I have that exact problem if I use DSP, moved to COS and PTT on DB25 and it stops. Did this in every case I tried, though the only platform I used was a D945 or D201 Intel board.
 
Ran 1GB of RAM and CPU is whatever a D945 is.
 
GeorgeC
W2DB
2360
 
 
Sent: Wednesday, September 11, 2013 11:45 AM
Subject: Re: [App_rpt-users] Distorted audio in app_rpt/Allstar
 
On 9/11/2013 12:20 PM, Andreas Pleschutznig wrote:
 
 
Best I can describe the effect is that the audio is time sliced in 20ms packets and every other packet is missing, left out. and it does not happen when audio is especially loud or quiet. Sometimes it happens on the time announcements, which are absolutely perfect 99% of the time.

Sounds to me like a computer with too little RAM or too little CPU horsepower.

When you run the top command, is it using swap memory?  If so, that's bad...and you need more RAM.

Kevin