DCS Bartok - Popping noise on some network inputs

Support
1

Hello DCS Community,

I’m experiencing the following issue with my setup, on all network inputs except Spotify, I experience a popping sound frequently.

Here’s the setup details: (Note we’re mid upgrade and just did speakers)

Wadia Transport
DCS Bartok DAC (No Apex yet)
Classe CA-200 AMPS
Wilson Audio Alexx V Speakers

Network side:
Ubiquiti edge switches
Ubiquiti agg switches for core
TrueNAS for data
Proxmox HyperVisor with various VM running streaming apps (Subsonic, Jellyfin, etc)

I’ve gone through the various information on the network and DCS Bartok side, such as log files, switch port errors, etc. Nothing to report at all.

Spotify streaming works great, no clipping, no popping, 0 issues other than lower than optimal quality.

Qobuz, Tidal, and AirPlay sources (Subsonic, JellyFin, etc) all generate popping sounds very frequently.

Any ideas, input, etc would be appreciated.

For background I’m an experienced engineer (AI, Cyber, Technical Operations, Network Engineering, etc) and I’m more than glad to do whatever troubleshooting is required even if packet captures or something complicated is required.

Thank you for your time and consideration.

Looking forward to the Apex upgrade and maybe a Rossini Apex soon!

2

Is the popping sound related to the music playing, pops on the rhythm of the music, the base, loud passages? Or is it random?

How is the output voltage set on your Bartok? 0.2 - 0.6 - 2 - 6V?

1 Like
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Hello Ermos, thank you for your reply.

The popping sound is random and present in every track.

I’ve tried with 0.2, 0.6, 2, and 6 volt and it’s still present.

The primary listener in my household prefers it at 6V.

We’re not using a pre-amp.

Thanks!

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4

Your welcome. I just try to figure out what is happening, so I tried to find out if your popping is clipping.

First: the input sensitivity of your Classe CA-200 is: 1.3V. So I would not output your Bartok higher than 2V. At 6V you are prone to clipping very easily. That it does not happen with Spotify might be because it is not high resolution material.

But your popping is random, as you say. Since your Classe is a bit old, that might be the cause, having difficulties with dynamics, or a problem with its power supply capacity: leaking capacitors.

Popping is almost always an arcing problem. The high voltage in the amp has found some path that cannot stand the high voltages and discharges suddenly through that path. The arc current is high, but cannot be sustained by the power supply, so the voltage drops a little, the arc extinguishes, and it takes some time for the power supply voltage to build back up to where the arc will start again.

I don’t see a reason why the network input might give you pops.

But let us see what dCS support says, and once again call in the magic @Phil

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Thank you so much Ermos, I’ve argued about the line voltage and also suspected the Classe CA-200 as the culprit, it makes a lot of sense given the equipment age.

Really appreciate the insights!

Yea I agree, it’s odd that only some network sources are affected, I think it’s related to the quality of the input as suggested.

2 Likes
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Interesting setup. You didn’t mention if this exact setup was previously working fine and the problem only just started happening?

My initial wild guess would be your Proxmox as the likely culprit where the problem lies. Did it ever work properly? If so, what’s changed?

Mind you, I’m not suggesting that Virtualisation is inherently the problem, in fact, I have a UPnP Server running on an ESXi VM which works just fine. Just that when there are drop-outs or popping in music playback, it’s usually the software source of the data-stream, rather than any hardware-wired element.

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It appeared to be working correctly with the previous speakers.

Since we’ve gotten the new speakers, it’s become evident with sources other than the Transport and Spotify.

Interesting idea, I will try running the software on a spare NUC instead of a VM on Proxmox.

Thank you!

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8

I guess the speaker change might have disturbed something else in the chain?

One additional question, which perhaps might confirm Proxmox as the likely culprit; You mentioned Spotify works great, was that Spotify Connect? If so, Spotify Connect streams flow directly from the Internet to the Bartok, Promox would not be part of the chain.

What about your Qobuz/Tidal streams? How are you connecting your Promox/Jellyfin to the Bartok; via USB, or Ethernet UPnP Control? (I’m not that familiar with Subsonic or Jellyfin :thinking:)

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Sorry for the delay - I’m here - let me have a read!

(Thanks for tagging me @Ermos !)

Phil

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Does this also occur on Internet Radio? (The reason I ask is because Internet Radio streams are usually very bandwidth limited and have very low data rates - like Spotify - but has a similar path to Qobuz and TIDAL into the Bartok.)

(Spotify is supported by Spotify Connect and has a different route into the Bartok.)

When you are using TIDAL and Qobuz is that through the Mosaic app?

OK - this is really odd as Airplay is / has a totally different signal path to Qobuz and TIDAL but is generally a higher bitrate than Spotify so my gut feeling here is we’re hitting a bandwidth limitation somewhere - especially if Internet Radio works OK when you test it out.

