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Calibrating speakers

Started by Michel Rouzic December 27, 2005

Michel Rouzic wrote:


>> >>Tuning the equalizer by trial and error requires a lot of work and a >>good experience with the audio. A low cost mike will greatly simplify >>the task. > > > Yeah, i tried by trial and error, and I can tell, it's nearly > impossible for me to get to a satisfying result. When you say low cost > price, what price range do you think about (or even, which precise mic > do you think about?)
Surpirisingly enough, a $2 Panasonic electret capsule from Radioshack does a good job.
>>Secondly, the delta function does not provide you enough energy for the >>measurement. Use a white noise or a frequency sweep instead. > > > Funny, I thought about both, but for some reason I thought that a white > noise wouldn't be reliable due to its random nature
With the noise, you have to apply the sufficient amount of averaging to the results.
> and that it would > be too complicated to deal with a frequency sweep.
With the frq sweep, you have to look for the peak values on the spectrum.
> By the way, do you know anything that would make you able to convolve > your Windows sound output with a user-defined kernel (even if it has to > be a pretty small kernel) because that may be very handy (imagine > recording the output of a white noise, a turning it in a way so it can > be directly used as a kernel in a convolution, not even talking about > how you could turn your kernel so it can pretty much cancel echoes)
As for myself I do such things in plain C. There are many different softwares for equalization, however I prefer to know what exactly I am measuring. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Michel Rouzic wrote:

>>Another solution (one I very often use): go buy yourself an >>AKG K-501 headphones [...] > > hehe, yeah but i'd prefer to calibrate it the way i'm trying, not only > i'll have a way to calibrate it an almost-automated way, but it's also > a good occasion to use my knowledge in DSP and my tools in a usefull > way.
Yeah... But you won't have an AKG K-501 !!! :-P :-) Carlos --
Michel Rouzic wrote:
> Richard Owlett wrote: > >>Michel Rouzic wrote: >> >>>I just got a new set of 2.1 speaker [snip] >> >>and elsewhere in thread reference made to "2.0 speaker". >> >>What is 2.0|2.1 speaker? >> >>PS. Only dumb question is the the one you don't ask. > > > It's not a dumb question :-). 2.0/2.1/4.1/5.1 means the number of > satelitte speakers and of bass speakers. Thus, a 2.1 system has two > satellite speakers, mostly dedicated to medium and high frequency and a > bass speaker, as a 2.0 system has two speakers which are usually able > of inputting any sound in the audible range. >
thank you I'm now educated ;}
Vladimir Vassilevsky wrote:
> Michel Rouzic wrote: > > > >> > >>Tuning the equalizer by trial and error requires a lot of work and a > >>good experience with the audio. A low cost mike will greatly simplify > >>the task. > > > > > > Yeah, i tried by trial and error, and I can tell, it's nearly > > impossible for me to get to a satisfying result. When you say low cost > > price, what price range do you think about (or even, which precise mic > > do you think about?) > > Surpirisingly enough, a $2 Panasonic electret capsule from Radioshack > does a good job. > > > >>Secondly, the delta function does not provide you enough energy for the > >>measurement. Use a white noise or a frequency sweep instead. > > > > > > Funny, I thought about both, but for some reason I thought that a white > > noise wouldn't be reliable due to its random nature > > With the noise, you have to apply the sufficient amount of averaging to > the results. > > > and that it would > > be too complicated to deal with a frequency sweep. > > With the frq sweep, you have to look for the peak values on the spectrum. > > > > By the way, do you know anything that would make you able to convolve > > your Windows sound output with a user-defined kernel (even if it has to > > be a pretty small kernel) because that may be very handy (imagine > > recording the output of a white noise, a turning it in a way so it can > > be directly used as a kernel in a convolution, not even talking about > > how you could turn your kernel so it can pretty much cancel echoes) > > As for myself I do such things in plain C. There are many different > softwares for equalization, however I prefer to know what exactly I am > measuring.
Isn't it a bit complex/delicate to make all of the sound output of your coputer go through your C program? I'd be curious to know how you can do such a thing anyways
Carlos Moreno wrote:
> Michel Rouzic wrote: > > >>Another solution (one I very often use): go buy yourself an > >>AKG K-501 headphones [...] > > > > hehe, yeah but i'd prefer to calibrate it the way i'm trying, not only > > i'll have a way to calibrate it an almost-automated way, but it's also > > a good occasion to use my knowledge in DSP and my tools in a usefull > > way. > > Yeah... But you won't have an AKG K-501 !!! :-P
haha that's right! but i don't have the $100 anyways! (i got cool 50 =80 Sony headphones anyways)
Richard Owlett wrote:
> Michel Rouzic wrote: > > Richard Owlett wrote: > > > >>Michel Rouzic wrote: > >> > >>>I just got a new set of 2.1 speaker [snip] > >> > >>and elsewhere in thread reference made to "2.0 speaker". > >> > >>What is 2.0|2.1 speaker? > >> > >>PS. Only dumb question is the the one you don't ask. > > > > > > It's not a dumb question :-). 2.0/2.1/4.1/5.1 means the number of > > satelitte speakers and of bass speakers. Thus, a 2.1 system has two > > satellite speakers, mostly dedicated to medium and high frequency and a > > bass speaker, as a 2.0 system has two speakers which are usually able > > of inputting any sound in the audible range. > > > > thank you I'm now educated ;}
you're welcome. "which are usually able of inputting any sound in the audible range" you surely understood that I meant outputting, not inputting, although they can input sound as well

