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Dual Sub Setup - LFE vs Line Level Y-splitter (and a Bonus RC Dip!)

Connor1a

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Hi Gang

My saga continues.

My two SVS SB 1000 Pros are in and powered up.

Right now I have them in a stereo configuration coming off my WiiM Ultra via a pair of Y-splitters to their RCA R/L in ports. So that’s:

WiiM Ultra (R) RCA-Out -> Y-splitter -> SVS Sub (R) RCA-In // -> NCx500 RCA-In -> Speaker
WiiM Ultra (L) RCA-Out -> Y-splitter -> SVS Sub (L) RCA-In // -> NCx500 RCA-In -> Speaker

Everything is cooking. However, nothing is flawless…

I do not currently have the Low Pass Filter enabled on the subs. I have Room Gain Compensation enabled on both subs at set at 25 Hz. I have 2 PEQs setup for both subs. One low Q at 50 Hz. Another low Q at 85 Hz. The resulting graphic is what WiiM’s RC software (with their custom PEQs) has come up with:

IMG_0561.jpeg

I’ve tried to affect that dip at 50 Hz a dozen times. It’s immune to PEQ. My theory is that it’s a resonance between WiiM’s RC wave and my house’s flooring / frame that can’t be addressed without a building permit. It’s a 1940’s home. The floors are right on top of vintage steel beams. There’s a pronounced vibration when WiiM sends out its wave that I can feel in the seat of my pants. It was there when I ran RC with just the mains as well. So it’s not just the subs. However, the effect is more pronounced. Regardless, I don't think moving the subs to another location would make a difference, but I’d be interested in your thoughts…

The other thing on my mind is whether to use LFE or keep the stereo configuration I have running right now. Thoughts? Is there value in running LFE vs stereo? It’s easy enough to switch out.iI’d thought the stereo setup would lend itself to better matching between the speakers. I didn’t intend to high pass my mains (Wharfedale Linton 85s - they extend to 40 Hz), but I was going to low pass the subs. My thought was to do that manually via the SVS app, but I wasn’t clear what I should set it to. Any recommendations? WRT blending, is that best done via volume? Once the low pass was established that is.

Thanks in advance!
 
The other thing on my mind is whether to use LFE or keep the stereo configuration I have running right now. Thoughts?
I'd use LFE.

There's a lot of sub integration features in the WiiM that are left unused by splitting the signal from Line out.
 
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Does the WiiM Ultra allow you to adjust distance / delay for the subs? You could probably fix at least some of the severity of those dips by aligning the subs with each other, and aligning the sub "pair" with the speakers.

Might be hard to get things really dialed in with just the WiiM. If you can do REW with a decent microphone, you'll be able to get much better measurements so you can use the WiiM settings with more accuracy.
 
You'd certainly do better using the subwoofer out to the speakers rather than tapping off the line outs as you currently do, as staticV3 pointed out.

I also don't see a good reason to avoid high-passing the mains. If you want to use your mains' extension, you can do the crossover at a low frequency like 40 or 50 Hz rather than the standard 80.

However, for the best integration you want something where you can EQ the subwoofers separately to integrate them. Wiim units can't do that unfortunately. You could add something like a MiniDSP 2x4 HD though.
 
However, for the best integration you want something where you can EQ the subwoofers separately to integrate them. Wiim units can't do that unfortunately. You could add something like a MiniDSP 2x4 HD though.
As referenced above by @staticV3, the SVS subs come with a Bluetooth management app (both iOS and Android). It’s not the friendliest app, but it covers all the bases. For the SB 1000 Pro it gives you 3 PEQs. On some of the larger subs they’ll give you 6. Screenshot attached.

IMG_0562.png
 
Yes.


The SVS subs have their own, built-in PEQ which can be used for this purpose.
Any idea what could be causing that dip at 50 Hz? I’m looking at buying a pair of isolation stands to see if they’d make a difference, but something tells me that they won’t; it’s a matter of the harmonics of the room I have (which is just not going to be helpful…). It’s strange that its so specific and pronounced.
 
Does the WiiM Ultra allow you to adjust distance / delay for the subs?
It has a latency setting for mains in aggregate (vs per channel) and one for sub(s) in aggregate.
 
Any idea what could be causing that dip at 50 Hz?
A room mode.

If you replicate your listening room in REW's room sim, then it'll likely confirm that.

looking at buying a pair of isolation stands to see if they’d make a difference, but something tells me that they won’t
They won't.

It’s strange that its so specific and pronounced.
Not strange at all. That's how most rooms measure.
 
That dip at 52 Hz corresponds with a mode of a room dimension of 330cm (if it’s a regular shoebox shaped room).
 
If you replicate your listening room in REW's room sim, then it'll likely confirm that.
Alright. I’ve been beaten into submission. I have an Intel Nuc PC floating around with Windoze installed and just ordered a UMIK-1 microphone (btw - if you don’t need Amazon’s convenience, the price for MiniDSP’s products is about 25% cheaper on their own website vs Amazon’s - that may be just for the holidays - don't know). It wont be pretty, but I’ll cart a monitor and keyboard up from the basement and get REW working in my listening room to see what it comes up with.

