Review and fixing the audio of the DMAS

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:

image

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.

10 Likes

You inspired me to do the same. but I stuck it in a box with a mic and played with it compared to a log graph of pink noise. My mic results showed a wildly different profile though. May I ask how you came to these values? I am always doubting my test methods / measures.

Like trying to tune a Ford Pinto for the Indy :grinning:

3 Likes

ohhh, just bump it from behind a bit?

My method was tuning it by ear using a spread of music (electronic, rock, and orchestral), games, and VRChat. And comparing that back and forth with the Valve Index (as its audio comes stock).

It’s not nearly as finely tuned as the other two EQ settings I’ve posted (for the mic and KDMAS) since I didn’t keep on with the DMAS for very long before settling on the KDMAS. There was a little more left to squeeze out of the DMAS, but it was clear by then that it wasn’t going to be my choice.

My main point in posting this one was the discovery of just how effective sharply cutting sub frequencies out is for improving the sound quality and volume of the DMAS.

To be bluntly honest, my earlier impressions of the DMAS were that it was trash. And this discovery turned that around. I won’t claim that it’s enough to make the DMAS audio as good the Index, but it elevated it enough that I would have been willing to switch to it from the Index in order to get that wide FOV of the 8KX. Whereas the stock audio quality of the DMAS was a deal breaker.

I do think this EQ can be improved further. And to your question, I wasn’t using any techniques intended to produce a flat studio monitor type frequency response. I was actually trying to match the color of the Index audio since it’s what I’m used to and also very positively reviewed.

so i have the kdmas is the upgrade to dmas worth it?are they louder?i would also like to use the dmas with the ear cups.

The DMAS is not nearly as loud as the KDMAS can go. The DMAS struggles to achieve a normal listening volume.

The DMAS will not work with the ear cups. They can be physically attached, but the DMAS is not designed to use them, and the sound quality with them on is awful and can’t be corrected.

The overall sound quality of the DMAS is inferior to the KDMAS. The only reason to consider the DMAS is if you really want off ear speakers for comfort.

oh lol thanks i didnt knew that i touhgt its gonna be louder lol,i like the outside to be sealed so thats a no for me then

Careful now. You risk a poop emoji if you give any indication you don’t consider these high end sound solutions… :laughing:

1 Like

One of the likes I received on this post was actually from PimaxQuorra. I was a little surprised by that since it’s not really a favorable review of the DMAS.

From what I’ve seen on these forums, Pimax representatives don’t seem to respond negatively to honest and meaningful feedback on problems with their products, but rather to comments which are in themselves unconstructive and impolite.

I actually put a lot of effort into my evaluation of the DMAS, and my intent is to be constructive and helpful both to Pimax and its customers. The DMAS has a lot of potential, but it is held back by a couple of issues which perhaps could be corrected in new product revisions.

7 Likes

Just to toss a note out there about DMAS on the 12K… the problems with the DMAS are largely caused by the weak amplification section of the 8KX. The DMAS itself has high quality drivers.

The 8KX is entirely USB powered. It’s amazing that Pimax has been able to run the 8KX off of just USB power alone. But I suspect that not having enough power in its amplification section to drive the DMAS properly is a direct consequence of USB power limits.

The 12K will have its own battery and so should theoretically not be limited to USB power. It should be able to mount a more powerful amplification section that can drive the DMAS properly. So the DMAS very well could be much better when mounted on the 12K than it is on the 8KX.

if Pimax mounts a more powerful amplifier on the 12K.

I also hope Pimax will upgrade the microphone. This needs to happen, too, if the 12K is to compete with the Index/Reverb G2 audio system.

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