Subwoofer setup with AVR and stereo amp

[jeffhk]

After reading the thread about whether subs are good for stereo music or not, I'm thinking I might give it a try. My sub (SVS SB-3000) is currently connected to my AVR along with atmos and surround channels, and the front L/R are connected to my integrated amp via the pre-outs from the AVR. So at the moment the sub is only used for watching movies but if I want to use it for my stereo listening I'll need to connect it to my integrated amp (music streamer is connected to integrated amp, AVR is not used for music streaming).

The amp has 2 RCA outputs labelled "sub out" so that's not an issue, but if I unplug the sub from the AVR and into the integrated amp, what happens when I want to watch a movie? The crossover is currently configured via the AVR setup menu, but if the sub is not connected to the AVR, then I can setup the low pass filter using the sub control app. What then should I do to the settings in the AVR setup? Should I reconfigure the AVR speaker setup to no-sub mode?

 

[Fer1000]

I will let the AVR speaker set up as it is and use the Subwoofer App to set them up properly..

I also have my Subwoofer connected for both Stereo and Multichannel listening using the Preamp and to my ears it is pretty good.

 

[NekoAudio]

Does your integrated amp have a subwoofer crossover feature? Or are the extra pair of RCA "sub out" outputs simply a full-range copy of the left and right channels?

Right now, your AVR is running a low-pass to your subwoofer and a high-pass to your L/R speakers. If your integrated amp does not also have a crossover, then connecting the subwoofer to the integrated amp's sub out will mean you end up running your L/R speakers as full-range "large" even if you make use of the built-in low-pass filter on the SB-3000. This will likely result in a worse subwoofer integration than what you currently have with your AVR—ignoring whether or not your 2-channel DAC sounds better than your AVR DAC.

However, if you did want to run things this way, then you can reconfigure your AVR to pass LFE to your L/R channels, at which point your integrated amp sends the result to both your subwoofer and L/R speakers (either with or without a crossover).

 

[Mr Peabody]

Check to see if your SVS has two separate inputs, my PC13 Ultra does. Use the input with no crossover for the receiver and the crossover input for your integrated.

If not, I'd leave the sub on your home theater, movie soundtracks have a dedicated Low Frequency Effect (LFE) encoded into the soundtrack, the .1 is that, n 7.1 etc. Most main speakers aren't designed to handle that LFE. If you tell your receiver "no sub"it will blend the LFE into your other channels, mostly the mains, it depends on how low each speaker can go.

It sounds like your systems are separate, not sharing main speakers, correct?

Some people use the integrated to drive a main set of speakers used for both movies and music, this would allow the option of running the sub for both by setting your receiver correctly in the menu. Your integrated will need a bypass input for this.

 

[tino27]

Don't know how old your SVS sub is, but I've always found that music and movies require vastly different settings to sound their best. Some of the newer SVS subs allow you to set up profiles that can be managed on your phone via Bluetooth. I have a SB13-Ultra in my 2.1 channel system and I've configured it to sound best with music, even though I do watch movies from time to time through it as well.

 

[jeffhk]

Thanks everyone for the helpful responses. I only have one set of main speakers, so having both the AVR and the integrated amp connected to the sub at the same time is not an option for me. The integrated amp doesn't have a subwoofer crossover feature so I would set that via the sub directly. I would then have to set the L/R mains to large for the AVR setup. If I understand correctly, the general consensus seems to be that letting the AVR handle the sub will give better results overall, but I guess the only way is to try it and see.

It's not that I'm unhappy with the sound coming from mains when I listen to stereo music, I was just curious to try it with the sub and see if it made a noticeable difference. At least now I know how to set it up properly.

 

[Mr Peabody]

So you switch speaker cables at the back of your mains to the systemyou will be listening too? I used to do that when my 2-channel system was tubes. In that case you need a sub with two inputs if wanting to use same sub for both movies and 2-channel.

