Members joedobronski Posted March 24, 2012 Members Share Posted March 24, 2012 [ATTACH=CONFIG]343986[/ATTACH]Ok, I don't get it. I just got some XLR cables to replace my 1/4 inch cables that run from my mixer to my powered speaker (Yam MG124CX to a Bose L1) That's the only thing I changed! Now, when I pull all faders down I still hear the music from a laptop plugged into 9/10. This didn't happen when I was using the 1/4 inch cables. I would guess that the Bose may be more sensitive on the Mic in vs the 1/4 inch in, but that shouldn't matter if infinity means infinite resistance on the fader. Right? What am I missing? Link to comment Share on other sites More sharing options...
Members Miko Man Posted March 24, 2012 Members Share Posted March 24, 2012 My best guess is there is a gain issue going on somewhere, or at several somewheres. By going with an XLR cable into the Bose channel input it engages a mic pre-amp. Did you turn down the trim on the input channel on the Bose unit? That is something you will need to do, irrespective of the channel 9/10 issue. Use a mic thru the mixer to set the trim on the Bose unit at an appropriate level. Just as an example of how much adjustment might be needed, when going from a line level input to a mic level input on a PRX612m speaker, I have to back off the trim level from 12:00 (straight up) to 8:00 ish. Does that solve your issue? While I would think that having the 9/10 fader all the way down "should" reduce the level of that channel strip to such a low level that it would silence the channel, I suppose it is possible that some signal might be passing if the send from the computer is all the way up. Is that the case? If so, turn that down. Is the mains fader still up when you are getting the 9/10 signal passing? Does the channel strip's sound go away when you bring the main fader down all the way? If there is still signal passing while the channel fader and the mains fader are all the way down, then I would suspect an issue with the mixer itself. Weird. Let us know what you find out. Mark C. Link to comment Share on other sites More sharing options...
Members joedobronski Posted March 24, 2012 Author Members Share Posted March 24, 2012 Hi Mark, Thanks for the ideas... let me address each. First, the trim on the bose is all the way down. You might think this is strange, but I always do this at home to keep the hiss to a minimum as I don't need the additional power here. when we play out, we usually have it at 12 o'clock or so. On the Mixer, I have ALL the faders all the way off. The laptop channel, the effects return channel, the mains everything off... that's why I am focused on the mixer. And when I use 1/4 out this does not happen. looking at the manual there should be NO difference going to xlr outs ?? I will try some more trouble shooting and let you know.. Thanks again Mark. Link to comment Share on other sites More sharing options...
Members joedobronski Posted March 24, 2012 Author Members Share Posted March 24, 2012 ?[ATTACH=CONFIG]343991[/ATTACH] 1/4 vs XLR out - what's the difference ? I don't see it. Link to comment Share on other sites More sharing options...
Members Miko Man Posted March 24, 2012 Members Share Posted March 24, 2012 1/4 vs XLR out - what's the difference ? I don't see it. I don't see the difference, either. That's why I asked about the gain on the Bose unit, because it does change with the input connector. I assume that you have tried channel 2 on the Bose and got the same results. Systematic troubleshooting (speaker vs mixer vs cables) is the way to go. Good luck. Mark C. Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 24, 2012 Members Share Posted March 24, 2012 XLR into the Bose mixer will have ~20dB greater minimum gain than the 1/4" input. This may be responsible for what you are hearing. The output of the mixer is line level going into a padded mic level input. Review the input specs. on the Bose mixer for verification of this. Link to comment Share on other sites More sharing options...
Members joedobronski Posted March 24, 2012 Author Members Share Posted March 24, 2012 Yea Mark, I did try each channel one at a time just to see. It looks like I will have to go back to 1/4 inch. It works just fine, don't ask me why I was trying to go XLR, I never had any problem with 1/4 in. I just thought it would be cool to make sure I was better shielded from external noise. Thanks Andy, I think that is exactly what I am experiencing - the 1/4 signal is below it's minimum and the XLR is above it's. I'll just go back to 1/4 no big deal.. Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 24, 2012 Members Share Posted March 24, 2012 Or the PROPER solution is to use a ~6:1 step-down audio transformer to isolate and bring down to (closer to) mic level into the XLR input. The possible benefits here are the reduction of noise and ground loops. Link to comment Share on other sites More sharing options...
Members Miko Man Posted March 24, 2012 Members Share Posted March 24, 2012 A 1/4" TRS cable is typically (AFAIK) made with shielded cable. Glad you have a workable solution. Mark C. Link to comment Share on other sites More sharing options...
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