Physics majors - What base is more stable: pedestal or tripod/quadpod? (speaker stands)

[MichaelD]

Originally posted by: EvilYoda
heh...lots of practice. I made sure that my earliest attempts were on corners that would end up on the back, facing the wall. It's not that hard, really, you just have to figure out a good method and take your time. Luckily, I have good hands, and I'm a perfectionist, so it came out well. There are still a few things I'd change, but oh well, I'm happy with how things turned out.

BTW, reading what you said earlier...it's much easier if you just drill all the way through one layer of wood and then glue that to the other piece (this is why most DIY stands have two layers), thus giving you the same final product w/o having to worry about drilling perfectly x" into a piece of wood. It's a good thing I went with 3 tubes too, since my friend didn't have a 4" hole saw.

finally going to sleep...I'll see how the thread's doing in the morning.

Thanks for the "drilling all the way through" tip. I appreciate that. Will do. I plan on gluing/screwing the two pieces together. I want the stands to be as acoustically dead as possible. Ergo, filling them w/sand. Are your PVC tubes filled?

 

[sxr7171]

Personally, I would go for the SS16 stand. I'd find out if they have spikes and if they can be filled with sand. But that's just me.

But if you've spent the money on materials for the stand already, the only thing I can add is that you can try using small spikes to couple the speaker with the top of the stand.

 

[MichaelD]

Originally posted by: sxr7171
Personally, I would go for the SS16 stand. I'd find out if they have spikes and if they can be filled with sand. But that's just me.

But if you've spent the money on materials for the stand already, the only thing I can add is that you can try using small spikes to couple the speaker with the top of the stand.

I've seen this done on higher-end stands. Why? As long as the speaker doesn't vibrate on the stand, why should it matter?

 

[Ornery]

Ever consider something like this? Use a 1/4" - 20 insert in the bottom of each speaker to attach it. Cheap, easily adjustable & positionable with lots of stabilty. Easy to return to Walmart if they don't work out.

 

[MichaelD]

:Q Ornery, that's one helluva novel idea!! Would definitely get me "style and creativity points."

For what I'm paying for these speakers, I don't think I'll be screwing anything into them for a long time!

Hmm. Lots of money (for me)...screwing...hell, for what I'm paying, they should PUT OUT for me, dammit!!!

 

[Ornery]

Hmmm, I didn't see link at first, showing them to be 20" tall. 20" tall speakers for a bookshelf?

If you can possibly set them on a shelf mounted to the wall, that would be most stable. Not sure how bad that would screw up their sound though.

If they have to be sitting in the middle of the room, you could still use the tripod. Just mount a base on top of the tripod, then set the speaker on that.

 

[MichaelD]

Originally posted by: Ornery
Hmmm, I didn't see link at first, showing them to be 20" tall. 20" tall speakers for a bookshelf?

If you can possibly set them on a shelf mounted to the wall, that would be most stable. Not sure how bad that would screw up their sound though.

If they have to be sitting in the middle of the room, you could still use the tripod. Just mount a base on top of the tripod, then set the speaker on that.

"Bookshelf speakers" is kind of a catch-all phrase these days. Basically it denotes any speaker that doesn't specifically sit on the floor by itself. I.E. "tower" speakers.

The M22s (what I'm getting) image and soundstage best when placed on stands. The idea is to have the tweeters at approximately ear level relative to your seating position. 20-24" high stands would do that for me.

Also, for proper 5.1/7.1 sound placement, the front three (L/C/R) speakers have to be arrayed in kind of an "arc". Putting them up on shelves would ruin that.

 

[Ornery]

I know about the ear level part. I was more concerned about harmonics from the wall being immediately behind them. It does effect the bass resonance. The main point I should have brought up, was about the stability of those PVC column homemade units. Whether it's square, triangular or round, the broader the base on the bottom, the better. Filled with sand? Getting pretty fussy there. A concrete block would be 16" high. That would put the tweeters at ear level when seated. Find a suitable cover and you'd have a dirt cheap, stable stand. I'm always looking out for budget solutions, if you haven't already guessed!

 

[MichaelD]

Concrete block? *rubs chin* Wow...I hadn't thought of that. Nothing is acoustically deader than concrete. It would make a MOST sonically excellent stand.

But the style points would be 0<

You get a "10" for creativity. I agree that filling the pipes w/sand is a bit fussy, but it serves two purposes:

1. Fills the pipe, killing any chance (big, if empty) of resonance inside the hollow pipe.
2. Weights the stand down, reducing "tippiness"

 

[Ornery]

If the pipe were cone shaped, it would reduced 'tippyness', but since it's a column, the weight at the top would add to instability. You can cover a block with anything from hardwood to cardboard, or even just drape fabric, like black velvet, over it.

 

[EvilYoda]

Having fun yet, MichaelD? As for my stands, yeah, they're filled with sand. And concerning the speakers falling off...unless you're really that big of a klutz (which is possible ), You won't really need it, as the speakers are pretty heavy, and will take a good hit to come off the stand. velco would work, but some people have used some form of that sticky-tac stuff that won't leave a mark on the speaker...I had an idea for my surround stands too, in the future, so if you want a quick MSPaint sketch, I can probably rig one up later today.

 

[Howard]

I would drape the stands, if I were you. Sound will diffract from the edge of the top of the stand (where the platform suddenly falls into the pipe, from the waves' point of view).

 

[silverpig]

Sorry guys, but most of the answers in this thread are wrong/incomplete. It's not so much weight, but more where you put it. A 6 lb stand could be much more stable than a 30 lb stand if you put the weight in the right spots.

For example, imagine 2 situations:

1. Have a 6 lb stand where you have 3 legs of negligible weight and a top of negligible weight, where the legs have a base of length l. Now you put 6 lbs of sand into the legs at the very bottom of each leg, causing all of the mass to be at the bottom of the stand.

2. Have a 30 lb stand where you have a single column of negligible weight and base width l with a top weighing 30 lbs.

Obviously the first configuration is much more stable, despite having less mass. The idea behind stability is to have the stand be able to return to it's proper position after being deflected through a large enough angle. If you put the mass in the right spots, a stable stand will return to it's upright position after being knocked over, where as an unstable one will continue falling.

It's called stable static equilibrium

eg: imagine a small steel ball on a stick. You can balance the stick up on your finger with the ball directly above. It will be in equilibrium, but a small deflection will cause the system to continue away from it's original state. This is unstable static equilibrium. Now imagine the same setup, but you hold it upside down, like a pendulum. Now if you move the ball it will return to it's original position. This is stable static equilibrium.

The idea is to build a stand with the lowest centre of mass possible. If your stand has minimum base radius r (from centre of object to closest edge... sort of), and the centre of mass is situated at a height h above the ground directly above the centroid of your base, then the maximum tipping angle a is equal to the arctan of (r/h).

(I really hope I did all that geometry right in my head. If not, someone fix it please )