Hissing sound from L1 Pro 32 & question about protections to the speaker

[Dj Giannis]

Hello. I just bought a pair of L1 pro 32. I am very satisfied with the sound quality and power output but I have some questions If you could enlight me. I play as a DJ and I am connecting my console to the second channel (XLR Cable) of the speaker. I hear extensive hiss sound from the speakers even at low levels (around 4 to 5 LEDs) even with no cable connected.

Secondly, I can't found if the speaker provides any protections such us overdrive limiter, thermal protection etc. I was playing and I had my eyes on the Led not to turn red. So if I rent the speakers and another Dj could play too loud is there an overdrive limiter that protects my speakers or they explode?
Thank you in advance.

[djrhouse]

Hello DJ; I am having the same issue. I just got 2 sets of L1 Pro32 with Sub2. I tried connecting through my T4S to my DJ controller and it’s a loud constant  hissing sound that you normally get when your gains are near maxing out on low quality amps.  But in this case, just as you said DJ, turn the gain up to the fourth LED on gain knob on the power stand, and you hear the hiss. 

I also tried without the T4S and the same result. 

ST, need your help. 

[djrhouse]

DJ; I figured it out.  I downloaded the firmware update this morning to my T4S and hooked up my connections exactly as shown on page 38.  Make sure you check the gain levels and reduce them on the T4S if you have one and set it up for DJ Playback.  The L1 Pro32 sounds dramatically better with the T4S than it does without it for sure.

[Dj Giannis]

Thank you, friend. But sadly I don't own a tonematch mixer and the hissing sound occurs even if I unplug the xlr cable. This only happens on the xlr channels of the loudspeaker. My speakers have the latest firmware. I run them at 4-5 dots but I have to check them every minute if they play on Reds like this! This is embarrassing for such expensive speakers. Many many users have reported this issue.

[djrhouse]

I believe you are correct. I disconnected everything and ran an XLR cable from the input on channel 1 and I tried channel 2 on the L1 Pro32 to my mixer to my Pioneer DDJ-1000SRT and put the gain on the L1 to the third notch and the hissing is extremely loud. When the gain knob is turned all the way down, the hissing goes away.

When I use the T4S, I connect it (left and right main out channels to the tone match port) to both of my power stands and use channel 1 & 2 on the T4S to my mixer master out so the gain knobs on the L1 are bypassed and you don’t hear the loud hissing, it’s significantly reduced.  I have a Rane 70 mixer and I get the same result (loud constant hissing) so it’s not the mixer and surely not my cables. I can see if we turned the gain all the way up but anything at the 12 o’clock position and lower shouldn’t exhibit hissing.  Let’s see what the techs have to say about this. 

[Dj Giannis]

Exactly! I am waiting days for an official answer from the admins but I get nothing back! I sent an email to the support of Bose and they told me to speak to my country's reseller instead of providing me with further information about this issue for God's sake. Anyway, I telephoned my country's official reseller and they didn't know what to say to me...

[Dylan_R]

Hello Dj Giannis,

Welcome to the Bose forum! Thank you for your post. 

Regarding your query on overdrive protection - The amplifier section in the L1 Pro32 and the separate amp in the Sub1 or Sub2 have built in thermal protection and limiter that protects both the speakers and amps. The units will shut down if they get too close to overheating. 

Concerning the hissing you mentioned - As the largest of our portable PA systems, the L1 Pro32 will also have the highest noise floor when compared to other systems. 

Does the 'hissing' sound appear the same for either channel 1 or 2 when the volume level is increased? 

Does the same issue occur when ToneMatch processing on these channels is turned OFF?

 

[Dj Giannis]

Hello Dylan! Thank you for your response. The hissing sound appears the same for both channels 1 & 2 but it differs every 3 dots. After 3 dots the sound decreases and on the next 3 dots becomes more and more intense. Is that a problem with my speakers that needs replacement? Because some users are facing it and some others don't. Thank you in advance.