Bluesound: 48KHz Down Sample Problem [Resolved in BluOS 2.10.9]

Thanks @brian - good to know that Roon are being proactive on this.

Despite the frustration around this issue I’m still glad that I changed from Sonos to Bluesound - better sound quality, ability to control from any IR remote (e.g. a £5 one), preset buttons which can be assigned to internet radio stations (much easier than reaching for iPad first thing in the morning). There’s also the bonus of being able to make the Flex portable (rechargeable battery pack). Ability to group with other RAAT endpoints is also important for me.

At least Bluesound are happy to work with Roon - from what I read the Sonos integration in Roon has been done without any support from Sonos. Sonos is limited to 48K (and 16bit) anyway by hardware limitations I believe. I am hoping that Bluesound’s reticence to explain why some products are limited to 48K is not caused by hardware limitations that they don’t want to admit.

What I find difficult is the lack of any real explanation about why only some Bluesound products are affected. Roon are normally very open and transparent about any issues so I guess that, in this instance, their hands must be tied by some sort of NDA with Bluesound.

The explanation should come from Bluesound since it’s an issue at their end. The fact that the 10.2.6 player update doesn’t contain a fix means that they are not able to solve it (yet).

That’s encouraging to hear.

This is what I read on the Bluesound forum regarding the latest update:

Microsoft Groove has made changes to their login authentication procedures. As a result, we have updated all BluOS Players to meet their new security requirements an ensure a continuation of service to all MS Groove and OneDrive users of Bluesound after March 31st of this year. MS Groove users may have to log out and log back in in the More Music Menu.

Was this fixed in Roon build 216?

Can’t see how any change in Roon can (on its own) change this - there is a setting in the OS for Flex, Mini and Soundbar that forces Roon to see 48K as the only sampling rate available for these speakers.

Any news @brian on your discussions with Bluesound?

There has been good progress on this since reaching out to them two weeks ago–but not quite ready to share the details yet.


Sigh. So Bluesound still isn’t quite RoonReady.

Good news that there are signs of progress - it must be a more difficult problem than originally thought. Despite the 48K issue I’m pleased with the Bluesound products - integration with Roon is much better than alternatives (e.g. Sonos) - just hoping that it’s not some sort of hardware limitation in Flex / Mini / Soundbar that is causing the 48K issue.

Great to hear.

Update from Bluesound …

Post by AndrewH » Mon Apr 17, 2017 9:10 am

We have not fully responded to all the questions arising from the Roon/BluOS implementation because we wanted to take the time to check fully with the design team after they discussed it all through with Roon to create the best user experience. Some clarifications are in order and here is a note from Greg Stidsen our Director of Technology and Product Planning that we found very helpful:

“The Bluesound (BluOS) ecosystem is built completely on our company’s desire to differentiate our solutions with the ability to manage and play or stream high resolution music files. Our belief is that offering products with easy access to the benefits that high resolution audio brings will only increase the enjoyment for music lovers and enthusiasts worldwide.”

“To clarify things, our BluOS protocol manages, via wireless or hardwire connection, music files up to 24/192 and allows these files or streams to be accessed anywhere in the home, grouped together, or played individually in various zones. The first four products introduced by Bluesound, our NODE, POWERNODE, VAULT and PULSE 2 (and original PULSE) accept files up to 24/192 and maintain the native sample rate until the DAC stage where signals are generally upsampled from Pulse Code Modulation, to Pulse Density Modulation or Pulse Width Modulation, depending on the specific DAC design employed.”

In the Bluesound Gen 2 family our design team continued to challenge ourselves to hit even more accessible price points and categories. This led to our launch of the PULSE MINI, PULSE FLEX and more recently the PULSE SOUNDBAR. To enable us to bring our high resolution music protocol to these price points and to optimize the performance in such compact designs, we utilize advanced DSP algorithms to linearize frequency response and optimize acoustic output and dynamics of the system. Paul Barton, Chief Designer of PSB Speakers and key contributor to our Bluesound acoustics design team, provided the following commentary on what this means for these products:

“In the three most recent Pulse designs (Flex, Mini, Soundbar) we have carefully balanced performance with cost by focusing our resources on the most important things. These models are completely closed designs enabling control over every aspect of the signal flow from the input to the transducer (woofer and tweeter) output. Since the weakest link in any sound reproduction device is the transducer, we have paid special attention to the woofer and tweeter designs and enhanced them with custom DSP control to improve all aspects of driver performance. Taken together, this advanced acoustic platform results in the exceptional musicality of the Bluesound systems. By operating the speaker DSP in these three models at 24/48 and the digital switching of the amplifiers at 384Khz PWM (Pulse Width Modulation) we achieve an optimal balance between performance and cost.”

