Victor_Z.

Added Sub to Bose Acoustimass System

My wife had a Bose Acoustimass 6 series II speaker set left over from her single days, so I decided to put it in our bedroom (we already have a nice 6.1 Energy set in our den, but I figured it would be nice to be able to watch movies in bed). I bought an Onkyo 501 receiver open box from Circuit City because it was cheap and had lots of features. I hooked the Bose's so-called "bass" module and ran the speakers and mounted them and they don't sound bad...except...there...is...NO BASS(!) when watching movies in Dolby or DTS. I know this is only for a second room, but I decided to pick up a cheap subwoofer to supplement the Acoustimass's lack of bass. I picked up an Energy S8.2 on sale and ran the LFE out to it's Xover bypass input--that prevents the subwoofer's crossover from interfering with the signal. I set the Onkyo's crossover to 100Hz, subwoofer mode 3--it sounded bad. I switched to subwoofer mode 1 (which is all 6 sattelites set to small), made adjustments--horrible. I tried mode 2 (large fronts, small center and surrounds)--horrible. It sounds best in mode 3 (using the LFE channel) but I can't get the sub tweaked right. Should I lower the Onkyo's crossover setting? If I do, wouldn't I lose the high end in the LFE channel when watching movies? Also, should I use the line in on the subwoofer that allows for the subs crossover?Wouldn't this be doubling the crossover on both ends? What should the Onkyo's subwoofer mode be set to for movies? Music? Thanks.

SethH

I don't know for sure since Bose doesn't post stats, but I think the bass module goes down to around 60Hz. So, you might be having some phase issues where the two are overlapping. Try setting your crossover down to 80 or 60 if possible and see if that will do anything.

Lewis Besze

Actually the Bose bass module has useable output[F10] to about 30hz.This was measured by Tom Nusaine,so better belive it.
My impression is that the whole set up is considered "full range",so I would use the sub to augment it only.Set the crossover on the sub or in the receiver if you can, to 60 hz or below, and all speaker's to "large".

Victor_Z.

Isn't 60 Hz low for the LFE channel in DTS and Dolby? Will I lose out on the top end of the LFE?

Jeff Gatie

60Hz is mid-high range for LFE. Just for comparision, SVS subs are tuned (meaning the frequency response is flat) from 25Hz all the way down down to 16Hz (16-46 cylider models). There have been films with LFE measured down to 10Hz. Although the bass of the "bass module" is usable down to 30Hz, the difference between "usable" down to 30Hz and "flat" down to 16Hz is enormous.

JamesCB

Could you please define "useable"? Where could I find a report on Tom Nusaine's measurements?

Keir H

30hz? really? Not as bad as I once thought..I wonder at what +- db level? But isnt that even harmonics or distortion down that low for a "sub" based on this design? Might be a solution for those with space contraints if usable level is high enough with corner loading??

Lewis Besze

Obviously it is, one is F10[or whatever one think it is] the other is F3. I did, I put "F10". It means it's about 10 db below the average FR output a speaker has in it's entire bandwith.Some people think that F10 isn't usebale so the reason I used the quotation marks around usable. Do search on this forum,there were several threads in the past talking about the list that shows dozens of subs he measured.