See, this is where I disagree. We go to great lengths to squeeze every last bit of performance out of our car audio systems. We spend insane amounts of money on speakers, amplifiers and DSPs. We spend insane amounts of money, time and effort to "sound deaden" our cars. We spend insane amounts of time tuning them to perfection.@jtrosky , I’ll take a stab at post #2 and post #8. Basically those small anomalies in the response you see, you probably can’t actually hear those. Many of the dips and comb filtering peaks and valleys you see on an RTA with a resolution of say more than 1/3 octave, and I would say definitely not more than 1/6 octave; you just cant hear those so don’t waste the DSP resolution and time to try and correct those.
This has been my experience anyway so often I tune using 1/3 octave and sometimes I flip back and forth from 1/6 to 1/3 for the lower octave FR response just to gain some additional insight at the larger dips and peaks. I think this is a trap that many people fall into when tuning and they fuss too much over that small stuff when it may not actually matter.
So why shouldn't we spend 15-30 minutes to apply a few allpass filters to correct 5dB+ dips in the L+R combined response? It doesn't cost us anything. Those bands on the EQ would probably go unused otherwise (at least on a Helix since it has 30-bands per channel). I mean we're talking about (3) 5dB+ dips that each "span" ~50hz - and all three are in the 200hz - 600hz (approx) range. To me, those dips can certainly be audible - especially when all three are combined. As long as the allpass filters don't cause any "unwanted" side-effects, to me it's a no-brainer. Why purposely leave those dips there if you can easily fix them without any unwanted side-effects?
RTA's are specifically designed to make it easier to identify and correct things that we can't easily identify with our ears. I feel that it's useful to correct all of these small "anomalies", that when combined, actually do make an audible difference. If we just say "well, you probably can't hear that anyway" for everything we see on an RTA, but can't easily identify with our ears, then we might as well just not use the RTA at all, right? Again, I think it's the combined effect of correcting all of these minor issues that makes a difference.
That doesn't mean that I'm actually right though.