Thanks everyone for the helpful responses. I only have one set of main speakers, so having both the AVR and the integrated amp connected to the sub at the same time is not an option for me. The integrated amp doesn't have a subwoofer crossover feature so I would set that via the sub directly. I would then have to set the L/R mains to large for the AVR setup. If I understand correctly, the general consensus seems to be that letting the AVR handle the sub will give better results overall, but I guess the only way is to try it and see.

It's not that I'm unhappy with the sound coming from mains when I listen to stereo music, I was just curious to try it with the sub and see if it made a noticeable difference. At least now I know how to set it up properly.

 

[NekoAudio]

The integrated amp doesn't have a subwoofer crossover feature so I would set that via the sub directly. I would then have to set the L/R mains to large for the AVR setup. If I understand correctly, the general consensus seems to be that letting the AVR handle the sub will give better results overall, but I guess the only way is to try it and see.

It's not that I'm unhappy with the sound coming from mains when I listen to stereo music, I was just curious to try it with the sub and see if it made a noticeable difference. At least now I know how to set it up properly.

Yeah, unfortunately with no crossover in your integrated amp there's a fair chance things won't sound so great with the full low-frequency data being sent to your L/R main speakers because once you turn the volume up past a certain point you'd be pushing your L/R speakers too hard in the bass region, causing distortion or compression or in the worst case bottoming them out which could result in physical damage.

But if you don't listen to music or watch shows loud enough for that to be an issue, then you can use the natural roll-off point of your main speakers to determine the SB-3000 low-pass crossover point by measuring the frequency response in something like Room EQ Wizard.

 

[Delija]

Don't know how old your SVS sub is, but I've always found that music and movies require vastly different settings to sound their best. Some of the newer SVS subs allow you to set up profiles that can be managed on your phone via Bluetooth. I have a SB13-Ultra in my 2.1 channel system and I've configured it to sound best with music, even though I do watch movies from time to time through it as well.

Exactly.

I use two profiles/presets with very different settings for stereo and HT usage. In fact, I even have two separate HT presets - one for HT with ARC room correction and other for HT without ARC. These presets are VERY useful on SVS subwoofers.

BTW, I've used high-pass filter in stereo system for long time - but not any more. I just don't find it 100% transparent. Pity, because Devialet have all needed subwoofer settings including delay. It's much harder to integrate subwoofer(s) without high-pass filter, especially with almost full-range speakers - but it's worth it in the end.


@NekoAudio
You don't want subwoofer(s) to act just bellow natural roll-off point of your main speakers - you want them to help you fight the room and room modes.
Since I'm still not allowed to post links - just search for "Geddes Multiple Subwoofers".

 

[jeffhk]

So you switch speaker cables at the back of your mains to the system you will be listening too? I used to do that when my 2-channel system was tubes. In that case you need a sub with two inputs if wanting to use same sub for both movies and 2-channel.

I don't need to switch speaker cables, my integrated amp is always driving the L/R mains. When I'm watching movies the L/R mains are going out of the pre-outs on the AVR into the HT bypass inputs on the integrated amp. The sub does have 2 inputs, and the integrated amp has 2 sub outputs so I imagine I would need to use both if I connect the sub to the integrated amp.

 

[NekoAudio]

You don't want subwoofer(s) to act just bellow natural roll-off point of your main speakers - you want them to help you fight the room and room modes.

Sure, but Jeff doesn't have a crossover available in his integrated amp.

So all bass, including the LFE channel from video content, would be sent full-range to his main speakers. If he sets his subwoofer crossover higher, there will be a bump from constructive interference. Using PEQ on the SB-3000 to counteract that is akin to lowering the crossover point.

You wouldn't want to run the subwoofer in opposite phase in an attempt to create destructive interference to address any issues due to the bass from his main speakers, as that would result in incorrect timing as you indirectly referenced. (Although I guess the timing could be a lesser concern for Jeff, versus bass output.) Plus any automatic distance measurements or EQ on the AVR would negate attempts to do that.

And he's currently running his main speakers full-range for 2-channel playback anyway.

