Frequency Response And The Need Of A Jl Cleansweep

I saw someone mentioning in these forums, that the best thing you can do for sound quality, is getting a JL Cleansweep device to flatten out the frequency response from the headunit. I was very curious about that and as the tech-nut I am , I wanted to see what the fuzz was all about.

Yesterday I replaced my factory default headunit to the Sony unit, and did measurements of both of them. My idea was that maybe it would not be nessesary to get a Cleansweep if you upgraded the unit. Here's what I found:

Green line is the factory unit, while the red is the Sony. Not much of a difference, so apparently they use the same DSP chip. I tested this using a CD with white noise and recording it to my laptop using a High level/Low level converter. The difference between the highest and lowest point is 10dB if you don't count the high rolloff (which you shouldn't because it's in the inaudible range).

So the Cleansweep can give you a flat response. It seems like a good idea, but I thought about it, and maybe there's a reason they add this DSP. Starting out with a flat response is a good starting point, but your room (and especially a car) would have an odd frequency response that you should correct using an EQ. The Cleansweep doesn't offer this ability. If they were smart, they actually supplied a microphone or at least an input for a microphone, so it could correct the DSP according to room response.

I might actually buy the Cleansweep and try to make some measurements. If I can get a good microphone, and get an analysis of the room response, I could apply the room response reversed to the pink noise signal calibration, they use, to fool it into correcting, not just the DSP but also the room frequency response.

There are some interesting Cleansweep demonstration videos on YouTube.

I hope this made sense :) I will update the post with my findings, if I get around to it.