Hi Kalorama,

The wonderful Sonos engineers have decided that you do no need the sub out when setting up your AMP as surrounds. In other words, they have purposefully disabled the subwoofer signal instead of giving you the option to turn it on/off as you like.

I can only speculate why they did this, but hopefully this will save someone else the many lost hours of troubleshooting why your 3rd party sub wont work with the AMP.

Details here: https://support.sonos.com/s/article/2237?language=en_US

Anyone else reading this needs to email Sonos and request a new feature to toggle the AMP’s sub on/off from the app.

No worries, I just returned the AMP. It’s false advertising or at least lack of full disclosure on how it operates.

I will be happy to repurchase it when Sonos makes the sub out available during surround setup.

Otherwise some customers might think this is a ploy to get you to purchase the Sonos sub. I think it’s just a feature overlooked by Sonos engineers.

I am glad I found this post about the sub issues. I can’t believe someone posted if you buy MCM Stereo LINE PRE-Amplifier, 15DB, 12VDC” it will resolve your issue. That’s like if you change your Tv you might get better audio out support.  For such premium price products  doesn’t  this stuff get tested before it is out the door.  All those high end artist that they advertise must have had the issue, wouldn’t you think.  Since it is a system depended on wires I don’t understand why people don’t use a new traditional amp. Amps today can connect to many different steaming platforms including airplay/2 without these types of issues/frustrations. They connect with alexa or google and some even allow power control from those. Better yet Nov /Dec is the time to look at buying those at a fraction of the cost. Yet another sonos product that I won’t buy and that makes this very disappointing again. QOS turns out to POS. As a consumer do we really ask for that much? 

True, but was hoping to save $100 and use my more powerful subwoofer (svs ultra). Having one less bulky device in my house would also make it easier with wife approval

I currently have 4 Sonos Amps that I’ve being using for the past 2 months with out any subs. Yesterday I got my SVS Ultra PB16 and for a good 3 hours I couldn’t get it to work, I thought I had a defective Sub, but after being on the phone with SVS support and messing with the Sonos App we came to the conclusion that the signal is way too weak, I was able to get a bit of base by cracking the level to +15 and setting the Sub to Max volume, which it sucks. We actually tested the sub with my Ipad by using RCA to Headphone Jack in the Ipad and its sounds amazing so this confirms the sub is fine. Unfortunately I can’t return my Amps and I dont want to return my sub, so what Im thinking of doing is buying a Yamaha receiver to power my In-ceiling speakers and sub for a true Surround system and control it with a Sonos Port.

Oh and by the way, if You have a Sonos Sound Bar and you want to create a 7.1 system, it wont let you, this is another reason as to why Im considering getting a Yamaha Receiver since Sonos is not all there yet.

Given that this issue is so easy to reproduce It is very frustrating that Sonos has yet to resolve (or even acknowledge it). 

I don’t know the 3rd party sub you refer to, but presumably Sonos Support were referring to turning up the volume on the sub itself? I know their ‘classic series’ subs support that.

http://www.cerwinvega.com/manuals/home/Classic-Sub_manual.pdf

I got a sub working with my system.

I did not make any changes in my Sonos app and system settings except in the EQ to get the amount of low end I wanted. It kicks whether it’s flat or with the EQ boosted five points, which is my preference.   

The one I tried initially, the Sonos Connect Amp was either not pushing enough gain to trip the amp on or the sub was defective. So since my Martin Logan wireless transmitter has a Left and Right input for my Home Theater sub, I pulled out the right that connected to my Sony amp and used that channel for my Sonos Connect amp (subs are mono anyway so left and right in is pointless), and now I use the same sub for both my Sony entertainment system and for my Sonos zone in the kitchen (it’s one big room anyway). Problem solved for me! The ML wireless transmitter is its own preamp anyway so I don’t have to send a stronger signal to kick on the speaker since it’s wireless. 

