Hi, My Bose L1 model II has start to make a squealing sound occasionally. First when I heard it I was performing quite loud in a bad acoustic venue, so I thought it was some kind of feedback issue. A had this problem since then and still thought it was related to high volume. But the gig yesterday the squealing came at very modest volume. So it can't be that. Do you know what it can be? or how I shall troubleshoot it? It seems I can't make It squeal on purpose. And It also seems like it doesn't occur until a bit in the performance so I guess it has something to do with the electronics in the footer when it gets warmed up?

I could also add that its not a regular feedback sound. It sounds more like its being overloaded, a peak sound that kind of yell so its not consistent. Still no red lamps that indicates that its being overloaded. The system is quite old now and didn't have this problem before.

Any ideas?
Where should I start to troubleshoot and how? with the footer or could it be the tower, or something else?

Original Post

Hi, Daniel Blohm.

That's going to be tricky to diagnose.

Let's find out if the squeal is originating in the L1®.

What kind of mixer are you using - and does it have a headphone output? If it does, then when you hear the squeal - do you hear it in the headphones too?

Do you hear the squeal if you disconnect all your input sources from the mixer? If not, then connect the input sources one at a time until the squeal returns.

Do you have another powered loudspeaker? If so, can you connect your mixer to the other powered loudspeaker - do you hear the squeal?

That's a start.


Thank you for answering, yes its tricky because I can't make it squeal on purpose. Its always happens during a performance :-/
It doesn't squeal if were not playing. Its like a peak that pops out of the speaker. It feels like its overloaded. (the squeal sound is just a half second or so)
I am using a Bose T8 as a mixer. I have used it today for an half hour. But only half of the tower because of the height of the roof in the basement. And just connected my digital drums to test them for a while. And during that period there was no squeal.
When I am performing live I play acoustic, sing and have a stomp box. I have so far not heard this when I play solo, but in duo with more mics and more instruments.

I also use the T8 mixer with my RCF 10" and subwoofer when I am playing with my band. We don't have that squealing problem with that setup.

Hi Daniel Blohm,

Here's why we want to check the firmware (and consider reinstalling it).

Notes from firmware update 1.1.4

Digital Noise

In rare circumstances, ToneMatch T4S/T8S mixers may produce an audio signal that sounds distorted or “clipped.” This is likely due to corrupt data in saved scenes.

Recommended Actions for Issue We recommend upgrading the mixer’s firmware to v1.1.4 and rebuilding any saved scenes using the new firmware. To do this, follow these steps:

  1. Record the settings of any scenes you want to rebuild after the firmware upgrade.
  2. Perform the firmware update to version 1.1.4
  3. After the firmware upgrade is complete, perform a factory reset to erase all scenes you have saved on the mixer:
    • Press and hold down Mute buttons 1–4 while powering on the mixer. Factory reset will appear on the display. The mixer is now ready to use and will no longer exhibit the issue.
    • Rebuild any scenes you want to use by referring to the settings you recorded in Step 1. Do not reload any scenes you have saved previously.

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