Separate subs for music and HT/surround

My stereo setup is comprised of Ayre 5/20 series digital hub, preamp and amp that drive KEF Ref 1s through a passive Marchand high-pass filter. For HT and surround, LR side and rear surround from an SP3 go to NAD Class D amps that drive LS50s. The SP3 receives HDMI from an Ayre DX-5 DSD, and its front LR output goes to a balanced by-pass input of the KX-5/20. I have two Velodyne SMS-1 bass managers that provide acoustic room correction, two HGS-10 subs, and two HGS-15 subs.

Question: Should I use one SMS-1 with the two HGS-10s for stereo and the other SMS-1 with the two HGS-15s for HT and surround music? I realize there are advocates for using 4 subs, and I could daisy-chain the SMS-1s, but separating the SMS-1s seems a neat way to keep stereo separate from HT.

Ag insider logo xs@2xdbphd
 “To learn something new, you need to try new things and not be afraid to be wrong.”
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My inclination is to separate the subs, but I was looking for arguments against that inclination.
Hello DB,

     Oh ye of little faith.  The goal is to use all four subs for both stereo music and HT to have near state of the art bass performance on both.  Run all four subs in mono because none of your music recordings were recorded with stereo bass below about 100 Hz anyway, they all have the bass summed to mono.  
     But don't worry, you'll perceive the bass as stereo.  Even though the fundamental bass tones below 80 Hz,  that you're not able to localize (tell where they are coming from), are reproduced in mono by the four subs,  the higher frequency harmonics or overtones of the fundamental tones that reach to frequencies above 80 Hz and are reproduced through the pair of Ref1s in stereo, are able to be localized.  Your brain does the rest by associating the harmonics or overtones to the fundamental tones and this allows you to perceive where the tones below 80 Hz are coming from within the soundstage image.
     Just trust me and give it a try, it works like a charm and you're going to love it.

... Run all four subs in mono because none of your music recordings were recorded with stereo bass below about 100 Hz anyway, they all have the bass summed to mono.
We’ve been through this before, and you’ve been provided with authoritative references to dispel your notion that all LF is monophonic/non-directional. I’m not sure why you choose to reject the science on the directionality of LF. In particular, 100 hZ is not especially low bass, and it pretty easily localizeable.

That many recordings have mono bass certainly doesn’t mean that all recordings have mono bass, as Richard Vandersteen noted.

Of course, if you connect your system so that all bass is mono, then it will not allow you the benefit of stereo bass. And mono bass can sound very, very good, especially in some rooms. Perhaps that’s the source of your confusion.
I don't have a separate music room, so my main music system is right in the family room with my home theater/general TV watching setup that my kids are using all the time.

But the music and HT systems are completely separate (electronics, speakers, subs) and kids not allowed to touch the music stuff.

Regarding subs, I use a REL S5 for music and unwilling to each time HT/Tv being watched by me or family to disconnect/reconnect the sub from my integrated amp to my receiver behind the rack, so I prefer to just use an older Energy sub that I had for HT, and it does a fine job there.

This way never have to reconnect anything, kids are clear on what they can operate and what they cannot, and I get highest quality music in general area of house.

Would 2 subs perhaps sound better for either application?  Maybe, but unwilling to go to that amount of effort when listening time is already short in a busy work/family/spouse filled week.
I'm not sure how this applies to the gear that you have, but my system initially started out more for home theater and over the years the focus has shifted to two channel listening.  I have 4 subs plus a HSU MBM-12 (12" "mid-bass module").

The four subs are connected to one pair of outs on my preamp, which has a home theater bypass option.  Each pair of subs are connected to one output using a Y splitter. 

The MBM-12 is connected to my Marantz pre-processor, which is only engaged for home theater.  The four subs are located throughout my living room in the fashion of a "distributed bass array" as best I can given space limitations.  

I have the subs optimized for music, but they also work great when I watch movies and the MBM-12 adds some visceral grunt to explosions, gunshots, etc.  It's easy to switch back and forth between music and home theater and both sound great.
My primary concern is keeping the stereo and HT setups separate even though there is only a single pair front LR speakers.  For stereo I want the link to be Ayre DX-5 DSD and QX-5 sources going to KX-5 preamp and VX-5 amp, with a Marchand passive high-pass filter between the preamp and amp.  An output from the KX-5 would go to a Velodyne SMS-1, and the output from the SMS-1 to the HGS-10s would be equalized not LFE.

