Just plotted Frequency Response for Monitors, what's next?

  • Thread starter Thread starter aznwonderboy
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COOLCAT said:
i would think closet would be open.
Click to expand...

Let's see, the right side of my room has a closet. If I leave it open...the hanging clothes will act as traps (right?). The left side of my room has a big window 6 ft x 3 ft, which has PVC venetian blinds. Do these help?

So, if I have to treat my room, I only need to worry about a small part of the left side and the rear?
 
yeah. hopefully you can hear an improvement.

i started measuring the rooms too, for the same reason.
start second guessing the ears.
"is it flat?" or am i going to old hifi habits of looking for speakers with a Vscoop? or is the harsh trebly midranges what a real Flat speaker sounds like.
The measurements help.

Traps, Ethans links are very helpful on the initial placements. Todzilla has some good pics too. If like me you may need to read it a few times, to get it. Its much simpler than it looks...even the X/Y formulas...its all based off you room dimensions and gives you a strong starting point for placements. Windows and your own stuff may require your own creative work.
You can save time from my mistakes and re-read this setup. I got excited and just stuck the traps on the walls.... then took 'em down and moved 'em (pretty good chore)...after it clicking! its like oh yeah, now i see!

balance your room with equal and centered spacing etc.. just read around here thats all i been doing. your ears will thank you!

Do you have a pc in your room?
 
Yes, I have a PC in my room. I bought a very quiet heatsink fan and a quiet hard drive, so noise isn't audible. Yeah, I know there are some very high-pitch frequencies floating in my room due to the fast spinning fan and all that electrical stuff in the PC.
 
Elaborate please....

Hello all,
I am new here.
I have been pondering these very questions for a long time now and it is nice to finally find a forum that has technically inclined people who actually tackle the question. I asked basically the same question over on John Sayers forum and his response was "use your ears". Uh....OK.
Yeah let me use my ears.. I understand the importance of knowing your room...but when it comes to speaker placement,phase, room modes,nodes , peaks , nulls, equilateral triangles, etc... I prefer to use math not my ears.

ANYWAY....

My question is can someone please elaborate on what exactly is catagorized as a "good" "fair" "poor" "awesome" frequency respose from the mixing position????
Please..
Post .gifs demonstrating.
My freq response currently doesn't vary more than 4db from 125-20k.
Below that I have a a couple problems around 108hz, 88hz,47hz.
I want the vary best I can achieve , but I have no data to compare against to know when enough is enough. No what I mean.???
When do I quit dickin' with this and concentrate on making music?
I know that even after I get this done I will have to learn my room, because it isnt always going to sound the way i expect it to.


Thank you.
Brandon
 
brandong said:
I asked basically the same question over on John Sayers forum and his response was "use your ears". Uh....OK.
Yeah let me use my ears.. I understand the importance of knowing your room...but when it comes to speaker placement,phase, room modes,nodes , peaks , nulls, equilateral triangles, etc... I prefer to use math not my ears.
Click to expand...
Brandon,

While I understand where you're coming from, math in and of itself will only go so far towards telling you how a room really sounds, and in some cases can actually lie to you (it depends greatly upon the nethods and accuracy of measurement to begin with.) At some point you'll have to forego the math and trust your ears. If you aren't yet at the point where you can fully trust your ears - and kudos to you for being objestive and honest enough to recognaize that - then it's a matter of training you ears for proper critical listening.

That said, don't hang up on my post just yet. There's more for you that you might like better than just that answer ;) ...
brandong said:
My question is can someone please elaborate on what exactly is catagorized as a "good" "fair" "poor" "awesome" frequency respose from the mixing position????
Click to expand...
Here's how I'd characterize it: The rating, from poor to awsome, is directly ties to the degree of translation required to correlate a the way a mix sounds in the studio to the way it will respond playback in "the real world". Poor would mean very difficult if not impossible to "plan" a mix in the studio in such a way where it comes out sounding in the real world the way you wanted and expected it to. Fair would mean you can get it to translate OK, but it takes quite a bit of work and a long degree of translation to make it do so, and that the character of that translation would not be immediately obvious to another engineer coming into your room. Awsome would mean that you or any qualified engineer could walk into your room and make an excellent mix without having to break a sweat in translating from your room to the outside world; what sounds "right" in the studio, sounds "right" on CD or on the radio.

There's no GIFs or math behind that because translation includes variables on both sides of the equation; both in the room acoustics and in the ear response and training. Think about that for a second. If it were as easy as a flat response, all decent monitors would sound equally well to everyone because they all approach (but never acheive) similar relative dgrees of flatness. Yet we have engineers who love to mix on NS-10s and engineers who hate to mix on them. The same thing with BX-8s, HR824s and even the more expensive Genelecs and Adams. You can put a given monitor in a given room, measure that coupling twice and get the exact same measurements, and have two differen yet equally qualified engineers walk in and have one hold his nose and the other get a shit-eating grin. The identical math generates two different responses for two different engineers.

