[haw1144]

This is definitely not my area of expertise... but I wanted to see if anyone can give me any recommendations... am I just running it too hot or do I need to do some calibration with the parametric EQ?

No I don't have a separate EQ to use... just want use what I have... which is pretty much the adjustable parametric EQ on the Bash plate amp on the SongSub.

Usually when I listen to music I never have any issues with the sub bottoming out or making wierd noises... I can run music pretty loud. It sounds great no matter what volume I goto.

However when I watch movies... once in awhile, depending on the movie, I get a loud thump/wobble sound from the sub which kinda scares me... not sure if it's bottoming out / clipping. Its most noticeable in Transformers BD when the Tank transformer gets hit by the final shot (killed by BumbleBee) in the city downtown fight.

All my speakers were calibrated to 75db via the Onkyo receiver and Radio Shack SPL meter... while the sub hits about 79-82db on the pink noise test.

Then I used my Radio Shack SPL meter to measure frequencies from 10hz - 80hz and graphed it out... this was done at 70db from my AVR.

Original SPL Measurements:


Radio Shack "Corrected" SPL Measurements:

[jsalk]

What is the subsonic filter set to?

- Jim

[Nuance]

That's your in-room response without any EQ?  Wow - that's pretty decent. 

What is your crossover frequency and what speakers are you using in conjunction with the SongSub?

[haw1144]

Yeah that's my in-room response from the listening position. Kinda wierd that the sub runs hot in a lot of those frequencies, but I calibrated to be ~80db while the rest of the speakers (SongTowers) were calibrated to 75db. Under most music listening conditions (as well as movies), it seems to be balanced pretty well the subs or mains aren't overpowering each other. I just get that occasional wierd wobble/thump sound in a few scenes (like the Transformers scene) --- though I also recall it made a similar noise in one of the final scenes Slumdog Millionaire as well

I have the LFE crossed over at 80hz via the Onkyo while the Mains are set to 60hz.

The subsonic filter is set to 16hz.

[Nuance]

The reason the sub response looks like it's running "hot" is due to room interaction/gain with the subwoofer.  Before I applied EQ to my subwoofer there was a huge rise from 30Hz to 58hz (looking from left to right) of about 16dB.  The midbass slam was cool, but it overpowered everything else.  This rise was due to room interaction, but now that it's been smoothed out it sounds a lot better.

The "thwack" sound that you hear is either the driver bottoming out or the amp clipping.  I dunno which or why that would happen, as that's Jim's department. 

What is your subwoofer gain set to?  If it's higher than 12 o'clock, set it to around 10 o'clock and recalibrate using the receiver's subwoofer level adjustment and your SPL meter. 

Do you have the subwoofer in a corner?  If not, you can always try moving it there, turning the subwoofer's gain down and using the receiver's level adjustment to re-calibrate.  A corner-loaded subwoofer will play off the room gain and give you more output naturally, allowing you to back the gain off on the subwoofer itself. 

Hope that helps.

[haw1144]

The knob on the subwoofer amp is set to the 12 o'clock position... subsonic is at 16hz and everything else is disabled (crossover and parametric EQ). The AVR is sending LFE over at 80hz.

The Songsub is in the corner, next to the L speaker. Since the Songsub has a sidefiring woofer... I have currently aimed the woofer into the room (facing same as as the TV would face) instead of facing it "normally" (doing so would aim the subwoofer right at the wall... only a couple of inches in between that side wall and the sub).

I'm debating if I wanna rotate the sub a little to have the woofer "angle" into that close wall.. like 45" to the wall and 45" into the room.... or even aim it into the wall directly and taking another set of measurements.

Or I can just run the Audyssey setup and pray it will smooth everything out!

[Nuance]

First, lower the gain on the subwoofer to between 9-10 o'clock.  Be sure the subwoofer crossover is rotated all the way to it's highest point, as to disable it's crossover.  Also, mess with the phase adjustment on the subwoofer, as there seems to be a phase issue between the speakers and the subwoofer.  Then re-run the pink noise calibration through your receiver and get your mains and subwoofer set to exactly 75dB (at this point don't run the subwoofer hot).  Finally, run Audyssey and report back.

I am guessing that you are clipping the amp or driving the subwoofer to hard while watching movies.  Part of this could be because the subwoofer is running too hot, or it also could be the listening level you're watching at.  How loud are you listening when the subwoofer bottoms/the amp clips?

[jsalk]

haw1144 -

You might try setting the subsonic filter at 20Hz and see how that does.  The lower you force the driver to go, the less power handling it will have.  It takes a lot more effort to move air at lower frequencies.  So by setting it that low, you are robbing yourself of some power handling.

- Jim

[haw1144]

I set the subsonic filter to 20hz and I decided to give the Audyssey a shot... I also dialed back the gain on the SongSub and set the dial in between the 10 and 11 o'clock position.

I didn't have time to run thru a frequency sweep again... but I tried watching the scene in Transformers where I normally get that thumping/wobbling sound and it didn't happen!

Just by the ear, it seems to be good so far... with the bass a little quieter than I'm used to. Gonna try to slowly increase the gain on the sub to see if I can run it just a little hotter and still not get that wierd sound.

Thanks!