Or am I missing something? Since you did say it is worth integrating a subwoofer without a high-pass filter, but also think it shouldn't be done based on the natural roll-off point of the main speakers?

 

[Delija]

Sure, but Jeff doesn't have a crossover available in his integrated amp.

So all bass, including the LFE channel from video content, would be sent full-range to his main speakers. If he sets his subwoofer crossover higher, there will be a bump from constructive interference. Using PEQ on the SB-3000 to counteract that is akin to lowering the crossover point.

He doesn't need crossover on integrated amp (crossover cascading could provide "cleaner" mid-bass, but that's another story), but he does need to turn off subwoofer pre-out when integrated amp is used in HT/bypass mode as a part of HT system with AVR - where basically integrated amp is used as a power amp for front channels. In HT mode subwoofer should be driven only by AVR and its bass management - so LFE goes only to subwoofer.

I don't know what integrated amp he has and whether it has that option - on Devialet you can configure subwoofer pre-out (and also high-pass filter, if used) to be turned off in HT/bypass mode and turned on for every other source used for pure stereo. Without this option he needs to do this manually every time he switches between stereo and HT listening. I don't see that as a major problem - I have this option, but I still need to manually change presets on my subwoofers - two button clicks on remote

You wouldn't want to run the subwoofer in opposite phase in an attempt to create destructive interference to address any issues due to the bass from his main speakers, as that would result in incorrect timing as you indirectly referenced. (Although I guess the timing could be a lesser concern for Jeff, versus bass output.) Plus any automatic distance measurements or EQ on the AVR would negate attempts to do that.

And he's currently running his main speakers full-range for 2-channel playback anyway.

Or am I missing something? Since you did say it is worth integrating a subwoofer without a high-pass filter, but also think it shouldn't be done based on the natural roll-off point of the main speakers?

Yes, you would

That's one of the main points of Geddes multiple subwoofers approach. Read about it - it's pretty useful. Use the hint I gave you for google search - "Geddes Multiple Subwoofers". I cannot add links and pictures yet - I have less than 10 posts on forum.

Also, search for "Perception of temporal decay of low frequency room modes"
If you don't want to read all - read chapter "5. Discussion and conclusions".
It's somewhat different subject, but pretty similar conclusion - for the lowest frequencies timing is less significant than magnitude.

Important note - the measurements are mandatory in the process of optimization of subwoofer(s) integration, but listening is crucial! I've seen too many "perfect" measurements which don't sound so good.

Plus any automatic distance measurements or EQ on the AVR would negate attempts to do that.

There is no AVR in stereo part of the system.

 

[Delija]

Just to add that one of the main drivers for me to buy Devialet was high-pass filter (together with delay and other options for subwoofer(s) integration), since I know for quite some time that there is no proper full range sound without subwoofers.

And I have used it for quite some time, but while it is highly transparent and better than any other I've heard - it's just not 100% transparent.
So far, I haven't heard any DSP processing which is applied on one part of the frequency range that doesn't affect the signal on completely different frequency range.

The higher the quality of the system - the easier to hear the "artifacts".

With Dynaudio Contours the difference with and without high-pass filter was less obvious than with Confidence.

I was close to change the concept of my system and get JL Audio CR-1, but I cannot try it before buying it (there is no local dealer) and I'm afraid that it's also not 100% transparent. It's not the problem in 3k for CR-1, but I would have to sell Devialet which I like a lot and buy separate components of the same (or higher) level - amp, preamp, DAC, streamer and interconnects for all this.

So, I tried different concept, without high-pass filter and after some struggle it works excellent in the end. I never had better bass and frankly I have heard just a few systems which have the same or better bass - but in dedicated fully treated rooms. "Geddes approach" is the way to go - for me and my room. For some other rooms and systems - something else could be better solution. I have a major room mode around 70 Hz that needs to be addressed - so integrating subwoofer(s) below natural roll-off is not working for me. And the situation is similar in most rooms. Someone is 100% happy with Dirac, Room Perfect, Trinnov, ARC, Roon manual EQ... and similar automatic and manual room correction systems / DSP effects. For me (and of course, not just me) - it's not good for Hi-Fi stereo system and critical listening. Not even close. I even ditched Anthem ARC from HT/surround system for the same reason.

