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Sonos Amp and High level input from Subwooder?


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I have a Sonos Amp, and a Definitive Tech Sub Pro 800 that has both the mono RCA LFE option (What is connected now) and also has the option to connect via high level input. Real Subwoofers have this too.

Can this work with the Sonos Amp? I searched but did not find an answer. So basically I’d connect my Def Tech sub to the left and right speaker channels of the amp, and then I would connect my 2 front speakers to the back of the sub.

Will that work or do I have to keep using the LFE? It’s for music, so I figured using the High Level input may sound better as the sub would get the same signal as the speakers, right? Or am I mistaken?

Thanks!
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Best answer by jgatie 10 April 2019, 14:28

You are mistaken. The signal will be the same, the only difference being use of crossover on the Amp vs the crossover on the Sub (and those differences should be inaudible).

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You are mistaken. The signal will be the same, the only difference being use of crossover on the Amp vs the crossover on the Sub (and those differences should be inaudible).
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The full signal input on a sub is usually for use with amps that don’t have a dedicated sub output. I think you’re better off continuing to use the Amp’s sub output, with the crossover frequency adjusted to suit your sub / your tastes.
In a high level connection you would wire your speaker terminals on the Connect Amp to the speakers as well as to the high level inputs on the Sub.
A cut paste on the alleged benefit of doing this:
"In fact, even if your preamp or integrated has a preamp/subwoofer output, you may want to consider using the high-level connection method. The most prestigious subwoofers in the industry are made by REL of England. They are the “Gold Standard” of the industry and priced accordingly, topping out at $9,000! REL recommends using the high-level input for all of their subwoofers. The reason they recommend this type of connection is as simple as it is logical: it ensures your subwoofer is seeing the EXACT SAME SIGNAL as your speakers. If you use the preamp/subwoofer output from your preamp or integrated, the signal seen by your subwoofer does not include the tonal balance and timing cues created by the amp. By using the high-level connection, the subwoofer gets the same signal as your main speakers, keeping them in better synch with each other, thus improving sound quality."
Easy enough to verify this claim if you have the time and the inclination to experiment.
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Sounds like audiophile snake oil to me (“tonal balance and timing cues”), but I guess it’s better to be open minded :)
Lol.
More on the theory of high level connections from the speaker terminals on the amp to both the speaker pair and the Sub:

"This might lead you to ask if there is any point using the high level connection, but for some there might be. Firstly there is a subtle difference between the crossover typically used in the high and low level connections. In simple terms, the crossover for the high level connection will usually use a more gradual slope, which in theory could lead to a smoother integration between sub and speakers, where the speakers are full range. This leads to the second important point. Speakers being run in full range mode will not crossover according to the setting in the processor, instead they will output material down to what ever frequency response they are capable of, so this is why the crossover on the subwoofer for the high level connection is more important. The crossover frequency should be matched to the natural low end frequency response of the speakers being used, and this will vary from speaker to speaker. If you are using small sats, then there seem little point in using the high level connection, but if you have larger more full range speakers, then for music this may be preferable. In my own experience, larger speakers will have their character changed when filtered by a processor at 80hz, and this can impact music negatively. If this is the case, then running the high level connection can restore the speakers natural character, while still allowing a subwoofer to improve the low end response, and the end result can be positive for musical listening experiences."

The point about high end being better for speakers that themselves go down deep with enough energy there seems to be a good one.

Again, easy enough to verify and decide for oneself.
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Ok, I had planned on getting a Rel sub and the high level connection sounded logical, sharing signal and blending with speakers, but if you guys say the LFE will give me the same signal and sound on the Amp, may not be worth it.

It made sense if lfe was more for home theatre, and the high level for music
rondocap wrote:

Ok, I had planned on getting a Rel sub and the high level connection sounded logical, sharing signal and blending with speakers, but if you guys say the LFE will give me the same signal and sound on the Amp, may not be worth it.


