Preliminary note: I tried to highlight the keywords in my rather long report - for those who want to obtain a quick overview of what I'm talking about.
INTRODUCTION:
There are several factors that influence the sound of a speaker system: the source, the amplifier, the speakers, the listening room, maybe the cables and probably some more like the quality of the current.
The most important factor however is the speaker. Just try it and change the amplifier or the source of your system. You'll probably hear some differences. Now keep the source and the amp and try another pair of speakers – the difference will be much heavier.
Ok, if you have been using a walkman as source and switch to an Accuphase CDP, the difference will be very clear too, but I'm only talking about equipment of a certain quality – the stuff people that read threads like this are usually interested in.
So what is the second most important factor?
In my experience it is the room. Or to say it clearer: the interaction between the speakers and the room relative to your listening position.
The main issues in this regard are wall reflections and especially standing waves that color the sound in an almost unforeseeable manner.
THE USUAL APPROACH:
There are different ways to address these problems.
One way is - of course - to pass on demanding speaker listening and use headphones instead. Although I like headphones a lot, they really lack the lifelike image good speakers can deliver - but I'm not going to discuss this subject here. There are already dozens of 'Speakers vs. Headphones' threads on Head-Fi.
Another way is to face the facts of room acoustics and start the battle.
The first lesson is to place the speakers symmetrically relative to the walls and at an equal distance to the the listening position. This is the basis for all further modifications.
The second approach is to use diffusers to handle the early reflections and bass traps or resonators to get rid of the standing waves. But this is quite a difficult task: diffusers often 'overdampen' the room if used too extensively – the result is a muffled sound because they not only diffuse, they also absorb the mid to high frequencies (depending on their thickness).
Bass traps are an even more complicated issue. Those things that are normally sold as bass traps are about 50 x 50 x 50 cm (20'' x 20'' x 20'') large and will not efficiently affect the typical room mode frequencies. What you would need in order to have an audible effect on the bass response should be really large.
Resonators can be smaller than bass traps and seem to be a much better solution. But their design according to your room size is difficult to calculate, and even if you're theoratically successful you will need the technical skills and the required equipment to build such a thing.
But even if the result of using absorbers and bass traps or resonators will be satisfactory soundwise, it will most likely look quite ugly. It might then be unacceptable from even an modest designer's point of view – for example your girlfriend's.
So if it's difficult to fine-tune the sonics created by the speakers, why not tune the bits before they are converted to electrical energy?
This leads us to the field of digital sound correction:
THE DIGITAL APPROACH:
In digital sound correction there are two approaches:
Digital equalizers and correction filters that can be used with a convolver. Digital EQs are a not bad, but the number of bands is usually limited and it takes a lot of attention to set them in order to compensate for the characteristics of the room.
Correction filters however are based on a fingerprint of the individual room.
First you need to measure the impulse response of your room and then you have to generate the digital filters which then should compensate for the acoustical problems of the system. These filters then can be used in a convolver, for example in foobar's convolver.
Well, calculating the filters is not an easy task, but fortunately there is an open source software that helps you to generate the filters. It's called Digital Room Correction (DRC) and has been programed by Dennis Sbragion some years ago.
But for computer-laymen like me even this software is quite difficult to handle.
And although there is a well structured guide (see links below) you'll have to follow a lot of steps from generating the test tones to calculating the filters with DRC.
What I was really looking for was something like a software only TACT-system (see link below).
Something that's really easy to handle. Just place a microphone at your listening position and hit a button to run some test tones and let the software calculate the filters based on the measurements.
When I was already about giving up on this comfortable solution I finally found something at hifi-forum.de. It is a software called Automatic Room Correction (ARC).
It's a quite new development by Ralf Stegmuller. This software is basically built upon DRC but does all the more or less difficult steps (see links) automatically. It's exactly what I was looking for – a 'hit one button to generate the correction filters solution'.
The only downside is that it's commercial software.
To use it you only need a soundcard with a capable microphone input and a measurement mic. You just plug in the mic, place it at your listening position, adjust the input level and the playback level (fairly high at about 85dB) and run the test.
First a 120 second sine sweep is played back through the left speaker, some calculations take place, then a 120 s sine sweep through the right speaker, some final filter calculations and voila: ARC opens a folder with your correction filters.
Then you open foobar, open the convolver in the DSP section and load your filter, set the attenuation (in my case at -4,5dB) and listen.
The most apparent improvement is the bass – no more boom. The standing waves seem to be perfectly compensated by the filters. And the overall sound seems more coherent and smoother. It's almost everything I was looking for when I entered the painful world of room tuning. (BTW: Some other users have reported that DRC/ARC sounds even better than the multi-thousand-dollar TACT systems.)
If the resulting sound is too flat you can still easily change the reference value. A little bit less highs and a little bit more bass – no problem.
Another interesting thing is that you are able to create filters for different listening positions.
I'm still quite new to this whole digital room correction thing, but so far it has proven to be a real capable and very flexible approach to compensate for one of the most important issues in speaker listening: the room acoustics.
I hope that my short report is understandable and is able to give you an impression about . Any linguistical obscurities are due to my poor English.
Links:
General guide to digital room correction: www.duffroomcorrection.com
TACT and Lyngdorf (the classical room correction DSPs): www.tactlabs.com www.lyngdorf.com
Dennis Sbragion's DRC website: http://drc-fir.sourceforge.net/
Ralf Stegmuller's ARC website (only in German): www.high-end-manufaktur.de/arc.html
I hope that my short report is understandable and is able to give you an impression of what digital room correction is about.
Any linguistical obscurities are due to my poor English.