HOVEVER...WAIT FOT IT! :) ....
brandong said:
My freq response currently doesn't vary more than 4db from 125-20k.
Below that I have a a couple problems around 108hz, 88hz,47hz.
I want the vary best I can achieve , but I have no data to compare against to know when enough is enough. No what I mean.???
When do I quit dickin' with this and concentrate on making music?
Click to expand...
You have the single most common problem in home and prosumer studios, untamed bass response. The best ways to attack this and get on with your mixing is to

a) make sure your monitors are placed symmetrically in the room, preferably along the long dimension wall, if possible. Keep them out of corners and keep them a decent distance away from the wall surface itself.

b) place quality bass traps in as many corners of your room as you can feasibly do and afford, staring with the corners of the rear walls and the rear wall/ceiling junction and working forward from there.

c) read everything you can find on building bass traps on the cheap, buying pro bass traps, and studio room layout and design in general from the website www.realtraps.com.

These steps will quickly and cheaply take you a long way to getting a room that'll let you translate well. From there it's simply a matter of learning your new, better room and how it translates so you can make mixes that'll work the way you want them to.

G.
 
Brandon,

> what exactly is catagorized as a "good" "fair" "poor" "awesome" frequency respose from the mixing position???? Post .gifs demonstrating. <

Glen gave you great advice, and I can help with the GIF images. :D

(You'll have to click the links below to see them though.)

The first graph below shows the low frequency response and ringing in a typical small room. The second graph shows the same for my well-treated living room home theater. I have a ton of bass traps in my living room, and I also do 5.1 surround mixing there.

Note that waterfall plots like this show much more than raw frequency response. They also show the extended decay times at modal frequencies - the "mountains" come forward over time. The decays are related to the resonances present in all rooms, and these resonances are at least as detrimental as a skewed response. Note that in the second graph, with bass traps, the peaks are also much wider (lower Q) than the untreated room. That too is very important.

--Ethan

art_etf2.gif

ethan-ht.gif
 
brandong said:
Hello all,
John Sayers forum and his response was "use your ears". Uh....OK.

Yeah let me use my ears.. I understand the importance of knowing your room...but when it comes to speaker placement,phase, room modes,nodes , peaks , nulls, equilateral triangles, etc... I prefer to use math not my ears.

ANYWAY....

My question is can someone please elaborate on what exactly is catagorized as a "good" "fair" "poor" "awesome" frequency respose from the mixing position????


When do I quit dickin' with this and concentrate on making music?
I know that even after I get this done I will have to learn my room,
Thank you.
Brandon
Click to expand...

Well the "use your ears", is what it comes down to.
Let's get back to reality...if it doesn't sound good and your mixes don't translate, who gives a ? about charts.
Joe Meek said it best, If it sounds good it is good...

Guitar Tuners work and are accepted and repeatable and quantifiable.
This is why I wanted some kind of ROOM TUNER too.
I agree, MATH is great and can help intelligently place your traps and do your EE triangle with the monitors. simple foundational things that work, like a round tire on a car not a flat tire... EE triangle and Bass traps. the old hand clap, no ringing test too. Your ears will like the improvement!

Studying Turds:
then the fine subtle differences are hard to quantify. The extra bass traps and foam didn't have the HUGE impact as the first set? You can't hear a difference. so the RTA mic comes out to try and convince yourself there was an improvement and to convince yourself your not insane like your wife keeps telling you.
then you'll most likely come across some articles on the human ear which state "the human ear works nothing like a measurement microphone." :eek:
you won't tell anyone though, especially your wife and friends, after you spent 88 hours and 3 days scratching from the fiberglasss you hung on the wall.

its a secret we keep here on the forums. Rehab is different for each of us.
Only sound engineers will understand you after awhile. Its like a SciFi where you change little by little until non-Sound Engineer types can't comprehend anything you say or do.

In the end, you already knew the answer...as you said...
When do I quit dickin' with this and concentrate on making music?
I know that even after I get this done I will have to learn my room,

you'd probably been further along learning your room and your monitors and exercizing your mixing skills,,,,after the room has the basic foundation layout done.

Listening to your favorites is a well known test..done with your ears.
People will listen to your mixes with your ears.
Charts are cool too, especially the colored ones. :D
 
Ethan Winer said:
I can help with the GIF images. :D
Click to expand...
Great charts and post, Ethan ! :)

Two quick Qs for you if I may borrow the thread for just a second:

1. What hardware/software did you use to generate those displays?

2. On the second chart is that long decay down around 25Hz real or is that just some kind of artifact of the measuring system?

