Live mic guitar

Tyeetime · #1 01-13-2016, 08:09 PM

I play a D15m that does not have a pickup, and I would like to be able to amplify occasionally. I own an SM57, a solid state Yamaha amp, a Fender Blues Junior, and a Marshall JCM800. I can't seem to get a good result running the mic into any of these amps. My question is this; will an acoustic amp make a huge difference? What does it do that an electric amp won't?

ricdoug · #2 01-13-2016, 08:23 PM

You have an impedence mismatch with a balanced microphone going into an unbalanced guitar amp input. The solution could be as simple as using an inline transformer, such as:

http://www.guitarcenter.com/Whirlwin...nce-Matcher.gc

...and an XLR Cable:

http://www.guitarcenter.com/Live-Wir...phone-Cable.gc

Br1ck · #3 01-13-2016, 09:17 PM

Electric guitar is all about mids. Design of amp and speakers is all about coloring the sound. This is the opposite of what you want in an acoustic amp. With acoustic you want more of an accurate reproduction of the signal. This is one reason powered PA speakers are so popular among acoustic guitarists.

Most acoustic amps will have a tweeter and a woofer, usually smaller than an electric guitar amp. They will often have an XLR input the proper impedance for a mic and more than one channel, as well as an EQ section tailored to the unique needs of acoustic.

You would sound better playing into a bass or keyboard amp. These have more common sonic needs than electric guitar.Neither is likely to have the XLR input you need.

Tyeetime · #4 01-13-2016, 09:30 PM

Thanks for the help, I am going to look into these options.

Quote:

Originally Posted by Br1ck

Neither is likely to have the XLR input you need.

I have an adapter to plug the mic into the amp jack, but I never considered the impedance issue. It seems like I need the amp turned up quite high just to get a bit of sound through, is this to do with impedance or is the SM57 the wrong mic?

varmonter · #5 01-14-2016, 09:26 AM

You will probably never get a good sound with
This setup.even if you get the impedance right.
if we knew a little more about what
You have available to you we could probably
Help some more.is this for home use only?

Tyeetime · #6 01-14-2016, 02:30 PM

Yeah, home use only. I think I will look into an acoustic amp that has a second channel for vocal. What I wonder most is if simply adding an acoustic amp will make a substantial improvement, because sound quality aside, the volume is not very good even turned up quite high (just before feedback).

I am very reluctant to put a pickup in my guitar, maybe it is irrational but I want my guitar left as stock as possible. That is why I thought of micing it when necessary. Is the SM57 the wrong mic, or will an acoustic amp solve my problem?

jomaynor · #7 01-15-2016, 01:00 AM

Quote:

Originally Posted by Tyeetime

Yeah, home use only. I think I will look into an acoustic amp that has a second channel for vocal. What I wonder most is if simply adding an acoustic amp will make a substantial improvement, because sound quality aside, the volume is not very good even turned up quite high (just before feedback).

I am very reluctant to put a pickup in my guitar, maybe it is irrational but I want my guitar left as stock as possible. That is why I thought of micing it when necessary. Is the SM57 the wrong mic, or will an acoustic amp solve my problem?

Ricdoug's answer addresses the primary reason that you currently can't get a good sound - you have an impedance mismatch.

Yes, acoustic amps have the proper impedance built in for your mic, but you could also buy the $15 lo-to-hi impedance matcher, and your guitar would sound much better through the amps that you already have.