In a new BluOS software release issued today (2.10.9), we have updated the Roon/BluOS implementation so that BluOS devices receive the native file format. We apologize for not getting that quite right in the first iteration of Roon Ready, and for any confusion this may have caused.
We have captured all of this information in an FAQ on our website at the following link: … 5005574428

Thanks for #LivingHiFi


That’s rather great. An interesting read too.

Here’s how I read this. Bluesound didn’t have enough signal processing bandwidth left over on some their products to handle the extra overhead associated with the Roon endpoint software. This is not necessarily a bad engineering decision as one always tries to optimize cost/performance trade-offs, particularly for consumer products. It seems clear that Bluesound knew about this performance limitation a long time ago as the products affected had higher bit rate capabilities disabled when they acted as roon endpoints. It sounds like they had to do some significant rewrites of the code in order to handle higher bit rates. The real issue as I see it is they just released the code, didn’t bother to tell any of their customers about the limitations, and then kept quite about it for 2.5 months before coming clean. One of the many reasons I won’t be buying Bluesound products in the future.

I can confirm 2.10.9 fixes the down-/upsampling problem. My Pulse Mini is playing at 192/24 just fine now. :slight_smile:

So they’ve turned off the DSP on the device to allow us to make full use of its 24/192 bit rate capabilities.
Seems like a fairly major problem to me with their implementation. We gain a bit now with the fix but lose something else… possibly!

One of roon’s many plus points the signal path revealing the truth that would have likely stayed hidden otherwise!

Maybe a non issue as I’m using roon’s DSP which I imagine is better anyway. Good to see the last of the green dot of death.

SQ wise I believe I am detecting a slight improvement with removal of a layer of murk though difficult to accurately compare before/ after.

Good there is resolution but am sensing a compromise/ workaround…

I’ll go reread the post from bluesound later when I have time, but I don’t think that’s what they said. I think they were saying their software wasn’t running fast enough on certain products to handle the added load of the roon endpoint. In order to still be able to ship, they hacked in a patch (without bothering to tell the clients) that limited the supported bit rate for the affected products, thus giving their software more headroom. Over the last 2.5 months they’ve been rewriting code to remove this bottleneck, which allows all BS products to run as a roon endpoint at their originally supported bit rate. Net, net is whatever DSP functions were there before are still there now.

We would not allow a product to achieve or maintain Roon Ready certification if something like the speaker DSP that Bluesound described were bypassed in Roon Ready mode. Nothing like that is going on here.


Allen and @Brian
Reading it again you’re right.
i don’t see why the statement refers so strongly to cost when that seems to have little to do with it.
i was reading into the DSP 24/48 being an actual limitation that they’ve had to bypass somehow.

Happy to be corrected.

As a Bluesound customer I found the almost total lack of communication about the issue during the delay highly frustrating and it made it look like there was something to hide. Highly unnecessary looking at the explanation now which could have been given (by Bluesound) at a much earlier stage.


Happy that it’s been fixed - I now have the option to use Roon to upsample to 192K before sending to Bluesound - but agree with @Scott_Fletcher that Bluesound could have been more open at an earlier stage. It confirms what I always thought (despite initial comments from Bluesound) that the issue was never a Roon problem but was caused by a setting in the BluOS (raat_only flag).

The question I now have (reading the explanation) - and it’s really a question for Bluesound (@Andrew_Haines) rather than for Roon - is whether the models affected still convert internally to 48KHz i.e. the change in 2.10.9 simply allows a range of inputs and then internally converts before feeding to the DAC and PWM amplification? If so, then this raises the question of whether it is better to use Roon to do the conversion to 48 rather than this being done in the Bluesound speaker?

Also interesting to note -looking at Roon’s product matrix - that the 3 products affected (Flex, Mini, Soundbar) were NOT tested in-house whereas those not affected (Node, PowerNode, Pulse) were tested in-house.

Just for info, The signal path is ‘Enhanced’ with 'amplifier crossover and eq ’ by bluesound. But still lossless (purple dot) from roon to bluesound.