Using a Subwoofer with Roon and crossover help

Hi, I am currently trying to integrate a subwoofer into my setup. Id like the sub to handle the lows and the Main speakers Elac Ub51 only the mids and highs. The way I currently have it is I have turned on the 3.5mm headphone jack to my RPI running Dietpi, this Dac also has a Hifiberry Digi2 pro I shoot out SPDIF to my dac. I then creted a group or zone using the 3.5mm with RCA outs going to power amp only for the sub. this allows the sub to get a seperate signal. So now how do I set up the EQ to send only say 80hz and above to Elac and rest to sub? DO I use a Low pass on sub and a high pass on mains?

I can’t tell you specifically how to set that up in Roon but can confirm this is how my system hardware handles this.
My settings are: Low pass @ 47.5 High Pass @ 67.5.
Avoid the common error of setting these the same as crossover slope isn’t (usually) a brick wall filter and you’ll get better integration with some variance in these settings.

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I think the easiest solution would be to use an integrated amp with a subwoofer pre-out. Yours may already have one.


Yes, I do have a Cambridge Audio with sub out, however this is for use with a ICepower amp I just built, no subwoofer out on that.

Let us know how this works out.
Not to spoil the party but I’m wondering if using two zones in one room might introduce some timing issues?

Edit: I’m real curious about this.
But also wondering if you’d be better served by a hardware crossover?

I’m not familiar with ICEpower, but that looks like a power amp, so you must be using a preamp, right? In that case, you can send the preamp out to both the power amp and the subwoofer. The latter most probably has its own lowpass filter, and I think it’s ok to send the full signal to the main speakers.

I think you can use it without a preamp, controlling volume from roon.

That is what I would do.

but if you do not have a preamp and use the dac controlled from roon maybe you can use an Y connector at the output of the dac and have one wire to ICe and one to sub (assuming the sub has left and right connections).

I once tried and grouped 2 systems in the same room, I did not notice any delay but it was just for fun. It would be risky but why not try.


Icepower is Danish Class D amp modules really clean amp, ita the ICEpower 125asxs so its a power amp and I ise my Dac as a preamp into it.

NO delay at all as Its both coming from same thins essentially. I have the RPI with digi2 pro shoot out to my Dac a Beresford Caiman dac, now I have BOTH grouped.

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Thanks for confirming. As @Traian_Boldea said, you can use an RCA splitter and connect the pre out from the DAC to both subwoofer and power amp. Input impedances should be high enough not to strain the output, but you should double check, just in case.
Or, since you built it yourself and if you’re in the mood, you could add an RCA pass-through out and not use a splitter - or perhaps even add a passive lowpass filter and make it a sub pre-out.

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THe sub is a Velodyne that the plate amp, died. I am using a Class D amp to power the sub now. no crossover on sub now just direct full frequenc, however this works great actually. I may get a passive crossover put it inline before the SUb in.

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It’s best not to send high frequencies to the transducer, just in case. If you add a crossover, you don’t need the splitter.

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Yes but the low pass filter Im using in Roon DSP is now only sending 70 and below

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Ok, I thought you were sending full frequencies to it, as you said. Still:

  • We are discussing solutions that don’t use Roon DSP.
  • Ideally, the subwoofer should work with any source, not only Roon.

Yes, but my original question or Topic was asking how to integrate a Sub woofer that doesnt have any physical crossover at all in the equation. I was wondering what was a good way touse the DSP to do that.
For now Im pleased with using two zones and using the DSP in Roon to split the frequencies. Its working very good right now using the Low pass and High pass on seperate zones. Thanks for help all. I am planning on getting a passive crossover to integrate it better.


To be clear, I gutted out a Velodyne sub, tok out the entire plate amp which failed and decided to try a cheaper alternative. Being the fiddler techy crazy guy I am I just bought a class D amp a smal chinese one for subwoofer, its the Nobsound G2 pro, this does have a crossover and its mono and appx about 200 watts or so. I didnt like the crossover on the amp much so decided open up the frequency to it and try roon DSP as crossovers. Im mostly just experimenting

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Sounds fun. I was planning to try roon grouping for crossover my subs after I bought a mic and started REW. Dropped any plans when got my head spinning with HQP, now researching computer parts for a HQP server build :slight_smile: I still might try the crossover as now I have 2 iFi Zen Dacs (one v2 and one sig v2). And when researching that I found that on Mac I can aggregate 2 usb into one.

It’s all fun, but don’t fall into the trap of getting a supercomputer to “improve” on crossover. There’s not much to improve there, other than the crossover frequency, which can be done with a trim pot.

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Oh, the computer is just for HQP. The crossover is just playing around. I still didn’t fully take all the things I wanted out of REW. And I still one day what to diy some speakers… and it never ends :slight_smile: