Node 2021 and Gapless playback, the whole story...

r22flyer

Active Member
My 3 year old Sonos Connect on my TV/AV system went faulty (constantly rebooting) so I started searching for a replacement.
I couldn't get a Sonos Port for at least 6 weeks, supply problems in the UK apparently, so after rejecting many other streamers I eventually found the Bluesound Node.
I settled on a Bluesound Node 2021... bought for £549 on Amazon UK.

Setup was relatively easy, the unit requiring an instant firmware update on start-up.
Initial listening tests were good - I was impressed with the sound quality, the easy to use app and easy to select albums or tracks from my library.
Then I noticed a slight click between tracks, especially noticeable on albums that were meant to play tracks back to back gapless.
We all know the usual albums, Pink Floyd especiallu, but there are many albums out there that require gapless playback.

To diagnose the problem I connected a Roland portable audio recorder to the Node stereo outputs and recorded a track sequence sample.
Then I opened the file in Wavelab 10 Pro, one of the best audio editors available.
The result was obvious, a gap between tracks where there shouldn't be...

ScreenShot000385.png


Zooming in on the green highlighted area...

ScreenShot000386.png


For convenience of capture, I played the same 2 tracks from the same source library through Winamp on my PC.
The zoomed in waveform from Winamp was...

ScreenShot000389.png


Very strange, Winamp plays it perfectly gapless, and let's face it, Winamp is an ancient software player but it's still a remarkably good player these days for PC.
I'm still using Winamp V5.666 from 2014 as its' music library filtering and management is excellent.
From Winamp I use directsound coax digital output to a Presonus monitor mixer then to my Adam A7X powered speakers and BK sub with inline Antimode device.
It's a great sounding setup, where I notice the slightest noise or anything wrong.

I digress...
I've never noticed any issues on my Sonos system but nagging doubts made me check.
Nope, all OK, same gapless playback on Sonos as with Winamp; thought so but had to double check.
Checked my Nvidia Shield TV, Kodi had no issues playing gapless either.
Checked my Ibasso portable player (great sound BTW with Beyer Dynamic DT770Pro 250ohm headphones), no issues with that playback either.

At this point I should mention my music library is MP3.
Many will scoff at that revelation but it's done purely for convenience of being able to listen to music anywhere, portable, car, Sonos, phones, AV system etc.
Approx 10,000 tracks using 177Gb of storage, fully tagged, 600 x 600 high quality album art (mostly from Album Art Exchange).
The ripped CD source of WAVs uses >400Gb of storage.
Maybe I could have used FLAC but its long road to back track and a lot of tagging work.

So I contacted Bluesound support, sent them the screenshots, MP3 and WAV tracks as requested.
They responded quickly but with a surprising reply...

Bluesound firstly confirmed they had replicated the gapless playback problem with my tracks and some of their own MP3 tracks.
The advisor also said he had reported the issue to their Quality Assurance Team too (more on that later).
Then it went downhill from there...
He stated that Bluesound players will only play gapless if using lossless sources!
A statement at odds with this screenshot from their website...

ScreenShot000391.png


Their own spec goes on to say MP3 is a supported audio format.

ScreenShot000392.png


I had already checked this info before buying the Node 2021 so I was astonished that they were now back-tracking on it.
When I complained about this the response was to blame my audio encoding for inserting "leading 0 gaps".
I was already aware that ripping directly to MP3 can cause gap issues so I've always avoided that by a proven ripping process.
I replied stating that those "leading 0 gaps" don't seem to trouble any of my other devices, including Sonos and Winamp, both of which play gapless perfectly.

My CD ripping process...
I use dBpoweramp V16 to rip CDs to wav format and save them as is.
AccurateRip confirms the tracks have ripped correctly so the basic rip MUST be correct.
I don't apply any DSP.
I've checked, the WAV tracks have no gaps between tracks.
Then I run the dBpoweramp batch converter, using a LAME encoder, to create max quality 320kbit CBR mp3 tracks.
For the majority of my listening these are indistinguishable from the WAVs but substantially more convenient.
The MP3 tracks are then tagged using MP3tag along with high quality album art (which looks great in control apps).
For many years this has been a flawless process for me and EVERY gapless CD has played perfectly.

So the question remained, why do ALL my other players play gapless perfectly and the Node 2021 doesn't?

Delving deeper on the Internet I found various deep conversations but this one stuck out from someone who clearly understood more than me.
Gapless Playback using LAME headers

It's a Bluesound support request from 2 years ago.
It's a long read but worth it.
The gist of it seems to be that Bluesound do not use the gapless header data embedded in MP3 tracks by LAME.
That appears to be an information nugget that gets right to the heart of the problem.

As Franz Nieroster posts...
"I have the impression that nobody at Bluesound understands that gapless playback of mp3 files is not just concatenation. The decoder has to actively remove samples to compensate for encoder delay and padding."

So despite the first advisor at Bluesound support escalating it to the Quality Assurance Team, they clearly know all about the issue and are not going to do anything about it.

Bluesound go on to state users should just re-encode their files 'properly' or use lossless but they fail to understand (or actively ignore) that using gapless header information for playback seems to be the key. 2 years after that discussion they basically said the same to me so there's never likely going to be a solution for their players. Despite how good everything else about the Node 2021 seems to be, it is a deal breaker for me and Amazon UK have now accepted my return for refund.

I was originally happy with the Sonos Connect - it played gapless perfectly and streamed well from Spotify.
My main gripe with Sonos is they have obsoleted my perfectly good Samsung tablet by not allowing the Sonos S2 App to work on it anymore.
However, with my Sonos discount for recycling the Connect, and potentially a new Samsung A7 tablet as a controller, and a new Sonos Port (when available) I'll still be £73 better off. I already know to switch off the Sonos Port volume control because that also applies some sort of audio levelling DSP that I definitely don't want.

Will I notice the sound quality difference between the two - I doubt it - but I will have got rid of the clicks!

So for anyone looking to buy a Node 2021, as long as you only want to play lossless, then you'll be fine.
You'll no doubt actually use FLAC for its' tagging compatibility instead of WAVs.
I suggest you choose something other than Bluesound Node if you use MP3.

Happy listening.
 

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