adding an XLR input to guitar amp

[fatecasino]

Hi,
I am building a small battery powered busk amp and I was wondering if there is an "easy way" to add an XLR input too.

*If I mix the two signals passively with a resistor to each signal (4.7K?) would I have a great loss of signal?
*Otherwise, what would there be as an ACTIVE alternative circuit?

Thanks!

[GibsonGM]

Oh, there are a couple fairly easy ways!  This is what a direct box does, after all...check this link out!! 

http://thehub.musiciansfriend.com/tech-tips/unbalanced-versus-balanced-i-o-and-how-to-work-with-them

[JerS]

If inclusion of the XLR input is to make plugging a mic in more convenient, as opposed to getting a true noise cancelling balanced signal, then it is as easy as connecting pin 2 of the xlr to the + with a mixing resistor and pins 1+3 to the - (signal ground). Since the mic is likely to have much lower output than the guitar, you may with to add a very simple preamp to the xlr + side: like a simple opamp amplifier, to get some more signal for the mic.

[ashcat_lt]

You're really not going to be able to make the mixing resistors big enough to maintain a reasonable impedance for the guitar. 

You will have to buffer the guitar at least, and you will probably want a gain stage for the mic as mentioned above.  Google for that $5 microphone preamp project that was going around a while ago.

[fatecasino]

(converting balanced to unbalanced - understood!)

Hence, by adding buffer resistors in both signals is impossible.
How about adding a mini active mixer and balancing volumes with trimmers?