Hello everyone ,
In this thread we will discuss rePhase and itís uses on many different platforms to be used in a car. Letís not talk about running jriver or cpu convolution unless itís going to be used in a car for the most part this will be discussing FFT convolution and relatively lower tap filter making techniques.
General fir filtering , we will go over the concepts, and the uses for corrections to be made in a car with fir capabilities. We will go over how rePhase and REW are interchangeable and how to make good measurements to be applied to your speakers using REW and how to make a measurement that would normally not mean much matter.
I have invited Thomas Drugeon (a.k.a Pos) from DIY to join us., Pos wrote rePhase and I hope he chimes in from time to time to help keep my info accurate I urge anyone who downloads rePhase and uses it to please go to surge force and contribute to Thomas for such an excellent software, same with John from REW this is a professional gesture we all should do to show our appreciation
I would rather not let this thread be crashed by noobs , if anyone doesnít know what fir filtering does or is , please educate yourself first on what the general terminologies are. In no way am I trying to drive anyone away however fir filters are complicated and it takes a lot of time to explain the basics and a simple search will give you all the answers you could possibly want. Once familiar with the basic terminology than please join in discussion.
So, Iíll get some of you up to speed on what I personally have done. In my car I use 4 dsps, 1 Dirac Live ddrc22di and 3 minidsp 2x4HDs. My system consists on a clairion headunit NX-706 running 96khz toslink with volume control embedded so volume is done completely upstream. That feeds into the Dirac Live 2ch Dirac room correction box that I use basically as my global EQ and the first stage of my correction. Toslink out of that into an active 3way toslink splitter that divides the toslink into three that goes into each of the 3 minidsp 2x4HD minisharcs and than analog single ended RCA out to 4 amplifiers in a 4way system.
The 2x4HDs is where I use the minisharcs and make 8 seperte fir for each driver (channel) to have , eq, crossovers, phase corrections , and magnitude corrections, spots where Dirac needs small adjustments all in each fir. That is where I will be talking about rePhase and how it is setup in my car.. however as far as rePhase , my system is unique and I could get the same results with just rePhase alone, I chose to use the Dirac box so when I change equipment or drivers out setup time is minimized. (Iím a freak and change speakers a lot) in a normal persons system no Dirac box would be needed. RePhase can get everything done right the first time.
So now I would like to talk about what it is exactly in a car that makes fir filtering really make a lot of sense. Mostly a linearized mid-bass HPF and the subwoofer LPF is a must have. But beyond that basic everyone should have in a car the principal of how ďphaseĒ works in a car, how to read the measurements and how to apply a measurement using rePhase. And lastly after all the corrections are done for each side (left and right respectively) how to apply another correction on top of all the separate corrections to offset not just the timing differences between Left and Right but to correct for the comb-filters caused by interaction of the Left and Right channels caused by the time of flight delay.
I will share this article from Dirac Research first to get everyone up to speed on exactly what that correction looks like and what has to be done to achieve it realistically in a car with the use of fir and rePhase!
without further ado the article from Dirac Research: This is a must read for anyone trying to use fir in car. As I canít go into everything in one post this thread will be evolving over the next weeks and months.
Iíve dug myself into every rabbit hole possible but once I was able to start to apply these type of filters is when I fell into the dam glory hole, and 2ch audio in car becomes an entirely different animal and takes on things never thought possible. Once one has begun to get this type of filtering, it becomes silly to think about all the ppl bickering about trying to get the ďtime alignmentĒ controls set perfectly, when actually ďtime alignment ď controls alone seem to collapse the stage and compress the recording so itís right biased. As inducing a delay on the signal causes a serious comb filtering issue between left and right , than the actual time of flight distance compounds the problem even worse.
Hereís the article for everyone to read. Iíll stop here for the night and continue tomorrow or the next day.