Roon 3 way - Active Crossovers

HI,

I would like to create an active 3 three way setup using Roon as my music player and crossover manager.

The configuration would be three stereo channels.
3x RPI 4’s connected to individual USB Dacs and amplifier channels.

I would like the following:

  • Ability to link three Roon zones. Creating Zones/Streams for filtered High’s, Mid’s, Low’s, via the individual RIP4’s (as above).
  • Utilise the Roon DSP PEQ functions for each RPI zone to create software based active crossovers.

Is this possible?
If not, is there another way to create an active three way setup?

Thanks
Steve

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It sounds like an interesting approach, but I would guess that latency/clock differences could be an issue if you were trying to listen to three zones at the same time.

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Roadblock:
I did some testing… It seems, PEQ DSP on individual zones is not maintained when grouped?
Not sure why this would be the case.

Additionally, it would be great to understand if the Roon zones are perfectly matched for latency when grouped. Maybe someone from Roon could answer this?

You need a multi-channel DAC. For your case minimum 6 x line outputs.

I’m mucking around with a 3-way DSP active setup using this:

https://focusrite.com/en/usb-audio-interface/scarlett/scarlett-18i20

Then use Audiolense software to create the convolution filters.

In Audiolense you set the DSP crossovers and room target curves.

You need a microphone of course, to take measurements. The Focusrite has a good built-in mic pre (mic input).

Audiolense will spit out your convolution files which you can import into Roon.

For Audiolense questions, best to join the Audiolense forum:
https://groups.google.com/g/audiolense?pli=1

Acourate is another good program you could use. Join the Acourate forum for any questions:
https://www.audiovero.de/acourateforum/

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Thanks that information, it is very helpful.

Do you know how many channels of convolution EQ Roon can perform simultaneously?

IMO, it seems like a glaring oversight that Roon cannot group zones, to allow users to create grouped streams (High, Mid, Low) for active setups. The Roon PEQ interface is a much simpler method for crossover implementation, IMO.

Nope I don’t know the maximum number but for your 6-channel case, not a problem in Roon.

Hi Stephen,

The good: you can do DSP with grouped zones. They must be RAAT zones, not Chromecast, AIrplay, Sonos, see here: Grouped zone DSP?

The bad: @dabassgoesboomboom is unfortunately right, it will only work well with a multichannel DAC. Three different DAC will have different clocks, they will drift, Roon will sort of keep them in sync but at the sample level, which is definitely not enough.
Your idea can work for a sub at let’s say below 500Hz, but even there measurements with a microphone are necessary to check time alignment.

So there’s no way but to build or buy a true multi-channel DAC. The low cost option is miniDSP DAC8, but I am not recommending it for high end hifi. Other options include Exasound, Okto Research.

For filters you can start with Roon Procedural EQ, but only one type of filters available (at various slopes though). A microphone is absolutely mandatory to fine tune frequency and time response of all speakers.
For filter designs and measurement, REW and Rephase are a good free alternative to Audiolense and Acourate. Roon convolution engine is very good and cope with various filter formats and configuration files.
My 2x4 active system has been developed with REW and Rephase, UMIK1 microphone. Convolution filters are implemented in Roon with a .CFG configuration file (stereo --> 8 way). DAC is Exasound E28. Very stable and works like a charm.

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Ok great information. Thanks. So a RPI ropieee end point or multiple ropieee end points would work fine?

If I use the same DACs for all RPIs would this not be ok? I can time align via REW, or similar.

I don’t understand why there would be a concern, assuming roon is latency and time matched.

I think you might find that the clocks in all of the DACs will be very slightly different and therefore the zones will eventually become out of sync. That said, I can’t give a view on how much of an issue it would be in real life. I think it is this issue which has held up the Roon Readiness of the D&D 8c active speakers for a few years - keeping two speakers with two separate DACs in time.

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It’s not the clocks in the dac. They don’t drift very much. It’s the ethernet buffering that causes drift. This is not a problem if your speakers of different zones ar far apart. You won’t notice a 1ms drift. For a crossocer a drift of 1ms is easily audible and unacceptable. This is not something Roon can easily solve. They would have to abbandon all buffering wich is not a good idea for ethernet audio transport. Stick with one zone and a multichannel dac. You can use PEQ crossovers that way too. Not advisable either, but for other reasons. It only knows textbook crossovers wich rarely work right with non-textbook behaving drivers (almost any driver that is) Just have a look at the procedual EQ tab, you can add peq per channel there.

