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Do Humfree Isolation tabs work?


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I have used Humfrees before, but found them awkward to actually use. The thickness is also inappropriate (won't work) on thick faceplate gear like Mesa's rackmount stuff.

 

Alternately, to isolate units from the rack rail, I use shoulder washers on the front of each unit (regular nylon washers with a "shoulder" to keep the rack faceplate from touching the screw on the inside of the hole) and electrical tape on the rack rail itself.

 

You can also use items to separate the top & bottom of each unit from adjacent units. If there is enough room, small rubber feet or adhesive felt pads separate each unit just enough.

 

In the end, you just have to make sure that each unit only has one path to ground to avoid loops.

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Chopping the rails sounds like it would be irreversable and potentially detrimental to the structural integrity of the rack... In otherwords, you could end up ruining a rack that way with no way to fix it.

 

Besides using shoulder washers & electrical tape to separate units in a rack, I also have placed my power amp in a separate rack before. That way the power amp is completely separated from the other units with exception of the signal cable and the AC main cable.

 

Alternately, instead of trying to isolate each unit, you could ground lift each unit at the AC main, then keep them to the rack rails as if the rack itself is one large grounded chassis...

 

Of the two methods usually used, star grounding or one chassis grounding, either of those would work without having to ruin a perfectly good rack case.

 

Terri had a GREAT post on grounding methods some time ago. You can probably still find it if you search this forum.

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Thanks El Grinder. Actually what I am thinking of doing is picking up a bigger rack case and actually chop the rack rails only to the size of the units and then leave space between the units so none of the units are in contact with each other through the rails.

 

 

You might want to rethink that. Chopping the rail and mounting it as individual pieces will compromise the racks stability, more so if it is a non-shock. A big rack without the lids attached can be very wobbly, but becomes much more stable once loaded with gear onto solid rails.

 

I had a ground problem and found that it was my GCX. So, I just disconnected the ground wire on the inside. No more obnoxious buzz/hum.

 

Some things to think about,

Scott

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Thanks El Grinder. Actually what I am thinking of doing is picking up a bigger rack case and actually chop the rack rails only to the size of the units and then leave space between the units so none of the units are in contact with each other through the rails.

 

I can't imagine how horrific my grounding problems would have to be to make me even consider going to that level of trouble over the issue.

 

I guess this is one case where I'm glad my rack is small. :)

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I was using the Humfrees clips and they did help with one instance of a hum that I was having, then the next time I reorganized my rack, I noticed that the hum was gone when I didn't install them...They did help keep my rack gear looking nice since the screws didn't actually come in contact with the gear, so that was an added bonus. Yeah; they're kinda tricky and you have to install them right or you'll mess 'em up.

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My mesa studio preamp hums like crazy sitting on top of my rack case. Lifting the ground only makes it louder.

 

Just yesterday I finally got the little rack mount wings but don't have any more rack mount hardware to actually put it in the case. I ordered a set of the gator rack clips, a pack of those isolator pads and a pack of these

 

http://www.sweetwater.com/store/detail/HPS/

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Glad I found this thread.


Is it possible to use the shoulder washers front and back to eliminate the electrical tape on the rack?


The price is right on those washers!

:thu:

 

Yes, that's essentially doing what Humfrees do, but cheaper, easier, and classier.

 

I only use electrical tape on the rails because it's thinner than the washers, which is important to me since the Mesa Triaxis has a VERY thick face plate. (And I didn't feel like buying longer screws.)

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