Velodyne Digital Drive Series subwoofer in stereo

Hi, I've been very interested in running two subwoofers in stereo (diff. signals to each subwoofer); I've heard many people swear by this setup.

My next room for my system will be 14' x 14' x 18' high ceiling loft living room. My question is, will two DD10 be enough to fill the room with organ music and scare me out of my seat for movie tracks? Should I move up to two DD12s? Money is not really an issue, but I'd like to save wherever I can.

Any help would be appreciated. Thanks,
All I can tell you is I have DD12 in a 18 x 24 x 9 high room and one is more than enough. I would say the 2 DD10s would be plenty.
I owned a DD-12 in a room 18x20x8 with one wall of sliding glass doors. Quite the sub but I replaced it with a DD-18. No comparison (nor should there be because of the cost). The 18" sub is just super with anything I use it for... movies or stereo listening. My thoughts are if your even thinking of two (2x the dollars) get the DD-18. Its increadible. Move it around a bit in the room if you can (have help!), find the sweet spot and then utilize the software to tune it to the room. This is one great subwoofer!

Better yet get two!

By the way... Velodyne has a pass through for a second sub built in to their DD series.
Hi Sailfishben,

A single DD15 or DD18 would be nice but I'm really interested in running two subs in stereo. When I say stereo, I don't mean two subs daisy chained to each other receiving the same LFE signal, but two subs receiving different left and right channel signals.
If money is relatively no object, go with the 12's.
My understanding is low frequency is basically non-directional so I'm wondering what the point is to use it in stereo? I know the sound stage created in my system has plenty of low end response and the low end seems to come from within the soundstage but certainly not from the corner of the room where the sub is actually located.

Wouldn't you have to run the speaker cables to the sub and then to the speakers, creating some long runs not to mention great expense for extra cabling? Although I wonder if you couldn't just use the r/l tape output (assuming they are not used already) letting the sub's crossover do its work on the signal.

Hi Sailfishben,

Well, I have never personaly experienced two subwoofers setup receiveing separate stereo signals. But I've heard from people who say it makes a big difference.

I figured I'd buy couple of subwoofers to try it out and A/B test it w/ a single subwoofer, and then sell the extra subwoofer if there is no significant difference.

As for actually hooking up cables, my McIntosh C45 preamp is perfect. For stereo inputs, it can simultaneously provide THREE (two XLR balanced, one unbalanced) outputs. I connect the preamp to my amp via XLR connection and will use the other L & R XLR outputs for the subwoofers.
Please repost after you do your experiment. I'm interested in the results. Thinking of changing my Adire Rava with either 2 Velodyne DD or the new REL Britannia. Speakers Dynaudio S1.4, amp Plinius 102, Preamp Supratek, TT REGa Denon/ DL103
I just found this on the Anthem website...

Q20: I have two subwoofers and want to use them in stereo. Can the surround preamp's subwoofer outputs run in stereo?

A: No, although the same job can be done by disabling the sub channel in the setup menu, then hooking up the subs through their own crossovers to the front left and front right channels. This is not recommended because a stereo subwoofer configuration has little value. Few recordings contain real stereo bass info, (e.g. large pipe organ using widely spaced microphones) and unless the subs are located outdoors and away from the ground, they can't reproduce it anyway. Inside a room, running them in mono instead is beneficial because they can be moved to wherever they create the least amount of resonance individually, and as a combination, make each other's response peaks and valleys less severe. As well, a "bass spaciousness" effect can be dialled in with the phase control if it's available on one of the subs (which is what happens when two widely spaced microphones pick up a low frequency source - same long wavelength, different phase between the two).


Thanks Sailfishben,

I was going to buy a Velodyne DD10 for my bedroom and then add another one when I move to my new apartment, but I found a really good bargain for DD15 and ended up ordering that... I'll update my system as soon as the subwoofer arrives.
GREAT... so glad you obtain the 15" driver. Simple math tells you it's 50 percent larger, which as Yogi would say, is a lot! Anyway if you stumble on the set up, e-mail me. I'm no installer but... Enjoy!