No, high level connections from the amp terminals to both speaker pair and Sub will NOT give the same signal as using the Sub out socket of the amp to the low level on the Sub because the main speakers will now get all frequencies and not just those above the selected cut.
See my two preceding posts.
Also, instead of a REL sub, I would get a Sonos Sub on returnable basis. It does a better job of integration with Connect Amp - and by extension I assume Sonos Amp - than any Sub I have used and for good music play, this integration is very critical.
Let extensive listening sessions then decide if you want to keep the Sonos Sub, after assessing the sound of the existing sub using both high level and low level connections.
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Kumar wrote:

Also, instead of a REL sub, I would get a Sonos Sub on returnable basis. It does a better job of integration with Connect Amp - and by extension I assume Sonos Amp - than any Sub I have used and for good music play, this integration is very critical.
Let extensive listening sessions then decide if you want to keep the Sonos Sub, after assessing the sound of the existing sub using both high level and low level connections.



I actually do have a Sonos Sub already, but I had it connected (in the same room) to a Beam and 5,1 setup for movie watching.

I have the Amp connected to two Bowers and Wilkins 685 S2, and a Def Tech Pro Sub 800. I use this for music.

The reason I got the def Tech sub was because I had briefly put the Sonos sub with the 685s, and really liked the way they made the speakers open up.

Not sure I want to get 2 Sonos subs in the same room, that’s why I tried something different with the Def Tech 800 and was considering a Rel Sub.
rondocap wrote:


It made sense if lfe was more for home theatre, and the high level for music


LFE is for movies and is when the Sub is connected to the .1 channel on an AVR. In sound coded for movies, the deep sounding effects are contained in just that channel, which is connected to a Sub for reproducing everything contained therein. If a Sub is not so connected, the channel isn't heard at all - this, from my AVR use back in the day.
The sub out on the Connect Amp isn't LFE; it is a line level output for a Sub after stripping out frequencies above the cross over selected; note that in recording music in stereo, both channels contain all the content, there is nothing separately dedicated to low frequencies. And if nothing is plugged into the Sub out jack, all content will be passed on to the front speakers, with low frequencies then heard from them to the extent of the capability of front speakers to go low.
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Kumar wrote:

rondocap wrote:


It made sense if lfe was more for home theatre, and the high level for music


LFE is for movies and is when the Sub is connected to the .1 channel on an AVR. In sound coded for movies, the deep sounding effects are contained in just that channel, which is connected to a Sub for reproducing everything contained therein. If a Sub is not so connected, the channel isn't heard at all - this, from my AVR use back in the day.
The sub out on the Connect Amp isn't LFE; it is a line level output for a Sub after stripping out frequencies above the cross over selected; note that in recording music in stereo, both channels contain all the content, there is nothing separately dedicated to low frequencies. And if nothing is plugged into the Sub out jack, all content will be passed on to the front speakers, with low frequencies then heard from them to the extent of the capability of front speakers to go low.



Ok so just to make it clear, should I just keep the sub plugged into the Amp sub port and not worry about the high level? Just wondered if I’d get a better music experience, not that it’s lacking now
rondocap wrote:


Not sure I want to get 2 Sonos subs in the same room, that’s why I tried something different with the Def Tech 800 and was considering a Rel Sub.


Even if Sonos Sub gives better results than the Def Tech in both high and low level mode? Because chances are that the REL will not do much better than the Def Tech.
Of course, the best would be to try everything and then decide!
rondocap wrote:


Ok so just to make it clear, should I just keep the sub plugged into the Amp sub port and not worry about the high level? Just wondered if I’d get a better music experience, not that it’s lacking now


Why don't you see what happens if you connect the high end inputs on the Sub to the speaker terminals on the amp? Some experimenting with the Sub cross over may be needed keeping in mind how deep your main speakers go with enough energy, but all it will cost is time.
By the way, from one of your posts I got an impression that you got better results with the Amp using the Sonos Sub bonded to it. No?
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Kumar wrote:

rondocap wrote:


Ok so just to make it clear, should I just keep the sub plugged into the Amp sub port and not worry about the high level? Just wondered if I’d get a better music experience, not that it’s lacking now


Why don't you see what happens if you connect the high end inputs on the Sub to the speaker terminals on the amp? Some experimenting with the Sub cross over may be needed keeping in mind how deep your main speakers go with enough energy, but all it will cost is time.
By the way, from one of your posts I got an impression that you got better results with the Amp using the Sonos Sub bonded to it. No?