For HT, the DX-5 sends audio via HDMI to the Bryston SP3 that delivers LFE to the other SMS-1 and use its LFE output to the HGS-15s.  My understanding is that the spectrum of LFE is modified to produce more spectacular sound effects for HT.

Okay listen first off its not gonna sound like it but I totally get it. People with HT setups love their HT setups in spite of the horrid sound. Or maybe even because of the horrid sound. I get that. Do not understand why anyone would want to waste their money on horrid sound but they do and so I totally get that.

This still leaves us with the fundamental problem of if it is in the pursuit of horrid HT sound truly necessary to ruin the sound of your stereo? Only you can answer that one.

Because make no mistake, that is what you are doing. Because it is established fact you will get much, much better bass in every way bass can be better- extension, power, smoothness, precision, on and on- with four than with two subs.

So the usual answer would be run all four, duh. But then you would be improving your HT. Which like I said, I totally get that HT people don't really want good sound. Unless maybe you could stand having HT with really good bass? It is after all the processors and HT electronics that are responsible for most of what makes HT such a wasteland, and you will still be able to keep all that. Just the bass will be better. Could you live with that?

Your call.
Hello DB,

    Millercarbon is correct, there's no good reason to split your subs as 2 for music and 2 for HT. Both will be improved by utilizing all 4 in both. I thought that was our plan before you had your non-working subs repaired. The 4-sub DBA concept provides excellent bass quality for music and HT.
    Is your main concern how to setup your components in one system and conveniently switch to music or HT? If so, I think we can come up with a good solution.  
    Basically, you want to use your KEF Ref1s as your front main speakers for music and HT, with your Ayre components for music and the Ayre DX-5 universal AV disc player, Bryston SP3 preamp processor, NAD amps and KEF LS50s as surround speakers. Your Ayre 5/20 series Digital Hub serves as your music preamp and has a bypass switch for HT, correct?

The SP3 distributes the front LR of HDMI audio to a balanced by-pass input of the KX-5/20 preamp that's connected to an SMS-1 as well as to the VX-5/20 amp.  If the subs are to be used only for front LR, then the SMS-1s can be daisy chained in a master/slave arrangement so all four are used for music and HT, and acoustic room correction is applied to bass from the four in unison.  Of course, bass associated with surround channels is likely to be ignored by the LS50s.  And so it goes.

It may be my imagination, but the bass seems better integrated with the speakers since I changed to the equalized input and output of the SMS-1 from the LFE input and output.  The bass hump seems to be gone.

Hello DB,

     " Of course, bass associated with surround channels is likely to be ignored by the LS50s.  And so it goes."

     I think if you go into the Bryston Ayre SP3's Source Setup menu, instructions beginning on page#13 of the SP3's manual,  and configure all the LS50s as "Small" speakers, the bass will be augmented by the subs for all your LS50 surrounds. Actually, it's best if you read your SP3 manual and, starting on page#3, go through all of the  setup screens and make sure everything is set to your requirements.  
     The speaker setup menus for setting the surrounds as "Small" speakers don't begin until about page#13 but it's important you set all settings properly.  I think it also will provide optimum performance if you experiment by initially configuring the KEF Ref.1s as "Large" (run full-range with no  bass cutoff frequency) and then compare this to configuring them as"Small" (with a bass cutoff frequency as low and as close to 40 Hz as you can set it while still sounding good to you.).  This is also the menu in which you configure all LS50s and can experiment with bass cutoff frequencies as low and as close to 40 Hz as you can set it while still sounding good to you.  
     The goal is to find the settings that sound best overall to you.  Remember, since you're setting up a Custom 4-sub DBA system, you're also able to experiment with the Volume, Crossover Frequency and Continuously Variable Phase control settings on all 4 subs individually as well as collectively through the Velodyne SMS1.  Using a Custom 4-sub DBA is much more complex than the AK Swarm 4-sub DBA that I use, but it's also more flexible and able to be finely tuned to your preferences.     
     Let me know if you have any questions.  I'm glad you decided to use four subs on music and HT and believe, once all the setup and configuration process is completed, you'll be glad, too.
     I know for certain from experience that the 4-sub DBA concept works extremely well by taking advantage of the benefits of psychoacoustics and the high quality sensors and processor in the priceless audio component attached to the top of our necks.

