# info about setting up room EQ



## allen_gibberish (Feb 8, 2010)

HELLO

i'm using room EQ wizard but i'm not figuring out very well how to set it up.

here are my doubt:

1) i've calibrated the sound card, if i calibrate it connecting the output i use for the speaker and a line input of the card i don't understand how to increase the input volume, because line inputs have no volume control, so i rise up the output volume of the sound card, to match the levels

2) calibrate the spl, i put a -18 db so i have a peak around -6, than i rise up the output volume until i read 75 db in the sound level meter, but than i realize that the input where it's connected the mic is at -50 db, shouldn't be the room EQ output level and the mic input level at about the same value?


ok, please give me some information about how to calibrate room eq, because i don't know if it's for my english or my poor knowledge or the room eq guide doesn't explain that part very well.

it says "rise the input level" but in room EQ is disabled and the input level from the mixer of the soundcard is a cue mix, it's the total mix of rme, so it doesn't rise the input level really

the only way to rise up the input level is turning the gain knob, but if i go over the middle position it gets color, i mean isn't that linear and to have a -20 db i should put the gain knob in it's max position .. 

every suggestion is appreciated!


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## glaufman (Nov 25, 2007)

Hi Allen, and welcome to the Shack!
It will help us to help you if you give us a list of your equipment: what kind of computer (MAC or PC), what OS, what soundcard, what receiver, what SPL meter, what microphone...
In some OS's, we find that the system won't let REW control the input level on the soundcard, but that can still be done in either the OS's audio controls or mixer or in the one in the soundcard's drivers.
Generally, what you want to do is set the output level to a reasonable level (as outlined by REW as you run the setup routines), connect a loopback cable from line out to line in. Adjust the input levels to get a resonable level. then you can go about running the soundcard calibration. Then run a measurement sweep without changing anything and verify the calibration is good by getting a straight flat line measurement.
Then you can go and connect the soundcard output to the system, and a mic (meter) to the soundcard input. You would adjust the volume on the amp to get 75dB, then adjust the input on the soundcard again to get a reasonable level, then tell REW that level is 75dB. Then you're ready to go.
For most, the only real trick is finding this input volume control.


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## allen_gibberish (Feb 8, 2010)

well i'm doing measurements with a macbook, fireface 800, ECM8000, but i'm using the windows version of room EQ so using the macbook with bootcamp, running windows, just because the first time i tried using room eq with osx i wasn't able to make it work.

so i never used it with osx, the other time i used was with windows and without calibrating the spl.

yes the problem is the input level, because isn't enabled in room eq and i don't know where change it, the OS volume work with the internal soundcard (right?) so the only one is the fireface mixer, but you can't increase the input level, i mean it's just a cue mixer, to make an headphone mix, monitoring mix, they don't affect the actual input level.

btw i'm using the rme preamps and if i want to keep them linear and without noticeable noise floor, i should keep them around the middle position, or little more, but over 3/4 the signal is colored and the noise is more evident.

so now i'm thinking to put the room eq output level at -24 and rise up the rme output level till i get 75 db, then adjust the gain until i read -24 (i think maybe i can arrive at -24, but i'm not sure) 

just because to use it at -18 i have to raise the gain at it's max position and there is too much noise etc.

i don't know other way to get the input level equal to the output level.

hey i thank you so much for your suggestion!! 
you are making me save so much time!


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## allen_gibberish (Feb 8, 2010)

well, i've found the way to enable the input and output control, by selecting them in the OS mixer and now i'm able to select them, but i'm not able to change the input gain, i mean now isn't gray (disabled) is enable, but if i push the up and down arrows to increase or decrease the input level, nothing happen, and even in the OS mixer i can't change the input level, which is at zero.