 

[NekoAudio]

He doesn't need crossover on integrated amp (crossover cascading could provide "cleaner" mid-bass, but that's another story), but he does need to turn off subwoofer pre-out when integrated amp is used in HT/bypass mode as a part of HT system with AVR - where basically integrated amp is used as a power amp for front channels. In HT mode subwoofer should be driven only by AVR and its bass management - so LFE goes only to subwoofer.

I think you missed that the OP is specifically asking about using his subwoofer with both his HT and 2-channel playback scenarios. His integrated amp has no crossover, so the "sub out" outputs and L/R main outputs on his integrated amp will send the same signal to both outputs.

That's one of the main points of Geddes multiple subwoofers approach. Read about it - it's pretty useful. Use the hint I gave you for google search - "Geddes Multiple Subwoofers". I cannot add links and pictures yet - I have less than 10 posts on forum.

The benefit of multiple subwoofers is clear, but the OP does not have multiple subwoofers. And since he's talking about an integrated amp where the LFE from his AVR and bass in 2-channel playback will be sent to both his L/R main speakers and the subwoofer, and he has no ability to PEQ his main speakers (only his subwoofer), and his main speakers are going to stay in the same location they currently are, and I'm currently assuming his main speakers cannot be run "full-range", I think the considerations I raised earlier apply.

Also, search for "Perception of temporal decay of low frequency room modes"
If you don't want to read all - read chapter "5. Discussion and conclusions".
It's somewhat different subject, but pretty similar conclusion - for the lowest frequencies timing is less significant than magnitude.

I'm familiar with the research that shows temporal differences as a function of frequency are less noticeable or not noticeable, but my own experience puts me in the opposite camp. I think it makes a big difference for the timing to be as coherent as possible. So that's what I advocate.

Edit: After reading your last post more carefully, I think I now understand what you were trying to explain to me. You're saying that if Jeff puts his subwoofer crossover down where the main speakers start to roll-off, he cannot use the subwoofer to address nulls located above that point. That's a valid point.

 

[Delija]

I think you missed that the OP is specifically asking about using his subwoofer with both his HT and 2-channel playback scenarios. His integrated amp has no crossover, so the "sub out" outputs and L/R main outputs on his integrated amp will send the same signal to both outputs.

I thought it's pretty clear that I'm explaining the optimal path of using the same subwoofer(s) in both systems, but with the accent on stereo part of the system, since HT/surround part is 100% straight forward.

The benefit of multiple subwoofers is clear, but the OP does not have multiple subwoofers. And since he's talking about an integrated amp where the LFE from his AVR and bass in 2-channel playback will be sent to both his L/R main speakers and the subwoofer, and he has no ability to PEQ his main speakers (only his subwoofer), and his main speakers are going to stay in the same location they currently are, and I'm currently assuming his main speakers cannot be run "full-range", I think the considerations I raised earlier apply.

In "Geddes approach" full-range speakers are treated the same as subwoofers.

Without external crossover (like JL Audio CR-1) between amp and preamp there is no way to drive his speakers without them being full-range - if he doesn't have integrated amp with high-pass filter functionality - which I doubt. The only way would be to use his AVR as preamp/prepro in stereo system - which is far from good, and I'm not even considering this scenario and neither is he - read his first post carefully.

I'm familiar with the research that shows temporal differences as a function of frequency are less noticeable or not noticeable, but my own experience puts me in the opposite camp. I think it makes a big difference for the timing to be as coherent as possible. So that's what I advocate.

That's why I added important note about listening - and not just measuring.

Edit: After reading your last post more carefully, I think I now understand what you were trying to explain to me. You're saying that if Jeff puts his subwoofer crossover down where the main speakers start to roll-off, he cannot use the subwoofer to address nulls located above that point. That's a valid point.