It’s been a long time since I read the Bryston SP3 manual, except for snippets. I should follow Tim’s advice. I had forgotten that HDMI from the disc player goes to the the SP3 for audio distribution, so the SP3 will control what’s passed on to the balanced inputs of the Ayre preamp for HT.

So fellow tweekers, I have a handsome high-gloss piano-black KEF Ref 204/2C sitting in my hall that I removed because the LR speakers image so well it seemed redundant. It’s about 3.5’ long and weighs nearly 100 pounds, with a Uni-Q surrounded by four 5.5" cones. Should I reinstall that and use the NAD M22 to drive it? That would entail moving the long low equipment rack from the front to the side of the room. I’ve never tried it with the Ref 1, but I suspect being so similar it might blend even better with the Ref 1s than it did with the Ref 107.2s, and that was pretty seamless. I think the 204/2C was designed for the Ref 207.2s that also had a Uni-Q. Advice sought.

Hello DB,

     My opinion is that you should reinstall it just to look at that beautiful beast.  Whether you want to actually hear if it sounds as good as it looks, is completely up to you.  C'mon man, get that thing reinstalled and don't hurt yourself moving that beauty.

"We’ve been through this before, and you’ve been provided with authoritative references to dispel your notion that all LF is monophonic/non-directional. I’m not sure why you choose to reject the science on the directionality of LF. In particular, 100 hZ is not especially low bass, and it pretty easily localizeable."

Hello cleeds,

      I think you may have me confused with someone else, you never provided me with authoritative references to dispel my notion that all LF is monophonic/non-directional. Please provide those references again.
    In rechecking my references, I noticed that the threshold of human localization of bass sounds, due to the results of the most recent scientific research, has been lowered from 100 to 80 Hz, meaning humans are capable of localizing bass soundwaves above the updated 80 Hz threshold but are not capable of localizing bass soundwaves below this 80 Hz threshold.
    One of my references is the owner of Audio Kinesis and designer of the 4-sub Swarm DBA system, Duke LeJeune, who I recently asked on another thread to verify my understanding of in-room bass dynamics and multiple sub solutions. Below are his responses that I believe are relevant to this thread:

"@noble100 wrote: "Duke... I was hoping to get your honest opinion on my thoughts on how I understand multiple sub systems function in general as well as my understanding of how bass is recorded on CDs and vinyl."  

In general I agree with what you wrote, so let me just toss out a few comments.
" We all are unable to localize deep bass frequency soundwaves..."  

My understanding is that’s generally true in a room. The figure I use is 80 Hz, rather than 100 Hz. I think Floyd Toole uses 80 Hz. This doesn’t necessarily mean that one cannot detect the location of a sub which is crossed over significantly lower, say at 40 Hz, because crossovers are not brick walls, so upper bass/lower midrange energy can give away a sub’s location if it comes through loud enough. Therefore in my opinion a steep lowpass filter on the sub helps to hide its location.  

"the bass is summed to mono on frequencies below 100 Hz on all vinyl and cd recordings."  

I wouldn’t say "all", but I would say "almost all". (If we’re talking about a Swarm/DEBRA system, a second amp can be added to give you true stereo bass).

"Our brains are able to associate the fundamental deep bass frequencies reproduced by the subs, that are not able to be localized, with the deep bass’s higher harmonic frequencies, that extend well beyond 100 Hz, which are reproduced by the main speakers that are able to be localized. This psychoacoustic association allows us to localize the deep bass in the soundstage, for example the kick drum is located in the rear center and the upright bass is located in the front to the left, which would not be otherwise possible without this psychoacoustic association our brain’s are capable of."

I agree.  


Here's the thread link:

Post removed 
I'm rethinking the sub woofer setup.  I plan to use the Bryston SP3 to manage the subwoofers, the Velodyne SMS-1 to provide acoustic room correction.  An output from the Ayre KX-5/20 preamp will go to the SP3; managed output from the SP3 will go to the SMS-1.

