Re: Amp Riser Effectiveness
Posted: Fri, 2019-Oct-25, 13:30
Taking this a little bit further now...
The 1800x1200mm riser above will be sufficient most of the time, but sometimes a bigger one would be useful for drum kits. Some drummers I've recorded here would require 2100x1800mm to be safe, and a bit larger could be useful. But a riser this size in the studio all the time would get in the way, especially when it comes to do some studio upgrades.
Also, sometimes it would be great to have several smaller risers for multiple musicians, amps and percussion. So I wondered if a modular riser approach would be possible? Here's what I have in mind using risers of a variety of dimensions based on the above design. 1 1800x1200mm, 2 1200x600mm and 2 600x600mm.
Imagine they are arranged into a base. The largest 1800x1200mm riser is in the centre to get it under the most loaded part - kick drum, snare drum and drummer. Intuitively I'd space the risers a little bit apart so the edges don't touch and buzz / rattle. The risers have T-nuts placed in them at appropriate positions;
And two 1800x1200 plywood boards placed on top, again a little apart to stop rattles. These are securely attached to the risers with flush fitting furniture bolts going into the T-nuts in the risers below. The seam is down the centre of the 1800x1200mm riser, so they are all held together giving a 2400x1800mm riser. That's 8x6', a good sized riser for sure;
When the drum riser is not required the 1800x1200mm top panels can be moved to another room, or stored on top of the 1800x1200mm riser. It would be interesting to measure the effect of the extra mass.
Another option is to use one of the 1800x1200 top panels to make a second 1800x1200 riser from the small ones;
The trouble is, I'm not even sure it it is valid to combine these risers in this way. Will they be less effective than a proper 2400x1800 riser? Or even worse than nothing at all? I honestly have no idea, so any comments would be most welcome.
Edited to add some more thoughts on this;
Assuming the top bolted on layers (combined 2400x1800mm) is also 18mm plywood, the bolts will make a proper join and the top layer of the riser sandwich becomes a single 2400x1800x36mm mass. If slides 9 and 10 on this Green Glue slide show are an accurate depiction of how the CLD sandwich works, this will be fine, the bolted layers will act as one thicker layer.
However the the link Adhoc posted states that for optimum damping the "wood" layers should be the same thickness, but up to 1:3 difference will still be good. It occurs to me that this might only apply in the case when the total mass is kept constant, i.e. one layer becomes thicker as the other becomes thinner. It might not apply if the proportions change due to mass being added. But it it does, there could be an argument there for making the top bolt on layer a bit thinner than 18mm. On the other hand, doing this will lose some structural strength.
The layers below in separate risers will not be joined directly to each other, but intuition suggests they will bend and flex in a similar way as if they were. The gaps between risers might allow greater overall movement relative to the top layer than a single 2400x1800mm sheet would though. So maybe the damping layer is less constrained, and therefore not quite as effective as a another sandwich of 2400x1800mm sheets? But I can't see it being any worse than having the same mass perched on top of the single 1800x1200mm riser.
On the other hand, green glue still works when applied to multiple overlapping sheets of drywall, so that is encouraging.
Cheers!
Jennifer
The 1800x1200mm riser above will be sufficient most of the time, but sometimes a bigger one would be useful for drum kits. Some drummers I've recorded here would require 2100x1800mm to be safe, and a bit larger could be useful. But a riser this size in the studio all the time would get in the way, especially when it comes to do some studio upgrades.
Also, sometimes it would be great to have several smaller risers for multiple musicians, amps and percussion. So I wondered if a modular riser approach would be possible? Here's what I have in mind using risers of a variety of dimensions based on the above design. 1 1800x1200mm, 2 1200x600mm and 2 600x600mm.
Imagine they are arranged into a base. The largest 1800x1200mm riser is in the centre to get it under the most loaded part - kick drum, snare drum and drummer. Intuitively I'd space the risers a little bit apart so the edges don't touch and buzz / rattle. The risers have T-nuts placed in them at appropriate positions;
And two 1800x1200 plywood boards placed on top, again a little apart to stop rattles. These are securely attached to the risers with flush fitting furniture bolts going into the T-nuts in the risers below. The seam is down the centre of the 1800x1200mm riser, so they are all held together giving a 2400x1800mm riser. That's 8x6', a good sized riser for sure;
When the drum riser is not required the 1800x1200mm top panels can be moved to another room, or stored on top of the 1800x1200mm riser. It would be interesting to measure the effect of the extra mass.
Another option is to use one of the 1800x1200 top panels to make a second 1800x1200 riser from the small ones;
The trouble is, I'm not even sure it it is valid to combine these risers in this way. Will they be less effective than a proper 2400x1800 riser? Or even worse than nothing at all? I honestly have no idea, so any comments would be most welcome.
Edited to add some more thoughts on this;
Assuming the top bolted on layers (combined 2400x1800mm) is also 18mm plywood, the bolts will make a proper join and the top layer of the riser sandwich becomes a single 2400x1800x36mm mass. If slides 9 and 10 on this Green Glue slide show are an accurate depiction of how the CLD sandwich works, this will be fine, the bolted layers will act as one thicker layer.
However the the link Adhoc posted states that for optimum damping the "wood" layers should be the same thickness, but up to 1:3 difference will still be good. It occurs to me that this might only apply in the case when the total mass is kept constant, i.e. one layer becomes thicker as the other becomes thinner. It might not apply if the proportions change due to mass being added. But it it does, there could be an argument there for making the top bolt on layer a bit thinner than 18mm. On the other hand, doing this will lose some structural strength.
The layers below in separate risers will not be joined directly to each other, but intuition suggests they will bend and flex in a similar way as if they were. The gaps between risers might allow greater overall movement relative to the top layer than a single 2400x1800mm sheet would though. So maybe the damping layer is less constrained, and therefore not quite as effective as a another sandwich of 2400x1800mm sheets? But I can't see it being any worse than having the same mass perched on top of the single 1800x1200mm riser.
On the other hand, green glue still works when applied to multiple overlapping sheets of drywall, so that is encouraging.
Cheers!
Jennifer