Welcome to the Bose Portable PA Community. Thanks for your question and all the great information.
My band has the Bose F1 top/sub system and on occasion we seem to be stressing the subs. The grills are rattling and to the ear the woofers sound stressed, but there also is not a whole lot of impact on the dance floor.
If the grills are rattling, you may need to have the F1 Subwoofers serviced.
Please say more about "the woofers sound stressed."
At the same time, there is no indication of limiting or clipping from the speaker. My thought (and hope) would be that the built in limiter should kick in and/or we should see a clip indication before there was the potential for damage to the speaker.
Yes, the limiters should prevent damage to the amps and drivers.
I guess it's possible that the limit and clip LEDs are not functioning correctly, but it'd be unlikely to have that issue with both subs, right?
Agreed, that's unlikely.
The subs sound 'normal' at moderate volumes so I don't think the drivers are damaged at all. It's just at high levels that we're experiencing this issue. In some cases we are likely asking a bit too much out of the system (bigger system is needed) but I'd like to determine what's going on - or not - with the limit and clip indicators.
Here are some details on the system and set-up:
Subs are run off an auxiliary send (Bus 6), and mains are direct from L/R of mixer (Behringer XR18).
I'm not familiar with the Behring XR18. Are you doing anything with the EQ to emphasize specific frequencies?
Channels sent to Sub Aux - Kick, Bass guitar, tracks, toms, playback audio for set breaks.
Kick and bass have channel HPFs of 45hz and 35hz, respectively.
Set the High Pass Filters (HPFs) at or above 40 Hz. The F1 Subwoofers won't use anything below that, so there's no need to have that content in the signal.
No channels are clipping and the mixer is kept in the green.
Try reducing the signal output from the Behringer and turning up the volume on the F1 Subwoofers. Does anything change?
Thanks for the reply.
"Please say more about "the woofers sound stressed.""
They sound overdriven. They sound clean and clear up to a point (pretty loud, to be fair) then begin to sound overdriven. Keep in mind, there is no indication of limit or clip when this happens.
"I'm not familiar with the Behring XR18. Are you doing anything with the EQ to emphasize specific frequencies?"
It's an 18 channel digital mixer:
No, there is no boosting of low frequencies, or much frequency boosting at all. Most of the EQing we've done on the channels is subtractive.
"Set the High Pass Filters (HPFs) at or above 40 Hz. The F1 Subwoofers won't use anything below that, so there's no need to have that content in the signal."
On our last gig (after I wrote this post) I moved the HPF for the bass up to 40hz.
"Try reducing the signal output from the Behringer and turning up the volume on the F1 Subwoofers. Does anything change?"
The volume on the subwoofers is all the way up. The mixer's sub output is typically run at unity. The subs have never limited or clipped with this configuration, just exhibited the overdriven sound.
FWIW, we run the tops with the volume at around 80% and that seems to give a good balance of lows to highs for our musical needs. However, on occasion the tops to go into limit at which point we adjust the mix to keep them out of limit.