FXRoute, browser-controlled Linux audio player and DSP control surface for mini PCs

[john61ct]

So all that was available for 2.2 stereo base before, just without the summing to mono?

 

[cobby]

So all that was available for 2.2 stereo base before, just without the summing to mono?

Not exactly. Before this, FXRoute itself was basically stereo-focused. EasyEffects still runs as the stereo DSP stage, but the 2.1 crossover is a separate real-time stage added after that.

The new mode routes L/R mains to outputs 1/2 and creates a summed mono sub signal for outputs 3/4, with crossover, level, polarity and bidirectional alignment. So this is the first integrated bass-management mode in FXRoute, not just an existing 2.2 mode with mono summing.

A real 2.2 mode would be a logical variant, the more useful next step would probably be dual mono sub integration: summed L+R bass sent to two sub outputs, but with separate delay/level/polarity/ maybe EQ for each sub. Below a typical 80 Hz crossover, room integration usually matters more than preserving stereo bass.

A true stereo-bass 2.2 mode could still be an option later, but it is not the same thing as two independently aligned mono subs.

 

[Salt]

J._J. recommends bass down to 40 Hz to be close to the main speakers, so subs placed apart of that, focussed on sub 40 Hz, would require 3.2, if main speakers are 3 (or 2 plus sub).

 

[cobby]

J._J. recommends bass down to 40 Hz to be close to the main speakers, so subs placed apart of that, focussed on sub 40 Hz, would require 3.2, if main speakers are 3 (or 2 plus sub).

Yes, I see what you mean. If the additional subs are only used below ~40 Hz, then everything above that remains with the main speakers, so it is more like stereo bass / full-range mains with infra-sub support.

My first idea for 2.2 was different: dual mono subs, with summed L+R bass on outputs 3 and 4, but separate delay/level/polarity/EQ for each sub to improve room integration.

Edit:
With main high-pass off and the sub low-pass set around 40 Hz, the current 2.1 mode already works as full-range stereo mains plus mono infra-sub support, tbc.

 

[john61ct]

A real 2.2 mode

Future feature request then please

IMO all tools that do "bass management" should allow stereo bass all the way down, with feature parity to ".1"

Especially since your tool allows for level matched ABX testing, would be super helpful in design choices.

But I understand low priority, maybe on the way to multiple bed channels sometime...

 

[cobby]

Future feature request then please

IMO all tools that do "bass management" should allow stereo bass all the way down, with feature parity to ".1"

Especially since your tool allows for level matched ABX testing, would be super helpful in design choices.

But I understand low priority, maybe on the way to multiple bed channels sometime...

Yes, I agree that this should be a separate future feature request.

I think there are two different “2.2” concepts that should be kept apart:

1. Dual mono subs:
L+R bass is summed to mono and sent to two sub outputs, but each sub has independent delay / level / polarity / EQ. This is mainly about room integration and smoother bass response.

2. True stereo bass:
Left bass stays on the left low-frequency output, right bass stays on the right low-frequency output, with the same feature set as .1 bass management. This is more about preserving stereo bass / localization cues and would usually make most sense when the bass sources are close to the main speakers.

The current 2.1 mode is the first simple bass-management step. A dual-mono 2.2 mode is probably the more practical room-integration next step, but I agree that true stereo bass would be useful too, especially for ABX testing and comparing different system designs.

So yes: feature request noted, ideas welcome.

 

[john61ct]

Yes, I think that is the commonly known distinction.

What I hope is one day to be able to instantly switch between those modes, ideally level matched

and blind ABX, even if that requires help from a fellow human

 

[cobby]

FXRoute 0.7.41: Auto Sub Optimize for 2.1 setups


FXRoute 0.7.41 adds a new Auto Sub Optimize feature for 2.1 mode.

The idea is simple: after setting the crossover frequency and a rough subwoofer level/alignment, FXRoute can automatically run a bass-focused delay scan around the current sub_alignment_ms value. The scan range is derived from the selected crossover frequency, so lower crossover points use wider delay steps and higher crossover points use finer steps.

The optimizer measures both Left+Sub and Right+Sub for each delay candidate and chooses one shared sub alignment value that works reasonably well for both channels.
If the coarse scan finds a close result, a fine scan is run around the best delay region.

The feature currently adjusts delay only. It does not automatically change sub gain, polarity, PEQ, target curve, or convolver filters.

The result display shows the applied delay, the overall score, and the individual L/R scores. In my tests this has been useful for quickly finding a plausible sub alignment without manually repeating many sweeps.

Recommended workflow:

1. Set up the 2.1 crossover roughly.
2. Run Auto Sub Optimize once.
3. Create or enable EQ / convolver correction.
4. Run Auto Sub Optimize again with the final processing active.
5. Verify with a normal 2.1 measurement.