The DD15 will be here any day now.

Sailfishben, as far as math goes, you should focus on the surface area instead of the length. The 15" driver has over double the surface area of the 10" driver. Actually more than 2.5 times as much considering the DD15 has 12.7" piston and the DD10 has an 8" piston.

I'm really happy to find a new DD15 at a really good price and can't wait to hear it!
The Velodyne DD15 is here! This thing is really ridiculous. The whole setup took me less than an hour and the bass frequency response is pretty much ruler flat except for a bump at 50Hz due to the tiny room.

I've talked to couple of my professors at U. of IL. and they convinced me that two subwoofers running in stereo makes no sense. After hearing the Velodyne DD15 in my system, I have no regrets and am no longer curious about two subwoofers.

I'm sorry to end this thread this way, but the DD15 and two professors from my Aerospace and Electrical Engineering department have convinced me that one subwoofer is all I need.
As someone who has run a mono ULD-12 and then a stereo pair of them, I can tell you there is a difference. Just because the ear does not sense the direction of low frequencies, does not change the fact that the information in the low frequency signal may be (and often is) different between the left and right channel. Summing them to mono can and many times does cause cancellations and peaks due to phase cancellation.

As far as your professors having the answers, don't be so sure that because they are professors they have the answers. Ask them is two amplifiers that put out the same power sound the same? What about different speaker cables? Acoustic engineering is a specific field and just because you are an engineer proficient in EE or AE, doesn't mean you know squat about another field.

Cary, I asked the professors because they are also in the hobby and definitely know a thing or two about audio, and both hold multiple Ph.D degrees in relevant fields.

Who should I ask if these professors aren't good enough? You?

Also, those little questions on your last paragraph would be insulting to ask them. Throw me a bone here.
I'm just another guy on the internet, so my opinion is as good as the next. I would suggest that you check out the some literature on Richard Vandersteen's site as he is a big proponent of stereo subs.
Dear Spacekadet: Velodyne: great choice nobody knows more about subwoofers that Velodyne people. I own two HGS-15, why two?: well not only because there are music information in the lef and right side of the recording signal but more important because those low bass ( left/right ) generate a lot of harmonics down and up the fundamental frecuency. So, if you have only one subwoofer you are missing a lot of music.

+++++ " except for a bump at 50Hz . " +++++

I can suggest that you can try other subwoofer position: side firing.

Now, the crossover point for the Totem's is very important ( critical ): which was your crossover point that you choose?

Regards and enjoy the music.
I'm no professor but it seems to me you can't 'miss' any of the bass if you've summed the two channels through the sub. Its all there, how can you 'miss' any? Has anyone really compared two subs run in stereo to two subs daisey chained together? And can you honestly hear any difference or do you perceive it? I just can't believe there is. A benefit to having two subs though is another matter. I know two different people running two DD-18's in their systems... from what I hear, I want to match my single DD-18 to a sister sub... holy cow! Neither runs their other then daisy chained and both are knowledgable people in the industry.
Two answer your question, I have compared my two ULD-12's running in mono and in stereo. There is a difference. Remember that the left and right channel may have different phasing when picked up by the microphone. The most extereme example would be where the mike picked up the signal 180 degrees out of phase. This would result in no signal when summed to mono, when in fact there is a completely different signal from left to right. When played back the summed mono would have no output while the stereo subs will put out the signal and the listener will hear the bass as picked up by the microphone.
I agree with Mcreyn and some of the other guys. No doubt about it two stereo subs are very easy to discern from a mono sub or two mono subs.Infact once you hear it ..all your questions will be answered.
Dear Spacekadet: Why I already say that you can loose music info. With a pair subs you have stereophonic sound reproduction that is exactly how its happen at the recording event.
Example, let's take a low drum that was recorded at left side of a music hall : if you have a dual mono subs ( left/right separates ) you will hear that drum at the left side on your audio system but if your subs are sum up ( left+right ) you will hear that drum at the center of your audio system.

