My partner and I have to mount some speakers in a community hall. And they have metal studs. We found a wall mount seen in the picture below. I've been reading online and as far as I can tell, metal studs aren't very good for mounting. These speakers weigh about 32 lbs. Looking at the mount, I was thinking of installing a piece of plywood to span two studs, and mount the mount on the plywood. Would spanning two studs be enough. And also, what type of screws would be sufficient for mounting a piece of plywood on metal studs for this mount and about 40-45 lbs of overall weight or so? Thanks guys!

Wood would be fine. I'd use a better grade of wood besides plywood for astethics of the edges. You could stain or laminate to get something nice looking.

Molly or toggle bolts into the metal stud.

Using Wall Anchors Including Molly and Toggle Bolts, Plastic Anchors, Expansion Anchors and More from The Natural Handyman Home Repair and Do It Yourself Website

The weight has a vector force based on your mount. Most of the weight is directed downward to the floor.

Toggles are easily removed. Molly bolts are not.

So I often forget to rate answers. You're always a great help kiss, as per usual so I thought I'd rate your answer. Actually, that web site was perfect. Every install we've done have been wood studs so far, and I'm very familiar with that. But metal studs, I just don't have experience with. I'm surprised at how much weight a 1/8" toggle will hold, even into drywall! It sounds like, 4 toggle bolts directly to drywall to hold up that mount would be enough. But we're going to do more.

My plan is to span two studs, with 5/8" plywood strips top and bottom to accommodate the mount (painted to match wall) and I'm going to cut the drywall out. And place the plywood into the spot the drywall was, to be right up against the studs. Two toggle bolts per strip, per side. And then mount the speaker mount onto the plywood with either more toggle bolts, or just nuts and bolts. This might be overkill, but I don't need one of these 32 lb speakers falling on someone during bingo night!

What is on the other side of the wall?

If you want to do it that way, do it that way, but I'll offer a few more suggestions:

1.Use "T nuts" on the back of the plywood board. Woodworking Assembly Hardware - T-Nut

2. I've seen speakers with steel cable tethers attached to them.

3. Make the plywood slightly thinner than the wall and use drywall compound. You might try glueing some tape to the wood before using the drywall stuff. My favorite drywall patching stuff is redi-patch.

-or-
Since your in the mood of patching drywall, there are plenty of different metal brackets to put framing lumber together. Why not use these and put two 2x4's between the metal studs.

Just cut out a large section of drywall with a utility knife. Do your cross braces and put it back.

hkstroud: Some of the walls are external walls, and I believe they are masonry of some kind (on the outside). The internal walls are hollow. Or at the very least might contain insulation. I think that the external walls are probably wood studs, but I know for sure the inside ones are metal.

Kiss: Those are great ideas, and actually I was thinking about putting a 2x4 between the studs. I might do that as well, I'm not sure yet. I want to get down there and have another look at it. And in regards to patching the plywood, that was exactly what I was planning on doing. I wanted to make the plywood and drywall match, and I would putty and paint, so it looks the same etc. Once I get in there, I'll know what thickness I'm dealing with.

EDIT: Oh, and in regards to suspending it with cable, there are a lot of options available for suspending with cable. In fact, I've done my fair share in halls etc. But the ceiling in this place is suspended ceiling, which wouldn't normally be an issue, but the metal roof and beam structure is a good 8 feet above the suspended ceiling. It used to be a roller rink. Anyway, it's a bit unruly. Plus, the owners wanted to be able to pivot the speaker in different directions, so we went with this idea.

I'm with you, this is a public place and you don't want to take any chance that something fall down on some little old bingo ladies head.

On the external walls , screwing into wood studs should be adequate. If you have metal studs cut out a 6" by however long vertical section of drywall and mount a 2x6 to the masonary with screws and lead anchors.
then screw some 1/2" plywood and then another 2x6. That should make you flush with a the metal studs for remounting your drywall.

On the interior walls I would cut out the 6" vertical opening over a stud. Put a 2x3 inside the stud and a 2x4 on the other side and screw together. This sandwiches the metal stud between the wood and does not depend on the screws holding in the thin metal studs. You will probably have to add a third 2x4 to one side or the other to make the span of the screw holes in the speaker bracket.

When I said "tether", I basically meant a safety line. In our church where there are hanging speakers pretty far up, the speakers are tied to mounts, but there is a safety 1/8" wire rope attached to the speakers as well.

Not sure how they attached it.

hkstroud: In the internal wall, I'm not sure if I follow you exactly. You say to put a 2x3 inside the stud. Do you mean, actually inside the stud itself? I think that's what you meant, but I want to make sure. Do you think toggle bolts into the metal studs won't be enough without wood re-enforcement?

Kiss: I see what your saying, and that's a fantastic idea. If we even had one single cable tether up to one of the metal beams, that, if ever the mount failed, the tether would support the speaker. I think I'd like to tether the speaker to the mount as well because the speaker just sits on that pole mount. If the mount fails, the speaker won't fall, but the mount will.

That is correct. I wouldn't trust a screw into the thin metal. A 2x3 because a 2x4 won't quite fit inside the metal stud. The wood would also distribute the stress along the stud and take advantage of the resistance to bending of the face of the metal stud.

But according to the link that kiss posted, a 1/8" toggle bolt in plain drywall can hold 50 lbs of weight. I would think that a metal stud and the drywall should be better? Plus, the metal is spread out over the entire size of the drywall if you catch my meaning. I would think the weight required to pull out a toggle bolt through the steel and the drywall would be huge?