Michel Rouzic wrote:

> Isn't it a bit complex/delicate to make all of the sound output of your > coputer go through your C program? I'd be curious to know how you can > do such a thing anyways
A set of tools I've used for Win98SE which only requires a .wav file containing the convolution kernel's are: Virtual Audio Cable http://spider.nrcde.ru/music/software/eng/vac.html Audio Mulch http://www.audiomulch.com/ Voxengo Pristine Space http://www.voxengo.com/ There are also tools for measuring your system's responses as convolution kernels and for inverting them to do equalization. The framework is Adobe's Audition sound editor using the Aurora plugins from Angelo Farina to generate stimuli, analyze recorded results and calculate inverses for equalization kernels which can be used with the above tool set. http://www.ramsete.com/aurora/ For loudspeaker equalization, however, about the best you can do is to equalize the speaker itself on axis from measurements taken in hemi-anechoic conditions (out of doors at a distance from reflections.) If you try to do anything about the room they are in you are doomed. A compensation at any given point in the room can be disasterous for other points. There's a lot of stuff you will have to get under your belt to understand and utilize these tools. There is a fair bit to DSP. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein
Bob Cain wrote:
> Michel Rouzic wrote: > > > Isn't it a bit complex/delicate to make all of the sound output of your > > coputer go through your C program? I'd be curious to know how you can > > do such a thing anyways > > A set of tools I've used for Win98SE which only requires a .wav file > containing the convolution kernel's are:
sounds good. however, I have little idea on how i'm gonna get to convolving my system's sound in realtime with a .wav kernel from what I red on these pages, I'd be very curious to know how you set those apps up to get to that. I wish I could do my own program to do that, but it required kernel programming, r
> Virtual Audio Cable > http://spider.nrcde.ru/music/software/eng/vac.html > > Audio Mulch > http://www.audiomulch.com/ > > Voxengo Pristine Space > http://www.voxengo.com/ > > There are also tools for measuring your system's responses as > convolution kernels and for inverting them to do equalization. The > framework is Adobe's Audition sound editor using the Aurora plugins from > Angelo Farina to generate stimuli, analyze recorded results and > calculate inverses for equalization kernels which can be used with the > above tool set. > > http://www.ramsete.com/aurora/
wait, I just looked at the screen shots... Adobe Audition == CoolEdit Pro?! awesome, I wondered what had happened to that kick ass app (that's the app I always use for um.. anything). I'll try that plugin anyways, seems like what I need.
> For loudspeaker equalization, however, about the best you can do is to > equalize the speaker itself on axis from measurements taken in > hemi-anechoic conditions (out of doors at a distance from reflections.) > If you try to do anything about the room they are in you are doomed. > A compensation at any given point in the room can be disasterous for > other points.
Yeah i'm giving up the idea of compensating reflection. My room is such a mess, there's hardly any hearable reflection anyways. For loudspeaker equalization (those that i'll use to record the output of my 2.1 speaker system), I just set the speakers on top of my bed, vertically and make them face each other at a distance of about 3 inches (and one plays while the other one records). So far it doesn't give such bad results, but if you think there's anyway i can improve my way of recording the output of it...
Michel Rouzic wrote:

>>>>Another solution (one I very often use): go buy yourself an >>>>AKG K-501 headphones [...] >>> >>>hehe, yeah but i'd prefer to calibrate it the way i'm trying, not only >>>i'll have a way to calibrate it an almost-automated way, but it's also >>>a good occasion to use my knowledge in DSP and my tools in a usefull >>>way. >> >>Yeah... But you won't have an AKG K-501 !!! :-P > > > haha that's right! but i don't have the $100 anyways! (i got cool 50 > � Sony headphones anyways)
Sony?!!! You're sooooo grounded!!! :-) What are the speakers, Bose? Radio Shack? ;-) Carlos --
Carlos Moreno wrote:
> Michel Rouzic wrote: > > >>>>Another solution (one I very often use): go buy yourself an > >>>>AKG K-501 headphones [...] > >>> > >>>hehe, yeah but i'd prefer to calibrate it the way i'm trying, not only > >>>i'll have a way to calibrate it an almost-automated way, but it's also > >>>a good occasion to use my knowledge in DSP and my tools in a usefull > >>>way. > >> > >>Yeah... But you won't have an AKG K-501 !!! :-P > > > > > > haha that's right! but i don't have the $100 anyways! (i got cool 50 > > =80 Sony headphones anyways) > > Sony?!!! You're sooooo grounded!!! :-)
lol, what does it mean : grounded?
> What are the speakers, Bose? Radio Shack? ;-)
um... no brand written on it. they came with some cheap Brandt stereo (not sure the brand) (i mean for the 2.0 system, the 2.1 system i'm trying to calibrate is Logitech X-230)