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Thanks for this information. Very Helpful, I will take at Procedual EQ.

Good information can be found here: Roon Active Crossover (or How Good is RAAT synchronisation)?

Hi Alec, thanks for your excellent post. I’ve just ordered an Okto DAC8 Pro to do exactly what you’re currently doing. I’m intending to set up 3 grouped zones for a 3-way low/mid/high setup using just Roon’s DSP. (Hopefully I can use ASIO.) Your post has given me more confidence that this should work fine.

I’ll post my findings once the DAC arrives and I’ve had a chance to try things… in case others want to go the same route.

Mani.

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Hello Mani, very good!
Don’t set up 3 zones but only one, with all channels. I believe Okto has an ASIO driver now check with them.

The Okto manual still says to download ASIO4ALL. But I’ll check with Okto support once the DAC arrives. I’m in the UK, but hopefully there won’t be any issues getting the unit across to me ;-).

I currently use PEQ with my 2-channel DAC and just assumed that I’d have to set up 3 grouped zones for 6-channels. But if I can use a single zone, and assign different filters to different ASIO channels, then that’d be great.

Might need your expertise, if you don’t mind…

Mani.

No worries. Use one zone. Roon DSP Parametric equalizer can do the 2way to 6 way filtering.

From a Roon perspective, its pretty straight forward. Go into your DSP settings.

Click Procedural EQ.
Click add operation bottom left.
Click Parametric Equaliser.

You will now see PEQ can be assigned upto 8 channels, in the right window.

Question?
Does the Okto Dac8 allow left and right stereo feeds to be routed internally to any channel inside the Dac? I have a sneaky suspicion you are going to need additional software, like audiolense/Ekio to make this a reality. My understanding is the okto dac8 is just a dac, it will not allow internal routing of stereo sources like an interface does.

Multichannel needs to be handled by your PC, roon doesn’t do this. Hopefully some okto users can chime in.

I know with pro interfaces like Focusrite, etc the supplied software allows internal routing capability (Which is a big benefit).

@grizaudio you’re wrong Roon handles stereo to multichannel up to 8 channels.

Uou can also perform all channel filtering and routing inside the DAC8 Pro (using the XMOS chip computing power) or and attached PI.

Hi there,

Are you an Okto Dac8 pro owner?
Have you tried the unit with a RPI4 personally? If so, I would love to know what OS you use, Linux, Ropieee, etc?

I have since done a little investigating via google and with Okto users in Australia.
Creating an active crossover appears to be possible within Roon using either Procedural or Convolution filters. It would be great if Okto provide a guide for this.

Reviewing Procedural EQ within Roon, the feature provides a quick and easy method of applying EQ/crossovers to multiple independent/group channels, as well as a mix routing option if needed.

Reviewing information on Roon Convolution filters, it seems third party software like Audiolense, REW, Rephase needs to be used to calculate your filters (Crossover, Delay, PEQ correction, Phase etc) utilising speaker and room measurements via microphone. These filters are then imported into Roon (via a zip file) which sets your crossover, filter correction and routing.

I agree the Okto Dac8 pro provides a basic I/O matrix, but for an active speaker setup whereby DSP crossovers are applied in the PC, I don’t think this particularly helps. Unless of course you have multiple channels using the same processing input. Signal processing/routing needs to be completed in the Roon environment, in order to provide discrete equalised channels for output.

As for performing filtering inside the Dac8 pro, this is not what the units documentation states.
The unit is a Dac only. The only filtering selection on the Dac8 pro, is the filter reconstruction settings.
7 filters are possible. https://www.oktoresearch.com/assets/dac8pro/DAC8PRO_owners_manual.pdf
These are not crossover filters.

But I agree the XMOS would be used to pass bidirectional audio across the USB connection, inline with your connections and application.

It would be great to hear from Okto Dac 8 pro Roon users with Active speaker setups, explaining their setups, and required configuration.

Hi Alec,

My Okto dac8 PRO has finally arrived… only 3 months or so late! Better late than never :slightly_smiling_face:

As you said, the dac8 PRO has internal routing that allows the input channels to map to any of the output channels. If I map input 1 to output 1, input 2 to output 2, etc., I can only get the first two channels to output anything.

I’ve tried all the various ‘Channel layout’ and ‘Mutlichannel mixing’ settings in Roon, but still, I get no output from the last 6 channels.

Any ideas?

Cheers,
Mani.

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