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## allen_gibberish (Feb 8, 2010)

i tried various different settings but at 3/4 of input gain i'm at -35.8 and i can arrive at -18 something if i turn the gain at its max position, but you understand that +18 of gain the last 1/4 of gain.. means that aren't very linear, plus there is noise here, it's an extreme setting that you never use.

i really don't understand how to get at least -24

i'm 12db lower

but i also would like to avoid the 3/4 position, i prefer to stay around 1/2

in the past i used it without calibrating spl etc, and i just rise the output level until i get enough volume to set the gain at a bit more than 1/2 

but keeping it at 75 it's impossible if i can't rise the input level..

any suggestions?

thanks!!


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## glaufman (Nov 25, 2007)

What version of windows is running that way?
Are you sure the fireface and REW are set to the same sampling rate?
You didn't mention an SPL meter. Without one, you can't calibrate the SPL anyway. All you could do is calibrate the soundcard for a flat response at whatever SPL it's at, which will be unknown.
How do you know there's too much noise?
Are you only experiencing the problem with the ECM8000? Or are you experiencing the problem with a simple loopback cable? With the ECM, have you enabled the 48V?


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## allen_gibberish (Feb 8, 2010)

glaufman said:


> What version of windows is running that way?


windows xp professional version 2002, sp2 

[/QUOTE]



> Are you sure the fireface and REW are set to the same sampling rate?


yes



> You didn't mention an SPL meter. Without one, you can't calibrate the SPL anyway. All you could do is calibrate the soundcard for a flat response at whatever SPL it's at, which will be unknown.


i have a sound level meter "Lafayette" over there is written SL-A but i think it's just the name of the model, i mean this should be an SPL meter, gives me the DbA level 



> How do you know there's too much noise?


well because i use this soundcard since 2005 and i know it become noisy at extreme settings, like all the soundcard i've used in my life  just extreme settings usually should be avoided for what i know.



> Are you only experiencing the problem with the ECM8000? Or are you experiencing the problem with a simple loopback cable? With the ECM, have you enabled the 48V?


yes 48V checked , as i said isn't a problem, is more a characteristic of every sound card preamps.

usually preamps has a great increment at the end, but they become also noisy.


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## glaufman (Nov 25, 2007)

> Are you only experiencing this with the mic, or when you connect a loopback cable as well?


?


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## allen_gibberish (Feb 8, 2010)

when i loopback the signal i have to rise the output level from the rme mixer to get the same value 

but i can't do this with the mic because the output level of the rme mixer controls the speaker volume, so if i want to get 75 db i have to keep it down


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## glaufman (Nov 25, 2007)

I see. Am I corrct in thinking that you tried first to adjust the input level in REW and then in the mixer? Try unchecking the "control input" box in REW and maybe it'll relinquish control to the OS. Or try checking it so it takes control.
You also can try closing REW, rebooting, and seeing (without opening REW) if the OS will then adjust the input level.


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## allen_gibberish (Feb 8, 2010)

well if i reboot, before opening room EQ i can adjust the input volume, but when i start room EQ i don't, despite the control input checkbox, i also disabled the output, but i still can't adjust the input from the OS input level control when room EQ it's opened.

why that?

i mean, i've unchecked, rebooted, input control works, i open room EQ and doesn't work anymore.

(plus isn't this only a passive controller? i think i can increase the input level only with gain from the preamp, am i wrong?)

THANK YOU very much, maybe we are close to the solution!  (i hope)


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## glaufman (Nov 25, 2007)

allen_gibberish said:


> why that?


I dunno. :huh:


> (plus isn't this only a passive controller? i think i can increase the input level only with gain from the preamp, am i wrong?)


Well, if you could, then you wouldn't have a issue, right?


> THANK YOU very much, maybe we are close to the solution!  (i hope)


I hope so to, but I'm afraid we're only close to the problem. :sarcastic:
PowerPC or Intel processor?


