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loopilleball
Joined: 05 Feb 2014
Posts: 4
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 Posted: Wed Feb 05, 2014 8:33 pm Post subject: Effects malfunctioning |
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I've recently been using my mic and guitar with my KP3 to make some music I enjoy listening to. I decided that I want to be able to hear how it sounds without headphones. In spite of my significant ignorance of music production technology, I decided to buy a small Behringer PA/monitor (the Eurolive B205D).
Plugged the KP3's mic output into the pa's line in/mic input. To my surprise the effect I was using on my guitar sounded much different than it did in my head phones--the volume of the effects was weirdly sensitive and delay times were off. Then I unplugged it from the pa and just used my headphones again.
Now the Looper effects (I use LoP.4 and LoP.5 a lot) actually slightly lower the pitch of my sound, just enough to ruin the overall quality of the music. I tried resetting the KP3 to see if it would return to normal, but now it just slightly raises the pitch!
Did I do something stupidly wrong by plugging my KP3 into this monitor? Or is there some other reason this has happened? What can I do about it? |
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xmlguy
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Joined: 26 Nov 2007
Posts: 3605
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| Posted: Thu Feb 06, 2014 4:43 am Post subject: |
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You probably fried part of your KP3 due to putting phantom power on it from the mixer. Sorry.
That's a hard way to learn the dangers of phantom power, but you aren't the first to fry something that way and you won't be the last. +48 volts DC can fry lots of gear that wasn't designed to expect it. |
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loopilleball
Joined: 05 Feb 2014
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| Posted: Thu Feb 06, 2014 5:25 am Post subject: |
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| xmlguy wrote: | You probably fried part of your KP3 due to putting phantom power on it from the mixer. Sorry.
That's a hard way to learn the dangers of phantom power, but you aren't the first to fry something that way and you won't be the last. +48 volts DC can fry lots of gear that wasn't designed to expect it. |
I actually intentionally never pressed the phantom power button on the monitor because I thought it might do something like that, and also because I don't really understand what it's for. I did however press the "instrument" button at some point while I was using it (see here http://i.imgur.com/9y2aerZ.jpg). Would that have done it too? |
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xmlguy
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Joined: 26 Nov 2007
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| Posted: Thu Feb 06, 2014 12:58 pm Post subject: |
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Exactly how did you connect the KP3 to the monitor? The proper connection would be a stereo cable with a pair of RCA plugs on both ends to connect the KP3 L+R output to the monitor's CD L+R input. The instrument button is on the input 1 jack, which is a mono input, not stereo. With the proper connection then hooking it up shouldn't have caused any problem. That the problem persists after disconnecting the monitor and power cycling the KP3 is troubling and indicates that something serious went wrong. You didn't use a Y cable or adapter to connect the 2 outputs together before going to the input on the monitor, did you? That could fry the outputs on the KP3 too. You can't connect two KP3 outputs via a Y because it shorts them together, and that can exceed their power handling capability. Each output must go only to another input, never to another output.
Connecting the outputs with a Y can also cause sound behavior you describe due to phase distortion and differences in the output power characteristics. It's like causing backflow from two water supply lines of different pressure, causing lower pressure line to reverse flow and the final output will vary in very strange (non-linear) ways. That should clear up when disconnected unless something got fried in the process. |
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loopilleball
Joined: 05 Feb 2014
Posts: 4
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| Posted: Thu Feb 06, 2014 4:16 pm Post subject: |
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I connected it in a couple different ways. I first tried connecting via the KP3's headphone out into the monitor's mic/line in with a trs cable; I did that with and without the instrument input on. I then used an adapter on a Y cable to connect the KP3's headphone out into the monitor's CD input. I never connected an output to an output though.
I guess something must've gotten fried because the problem definitely continues even when it's only my headphones and mic connected to the KP3. |
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xmlguy
Platinum Member
Joined: 26 Nov 2007
Posts: 3605
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| Posted: Thu Feb 06, 2014 5:22 pm Post subject: |
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| loopilleball wrote: | I connected it in a couple different ways. I first tried connecting via the KP3's headphone out into the monitor's mic/line in with a trs cable; I did that with and without the instrument input on. I then used an adapter on a Y cable to connect the KP3's headphone out into the monitor's CD input. I never connected an output to an output though.
I guess something must've gotten fried because the problem definitely continues even when it's only my headphones and mic connected to the KP3. |
Well, you apparently did connect an output to an output, without realizing it. That's what happens when you hook a stereo output like the headphone jack to a Y cable. You also shorted an output to ground when you hooked the headphone stereo output to the mono line input of the mixer. Both of these mistakes can fry the KP3. For future reference, headphone outputs are only for headphones, never for using as an audio line output. Can it work sometimes in an emergency? Yes, only if you know what you're doing and take precautions like keeping the level very low. But there's always a risk of blowing the outputs and other circuits if they ever get shorted together or to ground. Merely plugging a mono 1/4" plug into the stereo headphone jack can fry it, since the left channel that goes to the ring of the jack will be shorted to the shield ground on the plug.
The headphone output has a rather powerful audio amplifier with no overload protection. If you only hook up headphones, there's no need for this protection. If you hook it up to anything else, lots of bad things can happen.
The only connectors on the KP3 for hooking to other electronics are the RCA stereo line outputs. Since the KP3 uses stereo effects, the output should only go to a stereo input or two separate mono inputs. On your monitor, that means the CD input or both the Line1 and Line2 inputs.
It's possible that only your headphone output is fried, but that seems unlikely because of how you described the change in the sound of the looper effects. You might try hooking the KP3 up to the monitor properly to see if the behavior is different. Use a stereo RCA to RCA cable to go from the KP3 line output to the monitor CD input to hear how it sounds.
I'm going into such detail because this info applies to most music gear with headphone and stereo outputs, and might save you from much grief in the future. |
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loopilleball
Joined: 05 Feb 2014
Posts: 4
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| Posted: Thu Feb 06, 2014 7:01 pm Post subject: |
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I just tried connecting the RCA to RCA and the effects are still wonky. At least now I have a good reason to start saving for a Boss RC-505  I'm going to be so much more cautious about what gets plugged in where in the future.
Thanks so much for all the info. |
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