[Solved] Martin acoustic/electric gets distorted while recording

If your laptop has a WiFi adapter, these are notorious for causing massive DPC Latency spikes, which can do horrible things to the ability of your computer handling streaming audio processing, like what Sonar does.
 
So, try this: Just before launching a Sonar session, look for a physical switch to turn off the WiFi - or it may be a function key. If neither, than go into Windows Device Manager and temporarily Disable the WiFi adapter (NOT uninstall - just Disable).  Then, launch your Sonar session and see if things sound better.  When finished with your Sonar session, turn the WiFi adapter back on, or it it was Disabled, go back into Windows Device Manager and Enable it again.  That will restore access to the web.
 
If the above does not fix things up for you (it does for lots of folks though, so I am hoping it does for you), you can always download some freeware called LatencyMon and run it for a few minutes while Sonar is NOT running, and it will give you its opinion on your computer's ability to handle the streaming audio needed for applications for Sonar, and will give you an idea of which routines may be causing audio performance issues that you can then try to resolve.
 
I hope the above helps, 
 
Bob Bone
 

Check your cable?

gotta go with this as a +1
 

Kev999
Also try replacing the battery in the guitar.

Thanks for all of the suggestions. I am really new and learning quite a bit already.
 
 

I just had the exact same scenario happen at a practice session I was recording this past week.
 
One of the guitar players' direct acoustic guitar signal would play just fine, then turn into a really "grungy", distorted sound, then back to normal again.  It turned out that the batteries in the guitar AND the direct interface box he was using were low.  He replaced the low batteries and things sounded consistently good once again.
 
Paul

Adq
Usually it is consider as a best practice to record acoustic guitar with a mic, not with a piezo. Or to use piezo as addition to main mic sound.

The "piezo sound" usually sucks compared to a nice condenser mic, but piezos don't always have to sound bad. This article explains why there's a problem, and some potential solutions. 
 
This article goes into specific EQ settings that work well with piezo pickups. As luck would have it, all the examples use the ProChannel QuadCurve
 
Also, last February the Braintree release included the "Acoustic Piezo" CA-X Amp Sim. Give it a try...as the description in the Rolling Updates section of the site says, "This amp compensates for the deficiencies of piezo pickups to bring out the true beauty of your acoustic guitar. While not intended for acoustic guitars with built-in EQ, if you can disable the EQ you may find Acoustic Piezo a better alternative. Acoustic Piezo can also be very useful for clean, defined electric guitar sounds, especially with neck humbucker pickups."
 
The same update also included 15 ProChannel EQ presets for acoustic guitar.

No problem! I'm always glad to contribute what I've learned in the hope that it will benefit others.

Thanks everybody! I am happy to report that I have swapped out the battery on the guitar and so far it seems as though the problem has been solved. I really appreciate all the suggestions and info.

Kev999
Also try replacing the battery in the guitar.

My Taylor did that to me one time.  Freaked me out too.  Definitely check the battery.  The behavior of a dying one is exactly what you describe.