cmusic
06-27-2008, 02:41 PM
This is a tutorial on how to initially aim speakers for two seat listeners. This procedure I use may take only a few hours or could last a few months. I would say it is one of the most critical steps because it determines the sound quality’s foundation of the finished system.
I begin with the midrange speakers since they produce the majority of the frequencies that our hearing is most sensitive too. I leave all other speakers out for this first step.
The midrange speaker should be placed in the car where it gives 1) the most equal pathlength difference between both left and right sides of the car, and 2) a direct line of sight to the listeners. Minimal pathlength differences have been talked about many times but essentially the less the pathlength difference is the better the audible stereo reproduction will be. The line of sight is not for your eyes, but for your ears. Generally if you can see a speaker, then its sound has a direct line to the listener’s ears. You want to be able to hear the direct sounds from the speaker many milliseconds before the reflected sounds. (There are great sounding systems that mask the direct sound and let the listener hear the reflected sound first. For example, systems with dash speakers. The most successful of these reflected systems aim the speaker directly at the reflective surface so that virtually no direct sound will get to the listener.) Usually you want hear the direct sound at least 60 milliseconds before the reflected sound. In most vehicles this means the best area for the midrange speakers is in the kicks with the seats moved back as far as possible.
The second step is to bypass all equalization or any other audio adjustments in the system. When possible I like to run a head unit, one two-channel amp (or two matched mono amps), and the left/right midrange speakers only during this step. I use a full range signal void of any crossovers and filters.
I get two towels and bunch them up in the area the speaker will be mounted. I wire up the two speakers on both sides and sit them in the middle of the towels. I try to mold the towels around the speaker so that they soak up as much of the back wave sound (the sound coming from the back of the speaker) as possible. The lower midrange and midbass will suffer from the speaker’s back wave not being completely blocked, but this setup will be enough to find the best speaker angles.
It is very helpful to have a listening assistant that is as knowledgeable in sound as it will cut down a lot of time switching seats and re-listening with every minute adjustment.
I start with the speakers aimed at the center dome light on the ceiling of the vehicle. Both speakers are wired in straight polarity. I listen to a lot of well-recorded music that I am familiar with. Test CDs like from IASCA, MECA, and USACi are very useful too. I listen for tonality, staging, and imaging. I move to the other seat of the vehicle and listen to the same music and test tracks.
I then reverse the polarity to one speaker and play the same music and test tracks over. Again, I move to the other seat of the vehicle and listen to the same music and test tracks. (There is going to be a lot of switching seats during listening.) If the sound improved then I leave the speakers wired as they are. If they sound worse I reverse the polarity back to straight.
I then move the speaker in every direction plausible while listening in straight polarity and (one speaker) reverse polarity “rounds” from both seats. Initial changes can be a few inches at a time while fine-tuning changes can be as small as 1/8” or less. The speakers could be aimed up, down, across, directly at the listeners, away from the listeners, different directions, and basically any combination of speaker aiming. There is no set rule that states, “This speaker angle will work in every vehicle”. The best speaker aiming angle is derived from the acoustics of the vehicle and the on and off axis frequency response of the speaker. Since nearly every vehicle (model) is different and there are thousands of different speakers there can’t be one solution for every situation. I’ve had systems with the mids aimed at the ceiling dome light, aimed at the opposite side listener, aimed straight across at each other, aimed directly at the nearest listener, aimed directly up in the bottom of the dash, and other oddball mounting angles. If it sounds great then the actual angle you end up with does not matter (unless you place system looks above sound.)
There are some general guidelines that I use when adjusting the speaker angles. Soundstage width can be helped by placing the speakers as far to the outsides of the vehicle as possible, but that may hurt image focus. If the center image is skewed to one side, I aim the far side speaker more directly at myself and then aiming the nearside speaker away and towards the other side. Aiming speakers up does not automatically mean the soundstage will rise.
I then play the tweeters by themselves to find the best angle for them. I would use a high pass crossover to protect them from damage. I would also play them with and without the mids to find the best sound. To mount them up high on the dash or a-pillars or down low with the mids in the kicks or doors is up to the system owner. As many others have suggested, move the tweeters around to find the best sound for your vehicle and system.
The same steps can be used even if you plan on installing midrange speakers in the doors. I’ve found the best results by using a speaker with excellent off-axis frequency response and aiming them slightly forward towards the center of the firewall. This set the far side speaker with more direct sound, and therefore louder sound than the near side speaker. It helps balance the volume difference between left and right speakers. I then play with the polarity to further tune the system.
The goals are to get as equal of a pathlength difference as possible, a volume level between the left and right speaker as equal as possible, and the frequency response between the speakers as equal as possible. These steps above will help cut the need for signal processing in the system. One can get very close to these goals without using any signal processing. And then by using signal processors carefully one can make an incredible sounding system.
Hope this has helped. I think I have included everything I know (or can remember :D ). You can look up Mr Marv’s post HERE (http://www.diymobileaudio.com/forum/showthread.php?t=33740&highlight=chuck+music)with my tuning steps for more useful tips. If you have any questions just ask.
