Stereo convolution filter, multichannel recordings playing back only in stereo

[jhwalker (John Walker)]

Roon Core Machine

sonicTransporter i9

Networking Gear & Setup Details

Orbi mesh system

Connected Audio Devices

Using Windows 11 device to run Roon Bridge via HDMI into Denon 3700h receiver

Number of Tracks in Library

154,000 tracks

Description of Issue

I’ve created a convolution filter using Focus Fidelity, and it works just fine for stereo music; however, if I try to playback a multichannel file, it is obviously down mixed to stereo, though this does NOT show in the processing chain. If I disable the convolution filter, everything goes back to “normal”; i.e., all 8 channels (or whatever) play correctly, but my main speakers no longer have convolution applied.

I’d expect the convolution filter to apply to the front LR channels, and all other channels to be un-EQd (or, ideally, I’d like to use PEQ for all the other channels, but need to resolve this fundamental issue first).

[Suedkiez (Just a fellow user like you)]

Sounds like this? (And note the answer in the next post)

Surround loses center channel when convolution enabled

I’m not an expert here but have some DIY convolution experience. What you’re not hearing is probably the result of applying a stereo convolution impulse to multi channel audio (resulting in stereo?). Convolution is applied per channel and I think you’d need appropriate 5.1 and 7.1 convolution filters. Then Roon has to support multichannel convolution as well, not sure if it does or not.

[jhwalker (John Walker)]

Yes, this actually sounds like the same situation - frustrating. I’d hoped the convolution engine would be able to apply convolution to the channels mapped, and continue to pass normal audio through to the remaining channels. Seems an odd limitation.

[WiWavelength (Andrew J Shepherd)]

Convolution creates latency. Downmixing is the correct approach. Otherwise, some channels could be delayed by hundreds of milliseconds compared to others.

AJ

[jhwalker (John Walker)]

OR they could measure the delay (it’s a set number of taps per sampling rate) and add that to the channels not convolved

[Marin_Weigel (Bram Stoker's Cappuccino)]

Never tested it, but it may be possible to add band pass convolution filters for the surround channels when creating your main’s convolution file.

[jhwalker (John Walker)]

BTW, it appears JRiver Media Center does this correctly; i.e., it applies convolution to the LR channels and passes through the remaining channels as configured, applying the appropriate delay to keep all the channels in synch