I also experience the noise - so much so that I've stopped using the rig altogether, it's simply too painful.
This is a good news story by the way - keep reading.
Based on my reading of various articles about absorbing / blocking sound I have built heavy wooden boxes using 18mm thick beech, lined with a Basotect foam material. These wrap both the motor and the driver units. The basic principle appears to be to provide a way for the sound wave energy to be absorbed (open pore foam) in combination with a high density (reflective?) exterior shell. The idea isn't mine, I borrowed it from ideas I've seen in articles that describe how to wrap heavy machinery and heat pumps - the latter often uses a multiple shell technique with baffles.
I will be the first to admit that I am not following a strictly scientific approach here. I am not taking each material or combination in isolation; nor do I have a "clean room" (anechoic chamber) within which to measure the differences in sound absorption / reflection - heck; the only tools I've got to measure the sound are my ears and the Spectroid app on my Android phone.
The latest version of the driver unit box is a double shell design that uses 70mm thick Basotect acoustic panels along with the 18mm beech panels. Air flow is achieved by a large CPU fan pulling air through the entire unit via a series of 3 baffles (also padded with Basotect) at each end. The box isn't yet finished; I'll report more in the coming days on it's effectiveness.
Scornflake's recent discovery that Polyester fibre dampens the noise was a motivator.
Yesterday I decided to try the fibre idea. I took each of the wooden boxes I had made for the motors and ripped out the Basotect material, doubled up the cheap polyester blankets I'd purchased earlier that day and jammed them into the enclosure.
Each time I dropped one of the enclosures onto the motor while the rig was running (but stationary); there was an audible drop in the piercing level of sound within the room.
It's AINT pretty, in fact it's downright ghetto at this stage.
But guess what: I almost have silence. Almost - the piercing sound is still there and of course I'm listening out for it, but the difference is no less than
stunning.
The noise is without a doubt coming from both the motors AND the drivers in my case.
You will see in my pictures that the double walled box isn't yet finished; in fact right now the upper cover is just placed on there by hand and there isn't a front cover at all.
Power to my sim, CPU, drivers, the whole lot - is driven from a single wall socket. An electrician may well use a palm-to-forehead movement to properly express their dismay at the number of extension leads I'm using.
I'll attach some photos of the boxes in the spirit of sharing, I'm more than happy to receive any suggestions for improvements.
My current goal:
- from a whine/noise perspective - to go from "some" to "none" using absorption/blocking techniques
My next questions / steps (none of these have a basis in measured facts, e.g. it's more things to try):
Q: how can I quantify the improvements properly from this point forward? (aside from the obvious, stop being lazy and start measuring this you fool!)
A: try to roughly gauge how much noise is coming from the drivers vs motors (it's definately from both)
A: try using the Spectroid app at a constant distance from the source being measured and start writing some of this down properly to document the effect of each stage.
Q: does having more fibre layers increase the dampening effect?
A: increase the number of polyester fibre layers on each of the motors.
Q: what role does wood thickness / density play here?
A: increase/decrease the thickness of the wooden boxes and/or try the same number of layers with either a PLA wrap or different types of wood.
Q: is any noise leaking out the bottom of the motor mounts?
A: fully encapsulate the motors using wooden caps (try to reduce noise gaps at the base of the motor)
--
John C
PS: I'm Scornflakes brother, living in Switzerland.
