[arm-allstar] multiple echo link connections and "under water" audio

[Patrick Perdue]

Hi all:

     I realize that echo link isn't the primary focus of this group, as 
it relates to HamVoIP, but perhaps some of you may have suggestions.

I'm running a bridge between Allstar, DMR, DSTAR and echo link using 
HamVoIP, DVSwitch and XLXD. I've found that, if only one echo link 
station is connected, audio is as good as it can be, considering the GSM 
codec used by echo link, but subsequent stations hear any audio from 
Allstar as "under water." Echo link to echo link sounds OK, and echo 
link back to Allstar is fine as well.
I've heard this on a few Allstar to echo link bridges other than mine, 
and it sounds like GSM is being transcoded to GSM a second time. You can 
mostly understand what is being said, but the artifacts are doubled. I 
don't really understand how chan_echolink works, or why additional 
transcoding would be happening at that stage, but that's what it sounds 
like to me.

The echo link bridge is on it's own private node. Should I force GSM or 
G726 connections only for that node, or will that just make things worse?

I don't know for sure if it's multiple connections causing this 
behavior, or something else.
My thought, if this is the case, was to limit the echo link channel to 
only 1 connection, and keep it permanently linked to an echo link 
conference server, having people use that instead of my echo link node 
directly, but echo link doesn't seem to like it when people do that.
Any help is appreciated. Feel free to write off-list if you feel this is 
off-topic.
Thanks and 73
de
KE4DYI