Audiolense Filters in Roon, Revisited — Build 537

Core Machine (Operating system/System info/Roon build number)

CAPSZuma server with i7 processor running RoonServer Build 537 on WS2019 with Audiophile Optimizer

Network Details (Including networking gear model/manufacturer and if on WiFi/Ethernet)


Audio Devices (Specify what device you’re using and its connection type - USB/HDMI/etc.)

Multichannel DAC consisting of four Musical Fidelity V90 2-channel DACs networked as a single DAC with the miniDSP UDIO-8 interface connected to the 7.1 analog inputs of a Marantz 8802A pre/pro

Description Of Issue

This is a Roon channel mapping problem for which I have spent many hours troubleshooting with @Omid_Mostachfi over at the Audiolense user forum. We have discovered a solution but it is clearly a bug in Roon for future consideration. In addition to advising @support, this posting is to save others the troubles I’ve been through.

I apologize for the length here, but it may help the Roon engineering team to duplicate the issue for themselves.

Most of my multichannel listening is of 6 channel material, either DSF or FLAC tracks. In my main system, I have two subwoofers. Therefore, I have been working to use Audiolense filters in a Roon to support a 5.2 channel mapping.

Audiolense properly measures all seven separate channels, to wit: front left and right mains, center, left and right surrounds and the two subwoofers. On Marantz pre/pros, there are two subwoofer outputs. However, except for using Audyssey sound correction built into the pre/pro, the two subwoofer outputs run the same. So, the only way to measure and filter each sub separately is to plug one sub into the pre/pro’s labeled subwoofer outputs (either of the two) and plug the other subwoofer into a seventh channel. When Roon plays out through the Audiolense filters so created, there is no sound for the center and surround channels.

Disengaging the convolution filters causes all channels to be properly identified and populated with sonic output.

Audiolense created a filter that, in relevant part, looks like this:

48000 6 8 0
0 0 0 0 0 0
0 0 0 0 0 0 0 0

You can see that channel 0, the left front main, is mapped to the left front inputs and outputs. Same for channel 1, the right front main, and channel 2, the center channel. Yet, as noted above, no sound comes out of the center channel speaker in Roon when the filter is activated.

As a test, we edited the cfg for channel 0 to read:


We expected this would cause the channel ID for the left front input, which we knew was working with the filter enabled, to come out of the center channel.

Imagine then our surprise when not only did the left front channel ID come out of the center channel, but so did the center channel’s own ID! Reverting channel 0 back yielded silence out of the center channel again, so this was repeatable.

@Omid_Mostachfi thought with this unusual result that perhaps Roon could be fooled into properly reading the cfg file. What we did was merely to re-arrange the ordering of the first five channels from 0, 1, 2, 3, 4 — as above — to 0, 1, 3, 2, 4 AND we also placed a blank line between channels 1&3, 3&2 and 2&4. Everything else in the filters created by Audiolense are the same. This caused the filter to be properly recognized by Roon and all seven speakers now play out just fine!

I have Roon configured with event mode on, no swap of rear and surround channels, 7.1 channels and channel mapping only.

I am happy to provide further information on request to assist others or the Roon team with this problem. A shout out again to @Omid_Mostachfi for the assistance on this and to @Mitch_Barnett for his service in teaching me how to use Audiolense. Audiolense convolution filters are a great combo with Roon when they work correctly! Cheers. JCR


Hello @Jeffrey_Robbins,

Would you be able to provide copies of the filters used during your testing? Readme text files with the filter sets would be helpful for the QA team as well. Appreciate the detail you’ve provided, we’ll look into this.


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Hello, @john. I can’t upload cfg or txt files here. Where would you like me to send them to? JCR

Hi @Jeffrey_Robbins,

I’ve followed up via private message on an upload destination.

@noris and @john, I’ve uploaded materials to you via the zoho, as requested. There’s a README.txt file in there with further details to go with the upload materials. Kindly confirm receipt.

You will note there that, subsequent to my original post, I have discovered that the modified, functioning AL filters work for 5.1 FLAC files, but when playing 5.1 DSF files, both the center channel and left sub are missing. Have at it! Thanks. JCR

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Hi @Jeffrey_Robbins,

I can confirm receipt of the files, looks like they arrived successfully.
I’ll pass these over to the technical team and once we have further feedback, we’ll reach out.

@noris, just checking in on status here. Thanks. JCR

Hi @Jeffrey_Robbins,

Thanks for the ping, let me reach our to our technical team for a status update.

@noris, checking in again. I have discovered further convolution problems between Roon and Marantz products in another system in my home, but will wait to share that until we resolve this first one. Thanks. JCR

Hi @Jeffrey_Robbins,

I wanted to provide a status update - I see that our technical team has started reviewing your case, so we should have an update for you soon. Thank you for your patience here, we’ll reach again once the review is complete.

Thanks, @noris. I appreciate the update. JCR

@noris, any update? JCR

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