Feedback i have a supertuned 29ltd. with stock mic all is well. with after market echo mic there is horrible feedback through truck speakers even with stereo turned off.?

OOps, maybe the delay is there to destroy your feedback ?
Nasty solution though.
Please read the manual closely or download it from the NET.
Peace-

try reset the phone.

this happened to me in my truck (sounds as if your talking in a tunnel) what it turned out to be was i did not set up my phone on bluetooth properly (mute interal microphone on bluetooth) but i first noticed a sort of fix for this as i put my phone inside my lunchbox oneday and the echo went away on next call , but after looking into it i saw the mute function on phone bluetooth set-up

This type of audio feedback loop can happen on any mic if you are playing back audio at a loud volume on speakers that are close to the mic while the mic is on - which tends to happen on Skype calls. Try lowering your speaker volume or using headphones to hear the audio, then speak into mic, and the feedback should be reduced.

The control supposedly controls the mix of the echo... this is a reverb type sound. Please note that room acoustics AND if the mic's "hear" the speaker in this, it may create an echo that is NOT under control of the adjustment. Make sure the mic's cannot "hear" the speaker or a reflection off a wall.

Echo is caused by a number of variables. Are you in a large room with mic extended away from you? Mic too far away will create echo. Also try turning down the gain for the mic

LA 900? I am guess that is a linear amplifier. If so are you running a power mic? You are probably getting RF feedback. You need to turn the gains on the radio and mic down.

Some things you can try. Hold the mic cord in your other hand in the center of the cord while you key it. some times this will shield it form stray RF.

You can also get a bunch of RF chokes from radio shack. They are little black things you snap onto wires that shield form RF. Put 2 near the plug, and 2 near the mic. That will help shield it from RF.

you will most likely still have to play with the gains on the radio and mic to find a sweet spot where it doesn't squeel.

Try right clicking on yout Volume Icon in the system tray (where your clock is). Click on Open Volume Control.
Make sure you have some audio playing, then just go through each channel and mute each one, 1 by 1 until the echo has gone.
If that don't work, then again, right click on Volume Icon in Tray, click on Adjust Audio Properties, then under speaker settings, select advance, then choose Desktop Stereo Speakers, under the Speaker Setup Options.

One of those should work. If it is your Mic causing the Echo, then you would get loads of feedback if you whack up the volume. If you don't get the feedback, then it's more then likely the Speaker Setup or some Sound FX is enabled through your Sound Card Software.

do you record from
a) mic
or
b) line input ?

if a)
turn off your speakers, and use headphones.
or at least turn down the volume, and change the mics position (as far away from speakers as possible)

if b)
dont route the allready recorded channels to your master while recording (-> or mute them)

It might be a problem with their sound setting. If their speakers are on while using the mic, they might get some feedback that could be the cause of the echo. They may even just have to tweak their mic settings (through the control panel sound options or their soundcard options).