DIY studio monitor stands

[photoresistor]

hey all,

recently ive taken on the project of building my own studio monitor stands because:

a) im a poor college student and dont want to spend the money for a couple of nice stands
b) i need to have something for my new monitors to sit on and i think that they deserve something nice
c) its a fun (and more importantly, easy) project


so a few days ago i picked up all the stuff ill need from home depot... i got the design idea from various threads on recording and acoustic forums (recording.org / homerecording.com/bbs).

so here are the materials i picked up ($~50):

sorry bout the lines... my camera is screwed up.



2x2' plywood 3/4" tall

x4 closet flanges

x4 pipe end caps

x1 3/4" cement drill bit

x8 5/8" bolts + washers + nuts + lock washers

10' long 4" diameter pvc pipe

pvc pipe cement glue stuff

x2 12x12" cement slab, 2" tall



blocks being spray painted....

and here is the basic design layout (from top to bottom):

the plywood will be cut into 4 12x12" squares and one will be on top, which is what the monitor will sit directly on.  this is bolted to a closet flange which holds the PVC pipe.  the pipe is cut to be 33.5" tall and then goes into another closet flange bolted into another plywood square piece which is also bolted and glued to the concrete slab.  the slab adds some weight (~25lbs) and adds weight at the base of the stands which should help lower the center of gravity so it has a little bit better stabillity.  on the four bottom corners of the slab will be some sort of rubber/elastomer pads attenuate vibrations from being passed to the floor.  when finished, the stand should be about 36-37" tall (i made them with my new monitors, dynaudio bm5a's, in mind). according to some information ive read, in the standard 8' tall room, this is an ideal height for the best and smoothest frequency response (read something from ethan winer).

the whole stand will be spray painted black to try and hide its ghetto-ness and DIY-nature and then the inside of the pipe will ideally be filled with lead shot (if i can get my hands on some for cheap).  this will enable the stand to be pretty heavy and so hopefully its natural resonant frequency will be low enough so all producable notes of the speakers will be attenuated (and not some very low notes actually boosted).  


now i posted this here so i could get some feedback/ideas/suggestions from you guys as to this project... if anyone has any ideas on how to make a better stand or to use different materials that would be great to hear.  or if i have a wrong understanding of some acoustical concept please correct me... and what i really need to figure out is what kind of rubber/elastomer i need to use on the bottom of the cement slab (i know this will depend on the final weight of the stand, etc) and a place that i can get some from...

so? any input?  ill update this thread with some more pictures once the stands are done.  oh yeah, and it probably wont happen, but one time i was considering turning the speaker stands into broadband absorbers by building a rectangle frame (from the plywood square down to the bottom) and filling it in with rigid fiberglass and then covering it with like a black acoustic cloth or something. but... i dont know, i think that might be too complicated for me (im no paul woodlock haha).

thanks guys

dan

[Suntower]

1. I think the monitors should be at the height of your head. Someone will correct me if I am wrong, I hope.

2. I too would like to get a source for some elastomer/rubber.

3. I was thinking of doing the same thing, but -I- was going to place the rubber absorber directly under the monitor, rather than at the base of the structure. It seems to me that the de-coupling should occur as close as possible to the monitor itself, right?

---JC

[Suntower]

Well lookee what I found when I googled on 'Sylomer'...

http://forum.studiotips.com/viewtopic.p ... =elastomer

Maybe it's less work than one thinks...

---JC

[johnz]

search neoprene on ebay,   there is a shipyard parts guy that is auctioning off lots

[Andrew Steel]

JC,

It's unlikely that the monitor alone wil be heavy enough to work with the isolation element properly. With the weight of satnd as well it will be closewr.

Andrew

[Paul Woodlock]

1. I think the monitors should be at the height of your head. Someone will correct me if I am wrong, I hope.

The tweeters should aim at your head or rather just behind your head. My monitors are a little higher but are tilted downwards to aim at my lugs.

3. I was thinking of doing the same thing, but -I- was going to place the rubber absorber directly under the monitor, rather than at the base of the structure. It seems to me that the de-coupling should occur as close as possible to the monitor itself, right?

---JC

No you want the decoupled weight to be as heavy as possible. A properly decoupled monitor will be very wobbly. I never got around to showing you this in my room, but you can easily rock the genelecs+stand ( here with only a slgiht finger press. You want the weight to avoid the reaction/reaction of the speaker coil vibrating the cabinet at audible freqeuncies Otherwise loud bass will cause HF distortion due to wobbling speaker.

