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Splitting XLR for subwoofer

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#1
Hello forum,

I'm considering driving my home theater setup with an RME ADI-2 Dac. The problem is that it has only 1 set of xlr outputs but I have main speakers and a subwoofer.

I've had ground loop issues with my sub in the past. I fixed it by changing which outlets the sub gets plugged into, but there is still a very small hum you can hear if you sit close to the sub. I want to use XLR to try to remedy this problem.

I'll need to split the xlr signal for a power amplifier and the sub.

Is there any downside to using something simple like this?

https://www.sweetwater.com/store/de...emale-dual-xlr-male-interconnect-cable-6-inch
 
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#2
I used something identical just this weekend to split the XLR output from my SMSL SU-8 DAC; one lead to the THX headphone amp and the other to a balanced passive preamp which then leads to my studio monitors. This way I can use the headphones without having to power down the monitors (just drop the volume in the pre). Originally, I was taking the XLR out of the DAC to the Headphone amp and the SE out to the monitors but I was getting all kinds of noise. I suspected my cables but didn't feel like trying to diagnose and resolve so I went full brute force and kept XLR to both monitors and Headphone Amp.
 

AnalogSteph

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#3
As indicated, this usually works just fine.

That said, running a sub without a crossover is less than ideal, as your main speakers are still subjected to all the low bass and subsonics with corresponding excursion. I hope you have some room EQ going at least.
 
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#4
As indicated, this usually works just fine.

That said, running a sub without a crossover is less than ideal, as your main speakers are still subjected to all the low bass and subsonics with corresponding excursion. I hope you have some room EQ going at least.
That's the one thing I'm not sure about with going this way. My subwoofer has a configurable crossover built-in that I can use to low pass it, but I won't have any crossover to high pass the signal on the mains. I could of course buy a dedicated crossover device, but I'd rather not add yet another component to the chain. So I'd have to tune the DSP of the sub to match the natural roll-off of the mains. I understand this is usually considered less than ideal and that it's better to cross over the signal before splitting it?

The full plan is that I'm thinking about replacing my Devialet Expert Pro with (RME ADI-2 Dac -> Benchmark AHB2). I haven't committed to this yet, just considering it.

The main reason I'm thinking of this is because the Devialet doesn't have XLR outs for my sub (ground loop) and their software still doesn't support operation by a universal remote. I'll also end up getting money back if I sell the Devialet and buy these components.

The Devialet does have low/high pass filtering built in so that's how I do the crossover now.

I'm really surprised the ADI-2 DAC doesn't have high-pass/low-pass filtering built in. Seems like an obvious dsp feature. Even if it did that wouldn't help me here since it only has 1 set of xlr's.
 

andreasmaaan

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#5
The reason I think the RME doesn’t have crossover filters built in is that it’s really supposed to be a single output at a time device. It would be nice though.

If I were you, given it sounds like you’ve already invested quite a bit in the gear you have, I would forget the RME and put a dedicated xover in the chain. Without a HPF on the mains, you’re defeating half the purpose of having a sub. For every octave lower a woofer extends, the cone will have to displace twice as far to achieve a given SPL (if they’re sealed that is; if they’re ported the displacement below the box resonance will be even greater). I don’t know what your main speakers are, but unless they are quite large and robust to begin with, I doubt you want to do this to them.

Just my 2c...
 
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#6
I have these speakers:

http://www.salksound.com/model.php?model=Veracity+ST

If I move away from Devialet, I can't forget RME as I would still need a DAC/preamp at the head of the chain.

If I stay with the Devialet, I don't need a dedicated xover because Devialet provides software configurable DSP to high pass and low pass for mains vs sub already. The Devialet does everything in a single device which is great, but it has some annoying problems in its software. The main one being still not supporting any universal remote, which is insane to me.
 

andreasmaaan

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#7
I see. Perhaps something like this is would do that the job?

Audio performance is quite close to the RME, certainly good enough for there to be no audible difference between them. And other than crossing over your sub and mains, it has piles of useful features.

Just not sure about universal remote compatibility...
 
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#8
Wow from a feature standpoint that minidsp shd looks very compelling. I'd only need that and a power amplifier. I don't necessarily need an OS with network streaming functionality, but if I could run a roon bridge on it that would be icing on the cake.

It says it comes with an IR remote, so universal remote should not be a problem. The main issue with devialet is they don't use IR, so universal remotes like logitech harmony need to partner with them to have custom software support. It's been so long and never supported, so I don't believe it ever will be.
 

andreasmaaan

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#9
Wow from a feature standpoint that minidsp shd looks very compelling. I'd only need that and a power amplifier. I don't necessarily need an OS with network streaming functionality, but if I could run a roon bridge on it that would be icing on the cake.

It says it comes with an IR remote, so universal remote should not be a problem. The main issue with devialet is they don't use IR, so universal remotes like logitech harmony need to partner with them to have custom software support. It's been so long and never supported, so I don't believe it ever will be.
I hope that turns out to be the right solution for you then :)

Amir has measured this unit, I’m on the phone rn so can’t find the thread easily, but you should find it easily enough if you search..

