Help: My Grace 902 rocks back and forth(does not sit firmly) when placed on my shelf!

I feel for you. This can drive a person crazy. First check the shelf, maybe the more compact footprint of the Grace means you have never set anything on that part of the shelf before. If you think it's a problem with the unit send it back. You want to be happy with your purchase.

Mine does this a bit on some surfaces. The feet are not quite the same thickness, and some of the threaded holes seem to be angled. You can try swapping feet around. If that does not work, just unscrew the 2 feet on the corners that are too short until they touch the shelf. You could fiddle with thin washers as spacers between the foot and chassis, if you want a solid fix.

Another alternative, take the rubber discs off the metal feet and replace them with compliant (foam) discs. Those will self level. They can be found at hardware stores, intended for use on furniture legs.


gerG

The suggestions about troubleshooting the feet are helpful indeed, but my point is that the unit should not be this way in the first place. I would have Grace rectify the problem.

Hi Jay.

I can't think of any way this could affect the sound. Grace will fix the problem, but it may leave you without the amp for awhile. That would not be my choice. I would ask for some more feet, and swap them until the unit is solid. It seems unlikely that the aluminum base is warped, but you can check it with a straight edge. Turn the amp upside down, take off all the feet, and run the straight edge from corner to corner, front to back, side to side, and both diagonals. There should be no gaps under the straight edge.

A silly simple alternative: if the base is flat, just get some of the large stick-on feet from Radio Shack and place them at the 4 corners. They are more compliant than the factory feet, so more self adjusting to minor deviations out of plane.

While it is true that a 3 point mount is more tolerant of out of plane anomalies, it is absolutely not as stable as a four point mount within the boundaries of the gear that we are talking about.


gerG

"Aint no thang." In other words, why even bother worrying about those crummy stock feet, when this is a such a good opportunity to have fun experimenting with a nice aftermarket isolation platform, or some real nice footers? The Grace is essentially such a fine product that it's well worth the extra few bucks you'll spend on a set of Vibrapods, Sorbothane feet, or Black Diamond Racing Cones. I probably would have chucked those cheapo stock feet out the window by now, regardless of how level they were.

You can always loosen one of the feet until it is no longer "rocking". Much like how you adjust floor spikes for speakers.

If it is not more than a mm off, it should be OK, otherwise return the feet to Grace, they will most definitely replace the feet, I highly doubt it's the m902's case that is the problem.

But again as mentioned already, I'm willing to bet real money that it's your shelf that is not level. It may be bowed. Try putting the m902 on a known flat surface, do you have granite or thick stainless steel countertops? Formica? Or a glass table. Then see if it "rocks" back and forth like before.

I have an m902, and have not had any leveling problems. I love those little feet it comes with. Very nice touch to make it more of an audiophile pice of equipment and less of a rackmounted studio component.

-Ed

Yes, there are several sources for aftermarket screw-in footers from which to choose from. Mapleshade Records sells very nice solid brass cones that are equipped with threaded posts - you can specify the size and type of threaded post that you'll need on your cones and they will provide you with a custom fit. The nice thing about the solid brass Mapleshade cones is that they are heavy enough to help stabilize your component. The downside is that they are also fairly large (1" or more in height and diameter), so you will have to decide if you like the looks of them. And Music Direct sells footers for audio gear, including some threaded cones, in a wide variety of sizes, styles, and prices. Parts Express also used to sell replacement feet with threaded inserts. Check them all out.

You likely have a long foot on the LR or RF, or a short foot on the LF or RR. Diagonal swapping will not change anything. First swap the LF for the LR and check for a change. If no change, swap the RF for RR. If it is the feet, one of these 2 swaps will isolate the culprit. (LR = left rear, RF = right front, etc.).

As for 3 point vs 4, maximum stability will be achieved when no part of the body overhangs a tipping axis. The tipping axes are defined by straight lines drawn from foot to foot. In the case of a rectangular shape, like the Grace, this means a foot at each corner will achieve maximum stability. Reducing to 3 feet will make the unit less stable. Try it, place 3 feet under there in any formation that you like. Now go around and press down on all 4 corners, one at a time. At least 1 corner will tip. For the same reason, cars have 4 wheels.

To achieve a stable platform with 3 feet, one could construct a triangular base large enough that no part of the component body overhangs a tip axis. If you draw this up on paper you will see that it is a poor use of space.

The only advantage of a 3 point mount is that all 3 points will touch, even with irregular surfaces, or poor manufacturing tolerances. Trading a solid 4 point for a tippy 3 point is not a trade that I would recommend.

I have seen a few products that are designed with a 3 point mount (most notably turntables). As indicated above, if the feet are moved far enough outboard the platform can be stable. This in not relevant to a rectangular component designed for a 4 point stance.


gerG