Join Date: Apr 2003
Location: Westerville, Ohio
So I had my original second post all typed out when I started this thread but it was lost in a failed load. That's not all bad though because I'm still researching this part.
For my tuning I'm going to separate the discussion into two parts. One is all about what to do with the EQ power of the DSP, and that is where I still have a lot of questions to figure out.
The other part is using my measurement set up to get all the drivers to work together successfully. I'm going to talk about that part here first.
When I want a response graph of any part of my system I'll be using a pink noise generator and the RTA functions of my software. The first round of this is going to be to get a set of measurements for each driver individually. I'm doing this for the sake of mapping out it's actual response in my environment which at this point I just want to use to get a good idea of ideal crossover points. It should go without saying that for the sake of determining crossover points I need to set my crossovers during testing to points beyond where I'd consider crossing drivers but before limits of the driver that would be problematic.
Once I'm happy with my crossover points I'll probably re test the measurements under these conditions for the drivers just to double check that it's working as intended, but otherwise I'm going to put away the frequency response measurements and graphs for now.
This step is all about time alignment and phase. My specific procedures for how I'll achieve this aren't determined just yet. I'm going to have to stumble through both figuring out the software as well as my process for a while, but I know what my goals are.
I want drivers that are working together to create the same channel of sound to be in phase at the crossover points. I also want everything time aligned so that it's arriving at my ears at the correct time. You can't just set phase before time aligning though because that'll all get blown out of the water the second we touch the TA settings. You need to figure out the TA first and then tweak phase.
In order to make these adjustments I need to be able to measure timing differences, so this is where the pink noise doesn't work. I need some kind of pulse, tone, or even certain music where I can measure the same note coming in from different drivers. I'll have to play with my software a lot more before I know how I'll get those timing measurements. Music is something you could use with some ingenuity if you couldn't generate the signals from the computer you're measuring off of. Think about it this way. You could use a note from a separate driver like a sub as a timing reference to the other drivers, at least in theory I that's how I think you'd do it. Luckily my source unit is my computer anyways so I can directly generate the sounds from my measurement software.
I'll leave it at this point for now. There isn't a lot of debate over what I'm going for here, just getting all the different components of the sound system working together. My only real challenge here is in determining how to measure. We hear with two points on the sides of our heads, so are we TAing so that the L channel hits the L ear at the same time as the R channel hits the R ear? I would think so, but what about phase between left and right? We could end up with something that sounds right individually but when playing both channels together has weird effects. I need to do some more reading up on this but in the end I might just have to start experimenting.
My car won't ever be done because I'm insane. That is all.