Thanks for your continued excellent support in the field of room acoustics and for any answers to the above. :)

G.
 
thank you thank you thank you

My goodness it is so nice to finally meet some people who talk the language
I want to speak!!!!!
So this was a 5 sec freq sweep from 20 -200hz correct?
What was the db the sweep was emitted at?
I think that would help me to place the center line in my mind.
I will try to generate this type of chart on my room.
Is this type of chart credible when trying to measure reverberation time?
OR
Should a pink noise burst be used for that measurement?
If so...where can I get a pink noise burst .wav?(please)

Thanks again for all the reponses.
I just want to get as technically close to perfect as I can and then let my ears do the rest. I have mixed in awful mixing room conditions and my results were awful. I want to work smarter not harder. I used to have to burn 20 test cds for a mix. I would be happy If i could get that down to 3.
Maybe that is not realistic, but thats what I am shooting for.
I will learn my room and I don't think I will majically have perfect mixes.
There is alot to mixing and I want my room response to be the least of my worries.
THANKS ALL!!
B
 
another question for Ethan:

I noticed the graphs only go up to 200Hz. Is there any discernable difference between the original room and the trapped room that would be beneficial in the higher frequencies? Does modal ringing occur with HF the same way it does with the LF? And if so, will bass traps correct this and any nodes?
I assume the answer is yes, but most of the graphs I've seen on your sites don't seem to mention anything about the highs.

Or is being "beneficial" dependent on what a person wants to get out of the room. For example maybe some people may want more higher frequencies to make it livelier...others may not.
 
Last edited:
EQing a room

Additionally,
What is the concensus regarding using equalizers to
flaten the room response?
I have heard different things.
1. It is OK if it is to fix boudary effects , but not room modes.
2. Never try to fix a null with EQ.
3. It causes phasing.

Should the same eq settings be used on both speakers to keep the
signal consistant or is it ok to just insert one EQ on one speaker only?

Thanks,
B
 
I never quite got a clear answer (or simple enuff for me to understand) on that question either.

It seems using an EQ is not technically the best way, but it is ok to adjust the EQ switches on the back of the Active monitors. :confused:

you can really flatten out the RTA graph with EQ though.

its the same thing with high end guitars that are often ran thru an EQ pedal, and then the EQ on their amplifier or POD....then thru a mic that goes into a board that then gets EQ'd at mixdown and possibly during mastering.
 
Glen,

> What hardware/software did you use to generate those displays? <

I use the ETF software, and those graphs are from this article that explains it in more detail:

www.realtraps.com/art_etf.htm

> On the second chart is that long decay down around 25Hz real or is that just some kind of artifact of the measuring system? <

Yes it's real. It's a room resonance (mode). You can get similar results when measuring rooms if a loud truck etc passes by outside, but in this case it's legitimate.

--Ethan
 
Benny,

> Is there any discernable difference between the original room and the trapped room that would be beneficial in the higher frequencies? Does modal ringing occur with HF the same way it does with the LF? <

The bass range extends up to 300 Hz or so, and above that the resonances sort of switch from what I'd call ringing to flutter echo. There's a newer version of ETF called R+D that can display any arbitrary frequency range, as opposed to stopping at 200 Hz. But the graphs I show give the general idea. ETF does show higher than 200 Hz, but not at as high a resolution.

> And if so, will bass traps correct this and any nodes? I assume the answer is yes, but most of the graphs I've seen on your sites don't seem to mention anything about the highs. <

Again, problems above 300 to 400 Hz or whatever are more excess ambience, and slap and flutter echoes. The solution is the same though - absorption.

> For example maybe some people may want more higher frequencies to make it livelier...others may not. <

Small room ambience is always bad ambience. If you want good ambience you need something much larger than a typical bedroom studio. Maybe 20 by 15 feet minimum. Anything smaller should be more dead than live sounding.

--Ethan
 
Brandon,

> What is the concensus regarding using equalizers to flaten the room response? <

EQ does not work for that. The text below is from my Acoustics FAQ.

--Ethan

Another common misconception is that equalization can be used to counter the effects of acoustic problems. But since every location in the room responds differently, no single EQ curve can give a flat response everywhere. Over a physical span of just a few inches the frequency response can vary significantly. Even if you aim to correct the response only where you sit, there's a bigger problem: It's impossible to counter very large cancellations. If acoustic interference causes a 25 dB dip at 60 Hz, adding that much boost with an equalizer to compensate will reduce the available volume (headroom) by the same amount. Such an extreme boost will increase low frequency distortion in the loudspeakers too. And at other room locations where 60 Hz is already too loud, applying EQ boost will make the problem much worse. Even if EQ could successfully raise a null, the large high-Q boost needed will create electrical ringing at that frequency. Likewise, EQ cut to reduce a peak will not reduce the peak's acoustic ringing. EQ cannot always help at higher frequencies either. If a room has ringing tones that continue after the sound source stops, EQ might make the ringing a little softer but it will still be present. However, equalization can help a little to tame low frequency peaks (only) caused by natural room resonance, as opposed to peaks and nulls due to acoustic interference, if used in moderation.
Click to expand...
 
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