Optimizing Desk Design for Reflections

[Dave_D]

Hi all,

I'm designing a new production desk around my trusty (albeit behemoth) Kurzweil MIDIBoard and am wondering how to best address the reflection points. In the attached drawings, you can see that the high-frequency drivers (crossover = 2.8 kHz) of my flush-mounted Genelec 1238CF monitors are reflecting off the rear of the desk while the mid and low-frequency drivers pass the mirror test. So, I'm wondering if it's sufficient to block those reflections with strategically-placed video monitors, as shown?

Otherwise, I can angle the desktop just 5 degrees and pass the mirror test with room to spare. However, this raises my video monitors 4" and partially obstructs my view of the low-frequency drivers. [The attached POV image reveals my view of the LF drivers before raising the desk angle.] I can't hear any difference when the monitors obstruct the LF drivers (crossover frequency = 420 Hz) but am uncomfortable making a decision without expert advice. Is it safe to obstruct 420 Hz as with my subwoofer?

In case it is relevant to the conversation, the speakers are flush-mounted in a 5.1 surround configuration per Hidley/Newell non-environment strategy, with a front wall of ledgestone - needless to say, highly reflective and somewhat diffusive, especially at higher frequencies. For more room detail, my studio construction log post is here.

Any advice is greatly appreciated.

[Soundman2020]

Blocking with your video monitors should be OK, but angling the desk top a bit wouldn't hurt!
Basically, the issue is this: Sound waves are not affected by objects that are smaller than their own wavelength: they pretty much wrap around them, and seem to "go through" them. They ARE affected by objects that are significantly larger then their wavelength. so if you measure the dimensions of your monitors, you can figure out the frequency where they start having an effect, and compare that to the dispersion angles, frequencies, and levels of your monitors. That will give you a good starting point for determining if the monitors are big enough to deal with the frequencies you are worried about.
One other option might be to mount the speakers higher up in the soffit, to improve the angles, but to be careful that you don't move them so high that you are too much off axis at the mix position.
Yet another option is to lower the desk surface a bit (chop a cm or two off the legs), but there you need to be careful that you don't put the desk so low it is uncomfortable for your knees, or as a working surface height.

- Stuart -

[Dave_D]

This sounds promising. The sheer size of the MIDIBoard prevents me from lowering the desktop any further, but the math suggests that frequencies coming from the drivers that fail the mirror test will be no larger than 4.8 inches - well within the vertical and horizontal measurements of my computer monitors and, presumably, with ample margin for error.

And should I choose to angle the desktop (or a portion of it), the math is equally encouraging: Even if the computer monitors are consequently raised by the desktop to obstruct the low-frequency drivers, at 420 Hz, their wavelengths are no less than 32 inches. So, as long as I keep the mid-frequency drivers clear, this gives me some options to work with.

Thank you, Stuart!

[Soundman2020]