Procedural EQ Mix and Delta Signal Modulator

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

Roon 1.7 Build 555 running on SonicTransporter running 2.7

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

cat 8 ethernet connected to ExaSound PlayPoint

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

ExaSound PlayPoint connected by usb cable ExaSound e38 multichannel dac into Placette passive multichannel preamp (custom made) a 5.1 surround sound system of B&W 801s (matrix) with Custom North Creek crossovers. I have removed the base equalizers that were part of the original B&W 801s because running the line level signal though them diminishes the sound slightly. I have done all base management to correct for this is the analog domain with a subwoofer.

Description Of Issue

This is a question not a technical problem I am trying to solve. It is a request for technical information.

I have build my entire system around doing as little digital processing as possible. Most of my files are DSD 64 files and any processing for bass management or room EQ diminishes the sound quality.

With Roon’s Procedural EQ I am starting to make and exception by routing signals from the speakers into the subwoofer. All speaker are full range, so the sub is used only for the very bottom end. When I turn on the EQ with only the mix running and only routing full signal to the subwoofers, the Delta Signal Modulator is engaged. I understand the technicalities of why this is so–to mix various source signals and the reconvert them to DSD. My question is this: Does the DSD mess with the digital signal that is going direct to the speakers (Right to Right or Left to Left, for example)? Are these signals left unaltered? Are only the Digital signals that are going to the Sub modulated (Right to sub, Left to sub, etc.)? I can live with modulation in the signal going to the Sub, but do not want to have modulation of the signals going to the other speakers. I look forward to learning if the mix I am using leaves the main and surround speaker signals unaltered.

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Hello @Robert_Anderson1,

We’ve forwarded this question to the development team, we will be sure to relay their response once they’ve had a change to look over it.

-John

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Thanks John, I am noticing a subtle loss in delicacy in the music when I use the Procedural EQ to send signals from the speakers to the sub. I have stopped using it as I favor the sound with the EQ out of the mix. I would like and answer when they get back to you. Thanks, Bob

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Hello @Robert_Anderson1,

When the “Sigma Delta Modulator” is shown in the Signal Path, Roon is converting the 1bit DSD content to a 64bit “DSD Wide” representation to perform the required DSP for the operation. The sample rate of the content is retained when this occurs. Once the DSP operations have been performed on the audio, Roon then remodulates the audio back to single bit.

Roon does not selectively apply the process on a per channel basis. If the DSP requires the modulation, all of the channels will undergo the 1bit -> 64bit -> 1bit process.

-John

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Thanks John. This is consistent with my listening. I notice the loss in musicality and nuance from all the conversion. The sound is still quite good, but not as good. I suggest that you change this to leave channels unaffected if possible. For example if I am sending the right front channel to the sub, there is no need to modulate the right front channel, only the combined sub channel. This would maintaining the purity of the DSD digital path to the mains. I have no idea if this is technically possible, but, if it were, it would really improve sound.

On a side note, I have spent years customizing and building a DSD surround sound system that requires no digital manipulation of the signal. It always degrades the sound quality.

I love Roon by the way.

Bob

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