Bass Management with 5.0 files

I can implement bass management with 5.1 source files by a procedural MIX filter that reroutes all the 5 main channels to the LFE followed by a parametric file that implements an 80HzHP filter in the main channels. The LFE channel output device has its own LP filter.

However, the vast majority of classical multichannel recordings are 5.0 which Roon plays with proper channel management straight through. It inserts a silent LFE channel so that 5.1 output mapping is correct.

OTOH, if I implement the above 2 DSP filters with a 5.0 file, bass is still re-routed to the LFE channel but there is no output at all in the Surround Right channel. Clearly this is disrupting channel mapping but I cannot figure out a fix.

Hi @mitr, I’m almost sure, that I ran Roon in the past in the exact scenario that you’re describing here. And that I did not run into similar trouble. ( In the end I decided to give my multichannel processor the duty of doing bass Mgmt, so not 100% sure…).

I’ll do my best to reproduce what you experience, over the weekend. But seeing my past experience, I don’t know what’s going to happen…

Until then, it might be wise to provide some additional info. What is the OS of your core, what is your output device ?

Can you describe exactly the steps you took to achieve this bad result ? Preferably, with screenshots of all modifications ?

(You might want to edit the second appearance of the word ‘HP’ in your post; I believe that is a typo)

Win7, miniDSP U-DIO8 (feeds three Mytek Brooklyn DACs).

I cannot be more detailed nor provide screen shots because the system is in another house and I will not be there for about two weeks. I implemented the two filters as stated and they work as expected. In fact, it is fine with stereo or 5.1 files.

If I switch to a 5.0 file the channel problem occurs. I have not tried any 4.0 files.

Dear @mitr, or Kal as I like real names better :slight_smile: ,

Yes, I already properly understood the question. It never hurts to make things clearer, thanks you :).

I tried to reproduce your issue, in an attempt to help find a workaround.
Unfortunately however, I could not reproduce it exactly. Making it impossible for me, to find such a workaround.

I did find a lot of odd things though. I do not have the time today to properly look into it, but I’ll try to follow up next week. Looks like a hard task, as it doesn’t even seem to be reproducible 100% now…

Shortest possible explanation for now : it seems that Roon is mis-identifying some channels in the procedural EQ section. Left surround can be the right one in reality. LFE can be left surround, etc.
And that behaviour seems to change, once you add mixing. But I cannot be sure as of yet.

You may want to check if this is indeed causing your trouble. Until then, perhaps support can offer some insight, or try and reproduce ? (d

Thanks. I think you do understand the situation and I would appreciate your effort.

Dear Kal (@mitr),

You are absolutely right - this is impossible to achieve in Roon right now. You have to choose : either get the 5.0 files, or the 5.1 files to play nice.

In my opinion, there must either be a bug in Roon’s channel re-mapping, or something’s missing there. If so, then this post should simplify the way to reproduce.
My situation slightly differs from yours : I have no output on my physical center. You have no output on physical rear right. I believe this may be explained, by the way this bug ‘confuses’ the user (or perhaps me).

My findings are still not ‘final’, but I’ll share what I observe so far. Perhaps you (Kal) can confirm if you can replicate what I saw.
I would also kindly like to ask @support, if they can doublecheck this.

My opinion is, that it goes wrong when Roon tries to apply channel mapping from 5.0 input, to 5.1 output.
In case it matters : this is ROCK. HDMI output set up with 5.1 layout. Feeding an Anthem processor over HDMI.

When I take a 5.1 source file, I get the following result. A short way to describe : all is correct :slight_smile: :

Roon channel -> Physical channel that is mapped to :
Left front -> Left front
Right front -> Right front
Center -> Center
LFE -> Subwoofer
Back left -> Back Left
Back right -> Back right

However when I take a 5.0 file, Roon wants to (obviously) re-map it to 5.1, and things get mangled up:

Roon channel -> Physical channel that is mapped to :
Left front -> Left front
Right front -> Right front
Center -> Subwoofer
LFE -> Back left
Back left -> Back right
Back right -> (unable to determine, as I have no more physical channels)

It’s as if they’re skipping the center channel in the chronological list-of-channels, instead of skipping the LFE channel, when re-mapping 5.0 to 5.1.

One nasty thing is : I’m pretty sure there is no universally accepted ‘standard’, that describes how to perform such a remapping.
So this could be quite a challenge for Roon… On the other hand : the way that they’re doing it NOW, is not a known standard to me.

Thanks for confirming my experience.

What I have noticed is that Roon usually does a channel remapping after all the other operations rather than before and the user has no control of when the remapping occurs.

Sure there is for 5.1 and you have listed it in your left column listing. The problem is the conversion from other format maps.

Why? Other players (?) can.

One option is to allow the user the option to remap before the MIX filters and to specify the channel map.

You are probably right. As it seems. anything that happens in the procedural section, will screw up the channel mapping.

I ‘forgot’ to check, if 5.0 was properly remapped when NOT modified in any way. ‘Forgot’ meaning : did not have the time to check. I know you stated that it DOES properly map in your first post. And indeed, it does.

By the way : my test above were WITHOUT using mixing, to try and minimize complexity. Meaning : it is not likely to be be caused be the mixing itself. It’s more likely to be the entire procedural section. But I’m not available to test that over the coming week, sorry… :frowning:
But I DID use the procedural (EQ) section, as an easy tool to (mis?)identify all channels,

(sorry; skipping the discussion on how complex a solution might be. Did not intend that to be a discussion, shouldn’t have done that. Doesn’t speed up a solution in any way)