I made the resonant freqeuncy of my speaker + stand system at around 10Hz. This means 10Hz and upto 14Hz will easily wobble the cabinet, higher freqeuncies won't becuase of inertia reasons

hth


Paul

[Suntower]

OK, what you're saying makes sense, -but- I -thought- what Eric was saying in the linked article was that, at least for relatively small monitors, the rubber decoupling wasn't really necessary.

For example: Putting my 8" woofer sized monitors on a simple concredte tower wouldn't be significantly -worse- sounding than a concrete tower resting on neoprene/sylomer underneath for decoupling.

Again, please correct me if that is wrong -before- I build these.

---JC

[interface]

There are basically two negative effects which can occur by placing a speaker on an elastic layer in a wrong way.

Sylomer for instance has many freedom degrees.
The primary goal is to achieve a low system frequency to get the best isolation effect.
But an elastomer especially Sylomer becomes about 4 times smoother in the horizontal direction than in the vertical direction.
The membrane of the speaker system can’t push the air to the front in an effective way.
An adequate restoring force is missing!!!
E. g.: imagine two boxers fighting on ice or hanging in the air and fighting….
Putting a higher mass (much higher than the speaker itself) on the elastic layer might help.

If a speaker is too close to a boundary which can be easily excited by air sound (e.g. thin wood layer like a table or a shelf) the effect of the isolation will be of no use. The effect will be a secondary sound source. You need a higher mass as well. The energy in the nearest near-field of a speaker system can be almost as high as a mechanical exciter. A high mass with less resonance can solve this problem as well.

Best wishes
Will

[Paul Woodlock]

OK, what you're saying makes sense, -but- I -thought- what Eric was saying in the linked article was that, at least for relatively small monitors, the rubber decoupling wasn't really necessary.

For example: Putting my 8" woofer sized monitors on a simple concredte tower wouldn't be significantly -worse- sounding than a concrete tower resting on neoprene/sylomer underneath for decoupling.

Again, please correct me if that is wrong -before- I build these.

---JC

What Will says

Another thing.... the mass of the floor also contributes to the resonant frequency calculations.  Correct me if I'm wrong, but your floor is wooden on joists over crawlspace?  This of course limits the weight you can put on it. On the other hand I would decouple in this case, to avoid the floor becoming the secondary sound source.

If I were you and if *I* were doing this properly, I would highly consider removing some floorboards and building concrete foundations right into the earth underneath the speaker stands. As long as making good with the floor boards didnt' touch the concrete, this woudl perhaps avoid the need to decouple the speakers or stands.

Just a thought

[Suntower]

You're correct about my floor's construction.

It's all a 'bang for the buck' thing for me. Creating 100kg concrete stands is easy--the floor will easily support double that weight.

Building piers as you suggest ain't.

My question is, 'is it worth it?' IOW: Would I notice a -big- difference?

So: I guess my question remains: Is it worth it to make concrete stands on a rubber layer, or simply concrete stands?

I understand I will -ultimately- simply be transferring the vibrations to the floor, but wouldn't I have to be mixing fairly -loudly- in order to transfer significant energy down through 100kg of concrete? It just -seems- overkill at first glance.

I think getting the monitors off the desk will make more of a significant difference than the difference between 'rubberized' and non-rubberized stands. (I am not convinced that these Mo-Pads really help all that much.)

Again, I am open to all education and am not trying to sound combative.

THANKS!

---JC

OK, what you're saying makes sense, -but- I -thought- what Eric was saying in the linked article was that, at least for relatively small monitors, the rubber decoupling wasn't really necessary.

For example: Putting my 8" woofer sized monitors on a simple concredte tower wouldn't be significantly -worse- sounding than a concrete tower resting on neoprene/sylomer underneath for decoupling.

Again, please correct me if that is wrong -before- I build these.

---JC

What Will says

Another thing.... the mass of the floor also contributes to the resonant frequency calculations.  Correct me if I'm wrong, but your floor is wooden on joists over crawlspace?  This of course limits the weight you can put on it. On the other hand I would decouple in this case, to avoid the floor becoming the secondary sound source.

If I were you and if *I* were doing this properly, I would highly consider removing some floorboards and building concrete foundations right into the earth underneath the speaker stands. As long as making good with the floor boards didnt' touch the concrete, this woudl perhaps avoid the need to decouple the speakers or stands.