Out of curiosity, how does the WiiM’s DSP compare to MiniDSP’s DSP (the 2x4 HD model)? Clearly, the WiiM has a host of functions the MiniDSP doesn’t, but is the RC function materially different / more powerful?
 
Alright. I’ve been beaten into submission. I have an Intel Nuc PC floating around with Windoze installed and just ordered a UMIK-1 microphone (btw - if you don’t need Amazon’s convenience, the price for MiniDSP’s products is about 25% cheaper on their own website vs Amazon’s - that may be just for the holidays - don't know). It wont be pretty, but I’ll cart a monitor and keyboard up from the basement and get REW working in my listening room to see what it comes up with.
Actually, there's no need to move you entire PC setup.

You can export some test tones like pink noise and measurement sweeps from REW as .WAV files, play them back locally on your system, then record the result with the UMIK-1 and a phone or tablet.

Then, import the recordings into REW and it'll analyze them all the same.

Out of curiosity, how does the WiiM’s DSP compare to MiniDSP’s DSP (the 2x4 HD model)?
The miniDSP is more configurable and supports FIR filters, but the WiiM gets you most of the way there.
 
That dip at 52 Hz corresponds with a mode of a room dimension of 330cm (if it’s a regular shoebox shaped room).
What you’re suggesting is where the sound waves are “synchronizing” such that I’m getting a “trough” at ~50 Hz (sorry, I’m not a physicist). Would toeing in / out the subs help break that resonance? Alternatively, I guess moving one or both of the subs to the longer wall would also affect that phenomenon. I already have Room Gain Compensation enabled, but that’s different. That’s about boominess (excessive bass) vs a lack of bass at a specific frequency. Yes?
 
For that null at 50Hz I would probably turn one sub off and remeasure. Then I would measure again with the input signal inverted.

The other thing you could try would be a few REW measurements and then see what MSO suggests.
 
You can export some test tones like pink noise and measurement sweeps from REW as .WAV files, play them back locally on your system, then record the result with the UMIK-1 and a phone or tablet.
The tricky bit is getting the WiiM to play the measurement sweeps. Unfortunately, I’m invested in the Apple ecosystem. I have apps would play a file to the WiiM were it Airplay compatible, but its not (nor is there any outlook to be). It does act as a Bluetooth endpoint, but the connection is flakey (or at least it is for me). I’ll give it a try though. The mic arrives tomorrow.

For that null at 50Hz I would probably turn one sub off and remeasure. Then I would measure again with the input signal inverted.
So I was testing yesterday with one sub and that same trough existed. It was there with both subs off as well.

Do you mean changing the phase from 0 to 180 on one of the subs? Or do you mean changing the polarity on the sub(s)? Sorry, I’m still learning the vocabulary.
 
Do you mean changing the phase from 0 to 180 on one of the subs? Or do you mean changing the polarity on the sub(s)? Sorry, I’m still learning the vocabulary.

Either way would would work, I'm guessing that changing the phase 180 is easier and faster
 
Either way would would work, I'm guessing that changing the phase 180 is easier and faster
Give that guy a cigar! Changed the phase to 180 on one sub and achieved the following result:

IMG_0564.jpeg

To me, that’s a huge improvement. I can tinker to fine tune, but I think that’s a pretty decent result. Thanks @Devnull !!!
 
The saga will continue... I have a mic coming in and have pulled out my Nuc PC w/ Windoze. I’ll install REW and see what it can pull out.

To recap, I’ve managed to get from this:

IMG_0553.jpeg

To something along the lines of this:

IMG_0575.jpeg

I’m running my WiiM with Sub S/W enabled in order to set a HPF for my mains at 50 Hz even though I have the subs cabled in a stereo configuration (which from what I’ve read is the preferred configuration for a primarily music setup which is what I have / LFE being weighted more heavily for HT). I have my subs set to a LPF at 50 Hz via the SVS app. It seems to blend fairly well. My listening room still has several pesky issues. There are a couple of dips between ~ 75 Hz and ~ 200 Hz that I can’t completely PEQ smooth out. But progress if not perfection.

I’d love to see others’ scan results. I don’t honestly know whether what I have here is great, good, good enough or a pile ‘o poo. Qualitatively, it’s rocking along pretty good. My neighbors should be able to feel the bass. That alone is worth the price to admission…
 
I’m running my WiiM with Sub S/W enabled in order to set a HPF for my mains at 50 Hz even though I have the subs cabled in a stereo configuration (which from what I’ve read is the preferred configuration for a primarily music setup which is what I have / LFE being weighted more heavily for HT). I have my subs set to a LPF at 50 Hz via the SVS app.
For music listening with 50Hz crossover frequency, stereo subwoofer playback serves no real purpose and only complicates matters.

Feel free to let the WiiM downmix bass to Mono, then feed that to the two subs.
 
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