I don't know if Roon does surround, but the setup will be there if it does.

Hello DB,

     Okay, I trust you know what you're doing.  At this point, I'm mainly interested with your impressions of using your custom 4-sub DBA system on music and TV/HT.


Of course I don't know what I'm doing.  I'm vacillating with the idea of using daisy-chained Velodyne SMS-1s for both bass management and acoustic room correction.
Hello DB,

     My suggestion is to try out both alternatives to help you decide.  It takes more time and effort but you're ultimately making a more informed decision.  I can state with confidence that a properly positioned and configured 4-sub DBA system requires no room correction software or hardware.  
     I don't  believe running room correction will have any negative effects but, since I've never utilized room control on my 4-sub DBA, I can't be certain.

I've grown suspicious of inserting anything between the Ayre preamp and amp.  Even the Marchand fully balanced passive high-pass reduced the sense of openness and air that was quite noticeable.  I removed it.  That the Bryston SP3 provides 2nd order high-pass filtering made me realize I'd be inserting it between the preamp and amp, so I'll use the Velodyne SMS-1 for both bass management and acoustic room correction.

Surround is via HDMI, so the SP3 will pass front LR to a by-pass input of the Ayre preamp.
Hello DB,

      I understand, connecting the surround front LR main speakers outputs from the SP3 to a LR designated input on your Ayre preamp is functionally the same thing as having a HT/Bypass Switch on the Ayre preamp.  All resulting in you having a convenient method of switching between music and HT use/listening on your unified system.  
     Well done!  And you accomplished this all without taking my original advice of using your Oppo 205.   I meant it when I stated  I trust you know what you're doing.
     BTW, if everything functions up to your expectations, I'm willing to purchase your Oppo 205 at a reasonably premium price along with the shipping costs if you no longer need it.

Thanks and congratulations,

The HGS-10 is ready for pickup, but I'm waiting for the HGS-15 that I hope may be available next week.  Using the setup I described above works well, and an input of the KX-5/20 preamp can be set to by-pass so the SP3 controls level for surround.

I'm always amazed by how the addition of subs enhances depth of soundstage.  I look forward using four subs.  I dreaming about a way to use the big Ref 204/2C other than as a center speaker.

Hello DB,

     I really think you're going to be thrilled with the quality of the bass performance in your system/room once you have all four subs back from repair and set-up.  
     For optimum performance, I suggest you position and configure all four subs manually before running any room correction on the Velodyne SMS-1s.  I know we discussed optimum positioning of the subs previously and I believe you're aware of the importance of setting the volume and crossover frequencies precisely for seamless integration with your KEF Ref1 mains and how to do it. 
  However, I don't think I shared with you my simple trick method of setting the continuously variable phase control optimally on each of your subs. Here it is:

1.  Temporarily invert, or reverse, the polarity on both of your Ref1s by reversing the speaker wire connections to the opposite positions.   The positive speaker wire is connected to the negative speaker terminal and the negative speaker wire is connected to the positive speaker terminal. It's very important that this polarity inversion is done only on the back of each main speaker and the speaker wire connections on the amp are not altered and remain unchanged.

2.  Play some music with good and repetitive bass and sit in your listening seat.

3   Have an assistant slowly turn the continuously variable phase control in one direction and back while you determine when the bass sounds weakest or worst to you, which is the proper setting.  Repeat this procedure for each sub.

4.  Once completed, reconnect the speaker wire connections on both of your Ref1s to the proper, non-inverted positions.

5  Play the music with good and repetitive bass again, sit at your listening seat and verify the bass sounds very good and natural to you.

     This procedure works very well because it's actually much easier to determine when the bass sounds worst than when it sounds best.

     As I'm sure you know, trying to figure out an alternative use for your spectacularly beautiful KEF Ref 204/2C, besides the work of art room centerpiece and very competent center channel speaker it is world renowned as being and very obviously is, has been scientifically proven to be futile.  So, I suggest you just cut it out and reinstall it already.

I had previously done the quick setup of the Velodyne SMS-1 bass manager, so never really studied the manual. I discovered I should have been feeding the equalized output back to the preamp, a connection I had been failing to make. The aim is to set a comfortable spectrum level for the speakers using the video display then match it with the subs, a step I had been leaving out during my decade or more of use!

db, Piled Higher and Deeper
Hello DB,

     Have you fed the equalized output from the SMS-1 back to the preamp and gotten all your subs back from repair and setup yet? 

