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Quieter Mid-sized GEMs?

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#1 Peter Natscher

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Posted 30 May 2013 - 10:46 PM

I have used a Astro-Physics 900GTO mid-sized GEM with various OTAs since 2001. I like its build quality, tracking accuracy, and smooth operation but can be a bit noisy moving at its faster slew rates. Does anyone know of or use a GEM, for OTAs of 25-45 lbs., with quieter motor assemblies? Is the A-P Mach 1 GEM also as noisy? IIRC, I had a Tak NJP GEM back in 2000 that was quieter.

#2 orlyandico

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Posted 30 May 2013 - 11:02 PM

Yes the Mach1 is pretty noisy. But it's quieter when you run it at 600X slew.

I think you can't beat the Tak mounts for quietness, as most (all?) of them use stepper motor drives. I think the EM-200 is quieter than the NJP though.

#3 andysea

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Posted 31 May 2013 - 07:47 AM

The NJP is pretty loud. It sounds a bit like a dentist drill when it slews. Only louder.
I believe the quietest mounts out there are the ones that use a direct drive system.

Andy

#4 David Pavlich

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Posted 31 May 2013 - 07:52 AM

Orion's Atlas is a really quiet mount.

David

#5 andysea

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Posted 31 May 2013 - 02:57 PM

I found this on youtube.
You can "hear" how quiet that thing is.
https://www.youtube....h?v=9RAQmd7KrkY

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#6 WesC

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Posted 31 May 2013 - 03:16 PM

Wow, that thing is FAST as well as quiet.

#7 andysea

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Posted 31 May 2013 - 05:35 PM

I think those are the quietest mounts available. I'm not a big fan of super high slew speeds.

Andy

#8 Jesus Munoz

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Posted 31 May 2013 - 06:32 PM

As Andy said ASA mounts wins, second Orion's Atlas/Sirius, and third place to Takahashis EM200/400 mounts.

#9 JMW

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Posted 31 May 2013 - 09:00 PM

I have the AP900. I think if you cut down the max slew speed it would be much quieter.

#10 andysea

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Posted 31 May 2013 - 09:16 PM

hmm i doubt it. My mach1 which has the same motor and gearbox as the 900, even at the lower slew speeds it's pretty loud. I have actually not heard an ASA in person but judging by the videos that I have seen they essentially produce no easily audible noise because they have no gears.

Andy

#11 Peter Natscher

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Posted 31 May 2013 - 10:00 PM

I don't use the two highest slew speeds on my 900GTO. If I need to move the scope to a new object more than a few degrees, I manually reposition the OTA. Besides, high-speed slewing really uses up your battery power - a lot more than tracking. If you want to get longer life ut f your battery, say at a remote star party, then don't power slew all night. Use your hands and manually move reposition the scope to the new area of the sky. I only use the lower slew speeds - the ones you use centering an object in a optical finder or lowest power eyepiece view. That's the beauty of a tracking GEM. I don't use GoTo on the 900 mount either. So, high speed slewing object-to-object producing loud motor assembly noise is avoided. It is irritating to my hearing and I'm sure neighboring observers don't like it either. Two things I don't like being in a field with many other observers at a star party: 1. Bright laptops and LED devices; 2. Nearby loud GoTo slewing for hours on end. :bawling:

I have the AP900. I think if you cut down the max slew speed it would be much quieter.



#12 Peter Natscher

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Posted 31 May 2013 - 10:04 PM

I think the next best thing A-P could do for their mounts is to develop lower-noise drive assemblies. What makes this noise anyway? Is it the fine Swiss motors or the gears? With direct drive assemblies, aren't there still gears used (reduction gears)?

hmm i doubt it. My mach1 which has the same motor and gearbox as the 900, even at the lower slew speeds it's pretty loud. I have actually not heard an ASA in person but judging by the videos that I have seen they essentially produce no easily audible noise because they have no gears.

Andy



#13 orlyandico

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Posted 31 May 2013 - 11:07 PM

According to AP it is the very fine gearing in the motor gearbox.

The idea of running the AP at 64X slew seems a bit overkill though... it would be nice if there was an intermediate slew speed like 300X.

#14 FaronD

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Posted 01 June 2013 - 06:06 AM

The EQ6/Atlas is a very quiet mount. That ASA is amazingly silent! My Mach 1 used to be very noisy, especially the dec gears. I reset the gear mesh on both axis and there certainly was an improvement...it used to sound like a coffee grinder :) It's a simple two minute procedure and there are no actual adjustments to make. It's just a matter of loosening and retightening the bolts. Have you guys tried this on the Mach's?

Faron

#15 orlyandico

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Posted 01 June 2013 - 07:57 AM

I did this on my Mach1. No difference on noise. But prior to the adjustment my CP3 controller got very very hot - kettle of boiling water hot - (I think the gears were meshed too tightly, which overloaded the motors).

#16 JumboFlex

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Posted 01 June 2013 - 09:40 AM

The noise is the only complaint I have with the Mach1. The ASA is certainly quiet. Given a chance to redo my mount situation I would still go with the Mach1, the ASA mounts are not the all around performer I require, at least going on what I last knew of them.

There are still times I long for a more gentle sound on the AP though.

#17 andysea

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Posted 01 June 2013 - 01:12 PM

Faron,
I am thinking to re mesh the gears too. Did you have to redo your Pempro curve after that?

Andy

#18 orlyandico

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Posted 01 June 2013 - 02:32 PM

you should....

#19 andysea

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Posted 01 June 2013 - 03:32 PM

hmm i might put that off then

#20 FaronD

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Posted 02 June 2013 - 07:52 AM

Hi Andy, as per Roland, no you don't have to.

#21 orlyandico

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Posted 02 June 2013 - 08:00 AM

Yes, FaronD, you're right. I conflated the S chip upgrade with re-meshing the worm wheel and gear, as I did the two at around the same time.

#22 FaronD

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Posted 02 June 2013 - 08:03 AM

Here's the Yahoo thread, #37643.

#23 FaronD

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Posted 02 June 2013 - 08:11 AM

I've adjusted mine twice already, once at the beginning of winter and again the other day now that the warm weather has arrived. We have quite the temp extremes here.

Faron

#24 andysea

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Posted 02 June 2013 - 02:33 PM

Thank you so much!....sorry for hijacking the thread!
I re meshed it yesterday ad tested it last night. During times of good seeing I was getting 0.2" RMS. I think you guys are absolutely righ:)






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