Posted 17 January 2013 - 03:05 PM
We have a few mounts here, and, have compared them against others over time at star parties.
The EQ6-Pro and HEQ5-Pro (atlas/sirius in orionspeak) are the quietest of the bunch. Our neighbors have never noticed them. The Tak NJP is a close second, altho the prior poster is correct, it sounds much 'cooler'.
Our EQ3 sounds like a coffee grinder.
But, with that said, all of our mounts are substantially quieter than the cg5 and ilk we have seen at various star parties. When those start up, there is no guessing that someone on the field is slewing a telescope. Same can be said of the goto dobs, no question at all when they are slewing.
We've also had them set up beside an AP900, and, in all honesty, I dont remember what it sounded like, so, it must have been reasonably quiet.
As a general rule of thumb, if the motors and gears are hidden behind plastic, it's going to sound like a coffee grinder, or worse. If they are hidden behind metal, it's going to be substantially quieter. This is pretty much an across the board trend.