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## allen_gibberish (Feb 8, 2010)

glaufman said:


> Well, if you could, then you wouldn't have a issue, right?


yeah i mean the only way to increase the input level is with the preamp gain, because the total mix is passive and i think also the os input level is passive, so it doesn't really increase the level.. but i don' t know how the input level in REW is designed, i mean it is passive? if so, it will not increase the level

i don't know too, i've read many other with input level issues, but i haven't seen a solution for a case like mine



> I hope so to, but I'm afraid we're only close to the problem. :sarcastic:
> PowerPC or Intel processor?


Intel, i'm using it in windows, so windows doesn't work with powerpc

could it be the internal soundcard? but i have selected the fireface 800, even the OS volume is selected to the fireface 800

now, tomorrow i'm out for work, i will be back here friday, maybe i will try again to use it with OSX and to disable the internal soundcard in windows, but i don't know, because usually input level can be increased only with preamp gain, not from internal volume, unless the software provide an active input level, like sequencers does, but i can't increase the room eq internal input level.

well thank you!:hissyfit:


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## glaufman (Nov 25, 2007)

allen_gibberish said:


> yeah i mean the only way to increase the input level is with the preamp gain, because the total mix is passive and i think also the os input level is passive, so it doesn't really increase the level.. but i don' t know how the input level in REW is designed, i mean it is passive? if so, it will not increase the level
> 
> i don't know too, i've read many other with input level issues, but i haven't seen a solution for a case like mine


I haven't even a problem like yours. Once people find the input control it usually works. I'm sorry to say it sounds like a MAC compatibility issue. People usually have better luck with Intel processors than the PowerPCs, but not 100%.


> could it be the internal soundcard? but i have selected the fireface 800, even the OS volume is selected to the fireface 800
> 
> now, tomorrow i'm out for work, i will be back here friday, maybe i will try again to use it with OSX and to disable the internal soundcard in windows, but i don't know, because usually input level can be increased only with preamp gain, not from internal volume, unless the software provide an active input level, like sequencers does, but i can't increase the room eq internal input level.
> 
> well thank you!:hissyfit:


Worth a try. I'm also going to request some backup... addle:


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## allen_gibberish (Feb 8, 2010)

can't be mac compatibility because i'm using it in windows.


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## JohnM (Apr 11, 2006)

Basically you will need to turn up the mic preamp gain. You can still get decent measurements at lower input levels, and compensate somewhat for the reduced S/N by using a longer sweep, but increasing the gain would be better. I realise that for normal recording use you may want to avoid pushing the gain above your preferred mid point setting, but for measurement you are better having more level. If the volume mixer is not behaving properly with REW set to control it just uncheck the REW control and use the Windows mixer to set the levels, but often the mic preamp gain would be set in hardware earlier in the chain - the Fireface web page does say that volume controls are software controlled "_apart from the levels of the microphone pre-amps and the headphone outputs_" so sounds like the mic preamp gain is not set through the windows mixer anyway.


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## allen_gibberish (Feb 8, 2010)

but don't you think i will get false measurement if the preamp at high level push its color in the measurement? 

i mean i'm not talking about mid setting, even if i push it at 3/4 i haven't enough level and over 3/4 increase of something about 15 or more db, which is intended more as "extragain" to use in case of emergency (like you have set all up, you have to make a record and instead changing everything, you can push it more if you don't have enough level) but i doubt is linear at least it's not for my ears, plus gets a bit of noise, the signal to noise rate is better under 3/4 

i can't control room eq input but if i disable it i can't even control it from the window volume control

the rme mixer control the volume passively, if you have a max input at -12 for example, you can only decrease it


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## JohnM (Apr 11, 2006)

allen_gibberish said:


> but don't you think i will get false measurement if the preamp at high level push its color in the measurement?


Frankly, no. I would be surprised if the RME's frequency response changed significantly with the preamp gain setting, would be pretty poor of RME if it did. But you can easily find out, just make some measurements at different gain settings and see if the shape of the response is changing, you can use the trace offset controls in REW to move the traces so they overlay one another.


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