The release of the DMAS is what prompted me to buy a Pimax 8KX, and I was initially very disappointed. I’ve been using a Valve Index, and this was my first foray into Pimax.
Out of the box, the DMAS is tinny sounding. Virtually zero bass response. It looks like the Index off ear speakers, but its sound is worse than Quest 2 built in audio.
The DMAS seems to have high quality drivers similar to those in the Index, but unlike the Index, the 8KX’s amp doesn’t have enough power to drive them properly. Simply increasing the bass in software quickly causes the overall volume to become too low.
I’ve seen the suggestion of using software like Letasoft Sound Booster to deal with that, but I think these apps are kind of snake oil. I did do testing with Sound Booster, and while it worked fairly well in some scenarios, in others it produced terrible results. The software creates the impression of greater volume by making quiet parts louder, but it can’t actually increase the volume of loud parts, and it adds a great deal of artifacting. You can’t actually magically go past 100% in a digital signal. I don’t recommend the use of this software.
However, clever EQ can compensate for the limited amplifier power and actually get decent sound and volume out of the DMAS with a reasonable level of bass response. The key is eliminating frequencies below what the drivers can reproduce anyway. These low frequencies eat heavily from the limited power budget while producing literally no sound. When you cut them out, it frees power for those bass frequencies that are within the ability of the drivers to reproduce. This is a means of using the limited power budget more efficiently.
Using this approach, I was able to improve the DMAS sound quality and volume level considerably. Still not as good as the Index in my A-B testing between them, but closer to Index sound than I initially thought possible. I’d be using it except that the KDMAS is substantially better.
By my ear, the DMAS drivers themselves are better than the ones in the KDMAS. If the 8KX was able to use them to their potential, the DMAS would be the better option. The DMAS drivers need to be a little closer to your ears and be driven with more power. But since they’re not, the DMAS falls short.
There’s also another issue. The off ear DMAS suffers from microphone bleed. That is, when the DMAS is playing loud sounds, the 8KX’s own microphone will pick it up. Other people you’re talking to in VR may hear echoes coming through your mic. The Index, which is also off ear, doesn’t suffer from this. Neither does the KDMAS.
I did ultimately switch from the Index to the 8KX, but it ended up being the KDMAS, not the DMAS, which is mounted on it.
I used the free open source Equalizer APO to perform EQ. Peace is the open source GUI front end interface for Equalizer APO. Here are my exact settings for the DMAS:
DMAS EQ (no splitter)
Pre Amplifying=0
1 High pass filter Freq=80 Q=2
2 Peakfilter Freq=21 Gain=0 Q=1.41
3 Peakfilter Freq=42 Gain=5.5 Q=1.41
4 Peakfilter Freq=83 Gain=7.5 Q=1.41
5 Peakfilter Freq=166 Gain=2.5 Q=1.41
6 Peakfilter Freq=333 Gain=2.5 Q=1.41
7 Peakfilter Freq=577 Gain=-5.5 Q=1.64
8 Peakfilter Freq=1000 Gain=1.5 Q=1.41
9 Peakfilter Freq=2000 Gain=-3.5 Q=1.41
10 Peakfilter Freq=4000 Gain=-4 Q=1.41
11 Peakfilter Freq=8000 Gain=-0.5 Q=1.41
12 Peakfilter Freq=16000 Gain=0.5 Q=1.41
13 Peakfilter Freq=20000 Gain=-30 Q=2.99
Note the different filter type for slot 1.
With these EQ settings, the audio is slightly overdriven and can clip a little in some loud scenarios. The DMAS struggles to have enough volume, and this was the last bit it needed to get there. Not ideal, but it seemed the best compromise.
