Voice PE DISTORTED audio?

[Sawtaytoes]

Hello! I’m having an issue where my Voice Assistant, on the latest 12.1 firmware, is clipping hard on the audio-out. I say clipping, but what I mean is it’s super distorted. I assume it’s from clipping because it sounds like when your mic gain is too high on a crappy mic.

I recently bought a bunch of Marshall Stockwell II speakers. I’m not expecting much, but I don’t expect distortion.

Troubleshooting

Speaker/protocol changes

The first thing I did was the Voice PE (wired up to a GaN charger with 5V/3A) connected to the speaker over 3.5mm. Tons of clipping when playing audio over Music Assistant 2.7.1. It was noticable enough that my wife said it sounded bad.

Then I tried using Bluetooth from my phone to the speaker. No clipping even at max volume!

Then I tried using Google Chromecast Audio (that really old one they don’t sell anymore) to the same speaker from Music Assistant, and it sounded fantastic! Max volume had no clipping.

I tried Voice PE again this time powered by a PoE->USB adapter, and I had the same clipping issue. It sounds like the speaker is going to blow up it’s so bad.

DSP in Music Assistant

I tried multiple configs of changing the input gain on the Voice PE, messing with the tone controls on the unit and in Music Assistant, anything that might work. Tons of clipping still.

I think Voice PE is shoving too much bass into the signal or something, but even still, PEQ wasn’t fixing it either. It just sounds bad; like really bad.

The only other test I can think to do is to record the 3.5mm jack directly in Audacity and record the Google Chromecast Audio. Then I can easily show the clipping, but I’m not sure how easy it’ll be to fix.

Also, I don’t remember hearing any distortion the other day using the 12.0 beta firmware on a different speaker, but I did hear a subtle difference between the Chormecast Audio and the Voice PE.

Conclusion

Something’s up. It’s clearly something related to the Voice PE. Either it’s this recent firmware or the DAC, and its 3.5mm jack, but it’s totally messed up.

Possible Solutions

Has anyone else come up against this? What possible solution is there?

I saw someone send his Voice PE audio out over optical (digital to digital) avoiding this DAC, but my goal was to completely avoid needing any Google Chromecast device and only focus on Voice PE audio output.

I thought the DAC was good enough, but this is AliExpress cheap Chinese no-name brand level of distortion. It’s at the level of “bundled in headphones”.

[tmjpugh]

@Sawtaytoes

Then I tried using Google Chromecast Audio (that really old one they don’t sell anymore) to the same speaker from Music Assistant, and it sounded fantastic! Max volume had no clipping.

You cannot compare max volume from 2 separate unrelated devices.

To amp the voice PE output may be too high. I find that above the default 90% it clips/distorts but haven’t spent much time thinking about it. Below 90 audio is good.

If you reduce volume on PE how is sound? Can you adjust amp level be in line with voice PE max?

[Sawtaytoes]

I understand that “max” means something different on both devices, but the volume level sounded the same other than heavy distortion on the Voice PE.

Lowering the Device Volume

You’re correct that lowering the Voice PE volume helps, but then I run into a few issues:

1. I can’t hear it as well (overall volume is too low even if I max out the speaker compared Google Chromecast Audio over 3.5mm).
2. It still has distortion; it’s just lessened, but it’s hard to tell because the speaker only gets so loud.

If I measure the 3.5mm jack from both units in Audacity at the same gain, I should be able to show you what I mean. For the same volume to my ears, the sound quality is vastly different let alone “max volume” on the device.

Expectations

My expectation is that the source device’s max volume over line-out does not clip or distort. The speaker and the amp can do that, but the DAC shouldn’t be. In my experience, the DAC’s loudest output should be the song’s volume. It’s up to the amp to amplify the sound.

Unless this isn’t a line-out, it’s a pre-amplified headphone-out. At that point, we have 2 points of amplification, and it’s easy to distort as it’s like copying an already-inferior copy.