     Also, do you want to keep your unused Oppo 205 or do you want to sell it to me at a reasonable premium?  I'd put it to good use.


I haven't gotten a notice that the HGS-15 is ready for pickup.  I plan to feed the equalized output from the SMS-1 to the preamp today or tomorrow.  I've designated an input for that procedure.

I'll likely sell either the 205 or 105D or both, but I've yet to send the DX-5 DSD to Ayre.  The 205 presumably has the superior DAC process and does 4K; the 105D has a link to Netflix and is silver.  The 105D is boxed and ready to ship.


I think I ran the SMS-1 setup correctly, setting the overall spectrum level from the speakers to about 80 dB, then matching it closely with the subs.  The combined spectrum from 20-200 Hz seems pretty flat except for a hump around 60 Hz, and bit of rolloff at 15 Hz.  The HGS-15 is in a corner; the HGS-10 behind the left KEF Ref 1, a less than ideal arrangement.  When the other subs are returned, I plan to increase the separation of the Ref 1s about a foot and place an HGS-15 behind each.  I'll try various placements for the HGS-10s.

Hello DB,

     I believe that having four subs distributed in your room is going to increase the quantity of bass modes (peaks and dips), which is a good thing since your brain is going to sum the bass and average it by frequency. This will smooth out your perception of the bass, making it more detailed, natural and I think it's also going to get rid of your 60 Hz hump.
     I have an Oppo 105, I was hoping I could buy your 205 if you're not going to be using it.

db, were you able to get your subs repaired?   
   I think the SMS-1 has some memory presets that will allow you to EQ one unit for both stereo and HT. There are two manuals for your SMS-1 the Velodyne and the Outlaw.
   My DSP experience begins with the Digital Drive 18" and my current two DD-12 Plus. You should gain some insight by looking up both Velodyne's DD Plus User's Manual for multi sub connectivity pages 16-20 and the User Interface Manual. 
   You'll notice the subsequent additions to their software most notable the Frequency Response and Parameters Screen on page 10 of the Interface Manual. Following the Auto EQ program this one feature allows you to click on a frequency band diamond and manually make three adjustments siamotainously within that one band. 
   This adjustment allows you to closely duplicate the Q and filter the subs to closely match your main speakers presentation from 200Hz to within the crossover region. Beginning at 100Hz this adjustment can be feathered long before the main speakers low frequency begins to drop off. After some listening to music there will be some tweaking to taste. Opposed to a sub simply coming on at a set frequency this result is like braiding the subwoofers to the mains and literally defines seamless integration.
   After this adjustment I have four memory presets with slightly different gain settings. Take the time and get comfortable with the SMS-1 the rewards are worth the effort.

   When I purchased the DD Plus' in 2012 I still had the DD-18 and an EarthQuake Nova 15. Before equalization I ran all four subs and experienced the room loading and the lack of any modes. Using one 12 as a master and running Optimization and Parameters the results were greatly improved. I removed the Nova followed by the DD-18 with no sonic degradation but gained a mode deep in one unused corner of the room. 
   In my limited experience proper sub placement and this level of optimization far exceeds the need for four subwoofers in the two rooms I've used this system in. The variability between extra low frequency systems, rooms, and personal taste is so great I'm guessing there are very few absolutes. Good luck with it.           
Thanks for the information and suggestions, m-db.  The repaired subs should be installed Tuesday.  Using the equalized output from the SMS-1 during the setup process revealed the in-room acoustic response of the KEF Ref 1s in the 15-200 Hz region before I unmuted the subs, an unexpected benefit.  I'll try to dig more deeply into the SMS-1.

db, I forgot to mention Velodyne Acoustics may have suspended their audio related production due to successes with Velodyne LiDAR.  

Keep a list of any third party service providers and print any pertinent manual and wiring information from the site I linked in my previous post. Under Service the site lists two service providers. One on the east coast the other in the LA area. They may be the only access to actual product wiring diagrams.   
I used George Meyer on Jefferson Blvd in the Baldwin Hills area of LA.  The cost seems reasonable.
Good. Being in California they may be the best knowledge source going forward.

