F12G SERVO SUB
I read about the good and bad of various sub-woofer variations, including infinity baffles, but I kept coming to the sealed sub; accuracy attracted me more so than the sonic boom. I looked into Rythmic and its servo technology and the way Ryan and Danny explained how it works made sense to me, but because I was busy building surrounds and center channel from Danny’s kits, I was not ready to commit to anything. When all were completed and put to service, I had more time to evaluate my needs.
It took me a little while to make a decision because I was not sure whether I will need two subs and if that would have been the case; you all know that it is better to cut both at the same time. I did some reading and calculations and figured that one may be enough for what I was looking for, the area I have is 1700 cu/ft., open space. I became more familiar with the servo idea and was sold on the paper-based F12G from Danny. The main reason I went with the paper and not the aluminum is because I listen more to music than movies. I know, I know the new trend is the OB subs and as much as I like them I had to let them go for now; I do not have the real estate they required.
Talking about the build, I followed Danny’s recipe for his sandbox to the letter, except that I cut rabbets for the internal braces and enclosed the electronics in its own box because I used fiberglass and did not want any of it touching the back side of the amp. The inside also has No-Rez, one full sheet as suggested and all joints are sealed with silicone caulk.
As in my previous builds, there are no mechanical fasteners anywhere, but I used plenty of cookies mostly for alignment purposes. As far as the sand, make sure to tap the sides with a rubber mallet as you fill the cavities because this helps to compact the sand; if you do not tap it, you may think it is compacted, but will ended up with voids once you put the sub to service. I finished the sides with rattle can satin black. The top, front and feet is walnut with accents in oak and finished in satin medium dark walnut from Watco.
Setting it up took many trials, issues with time/phase alignment mostly; relying on my old ears and no instruments like a SPL meter is a bit frustrating, but once I figured out how to tune it, it was best to leave phase at zero and play around with delay distance from the ProPro until I managed to sync the sub with the fronts the best I could. I am still playing with the other controls and getting familiar with what they do, but for now the sub is set at 80Hz crossover from my PrePro and recommended settings in the sub end, it sounds very good. I am running XLR cable to the sub simply because the cable is going over the ceiling and down for a run of about 30-ft.
I have subjected the sub to different content, from movies to music of all sorts and I am impressed with its performance and the way it projects the sound. I may add that I did not have much of a problem about location, it is sitting along the longest wall and from my sitting position all the bass seems to emanate from the main and center speakers. The more I listen to my favorite songs, the more I like the sub, new bass content pops here and there, at times it seems like I am playing a different song; I can also feel it and when that happens I know the sub is going subsonic….awesome!! The SPL generated from this one sub gently rattles my house with authority and sufficient thump without displacing my china or glassware, and there are so far no complaints from neighbors at all and the volume is at 50%!! I bet if I cover or disguise the sub, friends will be wondering how my smaller speakers are able to reproduce sounds that low (I have not had friends over yet.)
Here are some pictures of the finished sub; sorry, I did not documented the build since it is basically a copy of the sand box Danny provided, but dressed differently as mentioned above.
Thank you Danny for your guidance, patience and for providing the plans for the box. I am really happy with the sound from this sub, it really complemented the overall sound without being intrusive with colorations or the so called sonic boom.