Originally Posted by DonH50
Yes, duh, brain-fart... Juxtaposed two things.
Higher crossover = more HF in sub, less bass in mains
Lower crossover frequency = less HF in sub, more bass in mains
Higher slope = less bass in mains, less HF in subs (less overlap)
Lower slope = more bass in mains, more HF in subs (more overlap)
When I first set up my F12s, I could not get them to sound right if my XO was 80hz or above. There was just something off about the sound, like they were nearing the upper limits of the frequency range they could produce. It's like the sound wasn't clean, but dirty. I knew this shouldn't be the case because I was aware of Brian's charts on the Rythmik website showing the frequency response reaching 200hz with LFE.
With some thinking and some discussion, it dawned on me: my hypothesis was that my F12s were producing sounds that were too high in frequency
and it sounded bad. REW measurements confirmed my idea: the subs were not dropping in output quickly enough as they crossed over to my mains, and were still producing 75db beyond 200hz! I could theoretically cut the top off of the FR by using Line-In and a steeper slope.
It worked amazingly well. It solved my sound quality problem. With my F12s settled in to a 100hz XO, ideally chosen with REW measurements and lots of listening, they now drop off much faster as they hand off to the mains. The sounds they produce no longer contain bad sound from the upper frequencies as they are no longer being sent to them. It is clean and powerful. It was this moment when I truly became proud of my Rythmik F12s.
In summary, I do not think the LFE input is the way to go if you want the best sound from these subs. They will be asked to do too much and it will muddy the bass. Play with the 12db and 24db slopes, but my system has more authority and cleaner bass set to the steeper 24db setting and for sure with Line-In. I likely gained headroom by restricting the frequency range as well but I did not graph that.