We have had the Motorola RDU2020 radios for several years now and they have worked great. We needed a few more so we purchased a couple RMU2040 radios and a couple RMU2080d radios. The problem we have now is that the newer radios sound like you are talking to the fast food drive thru speaker. How can we get all of the radios working together so that they sound clear?
Difficult to suggest without hearing the difference. Are the new ones distorted, or clean but lacking low or high frequencies, so they sound thin and weak, or too quiet so you have to turn up the volume, which then sounds rough. Or maybe they are setup for a narrower band like 12.5 or 6.25 and your old ones have deviation set for 25KHz. This often sound very unpleasant on the newer equipment with more modern filtering? All these causes sound ‘wrong’ but without hearing them, we don’t know and can only guess.
If you have companding enabled on some of the radios and disabled on the others, it will cause such an issue. Check both the old and new radios and either enable or disable companding across the entire fleet.
I have the same problem with a brand new RDU4160D, although I didn’t get it here.
The company got it for me for evaluation with our business repeater system for workhorse analog backups to our primarily Mototurbo system.
The biggest problem is that I can find no way to turn off the compander and they don’t want to force all the users with different manufacturers gear to turn it on - if they have it at all.
In the downloadable CPS software, when I fire it up it appears that companding is locked out preventing end-users from toggling it.
Other than that, they really like the radio, but unless the companding can be turned off, it is a big paperweight.
Is there any way to defeat the compander for an end-user? They are kind of bummed out about it, and so am I since I was the one who suggested they look at the 4160d.
Since narrow-band is now mandated, it is likely the companding function is turned on to increase communications quality in the narrower channels. It’s likely this option will not be able to be defeated.
While some think it sounds better (myself included), that would involve our entire site which has been narrowband for many years.
But that is only a vendor-specific audio option, and not something mandated by being narrowband. I probably should have had them evaluate Kenwood pro-talk’s instead.
There IS a way to change it, as the companding option drop-down in the consumer CPS is grayed-out - just like not being able to change frequencies from the default picklist -which I completely understand.
I was surprised to see companding locked out, and apparently requires a professional dealer option. I might seek that option just to help keep this thing from being a paperweight in our current application.
In response to the original post, I have had numerous complaints from customer regarding the audio from the new RM series radios. They had previously used the RDU2020 and started purchasing the RMU2040. Both radios have companding enabled so it is not a compatibility issue.
I am starting to believe it is a quality issue with the speakers used in manufacturing the RM series. I have a RMU2040 sitting here from a customer. Turn compander on and off, still sound like garbage 
Seems to happen after a few months.