Originally Posted by luan87us
They have an adjustable 7 bands EQ. You can turn it to flat (off). The problem is the sound processor. It just not sending out the correct signal frequency so that's why you're getting the weird boom in some range. Best thing to do is get a dedicated DSP, aftermarket HU with true Flat EQ, or an amplifier with built in DSP (only one I know of is JBL-MS-A1004).
A few things though:
How can you be sure that "flat" is truly flat? It's been shown that the non-nav radios have loudness and a vehicle (sedan/hatch) specific EQ applied when their 3 tone controls are "flat" Why would the NAV be any different? It's also quite obvious in listening to tones at various volumes that there is a "loudness" applied to some frequencies.
A sound-altering EQ (like a cleansweep or similar) is my LAST resort, but the idea in this build was to keep it SIMPLE. Adding that plus another amp, while keeping all that completely hidden is going to be a royal PITA, and unfortunately, changing the HU is absolutely NOT an option.
My point is - the Non-NAV guys can defeat the loudness setting and the factory EQ in a menu - why can't we?