GLM and front wall speaker boundary interference

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scoox, modified 1 Year ago.

GLM and front wall speaker boundary interference

Youngling Posts: 8 Join Date: 1/17/21 Recent Posts

Hi everyone, I'd like to know to what extent GLM can help with speaker boundary interference nulls. I've just finished reading through Genelec's monitor placement guide. My room ratios are decent but the room itself isn't very big so I'll be placing my monitors close to the front wall. The monitor placement guide says:

Another possibility is to place the monitor very close to the wall minimising the gap. This raises the lowest cancellation frequency so high that the monitor has become forward-directing, and the cancellation no longer occurs. Remember that the low frequency boost should be compensated for when the monitor is mounted close to the wall (up to +6 dB gain).

Acoustical treatment of the walls is another solution. It could mean modifying the wall and making it very absorptive so that the amplitude of the reflected energy is small and does not cancel the direct sound.

From this I gather that I need to put as much absorptive material as possible on my front wall so that the reflected wave is an attenuated version of the direct wave, and therefore they won't completely cancel out to a null. However, some amount of cancellation is unavoidable because the wall won't be infinitely absorptive, so the question is, as long as the reflected wave is less than the direct wave, to what extent will GLM be able to compensate for this? (it would help if we can put a value to this)

One more question, is bass roll-off taken care of by GLM or do I still need to fiddle with the switches on the back of the monitor?

Thanks

mans, modified 1 Year ago.

RE: GLM and front wall speaker boundary interference

Youngling Posts: 15 Join Date: 6/26/20 Recent Posts

Hi Scoox, when using GLM you'll never need to adjust any of the dipswitches as GLM will handle every monitor setting for you incl (custom) roll-offs, sensivity, DSP, Auto-power, delay, default input, leds, etc...

Once you've activated the 'store' dipswitch, the monitor will keep the 'pushed' GLM setting till you overwrite it again by GLM.

So you can but don't need to keep the GLM soft alive.

Fyi GLM 4.1 is extremely clever and a must have when using any kind of SAM product.

Btw since sw 4.1 we're also able to boost some of the actual FR, but wisely as the postive gain is limited till 3-6db depending the power of the monitor,

Enjoy man !

scoox, modified 1 Year ago.

RE: GLM and front wall speaker boundary interference

Youngling Posts: 8 Join Date: 1/17/21 Recent Posts

mans:

Hi Scoox, when using GLM you'll never need to adjust any of the dipswitches as GLM will handle every monitor setting for you incl (custom) roll-offs, sensivity, DSP, Auto-power, delay, default input, leds, etc...

Once you've activated the 'store' dipswitch, the monitor will keep the 'pushed' GLM setting till you overwrite it again by GLM.

So you can but don't need to keep the GLM soft alive.

Fyi GLM 4.1 is extremely clever and a must have when using any kind of SAM product.

Btw since sw 4.1 we're also able to boost some of the actual FR, but wisely as the postive gain is limited till 3-6db depending the power of the monitor,

Enjoy man !

3-6 dB is a conservative boost and I wasn't expecting miracles there, so basically room treatment is always a must. I expect GLM does a very decent job at dealing with peaks.

mans, modified 1 Year ago.

RE: GLM and front wall speaker boundary interference

Youngling Posts: 15 Join Date: 6/26/20 Recent Posts

Exactly, finding the most 'ideal' positioning and room treatment are fundamental, then use GLM to tame the peaks and adding some personal contour in case wanted :-)

Enjoy !