Originally Posted by tvuong
Alan, your before minidsp graph shows your subs ~ -6db from <20hz. Isn't the T18 supposed to be +-3db down to a single digit or at least 10hz? Your highest -3MV sweep with minidsp also shows similar behave from <20hz and the output is only around 105db with minidsp boost. I am expecting more output in this region from your T18 pair. How does it sound with minidsp?
I would expect more output too...I blame the MiniDSP.
It's been awhile since I've done compression sweeps and couldn't remember the best method...so, I did the above compression sweeps using the LFE CH output in REW but with the sweep level reduced 10db (to compensate for the LFE boost), so I would only need to see peaks of 105db to be at "reference" (correct?).
Originally Posted by basshead81
The T-18 is +/-3db @ 15hz. I agree output seems low... The more I think about it either the mic is not calibrated correctly (which I doubt because Alan is experienced with REW)or there is some cancellation going on in the lower frequencies. Alans room is big but I would still expect 110-112db down into the single digits from those subs.
As you say, of course the mic was calibrated correctly.
Not sure how I could be getting cancellations...I have XT32 with SubEQ HT and I have checked the time-alignment with REW and XT32 seems to get it spot on every time I've checked (twice). Next time I get the gear out, I'll mess with the sub distances again just to make certain.
Could just be the odd shape of my room and the huge space I've got to fill (+5000 cu. ft.), I don't know.
Anyways, did some listening last night after boosting the low end with the MiniDSP and was fairly impressed...but also a little bit confused. Overall, it sounded great! I'm getting more low-end for sure and the mid-bass even seems tighter. I went up to -10MV with WOW "Pod Emerges" and FotP "Plane Crash" and didn't hear any sign of strain. Couldn't really go any louder since the wife was in bed.
Before last night I had been running LFE+Main for quite some time....if I didn't use LFE+Main, music sounded "thin" (very reduced bass). After using the MiniDSP last night though, I was able to turn off LFE+Main and bass with music was very plentiful...almost too
The MiniDSP didn't really effect the music bass region (+30hz) according to REW, so why in the heck would I experience what I did?? There's gotta be other things going on with my system. Sometimes I make a change and it changes things I didn't expect (for better or worse) and I just can't explain it...and that is very frustrating to me.
My above statement is illustrated below with these spectrograms. Obviously with "No MiniDSP" there is more
energy going into the mid-bass region. I just don't understand.