Regards and enjoy the music.
Possibly the difference between one or two subs is non-quantifiable. I certainly heard a difference when I added a second Vandersteen 2W sub to my system running in stereo. I believe I hear quite well the stereophonic effect of the low frequencies. The room certainly fills with low sound better than with one sub, and there have been no problems with nulls that I'm aware of. Currently I have ten 8" bass drivers operating and simply the presence of the additional drivers makes exceptionally deep frequencies audible. Previously, when I operated two subs (with six 8"drivers total) an incredibly low bass note was not even audible. With the addition of four more drivers it could be sensed.
Dear Douglas: +++++ " . I believe I hear quite well the stereophonic effect of the low frequencies. " +++++

The stereophonic effect: I tottaly agree with you and that issue is all about the use of two sub's instead only one.

Regards and enjoy the music.
This whole stereo sub thing is nonsense. Hardly any info there. Hardly heard. If you can detect a difference, it's because there are now TWO subs in the room instead of one, and the strain on the single sub will now be halved. It's the transients you hear first when it comes to bass, and those transients are almost always located above the crossover your mains. The ONLY possible way you "might" be able to increase the "spaciousness" in your subs is if you physically locate them directly to the sides of your head (ala Lexicon pre-pros)...and even THAT is of dubious benefit. MUCH research has been done on this. If you really want to improve the bass, yeah, buy two subs...but DON'T bother running them in stereo. Either stack 'em or spend a LOT of time and effort situating them properly.
Truthseeker if you haven't tried this in your own room what you speak is nonsense.LOL

"If you can detect a difference, it's because there are now TWO subs in the room instead of one, and the strain on the single sub will now be halved"

I'll be damn you answered your own question. If there are two working less than have lower distortion correct. I've not heard a single speaker that could create a stereo image all by itself. If you have please let me know. :-)
Think of the money you could save by only needing a single speaker!WoW

Have a great day!
Truthspeaker, I'm amazed at the amount of mistruths and ignorance that can be packed into a single post. Congratulations!!
Dear Spacekadet: I'm not against your advisors that convince you to one sub instead of your original and correct idea of two subs in a stereo fashion.

The integration of subwoofers in an audio system is not only for abetter low bass performance: far from this, please read these links about:

Regards and enjoy the music.
Amazing how strongly some (Truthseeker - funny handle...) confuse opinions with experience. I was skeptical about multiple subs. My neighbor considerately lent me his sub to pair with mine, and the reponse was better - smoother, more toneful, more texture, less nodes. Multiple subs placed symetrically minimize room nodes effects. Multiple subs are NOT about more bass. Also, subs are NOT omni-directional. Try turning off your mains and running tones through your sub. Believe it or not, you will hear the sub above 200 Hz! And mine is an active 24dB/octave crossover at 60Hz.

There is so much BS on the Internet passed off as fact, by punters who never bother to learn for themselves. Warning - too much time in these discussion forums is dangerous to your audio health ;-)

Truthseeker, not to argue...but I my understanding is that there is indeed different information that is sent to L/R subs when run in stereo. I may be wrong about that.
I know that my system (using Vandersteen subs) does not simply make a dual mono presentation. They are literally receiving only L/R signals. Are naysayers suggesting that in all recordings there is never low hz information sent to either left or right, but only both chanels? This may be, but I have never heard of it.
I have listened for years with one sub, then added the other. Whatever it does, using stereo subs alters the listening experience, especially since (and I don't care much if it's technically appropriate or not - it sounds great) the subs are directly behind the main planar speakers in the front corners of the room. To me, it's the ultimate way of integrating the subs with the mains.
Perhaps Truthseeker has not had experience with a high end system using a pair of properly integrated subs but the difference vis a vis a single is quite pronounced. I would suspect most audiophiles that have switched from a single sub to a pair will testify to this.
No question about Wc65mustang.

