John Sayers' Recording Studio Design Forum Archive

Hello.

This is a project I have to do to try to control the drum loudness until I build a floating floor.

I have two designs:

1. Drum riser with open bottom
2. Airtight drum riser

The graphics below explain better. Wich one do you think is best or will retain more sound?

Thanks.
Ed.

I would say the first one. The second one had a 3 leaf system design.

I would use a rockwool/mineralwool or semi-rigid fiberglass in the cavities. Also make it 2 layers on top, instead of one.

Do a search for drum risers. There's some good info and designs already posted somewhere here on the site.



Aaron

Hate to ask a dumb Question. this is a drum riser correct?? Where is the 3rd leaf in the second design.

far as I can tell he is building a DEAD SOLID platform sorta like what i request when I am on the road. a Solid platform (even though what I ask for is thinner, they have a foam core.)

Ok now to Ed, control loudness, elaborate. What you have designed will give your kick WAY more difinition. Ever performed on an enclosed HOLLOW Plywood stage??? They are the worse, but if you use the Carpeted risers with metal sides, miuch tighter sound.

Is the attempt to prevent sound from traveling downstairs?? If so, either design will help as you are isolated the platform from the floor via the Neoprene pads.

Finally I do agree with 2 layers of wood on the top for stifness.

Bryan Giles

Ok.

The layer is 15mm thick not 10 so I think it is stiff enough.

I see you prefer the second design. Do you think that because it is airtight is better than open in keeping the kick solid?

I want to eliminate the resonance the kick drum makes and get a more defined kick sound not boomy.

I'm not a drummer that's why I ask.
Thanks

In My experience, I have found a dead closed riser sounds better than open riser when recording Drums.

Of course that is all based on many variable and my personal taste.

I use Beta 52, D112, M88 and RE-27N/D Mikes (interchangebly) when recording Kick.

In the various situations I am in (Remote and Studio) I have found That I prefer a closed internally dead riser for the drum sound I chase.

Drums will resonate, but the extrnal ocillations caused by a hollow platform will get squashed with your design.

Finaly 15mm should be cool that is like 2-3/4 sheets of plywood.

Again this is my prefernece based on my 14 years of recording drums.

the third leaf is the floor...........btw

My reason for the rant is a leaf by design is a sealed system, the floor does not qualify as a leaf as the riser is not "sealed to the floor so there is no additional airspace."

That is a crude way of describing it.

Bryan Giles

If I am wrong I am sure someone will correct me, but the physics I see dictate I am right.

Thank you notbradsohner. Just getting back to the thread here.

Yes, the floor is the 3rd leaf, since he has another room below. The rubber in the middle creates the "air gap" between the 2 layers of mass.

So you'd have top of riser...leaf one.
Framing w/ insulation is...air space.
Bottom layer of mass...leaf 2
Between bottom layer and floor...air
Floor...leaf 3



Aaron

The problem I have with that Aaron is the it is not an ENCLOSED Air Space.

Look at his Riser design and you will see the "air space" you indicate below the riser is not closed which disqualifies it as an air space. The riser is located in the room air space....

Bryan Giles

Hello Brian,

I'm really sorry to jump in here, but Aaron is right.

Maybe you like the sound of the closed design, since it will cause additional resonances.
But technically if decoupling is the idea the open design is right.

Warm regards
Eric

Now I'm confused!!!!

I was thinking that what Brian said makes sense with the drum riser dead closed. Perhaps every design has his advantages depending on what I want the drum set to sound to.

What I want is a way to eliminate the resonance of the drum kit, specially the Kick or bass drum. I want the riser to act like a "mattress" and muffle the sound making it less loud.

So, having clear what I want, wich way should I go?

Thanks a lot guys for taking part of your time to help me.
Ed.

That's indeed confusing isn't it? ........
Different visions on the net: which one to believe??

You can see it as a vote:
It's 2 to 1 (at least until now, don't know when it closes) .......

Now serious:
In fact such a riser knows several springs which interact with one another:

1) the neoprene.
2) In your option 1 the air layer between the new floor and the existing floor.
3) In option 2 (the closed floor) the additional panel versus the floor but also versus the new upper floor.

If designed well (deflection neoprene large enough) this neoprene resonance will most likely become the lowest resonance (best).

The upper floor is rather lightweight versus the cavity, and will be the weaker point of the 2 (neoprene = spring resonance, new floor existing floor).
By adding this additional panel (without damping) you create additional resonances, which will diminish the overall performance of this riser in function of decoupling (increases the highest resonance, which is bad since it lowers decoupling in the lower frequencies, which are mainly defining).

The vote thing is just a poor joke .
Bryan gives always good advice. Just overlooked something here.

Bryan wrote:Look at his Riser design and you will see the "air space" you indicate below the riser is not closed which disqualifies it as an air space. The riser is located in the room air space....

Bryan, this shortcut to the surrounding space will lower a bit the dynamic stiffness of this in-between air layer, but those frequencies are too fast (law of inertia). It really will continue acting as a spring (only with a bit shifted frequency).

A panel in front of a wall, will still act as a membrane damper/resonator, even when the edges aren't closed.
And just for the sake of argument:
Suppose (which isn't correct) that one could indeed ignore this small cavity, assuming the dynamic stiffness of this small air layer to equal the room volume, still then it should be bad, since it should mean that one must calculate the mass-spring resonance of this riser versus the much lighter bottom panel which also should cause a significant increase in resonance frequency.

I hope I explained this understandably (otherwise sorry).

Kind regards
Eric

Edited

Eric - how do you think these designs compare to 4" slab of concrete floating on 703 ?

Hello Andrew,

I don't know about the 703 (I mean dynamic stiffness).
It's a matter how much it deflect (the more the better)

So while you can get the wood floor solution vibration technical at the same resonance frequency, The mass-spring of the concrete slab in function of the aircavity is certainly better.

So if movability or weight load is not an issue then you can be sure that the concrete slab solution is the clear winner in function of decoupling and will give a more stable solution, without an own sound (neutral).

It's a matter of calculating mass-spring.

Normally any glassfiber or rockwool producer has specific boards for such purpose, for which the dynamic stifness is published allowing to calculate this stuff. This does not mean that other boards as 703 or 705 shouldn't work, but if no data is published then it becomes try and error.

Simple if the wool compresses with 10 to 15 % under load it's OK, and the thicker the wool the better.
Summary: the higher the total deflection under static load the better it will be.

Best regards
Eric Desart