mzmtg said:Yeah, it looks like I may be chasing some cancellation with that boost at 400. I'll cut that back a little.
The volume scale on the head unit maxes out at 35. In my previous testing, I have confirmed that it does not clip with a 0db sine wave tone at 40Hz or 1000Hz played at max volume (35).
With the EQ set as described above, with a couple of big boosts, now the sound actually stops getting louder at a volume setting of 29. Turning it up past 29 doesn’t make the music any louder. So It looks like the head unit is cutting overall output when I’m asking it to put a bunch of power into a couple specific bands, possibly to avoid distortion. I don’t think I’m hearing any distortion in normal listening.
My previous setup was using the gains in the amp and the head unit crossover to get that ~12db boost in the sub bass that we all like. The result was, as everyone knows, it’s hard to get the subs and the mids to stay together when you turn it up.
I'm trying to emulate the bass control that the MS-8 does, as described here: http://www.diymobileaudio.com/forum.../8257-jbls-ms-8-processor-86.html#post1002963
And further explained here: https://www.audiofrog.com/community/tech-tips/time-alignment-part-4-getting-the-bass-right/
"5. The subwoofer level control in MS-8 isn't a level control for the subwoofer output channels. It's a shelving filter that boosts bass in ALL channels below 60Hz, but never above 160 Hz. When you boost or cut, the slope of the filter is adjusted. This helps to maintain the illusion of bass up front by sending the appropriate amount of midbass to the front speakers and bass to the subwoofers. It also maintains the crossover point. Here are a couple of graphs that illustrate this and why it's better.
The first one is a conventional control. It's pretty obvious why this moves the image of the bass to the back and sounds boomy. There's too much interaction between sub and midbass. This is why people claim that "underlapping" the bass is important and why so many people try to get big-assed midbass drivers in the front of the car and cross the sub at 50Hz. With MS-8, that's totally unnecessary, and the evidence of that is in the second graph.
I use a pair of 6" speakers driven by about 40 watts in the doors, another one in the center channel and a 500 watt amp on a pair of cheesy 10" woofers in an IB in the rear deck. The bass is seriously anchored to the front and the midbass is great. No hassles, no constant tweaking and I can boost bass by as much as 10dB on top of the target curve (which is a total of about 20dB) without the image shifting to the rear. I think my crossover point is about 80Hz, 4th order.
Looking at my EQ’d frequency response above, it looks like my sub-bass is actually more like 16-18db hotter than my mid-bass bands. So I can probably pull that bottom EQ band down from +9 to +7 at least. I’ll give that a shot later today and see how it goes. If it gives me back some more headroom in the head unit to play louder overall, I’ll be happy with that too.