Just a thought

[Paul Woodlock]

You're correct about my floor's construction.

It's all a 'bang for the buck' thing for me. Creating 100kg concrete stands is easy--the floor will easily support double that weight.

Building piers as you suggest ain't.

My question is, 'is it worth it?' IOW: Would I notice a -big- difference?

So: I guess my question remains: Is it worth it to make concrete stands on a rubber layer, or simply concrete stands?

I understand I will -ultimately- simply be transferring the vibrations to the floor, but wouldn't I have to be mixing fairly -loudly- in order to transfer significant energy down through 100kg of concrete? It just -seems- overkill at first glance.

the 100Kg of concrete will certainly stop a fair amount of vibration. Although IIRC Brian R said recently that the midrange is more likely to be transmitted through the concrete than the bass. In which case it would be easier to decouple ( not so lower resonant freqeuncy required, although lower is always better ). You'd have to check that witrh Brian though,

I think getting the monitors off the desk will make more of a significant difference than the difference between 'rubberized' and non-rubberized stands. (I am not convinced that these Mo-Pads really help all that much.)

most definitely.

[photoresistor]

hey guys,

i just "finished" putting together the stands today.  i say "finished" because i have not yet been able to find a source of cheap lead shot to fill the 4" diamter PVC pipe with.  also i havent figured out anything for the rubber/elastomer... as a temporary solution, i cut a white eraser into four squares to set the concrete on (it has bolt heads sticking out of the bottom so it needs something to sit on to be stable).   so yeah, i still need to fill in the pipe, get the right stuff on the bottom to act as the spring, and someday ill probably add another coat of spray paint too.

but anyways, here are the pics (also showcasing my new dynaudio bm5a monitors wee!):  





sorry bout the lines... my digital camera is retarded.

let me know what ya think... overall, im pretty happy with them.  they might not look totally professional or something youd buy in a store, but i dont think they look bad either.

-dan[/img]

[MarkEdmonds]

Fill that pipe! Well, having said that, I don't know the exact consequences of not filling it but my instinct says without any filling, it will be acting like a resonant chamber. How does it sound if you tap it hard?

Lead shot for that volume will probably be quite expensive so consider sand. If you don't want to buy sand, just go a to a beach and grab some but give it plenty of time to dry. Spread it out really thinly on a plastic sheet in the sun and leave it for two weeks.

Hope that advice is valid!

Mark

[David French]

Yes, fill them.  I have almost identical stands, mine are filled with lead shot, and they sound quite snappy.

[Suntower]

'Fill that pipe!'

Maybe my three favourite words in the English language. (Followed by 'I love you', of course. ;) )

I suggest -sterile- play sand from the home centre. I'm no biologist, but I do have a boat, and anything you get from the beach will have various flora and fauna that can't be gotten rid of by sun drying. If they get wet again, you'd have an instant science project inside a nice, dark, warm tube. Yeuch.

----JC

Fill that pipe! Well, having said that, I don't know the exact consequences of not filling it but my instinct says without any filling, it will be acting like a resonant chamber. How does it sound if you tap it hard?

Lead shot for that volume will probably be quite expensive so consider sand. If you don't want to buy sand, just go a to a beach and grab some but give it plenty of time to dry. Spread it out really thinly on a plastic sheet in the sun and leave it for two weeks.

Hope that advice is valid!

Mark

[J.F.Oros]

I suggest -sterile- play sand from the home centre. I'm no biologist, but I do have a boat, and anything you get from the beach will have various flora and fauna that can't be gotten rid of by sun drying.

Or maybe you can "cook" it in the even, to sterilize it. I used to do that sometimes with the sand for my cats  :)

[photoresistor]

thanks for the input and ideas guys...

i may have to go the sand route because im having a real hard time finding a good supply of lead shot that wont cost me an arm and a leg.

-dan

[Suntower]

I just wanted to add the following:

Just for grins, I went and took my monitors off of the desk where they've been since I moved here and put my monitors on 2 cinder blocks + mo-pads (so prox. 33" high and 20kg) ea.

WOWOWOWOWOWOWOWOWOW

What an immediate and huge improvement in imaging. Brilliant. Can't believe the difference in quality.

How stupid do I feel now at not having done this 2 years ago?

---JC

[David French]

JC, that is exactly how it went for me, too.

[johnz]

well i think they look nice