Exactly, but not just nulls, but also peaks (room modes) which are probably even more important. If you ask me - they are more important.

 

[Delija]

Now I can add links I've mentioned earlier

Serious Audio: Two Great Articles on Multiple Subwoofers by Dr. Earl Geddes



https://assets.ctfassets.net/4zjnzn...04_karjalainen_antsalo_makivirta_valimaki.pdf

 

[NekoAudio]

I thought it's pretty clear that I'm explaining the optimal path of using the same subwoofer(s) in both systems, but with the accent on stereo part of the system, since HT/surround part is 100% straight forward.

Sorry, I must not have understood you.

In "Geddes approach" full-range speakers are treated the same as subwoofers.

Exactly, but not just nulls, but also peaks (room modes) which are probably even more important. If you ask me - they are more important.

I agree they are important, but I'm not seeing how you can use the main speakers without PEQ with a subwoofer that has PEQ to address peaks created by the main speakers without also running the subwoofer out of phase with the main speakers. For the nulls created by the main speaker, the subwoofer can act on its own and be placed in the room so as not to have a null at the same frequency. But for the peaks created by the main speaker, the subwoofer would need to create destructive interference for that frequency, while not creating destructive interference for other frequencies. So unless you're willing to gain flat frequency response at the expense of time alignment? Which might be what you're suggesting with your reference to Geddes' approach?

 

[Delija]

Yes, that's what I'm suggesting :thumbsup:

My experience is aligned with quoted scientific paper - for the lowest frequencies timing is less significant than magnitude. Not irrelevant, of course. If not addressed, it could make the sound "muddy" even with perfect FR measurements (including waterfall). That's one of the reasons why it's very important to use your ears (besides measurements) for fine adjustments of all integration parameters for each subwoofer in system - position, gain, crossover point and slope, phase, PEQs...

Trust me, I'm pretty demanding when we talk about good bass - and all my Hi-Fi friends know that pretty well
If I didn't get significantly better bass with subwoofers in system - I would just use my stereo speakers without subwoofers, since they have pretty good bass on their own.

It would be a little easier to understand each other if we could just seat and listen to some music (Yello is great for bass evaluation) with a beer or two in our hands - unfortunately, we have more than 6k miles between us

p.s. Even two speakers (left and right ) in stereo system combined with the usual room (which is not rectangular) are not 100% time aligned in the lowest frequencies where direct sound waves are not so dominant and wall reflections participate a lot in what we hear.

Also, subwoofers and speakers are not time aligned. Even if you align their phase on one frequency - it won't be aligned on others (especially if you combine ported speakers and sealed subwoofers - and vice versa) - and no matter how high or low you put the crossover point, crossover is not a brick wall. And that's even if subwoofer don't have any latency - which is not true, of course. Various factors affect phase / time alignment / latency - location of subwoofer(s) and speakers, DSP in subwoofers (just being on the signal path is adding latency), crossover (both low and high-pass filter), PEQs or any other EQ... and when integrating subwoofers with common integrated amp - you can not avoid any of these in the first place. If your subwoofers have variable phase setting (e.g. REL subwoofers don't have it ) you can somewhat adjust phase (for some frequencies, not all - as stated above), but not delay, of course.

 

[NekoAudio]

Yes, that's what I'm suggesting :thumbsup:

Got it. It took me a while to get to where you were coming from, since I was starting with a different requirement of maximizing time-alignment. But yes, I understand completely now what you're advising.

Also, subwoofers and speakers are not time aligned.

I use Room EQ Wizard to measure the relative delay between subwoofer and speaker, and then (as I think you've done as well) can set the exact delay in µs in the Devialet Expert Pro settings. Or I let Trinnov or Dirac set the relative delays based on its measurements. This can account for DSP-introduced delays but you still have the other issues you've described. (A reason to avoid ports.)

As you say, it's not perfect, but I find it makes a huge difference in clarity and realism. The impulse response and measured phase can be significantly improved across a majority of the audible spectrum.