Regards and enjoy the music.
Dear friends: THis is a very interesting link about the subwoofers number that we need.
This link was posted by Skushino on other thread. The conclusions are on the page 28, yes is a long history:

Regards and enjoy the music.
Folks, as it so happens, I had a pair of Velodyne HGS-10 subs. Yes, a PAIR. I experimented with many locations...stereo, opposite walls, 1/3 wall, staggered, etc. I ended up stacking them and placing the stack just outside of a corner. Even played with a Behringer (very difficult learning curve).

Gmood1, what I meant to say is that there's hardly ANY out-of-phase information in the low bass regions where subs operate, and even if there is, it's makes no difference. There is NO imaging at frequencies that low. If somebody thwacks a 50hz bass drum note, the imaging will come from the over-80hz transients located in your MAINS, and not the sub.

And btw, the Velodyne HGS series play with undetectable distortion in the first place, so the addition of the second sub served merely to increase overhead. The pair of HGS-10's has been replaced with a single DD-10, which will soon be upgraded to a DD-12.

Wc65mustang, my system is indeed high end enough to be able to discern a difference IF there was one. There wasn't. And my subs were as properly integrated as experimentation allowed. If I should ever decide to experiment with two subs again, I'll have YOU come over to demonstrate your special integration skills, but only if I can blindfold you to see if you can detect a difference. :)

On 99% of cd's, low bass out-of-phase info just isn't there...period.
Truthseeker, I suggest you spend part of your discretionry dollars on a good audiologist. Perhaps that is the problem. Good luck and I'd be glad to help you.
>>I suggest you spend part of your discretionry dollars on a good audiologist.<<

Do you have to work on being obnoxious, or does it come naturally?

Instead of attacking the message, you choose to attack the messenger. Instead of giving your own opinion about the sonic superiority stereo configured subs, why not show some pertinent research. If you actually DO do some research, you'll find that when multiple subs are recommended, they are never done so in a stereo configuration. Multiple subs ARE sometimes recommended by those who have the patience, expertise, and measuring equipment necessary to find the nodes, nulls, etc., but given the total number of possible sub placement permutations, I doubt that you are capable of such an installation.

Enjoy your stereo configured subs if you will, but please don't try to pass off your opinion as fact.
Much of this conversation boils down to whether or not you believe that sub-80hz bass is directional. I don't believe that it is...and my experience has born this out. Therefore, the notion of stereo bass below 80 is meaningless to me. I suspect that most manufacturers feel the same way, and this is evidenced by their inclusion of the THX standard 80hz crossover point.
LOL my friend. Enjoy what you can hear.
I shall, my friend, and YOU enjoy what you THINK you can hear. :) need to bother if you can't hear the difference.Just enjoy the mono string plucks.:-)

Good listening
I can put my hands on each driver simultaneously
and feel them vibrate at different times on the same tracks. I suppose the subs only think their receiving a stereo signal as well. LOL
Maybe it's time to replace those Bose 901s Truthseeker. Move on up to a pair of Advents.
Actually, I'm using some extemely high end Radio Shack speakers for which I paid $34.95...which is probably more than what you paid for your Walgreens Sonicbox speakers.

You children obviously need to do quite a bit more research if you'd like to carry on an intelligent conversation about bass. Didn't realize I was playing in a sandbox....I'm outta here. :(
Don't let the door hit ya.Where the good lord split ya!

Truthseeker it's interesting that among all of the posts in all of the threads regarding the sonic advantages and superiority of a stereo subwoofer system, that you are the sole dissenter. That speaks volumes to either your ear or system. Here's a thought:
Thank you an have a nice day.
Dear Truthseeker: +++++ " This whole stereo sub thing is nonsense. Hardly any info there. Hardly heard. " +++++

I think that you have a misunderstood of what happen in a real stereo subs integration to any audio system:

First, we choose the crossover frecuency ( say, 80Hz ) in the high/low pass filters. What this means?
That the main speakers will handle frecuencies over 80Hz and that the subs handle below 80Hz.
Normally, the self electronic subs crossover is a second order design ( 12db per octave ), this means that the subwoofers will work with frecuencies as high like 200Hz and now in the whole subs frecuency range will be stereo information.