Cheers,
Marco
INTRODUCTION:
There are several factors that influence the sound of a speaker system: the source, the amplifier, the speakers, the listening room, maybe the cables and probably some more like the quality of the current.
The most important factor however is the speaker. Just try it and change the amplifier or the source of your system. You'll probably hear some differences. Now keep the source and the amp and try another pair of speakers – the difference will be much heavier.
Ok, if you have been using a walkman as source and switch to an Accuphase CDP, the difference will be very clear too, but I'm only talking about equipment of a certain quality – the stuff people that read threads like this are usually interested in.
So what is the second most important factor?
In my experience it is the room. Or to say it clearer: the interaction between the speakers and the room relative to your listening position.
The main issues in this regard are wall reflections and especially standing waves that color the sound in an almost unforeseeable manner.
THE USUAL APPROACH:
There are different ways to address these problems.
One way is - of course - to pass on demanding speaker listening and use headphones instead. Although I like headphones a lot, they really lack the lifelike image good speakers can deliver - but I'm not going to discuss this subject here. There are already dozens of 'Speakers vs. Headphones' threads on Head-Fi.
Another way is to face the facts of room acoustics and start the battle.
The first lesson is to place the speakers symmetrically relative to the walls and at an equal distance to the the listening position. This is the basis for all further modifications.
The second approach is to use diffusers to handle the early reflections and bass traps or resonators to get rid of the standing waves. But this is quite a difficult task: diffusers often 'overdampen' the room if used too extensively – the result is a muffled sound because they not only diffuse, they also absorb the mid to high frequencies (depending on their thickness).
Bass traps are an even more complicated issue. Those things that are normally sold as bass traps are about 50 x 50 x 50 cm (20'' x 20'' x 20'') large and will not efficiently affect the typical room mode frequencies. What you would need in order to have an audible effect on the bass response should be really large.
Resonators can be smaller than bass traps and seem to be a much better solution. But their design according to your room size is difficult to calculate, and even if you're theoratically successful you will need the technical skills and the required equipment to build such a thing.
But even if the result of using absorbers and bass traps or resonators will be satisfactory soundwise, it will most likely look quite ugly. It might then be unacceptable from even an modest designer's point of view – for example your girlfriend's.
So if it's difficult to fine-tune the sonics created by the speakers, why not tune the bits before they are converted to electrical energy?
This leads us to the field of digital sound correction:
THE DIGITAL APPROACH:
In digital sound correction there are two approaches:
Digital equalizers and correction filters that can be used with a convolver. Digital EQs are a not bad, but the number of bands is usually limited and it takes a lot of attention to set them in order to compensate for the characteristics of the room.
Correction filters however are based on a fingerprint of the individual room.
First you need to measure the impulse response of your room and then you have to generate the digital filters which then should compensate for the acoustical problems of the system. These filters then can be used in a convolver, for example in foobar's convolver.
Well, calculating the filters is not an easy task, but fortunately there is an open source software that helps you to generate the filters. It's called Digital Room Correction (DRC) and has been programed by Dennis Sbragion some years ago.
But for computer-laymen like me even this software is quite difficult to handle.
And although there is a well structured guide (see links below) you'll have to follow a lot of steps from generating the test tones to calculating the filters with DRC.
What I was really looking for was something like a software only TACT-system (see link below).
Something that's really easy to handle. Just place a microphone at your listening position and hit a button to run some test tones and let the software calculate the filters based on the measurements.
When I was already about giving up on this comfortable solution I finally found something at hifi-forum.de. It is a software called Automatic Room Correction (ARC).
It's a quite new development by Ralf Stegmuller. This software is basically built upon DRC but does all the more or less difficult steps (see links) automatically. It's exactly what I was looking for – a 'hit one button to generate the correction filters solution'.
The only downside is that it's commercial software.
To use it you only need a soundcard with a capable microphone input and a measurement mic. You just plug in the mic, place it at your listening position, adjust the input level and the playback level (fairly high at about 85dB) and run the test.
First a 120 second sine sweep is played back through the left speaker, some calculations take place, then a 120 s sine sweep through the right speaker, some final filter calculations and voila: ARC opens a folder with your correction filters.
Then you open foobar, open the convolver in the DSP section and load your filter, set the attenuation (in my case at -4,5dB) and listen.
The most apparent improvement is the bass – no more boom. The standing waves seem to be perfectly compensated by the filters. And the overall sound seems more coherent and smoother. It's almost everything I was looking for when I entered the painful world of room tuning. (BTW: Some other users have reported that DRC/ARC sounds even better than the multi-thousand-dollar TACT systems.)
If the resulting sound is too flat you can still easily change the reference value. A little bit less highs and a little bit more bass – no problem.
Another interesting thing is that you are able to create filters for different listening positions.
I'm still quite new to this whole digital room correction thing, but so far it has proven to be a real capable and very flexible approach to compensate for one of the most important issues in speaker listening: the room acoustics.
I hope that my short report is understandable and is able to give you an impression about . Any linguistical obscurities are due to my poor English.
Links:
General guide to digital room correction: www.duffroomcorrection.com
TACT and Lyngdorf (the classical room correction DSPs): www.tactlabs.com www.lyngdorf.com
Dennis Sbragion's DRC website: http://drc-fir.sourceforge.net/
Ralf Stegmuller's ARC website (only in German): www.high-end-manufaktur.de/arc.html
I hope that my short report is understandable and is able to give you an impression of what digital room correction is about.
Any linguistical obscurities are due to my poor English.
Cheers,
Marco
I'm glad SonicDawg brought it to the top again since I missed it when first posted and since he offered more info.