 

[cobby]

FXRoute 0.7.42 is a small hotfix for 2.1 measurement handling. It fixes a frontend, changing a subwoofer setting.

 

[cobby]

Before After, Blue is 0ms (default), Orange is with delay.

 

[cobby]

0.7.43 - FXRoute now supports 2.2 Subwoofer mode for stereo systems.

This is stereo playback with two independently controlled mono subwoofer outputs: Out 1/2 are the mains, Out 3 is Sub 1 and Out 4 is Sub 2. Both subs receive summed L+R bass, but each has its own level, polarity and alignment delay.

This allows more flexible sub placement, for example front/back or asymmetric room-based placement.

Auto Sub Optimize also works in 2.2 mode: it optimizes each sub individually and then runs a small combined matrix refinement with both subs active.

 

[john61ct]

Hoooraaayyy!

Please support stereo subs, one day.

Rest here is just OOTB wishlist stuff, thanks for all your work, no expectations just input FYI consideration.

In my case there is a pair of MBM Couplers, from 70-80Hz up to ~180Hz supporting the main pair.

And to get all the way down to 20Hz within my form factor limitation, I might end up with a stack of 4x total boxen each side, as "emulated floorstanders"

the subs below 80Hz I want to be able to quick-switch ABX blind test between stereo and summed mono.

 

[Salt]

Hoooraaayyy!

Please support stereo subs, one day.

Rest here is just OOTB wishlist stuff, thanks for all your work, no expectations just input FYI consideration.

In my case there is a pair of MBM Couplers, from 70-80Hz up to ~180Hz supporting the main pair.

And to get all the way down to 20Hz within my form factor limitation, I might end up with a stack of 4x total boxen each side, as "emulated floorstanders"

the subs below 80Hz I want to be able to quick-switch ABX blind test between stereo and summed mono.

Ehem..
https://www.audiosciencereview.com/...ntrol-surface-for-mini-pcs.70930/post-2622740

 

[john61ct]

wut?

 

[Salt]

.7.43 - FXRoute now supports 2.2 Subwoofer mode for stereo systems.

 

[john61ct]

> stereo playback with two independently controlled mono subwoofer outputs

> Both subs receive summed L+R bass

 

[Salt]

You're short on ignore list, and not only here...

 

[cobby]

Sry guys, my fault, to get that straight.

The current 2.2 mode is meant for stereo listening, but it is not stereo-bass routing. The main speakers remain normal L/R stereo, while the subwoofer feed is summed mono bass.

So the current mode is:

stereo playback + two independently controlled mono sub outputs

Both subs receive L+R bass, but each has its own level, polarity and alignment delay. This is more like classic mono multi-sub bass management, mainly intended for flexible placement and room integration.

A separate 2.2 stereo-bass mode absolutely makes sense, especially for setups like yours with MBM couplers or higher crossover points around 80–180 Hz. In that mode Sub 1 would follow the left bass channel and Sub 2 the right bass channel.

I think the clean solution is to keep both concepts separate:

- 2.2 mono multi-sub: both subs get summed L+R bass
- 2.2 stereo bass: left sub gets L bass, right sub gets R bass

The current release is the first one. Stereo-bass is a logical next step, working on it.

 

[john61ct]

Wow, so responsive thanks! Feel free to put more central /critical stuff higher priority.

And sorry Salt did not think that would ruffle any feathers

 

[cobby]

FXRoute 0.7.45 adds a separate 2.2 Stereo Bass mode.

The previous 2.2 mode is still available and remains mono multi-sub bass management: both subs receive summed L+R bass, with independent level, polarity and alignment.

The new 2.2 Stereo Bass mode keeps the bass channels separate:

- Out 1: Left main
- Out 2: Right main
- Out 3: Left sub
- Out 4: Right sub

So Sub 1 follows the left bass channel and Sub 2 follows the right bass channel. This is meant for setups where the subs are placed close to the main speakers, or where the crossover is high enough that stereo bass / midbass information may matter.

Auto Sub Optimize also supports this mode. In stereo-bass mode it aligns the left sub to the left main and the right sub to the right main, instead of using the mono multi-sub matrix approach.

The screenshot shows a quick test with a very imperfect second test sub it was good enough to verify that the routing and alignment work: blue is after AutoSub, orange is before, and the improvement is clearly visible in the crossover / midbass region.

GitHub - CobbyCode/fxroute: Browser-controlled audio player and DSP control surface for Linux mini PCs, desktops, and dedicated audio machines.

Browser-controlled audio player and DSP control surface for Linux mini PCs, desktops, and dedicated audio machines. - CobbyCode/fxroute

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