I found a contact in Los Banos who seems to discounting their remaining new stock which seems to be located in Fremont CA. 
The four subs, 2 Velodyne HGS-10s and 2 HGS-15s, are installed and the SMS-1s daisy-chained, although I'll need some help in relocating each HGS-15s from a corner to behind the Ref 1s.  I did an initial set up of the SMS-1s, but it will need to be redone when the subs are moved into place.   I need to read the manual carefully, because there are subtle  parametric adjustments I do not yet fully understand.  One notable change with the additional subs is the elimination of the mild roll-off from 20 and 15 Hz.  A first listen suggests the four sub array might sound superb.

Don't forget to printout that Outlaw manual from the Velodyne site I posted above. Its a different format with some useful tips which might be of help. 
dbphd: "The four subs, 2 Velodyne HGS-10s and 2 HGS-15s, are installed and the SMS-1s daisy-chained, although I’ll need some help in relocating each HGS-15s from a corner to behind the Ref 1s. I did an initial set up of the SMS-1s, but it will need to be redone when the subs are moved into place. I need to read the manual carefully, because there are subtle parametric adjustments I do not yet fully understand. One notable change with the additional subs is the elimination of the mild roll-off from 20 and 15 Hz. A first listen suggests the four sub array might sound superb."

Hello DB,

I know we previously discussed the optimum sub positioning and configuration of the four subs in a custom 4-sub distributed bass array (DBA) system but I think a few important points bear repeating.
For optimum performance when positioning the 4 subs in a DBA system each sub is run in mono mode and positioned sequentially in the room position that the bass sounds best to you (most accurate, detailed and natural). It’s best not to place subs in positions that are the most convenient or positions that you suspect the subs may sound best. The optimum results will be attained by just trusting the proven procedure of systematically and sequentially positioning each sub in the precise position the bass sounds best to you. You’ll also avoid the need to position any single sub more than once.
A properly positioned 4-sub DBA system requires zero room correction but, if you insist on using it, it won’t have any negative effects as long as you wait to run it until after all four subs have been optimally positioned in the room utilizing the very effective "Crawl Method".

Best wishes,

For the two HGS-15s I think I'll start with Velodyne recommendation to place each next to a front LR speaker.  Each HGS-15 weighs 95 pounds, and I use Auralex SubDudes under them so sliding on the carpet is not easy.  I can lift the HGS-10s.  Right now, the big subs are in the corners and the small ones are next to the speakers.

In rereading the SMS-1 manual I realized I missed a step in daisy-chaining the units:  The slave unit should be set up independently first, then daisy-chained to the master unit and a full equalization performed of the combined acoustic output of the four subs.  I had not set up the slave unit.  Eventually I'll get it right.

I discovered the lack of slam I thought might be endemic to smaller speakers like the KEF Ref 1 is an artifact of some problem between the Bryston SP3 and Ayre KX-5/20 when playing Blu-rays.  Large orchestrations sent by Roon to the QX-5/20 digital hub have satisfying slam, but I've been using Roon for chamber and jazz music.  I'll explore the Blu-ray link when I install a Sanus rack next week that will make access to the rear of the components much easier.

Hello DB,

     For best results, I seriously suggest you ignore Velodyne's recommendation of placing one HSG-15 near each main speaker and instead just position them where they sound best using the crawl method.  They're probably catering to users who don't understand stereo deep bass is a myth with almost all music source material below about 80 Hz actually recorded as summed L+ R mono bass.  It's best, therefore, to just run all subs in mono and position each where they'll sound best sequentially which will also be the same positions the four will sound best playing in unison as a whole DBA system. 
     To prevent moving the 2 HSG-15 heavy subs more than once, you could place one of the 10s at your listening seat, use the crawl method to determine the optimum position of the first two subs likely along your front wall and place the two HSG-15s at both of those positions instead of the HSG-10s. Then use the crawl method to optimally locate the remaining 2 HSG-10s as normal, which could be anywhere along the side walls or long the rear wall.   This will result in the optimum bass response in your room for both 2-ch music and HT.
     You can properly set up the master and slaves in the proper order  and equalize them after the optimum positions are established.