Hi everyone, thanks for sharing your experiences with different devices and the Sonos Amp. We’re always interested in seeing what you have to say, and are eager to investigate any issues that might come up. Our engineering team has been looking into this issue and would love some more information. Currently, there isn't a major trend that has been identified, but they'd like to see some more cases where subwoofers and the Amp aren’t behaving as expected. 

If you’re having trouble with the Amp outputting low or no audio to a subwoofer and haven’t worked with our support team yet, please feel free to reach out to us using the contact details here. The support team will help sort out issues where possible, and if needed, they’ll gather the right information and get it up to the engineering teams for investigation.

I purchased my Sonos Amp last weekend to connect to a Sony TV, 2 x B+W bookshelves and a B+W ASW610 sub. I read various posts to work out how to connect the sub and initially tried connecting via a split RCA. This gave me a weak, or non existent signal as described in a lot of posts in this thread. I was freaking out a bit. After reading about LFE channels, and re-reading my sub manual, I connected a single RCA from the amp to the left RCA input on the sub, which I think is the LFE input, and I switched off the low pass filter. It now works well in a surround set-up and puts out a lot of bass. I’m really enjoying the amp. The TV and Spotify sound great to me and I like the look of the amp. The app is really useful and I’ve found myself adjusting the sub level with the app which is really handy.

Your mileage may vary but the bug seems fixed on the latest firmware 11.1.

I had to turn the in-app sub level down from +14 to +2 

Me too!
 

I'm not sure yet if it has fixed the “auto-sleep” issue with my sub. But it's definitely fixed the gain issue! It's very loud now!! I've got from +15 to +3, and may go down further yet!

2 hours of TV later - no turn off!

I've halved the gain on the sub, and increased back to about +8 on the app. Keeps the sub alive. 

Puuurfect. 

Means I can now spend money on some new KEF LS50s to go with my Amp!

Thx!

In your own thread the explanation for this is given by Melvimbe:

“I believe he wants the sub port on the amp enabled while the amp is in surround mode, so that he can use a 3rd party sub.

I don’t think you can conclude it’s an easy change, only disabled for marketing reasons though.  As it stands now the Arc/Beam is currently configured with or without a Sonos sub.  If no sub, then it plays the bass frequencies itself.  With sub, it sends bass to the sub and adjust it’s own speakers to no longer play those frequencies.  Now you’re talking about a 3rd scenario where the Arc/Beam needs to be told that the amp for surrounds has a sub attached to it, so it should adjust it’s on playback accordingly and send the L/R surround channels AND sub channel to the amp wirelessly.  Not sure that the amp is built to handle 3 channels of audio like that over wireless, and process it accordingly.  Maybe, but I certainly couldn’t conclude that it’s a trivial matter. 

Note, this is not the same as when a amp w/sub attached is playing music in a group situation.  The amp would receive the 2 stereo channels and extract the bass from that.  It can’t do that when it’s doing surround duty as the bass is a part of the front channels, not rear surround channels.”

Sonos Amp Feature Request | Sonos Community

I’m Exhausted. Searched the web for hours. Read this thread 2 times. 

I have a Sonos Amp. Trying to use the SUB out on it. Yes, it has the latest firmware.

Brand: OSD Audio Model Name: FORZA 10 Sub running thru an external Amp. Using an RCA Y cable from Sonos Amp Sub out to the line in on the Amp. Zero on the Sub. I do get the Sub enable/settings once I plug in the RCA but thats it. Useless.

Other than buying a Sonos Sub, What Amp works with this. The external AMP for this Sub is Nobsound G2 PRO Hi-Fi 300W Subwoofer Power Amplifier Mono Channel Class D SUB Audio Amp. 

But like so many others here, struggling to get this to work. 

Any help is greatly appreciated.

Why the Y cable?

A simple male-male RCA is all that should be needed.

If you connect another audio source to the external amp’s input using your cable can you hear anything?