Hi to you all, I am Fabrizio from Italy. I have a couple of used (not by me) L1's classic with 4x B1. One is perfect, the other nope. I run them always with a line input in the input 3 (at volume 3) and already tried the input 4. The broken system sound awful, No eq and NO x-over. I have full range in the sub output, Removed the radiator and checked the 3 amps individually. All works correctly if driven from their inputs. If I use one of the classic line inputs (3 and 4) in every amps out I have the same signal as I use the "all amps" input. Tried also to plug in/out the B1s. In the working PS1 i had an audio lack, due to the DSP is arranging new set-up, all normal. In the "broken" PS1 all the amps out works as a full range amps, nothing happens pluging the B1, no lacks, no eq and DSP starts. It works always in all amps mode, with every input and every speaker configuration. I hope my english can be enough for let you understand my issues. So, I really hope someone can help me with some tips, I can open and check some electrical inside, not an expert, but able to do it. Cheers. Fabrizio.

Original Post

Hi Fabrizio,

Welcome to the Bose Portable PA Community.

It sounds like the broken L1 CLassic is stuck in diagnostic mode. This is usually triggered by applying a resistor across the B1 Bass Module Output pins 2+/2- with a value of less than 5 K ohms.  This could happen if you connect more than two B1s to one power stand. 

Try connecting a single B1 to the L1 Classic that is working. Then try the same cable and B1 with the L1 Classic that is not working.  Do you get the same result (not working)?


Just make the test. Nothin' changed. I first try with the good one, playing audio from PC without sub, then while playing I plugged one B1, audio stop then restart in a second with correct DSP settings and EQ. Well, tried the bad one. Start playing w/out sub than I plugged the same sub and cable I used before, no audio stop, it's still in diagnostic mode, awful sound and full range from all 3 amps. Aside question, where is the resistor in the cable? I checked my Bose original cables but no resistance inside the connector. Btw, they works with the good PS!. So, any further suggestion? Thank you and best regards. Fabrizio.

Hi Fabrizio,

The only other suggestion is to disconnect everything including the AC power from the broken PS1. Leave it sit like that for at least 15 minutes to let the unit reset. then reconnect things and try again.

There is no resistor in the cable. It is in the B1 bass module.


Hi Fabrizio,

I'm sorry you haven't been able to get the second power stand working. 

Fin posted:

Thanks for the suggestion. But it was unplugged for hours before the test so I think that the problem could be in the power supply of DSP. Do you think that reload the firmware could be an option? 

I don't know if it will work. Here is a link to the instructions and the file you need to reload the firmware if you want to try it.

Classic: Presets 2.0 download


Hi there, the firmware 1.84 and 2.0 presets was updated correctly. The issue is still there. Stuck in diagnostic mode, ****. I try the input 1 and 2. If I change the presets the system correctly stop the audio for a second (to load the preset) then come back and the sound changes as well. So the software is running, the electronic seems to be ok except the amp section, stuck in diagnostic mode. Something happens there, imho. 3 amps with no eq or DSP. Did someone has the same issue in the past? Thanks to all.


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