OK!No. Place it in the absolute center, no different positions for left/right
yep,You do not have that ability.
Thx Alextaastrup,Much better this time. I will remake the test for both fronts - to see how big TA values should be for their alignment (both on one graph). In any case, both fronts have to be delayed appr. 16-18 ms for better connection with the sub.
Great thread, and an important venture in an important topic.I have to stress this:
DO NOT SIT IN SEAT WHILE MEASURING. DON'T TOUCH THE MICROPHONE.
Clamp it in headrest, in the middle where your head is normally. If you move the mic even an inch the measurement will be messed up. If you are aiming for repeatable results while correcting time coherency the mic must be absolutely stationary.
Elgrosso, The results you seeing on right side are probably due to destructive interference. I assume there's dips in the frequency response (AFR) at the same spots. Is this a 2 or 3-way? If it's a door mid it's perfectly normal. A small dedicated midrange should do better if placed optimally. Where is the crossovers?
TDA is some kind of mashup between a CSD and Group Delay plot.Great thread, and an important venture in an important topic.
I've worked with CSDs in the past but the lack of software to sum up time domain responses from multiple mic positions is a huge drawback. The only way to receive an input signal unbiased is to average many many times from correct positions, with your body in the seat. That way your measurement is centered on the "true" signal your brain receives and measurement error is mitigated through averaging.
If the "measurement is messed up" by moving one inch, you have big problem. The solution is not to keep the mic fixed but to implement some form of averaging and to place the mic correctly around your years when your head is next to it.
I have no doubt that you measurement is correct for that location and an empty car, but whether that is relevant to what you hear when in your seat is ultimately a very important topic. Even if you repeat the measurement exactly by mimicking your previous test position it does not mean your results are accurate, just that the software has high accuracy. You still have to feed it the right signal.
It GD and CSD are basically the same thing no? I can see this platform has various ways to show you a plot but the information contained should be the same. The 2D plot is very nice.TDA is some kind of mashup between a CSD and Group Delay plot.
You are correct that you need to do a lot of averaging when doing CORRECTIONS in the frequency response.
This is different. We are measuring ONE point in space, time domain measurements are always and only available at one specific point in space. If you are sitting in the car while doing time domain measurements or impulse aligning, it will most likely be messed up because the head cause "shadowing". It can cause significant changes in the frequency response and it will impact the phase response / time domain as well. You are also correct that we need to correlate this with what we are hearing, the head shadowing is a distortion in the measurement we don't want, we don't perceive the sound that way, there is always acoustic crosstalk. I've done extensive testing into this and found that an empty car with the mic is usable for two types of testing.
1. Time domain measurements.
2. Subwoofer measurements (matters very very little if you sit in the car or not, no averaging is required either).
Don't understand what you mean by "feeding it the right signal" though. TDA creates the sweep and measures at the same time.
Here they're really almost the same.Check your vertical axis. It appears you changed the axis settings between left and right. The software likely gives you the option to focus on certain frequencies and you may have done so not knowingly.
Nice, where do you cross your mids here, 200hz??
And how did you change the time window on the graph? Or I guess you have the full version now