I will have to try it out, and test the Sonos sub again as well. Not sure if it was better or similar, just had a brief test and liked it enough to get a separate sub.

I’m using banana plugs, so I will try to put the sub to the amp first, and the 2 speakers connected to the Sub instead of crossing both at the amp end, wonder if that will work well with the amp
rondocap wrote:


I’m using banana plugs, so I will try to put the sub to the amp first, and the 2 speakers connected to the Sub instead of crossing both at the amp end, wonder if that will work well with the amp


No no no. For it to be meaningful the speaker terminals of the amp have to be double wired. To both the main speakers as now, and also to the high level left and right terminals on the Sub.
Your way will deny the main speakers of the low level content that will be stripped out by the Sub crossover. Unless the Sub, as a few do, allows a full pass through of the signal.
For your evaluation remember that with the Sonos Sub, you can select the crossover that is most suited for the main speakers in use. If therefore your speakers already do a decent job of bass delivery, set the crossover on the Sub at the lowest - 50/60 hz if the speaker pair goes down adequately till there. This then will be very close to what high level connections are supposed to do, allowing the main speakers to do as much as they are capable of doing, and the Sub only for frequencies lower than that. Unfortunately, this choice is not available for third party subs where the crossover can be set to only 80hz.
Also, best results are obtained when the Sub is placed between the two main speakers, in the same plane. While centre position is ideal, offsets to either side to an extent do not make an audible difference, if the central position is not available. For movies, Sub placement isn't so important, but I have found it to be so for music. A Sub away to one side of the speaker pair certainly isn't good for stereo imaging and integration with the front speakers, for music sound quality.
Finally, if you are setting the crossover at the 50-60 hz levels, make sure that the content goes below that with some emphasis on the lower frequencies, else the Sub won't be doing much that is heard/felt.
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I got the Rel sub.

to clarify, I have a Sonos Amp, and a Rel t5i subwoofer that lets me connect either via high level input, low level input, or .1 LFE


LFE gave me more vas’s, low level I could barely hear the sub. Have not tried high level yet

Here was my question, rephrased again:

What is the best way to connect to the amp? For music only

1. High level input where I connect my main speaker cables together with the Rel sub supplied left/right cables together on the amp

2. Low level input, Rca mono cable from sub out on amp to Rel low level input

3. LFE from amp sub out to LFE input on Rel
REL suggests 1, but it is easy enough for you to decide after trying all. After all, you will be the one listening to it long term.
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Kumar wrote:

REL suggests 1, but it is easy enough for you to decide after trying all. After all, you will be the one listening to it long term.



I connected it via the high level connection, and it seems to work best. The low level I would barely get any bass, and the lfe I'd get bass but not sure how optimized it was for music.

I connected all wires at the amp side, and the black ground from the Rel on the negative on the amp as well. They recommend to connect the LFE connection just to ground it better and avoid a hum, which I did, and seems to work.

It's definitely a bit of a complex way to make a connection, but I think it works for the little listening I did today.

Now what's confusing me is the Sub advanced setting in the sonos app - do I leave it on, or off? I thought the cross over would be taken care of by the sub itself via high level, but I did notice some more bass when the sub is on in the settings. Of course LFE is connected but volume on the sub is set to 0, so it's just a ground.
If you are using high level, there should be nothing plugged into the Sub out jack on the Sonos Amp; doing that will strip the lower frequencies from the speaker terminals. And if nothing is plugged into that jack, nothing you do in the Sonos controller app to the Sub will make any difference.
What does REL recommend connecting their LFE jack to?
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Kumar wrote:

If you are using high level, there should be nothing plugged into the Sub out jack on the Sonos Amp; doing that will strip the lower frequencies from the speaker terminals. And if nothing is plugged into that jack, nothing you do in the Sonos controller app to the Sub will make any difference.
What does REL recommend connecting their LFE jack to?



In order to avoid "hum", they recommended to connect the sub out to their LFE, and just put the LFE on the sub to 0. Apparently this helps ground the system. I was getting some hum before I did this, and now it's fine.