Second, the subs reproduce not only the fundamental frecuency but their harmonics too where we can heard the left right info.

Third,it is not totally true that the CD recordings has only mono low bass. One of the CD advantages is that there is no problems for to record left/right low bass frecuencies ( in the LP is different ) and that's what the CD industry is doing: taking advantage of the CD medium.

Fourth, when you attend to a classical music performance you can heard bass sound coming from the left /right side of the hall, example: bass drum to the left and double bass at the right and this is exactly what we heard/feel when we have two subs in a stereo way at home.

Dear friend, I respect your opinion and that was mine.

Regards and enjoy the music.
I listen to a lot of electronica and there is def info at or below 80 hz in stereo,even panned from left to right,,so i can see where running 2 subs in stereo would be a good thing,,one day i would love to try it!using just one sub drove me crazy!I decided not to use a sub again untill i can do it in stereo! Just my opinion of course.
Truthseeker. Did you read this AA thread? There is only one other misguided person that agrees with you compared to the hundreds of others whom are actually correct about the 2 sub deal. I suggest you quietly walk away from this one.
If any of you folks could produce some type of coherent argument or refutation of the widely accepted acoustic theory (OTHER than your weak anecdotal evidence), I'd have more respect for you. None of you is particularly versed in crossover filter theory. None of you can hold a beginner's discussion regarding bass management theory. None of you can even admit that whoever convinced you to buy an extra sub for the purpose of achieving stereo bass separation RIPPED YOU OFF!


Those of you who think they can, own cheap subs that produce significant harmonic distortion. This is DIFFERENT than the HARMONICS instruments naturally produce. An INSTRUMENT playing a 70hz note will also emit a first harmonic of 140hz. That 140hz tone will give directional clues as to its direction. A sub reproducing this 70hz tone will ALSO produce the harmonic....but at the outer band of its crossover's down from the original signal. The harmonics from your mains will COMPLETELY mask that of the subwoofer if your subwoofer is decent and has low distortion. THUS, if you use a decent, low distortion sub, with a 24 db/octave xover, the sub will play the 70hz tone, and the mains will provide the directional cues in stereo.

You can't deep bass in stereo no matter HOW much you THINK you can. The stereo effects are produced in your mains. Cross the sub over at no more than 80hz, use a higher order xover, and save the money you would have spent on an extra sub for CD's and DVD's. OR...give it to the dealer who convinced you to buy the extra sub...heh heh.

"You think, therefore you hear".

experiment: If you have a LOW distortion sub (like a Velo HGS or DD model) and have it crossed over at 80hz or lower, disconnect the mains. Then, close your eyes and have a friend move the sub around. See if you can point to the sub with your eyes closed. You won't be able to.


I think you have your xover notion a little mixed up. The THX standard (they don't know anything about sound now, do they?!) xover is a second order HIGH PASS of 12db per octave at 80hz for the mains or satellites and a complimentary LOW PASS Linkwitz-Reilly (24db/octave) crossover of 80hz for the sub. This means that an 80hz tone will be down 12db's at 40hz in your satellites, and down 24db's at 160hz in your sub. That is why it is suggested that satellites or mains be capable of decent output one octave below the xover frequency.
And the reason you can locate the bass drum in a concert hall is because of the harmonics of its transients and the fundamental tone...which will be played in its full stereo glory BY YOUR MAINS. If that same bass drum could ONLY play it's fundamental tone (no harmonic), you WOULD NOT be able to locate it.

Go play now, children.

OR do some real research.
Truthseeker is correct.
LOL Truthslayer. You're too much!!!