[Thyraz]

Take a look at the last posts here:

Home Assistant Voice - Aux speaker

Yes, this was also my understanding. But the CB speaker that @TheHuntyBadger linked doesn’t have a external power source. So its a passive speaker that would have to be driven by the Voice PEs audio output alone. Also tom_i wrote: your powered speakers are expecting a line level input. However the Voice PE outputs a low power speaker drive level which expects a low impedance load Which is why I asked how this passive speaker setup behaves. Never had a Gen1 echo dot. But not sure if it…

Seems to be somewhere between line-out and pre-amplified.
So you most likely have to test around at which level you get a good gain without distortion, but avoid base noise because of too low levels…

[Sawtaytoes]

Is it possible to change this line-out issue in firmware or to use the Grove port somehow?

Seems like you nailed it. This is what I was thinking too. If there’s that kinda distortion, it’s because it’s amplified (like for headphones) and not line-level.

I don’t have a way to turn down the unit and get enough volume output. I get enough from one of my speakers, but the other does not have enough sound output when I turn down the Voice PE. I need the Voice PE to be line-level by default.

Whatever the Google Chromecast Audio is doing, the same output from it is loud and not distorted. Even outputting at max volume via Music Assistant, the Google Chromecast Audio has no audible distortion out these speakers with the same volume on a Voice PE.

I have some Grove cables I could plug in to the Voice PE if that’d help. The biggest issue is how messy it’ll be, but it’s not like I can just buy a Google Chromecast Audio in 2025 either. Sure, they’re on eBay, but instead of $25 like when I bought my 5, they’re $80+. Forget that.

[Sawtaytoes]

I’ve got more data! Took a while to get this set up, but I recorded the 3.5mm output of the Voice PE and the Chromecast Audio for the same song:

Top: Voice PE
Bottom: Chromecast Audio

Both are at Max Volume with no options configured in Music Assistant. The Voice PE is clipping like mad whereas the Chromecast Audio not only has more headroom but also a lot higher volume!

I read that the RMS is 2V (2.8Vmax peak) for the Chromecast Audio on the AKM 4430 DAC chip.

Not sure about the one used in the Home Assistant Voice PE, but from what I’m seeing, something’s very wrong.

[tmjpugh]

@Sawtaytoes

I read that the RMS is 2V (2.8Vmax peak) for the Chromecast Audio on the AKM 4430 DAC chip.

Isnt clipping a setting issue.
With distortion being DAC, processor, etc?

Outside of direct failure of hardware I cant think of a cause for clipping outside settings (source input and amp out not matched properly).

[Sawtaytoes]

It’s clipping

@tmjpugh

Isnt clipping a setting issue.
With distortion being DAC, processor, etc?

I wrote “distortion” because all I knew is it sounded bad, and I thought it was clipping but didn’t have any measurements.

Now that I’ve done some measuring, it’s clearly clipping; you can see it in the waveform. Clipping is a form of distortion.

I updated my post just now to include a legend “top is Voice PE”. That text somehow got removed before I posted.

Provide me with data

@tmjpugh

Outside of direct failure of hardware I cant think of a cause for clipping outside settings (source input and amp out not matched properly).

If you can measure the output of your Voice PE, we can verify the waveform. If it looks like what I recorded, then it’s not a settings issue, it’s a hardware design flaw.

Thoughts

I believe the Voice PE’s hardware, the physical circuit board, is the problem. They amped the DAC output for the built-in speaker, but the 3.5mm jack is also amped for headphones and not line-level.

This cannot be fixed without opening it up and rewiring some things or bypassing it entirely in favor of an optical connection via the Grove port on the bottom.

Also note, the Voice PE doesn’t allow attaching a USB soundcard in the USB-C port either.

[Thyraz]

If you want more details on this, you could try to open a discussion on Discord in the hardware section and set the voice pe tag.

The devs are more likely chiming in there instead of the forums here.

[Sawtaytoes]

Thanks for that info!

I went ahead and put up a thread on Discord

[Sawtaytoes]

Someone showed me a schematic of the Voice PE’s audio interfaces, and showed that the amplifier only goes to the speaker, not the 3.5mm jack meaning it’s coming direct from the DAC with that horrible sound quality .