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Recently I bought preamp Behringer Pro MIC2200 and I wonder if I can plug my guitar straight to it with a help of jack 1/4" connector.

This preamp has switch MIC/LINE with mic having 3k impendance and line 60k impendance. I wonder if 60k impendance for line input is enough to plug there a guitar. I know that normally it's up to 1 milion impendance needed in the input.

The manual says I can use this unit as a DI box for a guitar and keyboards and boost it with "gain output" knob. Will boosting my guitar signal with "gain input" knob change anything? I would rather do it that way to avoid boosting some additional noise on the output.

Toby
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2 Answers2

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I agree to @Laurence, nothing will be damaged.

But I advise you against doing so.

Modern audio connections are bridged connections that is: Low impedance source connected to high impedance input. This way only little power is transfered resulting in unchanged response and high signal level is maintained resulting in low noise and low susceptibility.

Your instrument output is a high impedance output, likely in the order of magnitude of some 10kΩ and a typical instrument input will accordingly be in the order of magnitude of some 100kΩ.

A typical mic has an impedance in the order of magnitude of some 100Ω so a typical mic input has an impedance of some 1000Ω. Your behringer e.g. has an input impedance of 3kΩ to my knowledge.

By connecting your high impedance instrument output to the low impedance mic input you will loose a vast amount of your signal, making higher gain necessary, which lead to higher noise. Also because the mic input is a high load for your instrument output the frequency response will change. You will loose low and high frequencies making your instrument sound more dull.

DrSvanHay
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  • Thank you for introducing this stuff to me. However I mentioned in my question that I want to plug in my guitar to 60kΩ line input and this is much closer to 100kΩ mentioned by you.

    Manual says that I can use it as a direct box but I wanted to be sure I would not damage anything. That's why I ask.

    I would never plug my guitar to mic input. Thanks for explanation DrSvanHay :)

     – Toby Dec 10 '18 at 15:06
  • Ah, ok, sorry, did misread that. A typical instrument input will have several hundred kΩ up to 1MΩ so 60 kΩ compared to lets say 500 kΩ is still "inversed" bridging, still resulting in much more noise than necessary. But hey, if the sound is ok for you? Why not. You will not damage your equipment. – DrSvanHay Dec 10 '18 at 15:14
  • Ok. I will give it a try then. I thought about connecting my guitar to preamp and then to computer because when I connected it straight to my audio interface (tascam us2x2) and turned the gain knob to about 60-70% it became kind of noisy. I did some testing before with microphone and realized that my preamp gives clearer sound than my audio interface and this is why I thought about connecting guitar through this preamp too :). – Toby Dec 10 '18 at 16:16
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Try. No, it isn't specifically a guitar input. But nothing will be damaged, and sound will come out. If the gain control allows sufficient volume and you like the sound quality, use it.

Laurence
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