EDIT: here it is.
 
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#10
I have another subwoofer question.

I have an 18" sub in my apartment. My neighbor below complained that his ceiling shakes when I play music loud. Is there anything I can do to dampen the affect of the subwoofer on the floor and consequently the apartment below me?

I'm guessing probably not..
 

andreasmaaan

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#11
I have another subwoofer question.

I have an 18" sub in my apartment. My neighbor below complained that his ceiling shakes when I play music loud. Is there anything I can do to dampen the affect of the subwoofer on the floor and consequently the apartment below me?

I'm guessing probably not..
Not within reason ;) You'd need to get inside the building and add heavy isolation material to have any serious impact I believe. I'm no expert on this , however.

If you currently have a good relationship with your neighbour you could use a sinewave generator to work out which specific frequencies resonate and cause his ceilings to shake and then filter out these frequencies using something like the MiniDSP SHD we've been discussing...
 

DonH56

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#12
re. sub vibrations: If they are from coupling to the floor you can try one of the isolation mats and see if it helps, e.g. Auralex subdudes or whatever they are called (Google: https://www.auralex.com/products/iso-series/). If it is through the air not really much you can do except turn it down. You could try playing the sub then lifting it off the floor (just hold it or place it on a couch or something fluffy) and seeing if the coupling is reduced (ask your neighbor to help monitor from downstairs). If so, then the SubDude might help; if not, bummer.

re. crossover: You can buy crossovers from ~$10 for line-level inserts to >$10k for fancy devices with lots of bells and whistles. For an inexpensive analog crossover, my go-to for many years has been the little dbx 223x. It is a pro unit, Linkwitz design, and balanced (TRS) in/out (get adapters or patch cables to convert 1/4" TRS to/from XLR). There are also miniDSP units, Marchand active and passive units, and Bryston's active design (the dbx falls between miniDSP and Marchand in price at about $200 USD).

HTH - Don
 
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AnalogSteph

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#13
The Devialet does have low/high pass filtering built in so that's how I do the crossover now.
That's good then. Possibly a bit cumbersome to match with the sub setting, but should work decently enough assuming the filter order matches. A measurement setup may be useful for fine tuning.
 
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#14
That's good then. Possibly a bit cumbersome to match with the sub setting, but should work decently enough assuming the filter order matches. A measurement setup may be useful for fine tuning.
I disable the low pass filter on the sub when using the Devialet. No reason to do it twice as you said.
 

Fone

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#15
That said, running a sub without a crossover is less than ideal, as your main speakers are still subjected to all the low bass and subsonics with corresponding excursion. I hope you have some room EQ going at least.
Agreed.

One caveat is that good subwoofer integration is difficult and takes a lot of time and effort.

Try some measurements at listening position with speakers only, with sub only, with both. You can use the free REW software; measurements are incredibly helpful. Try moving the gear around a bit. Even just a little. Placement of the speakers, sub, furniture, rugs and you can make a big difference. You can try some EQ and learn a lot through this process. You don't need perfectly flat measurements or even close. After some time maybe you find a good placement and significantly better sound.

Once I got my system sorted, I found best results running the monitors without high pass filter & without EQ. YMMV.

Without a HPF on the mains, you’re defeating half the purpose of having a sub. For every octave lower a woofer extends, the cone will have to displace twice as far to achieve a given SPL (if they’re sealed that is; if they’re ported the displacement below the box resonance will be even greater).
True. I suppose as your speakers are marketed with "sensitivity 88db" that requires a lot of horsepower.

I have an 18" sub in my apartment. My neighbor below complained that his ceiling shakes when I play music loud. Is there anything I can do to dampen the affect of the subwoofer on the floor and consequently the apartment below me?
Haha. That is problem #1.

A few tricks I found with subwoofers:

1. Once you get the subwoofer properly integrated, you really should try dropping the "volume" a bit. So the sub just disappears. This is what the good Bass player can do in a Jazz trio. It also makes things sound more integrated.

2. The so-called Fletcher Munson curve probably was the basis of the loudness button on old stereo gear. Your hearing is not linear. One easy compensation is to reduce the "volume" of the subwoofer when you are listening to music at higher "volumes". You won't get this perfect but try quick-and dirty with these pictures.
https://www.hometheatershack.com/fo...devices/12116-dynamic-eq-recommendations.html
 

andreasmaaan

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#16
True. I suppose as your speakers are marketed with "sensitivity 88db" that requires a lot of horsepower.
The horsepower (if by that you mean amplifier watts) isn't usually an issue. The problem is that even an excellent 6 to 8" woofer will struggle reproduce the bottom octave or two without significant distortion.
 

Fone

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#17
The horsepower (if by that you mean amplifier watts) isn't usually an issue. The problem is that even an excellent 6 to 8" woofer will struggle reproduce the bottom octave or two without significant distortion.
Agreed. All. Need a lot of watts. The tiny woofers just aren't going to produce much in the lower frequencies. Lots of excursion and distortion from drivers that are being pushed hard.

Blessing in disguise as OP has neighbor problems.
 
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