So no danger connecting both the LEF and high level with a ground to the speaker neg terminal on the amp right? Seems to be working fine, just want to avoid any shorts or issues.

So the Sonos app sub settings will only control whatever is connected to the sub out amp correct? It did seem to have some effect, even with lfe turned down to 0 and high level being used.

I tried to use the low level output on the sub to the sonos sub amp first, with a mono rca cable, but I would get very low bass - only lfe and high level gave me the right levels. Any idea as to why that is? Volume and crossovers were the same as is working on the high level
rondocap wrote:



So no danger connecting both the LEF and high level with a ground to the speaker neg terminal on the amp right? Seems to be working fine, just want to avoid any shorts or issues.


I tried to use the low level output on the sub to the sonos sub amp first, with a mono rca cable, but I would get very low bass - only lfe and high level gave me the right levels. Any idea as to why that is? Volume and crossovers were the same as is working on the high level


The way the Sonos Amp is architected, anything plugged into its sub out will immediately strip out low frequencies from the speaker terminals on it, even if there is nothing connected at the other end. So using that socket is not to be done unless there IS a working Sub at the other end that will reproduce the stripped out frequencies. And even with nothing connected at the other end, the Sonos app will work on the connected Sub out jack on the Sonos Amp, but obviously nothing will be heard if there is nothing at the other end. But, as explained, the main speakers will be deprived of frequencies below 80hz, whether the other end is connected to a Sub which is left at zero, or there is nothing connected to the other end.

There is no danger in connecting a double pair of speaker wires at the Sonos amp speaker terminals - one set running to the main speakers and the other set to the high end inputs on the Sub. As to the ground connection to the speaker terminals on the amp, if you do exactly what REL has recommended, there should be no danger; with respect to what is happening at its speaker terminals, the Sonos Amp is like any other stereo amp.

I don't know why the low level connection from the Sonos Amp sub out jack to the low level connection on the REL does what it does. Maybe the user manual will tell you what needs to be done if that route is used.
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Kumar wrote:

rondocap wrote:



So no danger connecting both the LEF and high level with a ground to the speaker neg terminal on the amp right? Seems to be working fine, just want to avoid any shorts or issues.


I tried to use the low level output on the sub to the sonos sub amp first, with a mono rca cable, but I would get very low bass - only lfe and high level gave me the right levels. Any idea as to why that is? Volume and crossovers were the same as is working on the high level


The way the Sonos Amp is architected, anything plugged into its sub out will immediately strip out low frequencies from the speaker terminals on it, even if there is nothing connected at the other end. So using that socket is not to be done unless there IS a working Sub at the other end that will reproduce the stripped out frequencies. And even with nothing connected at the other end, the Sonos app will work on the connected Sub out jack on the Sonos Amp, but obviously nothing will be heard if there is nothing at the other end. But, as explained, the main speakers will be deprived of frequencies below 80hz, whether the other end is connected to a Sub which is left at zero, or there is nothing connected to the other end.

There is no danger in connecting a double pair of speaker wires at the Sonos amp speaker terminals - one set running to the main speakers and the other set to the high end inputs on the Sub. As to the ground connection to the speaker terminals on the amp, if you do exactly what REL has recommended, there should be no danger; with respect to what is happening at its speaker terminals, the Sonos Amp is like any other stereo amp.

I don't know why the low level connection from the Sonos Amp sub out jack to the low level connection on the REL does what it does. Maybe the user manual will tell you what needs to be done if that route is used.



Only issue if I unplug the Sub out from amp to the LFE on the Rel, the Sub gets a hum/vibration when music is off,and connected via high level.
I looked up the user manual online and did not find any reference to such a connection there. Where are you seeing it? When High level is used, per the user manual I found, the only connection from REL to amp is to its speaker terminals via the red, yellow and black cables at the other end of the REL supplied cable that has the speakon plug for use at the Sub end.
Further to the above, what happens if you let the black wire float, unconnected? If the hum goes away, properly cover the end of the black wire with insulating tape, and rollup/tuck it away out of sight.

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