strategy needs refined. It is my check point.

Perhaps soon I will be able to get the system outdoors and run it at concert levels to see the difference -- if there is any. The traces you showed -- imply that it does. The recorded main out with a different know source helped to give me another angle and I have to say has made a fantastic difference in my system.

Also music played thru the system with NO EQ should sound good from the start.

I now have a curve set for MY system that sounds better than it ever has and it is far from Flat. I am curious how it will sound at an outdoor event but I won't get to test that Curve out for another month and a half. Maybe a more flat response would be better suited for the outdoor stuff??? I will find out.

Don't know if this helps or not but if you own your own system and everything pretty much stays the same gig after gig then I bet you would benefit from this a great deal.

BTW -- This is a Dave Rat inspired method in which he learned from someone else and shares with his friends. For me -- it does indeed work great & I will never make my system flat again because the way I am interpreting the data -- just doesn't work.

FLAT is just a good starting point to get familar with the system. IMO

[jinkemao]

I think this is recording the CD 85-90dB, However, we replay the 100-120dB Speaker on-asix curve is flat, we have a EQ method, the human ear sound pressure regulator.

85dB 90dB 100dB 120dB

According to this sense of the human ear curve, the need to 2500Hz-6dB to listening to a sense of balance.

This music CD playback, how balanced, according to the sound pressure change, the human auditory system is more balanced。





Thank you

[jinkemao]

in the Club / Bar need.... Thank you

[luigichelli]

Jinemao, we assume that a pa is a linear system…
think to a linear equation
eg: y=2x
it's the same of doing 2y=2(2x)

so that's what smaart assumes…
you can tune your system at low db spl since it's linear, and will react the same at higher spl.

Distortion is a non linear function…

Our perception is not linear, but this is a different thing, we are tuning a PA not our ears.

Pls correct if i'm wrong
Regards,
Luigi.

[PrestonSoper]

Here are a couple of links that may be appropriate for this thread:

Howard Page article on excessive low end in system tuning
http://clairglobal.com/2011_news/2011/LowEnd.pdf

Frequency Response Contour EQ
http://soundforums.net/varsity/2348-...e-systems.html

[Dr. J]

Here are a couple of links that may be appropriate for this thread:

Howard Page article on excessive low end in system tuning
http://clairglobal.com/2011_news/2011/LowEnd.pdf

Frequency Response Contour EQ
http://soundforums.net/varsity/2348-...e-systems.html

Thanks Preston! I have actually been following the "Sound Forums" thread until it died out. I have somewhat approached my system tuning in reverse order...... LoL Well -- initially I tuned it outdoors to be flat from 100Hz on up to around 8kHz BUT once I got it inside a place the lower frequencies like 100-300 even up to 500Hz just went thru the roof. I was cutting them out on the channel strip and all kinds of things you shouldn't do until I recorded my main out. I was horrified at the board mix.... So I started exploring how to make it sound correct simply because I am asked occasionally if a recording can be obtained off the console. So I started mixing with headphones to make it sound correct at the console and then just did what I had to do at the System EQ to bring it back. The next day I would drag the system out back and fire it up to look at the trace NOT fooling with the shape or contour of the curve BUT making it smoother throughout. Then I would take it out to a gig and repeat. I have done this about four times now -- each time refining the initial curve. I have never been happier with it. I can mix with headphones on and take them off and the system will sound very close except the sub lows and extreme highs. I would be happy to give someone a board feed now because it sounds more in balance than before. I really dig using Smaart for all kinds of things but this was one way for me to use a little of everything (smaart, CDs, recordings & headphones) to refine my system.

I also did this with all my monitors too. Seemed to really clean up the overall tone. The changes I made to my system EQ (DR260) of course were on the INPUT side and not the Output side. The output side is dedicated to driver corrections (completely flat) & I will most likely never touch those.

Thanks again for the article links.

[Dr. J]

Jinemao, we assume that a pa is a linear system…
think to a linear equation
eg: y=2x
it's the same of doing 2y=2(2x)

so that's what smaart assumes…
you can tune your system at low db spl since it's linear, and will react the same at higher spl.

Distortion is a non linear function…

Our perception is not linear, but this is a different thing, we are tuning a PA not our ears.

Pls correct if i'm wrong
Regards,
Luigi.

Yesterday for the first time ever --- I got to do a tuning session outdoors where I pushed the system pretty hard. I will say that my initial trace DID NOT change at high volume compared to low volume. However, the coherence trace was a high as it would go (LOL) BUT I will say there is something to higher volume levels for the subs. I have EQ'd the subs in the past at low volume only to see it change with high volume. I just did this again yesterday and when the subs were pushed -- the trace just takes on a different shape.

Now about how the ears hear....... I see what you are saying Luigi. Seems to me that if it is our ears changing with higher dB levels then are there ways to compensate for that with Smaart? If our ears are waay more sensitive to 3.5k at 115-120dB than say any other frequency lower than it -- why in the world would we ever want it to be equal with it? The sound guy is just going to cut it anyways.

My system trace looks more and more like the Equal Loudness Contour trace....... at least in the 2.5 - 4k region. Anyways -- thanks for your input! I still have tons to learn....

[Ferrit37]

Hey Dr. J,
The change in EQ or contour on the subs from low level to higher levels suggests that the subs are being pushed into a non-linear region, prehaps more 2cnd harmonic distortion.
Also remember that changing the level of a passband will affect its acoustic crossover point.

cheers