I begin with the midrange speakers since they produce the majority of the frequencies that our hearing is most sensitive too. I leave all other speakers out for this first step.
The midrange speaker should be placed in the car where it gives 1) the most equal pathlength difference between both left and right sides of the car, and 2) a direct line of sight to the listeners. Minimal pathlength differences have been talked about many times but essentially the less the pathlength difference is the better the audible stereo reproduction will be. The line of sight is not for your eyes, but for your ears. Generally if you can see a speaker, then its sound has a direct line to the listener’s ears. You want to be able to hear the direct sounds from the speaker many milliseconds before the reflected sounds. (There are great sounding systems that mask the direct sound and let the listener hear the reflected sound first. For example, systems with dash speakers. The most successful of these reflected systems aim the speaker directly at the reflective surface so that virtually no direct sound will get to the listener.) Usually you want hear the direct sound at least 60 milliseconds before the reflected sound. In most vehicles this means the best area for the midrange speakers is in the kicks with the seats moved back as far as possible.
The second step is to bypass all equalization or any other audio adjustments in the system. When possible I like to run a head unit, one two-channel amp (or two matched mono amps), and the left/right midrange speakers only during this step. I use a full range signal void of any crossovers and filters.
I get two towels and bunch them up in the area the speaker will be mounted. I wire up the two speakers on both sides and sit them in the middle of the towels. I try to mold the towels around the speaker so that they soak up as much of the back wave sound (the sound coming from the back of the speaker) as possible. The lower midrange and midbass will suffer from the speaker’s back wave not being completely blocked, but this setup will be enough to find the best speaker angles.
It is very helpful to have a listening assistant that is as knowledgeable in sound as it will cut down a lot of time switching seats and re-listening with every minute adjustment.
I start with the speakers aimed at the center dome light on the ceiling of the vehicle. Both speakers are wired in straight polarity. I listen to a lot of well-recorded music that I am familiar with. Test CDs like from IASCA, MECA, and USACi are very useful too. I listen for tonality, staging, and imaging. I move to the other seat of the vehicle and listen to the same music and test tracks.
I then reverse the polarity to one speaker and play the same music and test tracks over. Again, I move to the other seat of the vehicle and listen to the same music and test tracks. (There is going to be a lot of switching seats during listening.) If the sound improved then I leave the speakers wired as they are. If they sound worse I reverse the polarity back to straight.
I then move the speaker in every direction plausible while listening in straight polarity and (one speaker) reverse polarity “rounds” from both seats. Initial changes can be a few inches at a time while fine-tuning changes can be as small as 1/8” or less. The speakers could be aimed up, down, across, directly at the listeners, away from the listeners, different directions, and basically any combination of speaker aiming. There is no set rule that states, “This speaker angle will work in every vehicle”. The best speaker aiming angle is derived from the acoustics of the vehicle and the on and off axis frequency response of the speaker. Since nearly every vehicle (model) is different and there are thousands of different speakers there can’t be one solution for every situation. I’ve had systems with the mids aimed at the ceiling dome light, aimed at the opposite side listener, aimed straight across at each other, aimed directly at the nearest listener, aimed directly up in the bottom of the dash, and other oddball mounting angles. If it sounds great then the actual angle you end up with does not matter (unless you place system looks above sound.)
There are some general guidelines that I use when adjusting the speaker angles. Soundstage width can be helped by placing the speakers as far to the outsides of the vehicle as possible, but that may hurt image focus. If the center image is skewed to one side, I aim the far side speaker more directly at myself and then aiming the nearside speaker away and towards the other side. Aiming speakers up does not automatically mean the soundstage will rise.
I then play the tweeters by themselves to find the best angle for them. I would use a high pass crossover to protect them from damage. I would also play them with and without the mids to find the best sound. To mount them up high on the dash or a-pillars or down low with the mids in the kicks or doors is up to the system owner. As many others have suggested, move the tweeters around to find the best sound for your vehicle and system.
The same steps can be used even if you plan on installing midrange speakers in the doors. I’ve found the best results by using a speaker with excellent off-axis frequency response and aiming them slightly forward towards the center of the firewall. This set the far side speaker with more direct sound, and therefore louder sound than the near side speaker. It helps balance the volume difference between left and right speakers. I then play with the polarity to further tune the system.
The goals are to get as equal of a pathlength difference as possible, a volume level between the left and right speaker as equal as possible, and the frequency response between the speakers as equal as possible. These steps above will help cut the need for signal processing in the system. One can get very close to these goals without using any signal processing. And then by using signal processors carefully one can make an incredible sounding system.
Hope this has helped. I think I have included everything I know (or can remember :D ). You can look up Mr Marv’s post HERE (http://www.diymobileaudio.com/forum/showthread.php?t=33740&highlight=chuck+music)with my tuning steps for more useful tips. If you have any questions just ask.