Is your Ubiquiti kit all hard wired end to end?

Are you using any Ubiquiti AP’s configured as a mesh to extend your network?

Which edge switches and aggregation switches are you using?

Cheers

Phil

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11

Hello DCS Community,

I wanted to follow up, my apologies for the delay, home construction and upgrades.

We upgraded from the Bartok DAC to the Rossini APEX DAC.

All issues have gone away for now.

I still haven’t had a chance to visit my Colo to remove a spare computer for testing streaming without a virtualization layer.

Will update as things progress.

Thank you for your input!

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12

I am using Bartok (not APEX) and the popping noise is happening on AirPlay2 connection 95% of the time. Connecting via USB and Roon are perfectly ok.

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Hi BartokATC. I see that this is your first post but I am afraid that without further information it is difficult to work out what is going on and may be why this thread is not being picked up on by members here ( 15 hours since you posted at the time of writing). Currently I can only deduce that you have a Bartok and ( I presume from your moniker) some ATC speakers.

These type of questions may need a chain of emails to solve and this is not the best medium for this. So to shorten matters I suggest that you contact dCS support directly:

[email protected]

BTW, Bartok has AirPlay 1, not 2.

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thanks for your advise.

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I have also notices anomalies with AirPlay on my Bartok. Very difficult to describe but it sounds like light popping sound every 20 seconds or so, but it is random not regular. Something that one might attribute to network instability. But that is unlikely the case, given how reliable Qobuz through Mosaic. Thought it might be related to buffering or clocking issues but I’ve never been able to isolate it consistently.

Related but a little off topic… Given that AirPlay (in our house at least) is use for multi room streaming, and that the Bartok only supports AirPlay 1 - this functionally goes un used most of the time. I’ve migrated to a Wiim Pro Plus streamer (connected to my Bartok via Toslink) to cover Airplay 2 streaming (and as a A to D converter for my phono stage)

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Not quite apples to apples though. Don’t forget with Airplay, your streaming source “trombones” through your home network twice; once from the 'net to your iDevice, and then from it to your Bartok. That doesn’t happen with Mosaic/Qobuz where streams go direct from the ‘net to your Bartok.

I can’t tell what might be the problem exactly, but it’s possible there’s congestion on your home network (possibly the WiFi AP that your iDevice connects to) causing Airplay buffer underruns which you hear as popping sounds.

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indeed. I didn’t note there is an added layer of a VPN in there as well… I’ll try AirPlay via Apple Music and see how it goes.

It is worth noting that there are no issues with multi zone AirPlay 2 playback via the Wiim into my Bartok.

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Not VPN as such, With Airplay, it’s always your Apple iDevice which receives streams from the ‘net through normal REST calls, and then the iDevice uses the Airplay protocol to re-send that received stream to your Bartok.

So, the streaming traffic always criss-crosses your home network twice with Airplay1 & 2.

This is where things get interesting :laughing:

There are some very fundamental differences between Airplay 1 and Airplay 2 at the protocol level, so, you can’t easily compare them with respect to network performance.

For example, Airplay 1 uses a full (heavy) TCP to stream in near real-time at an almost constant rate with a shallow buffer (~2sec) at the receiver. So, buffer underruns happen very easily. Whereas Airplay 2 uses the light-weight UDP and aggressively bursts traffic into deep buffers (almost 60sec) at the receiver, so it can handle network congestion far better.

You can test this for yourself; turn off an iDevice playing with Airplay 1 and the airplay end-point music will stop almost immediately. But with Airplay 2, when the iDevice is turned off, the airplay end-point will continue playing for quite a bit longer (till the receiver’s deep buffers empty) before the music stops.

The other big difference is that Airplay 1 uses ALAC for Redbook quality streams, whereas Airplay 2 can dynamically adjust down to lossy AAC when it detects network congestion.

There are lots of other differences around timing and synchronization, but they’re not as relevant to the sound quality issues being discussed here.

1 Like
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Hitherto I’ve never tested AirPlay 1 playback through the Apple Music app via iOS to the Bartok. I just tested this AM and playback is flawless and sounds very very good!

My other use case where slight popping occurs is likely due to the AirPlay 1 shallow buffer you mention above - in this case, play back is from a separate app that streams a radio station.

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Ahh OK. Well, the problem could manifest when there’s an issue with your network.

Typically Wired networks at home rarely see congestion issues, but WiFi Access Points, even WiFi6 or 7, especially if they’re consumer focused models, could encounter what’s typically called “micro-burst” congestion issues, leading to audible impacts from packet loss for near real-time traffic.

Such micro-bursts won’t impact your Web browsing or YouTube watching or even regular Qobuz streams, as those are heavily buffered at the application layer, so everything seems fine on the surface.

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