Velodyne Digital Drive Series subwoofer in stereo

It's just a stone cold fact that 65hz bass (which is where I cross over my Velodyne with full range speakers) is not locatable because of the extreme -about 15 feet- wavelength. There is simply not enough phase difference from one side of your head to the other for your brain to differentiate. Anyone who thinks they can is hopelessly delusional. So there are ONLY 6 possibilities:

1. The guys who hear bass in stereo have sub/small satellite systems with their variable crossover frequencies set way too high.

2. The guys who hear bass in stereo are actually hearing the effect of room nodes from the unpredictable interaction of the two subs nearly identical output, and interpreting that as "better" bass.

3. The guys who THINK they can hear bass in stereo on CD's have suboptimal systems with audible distortion coming from their subs which allows them to "locate" the subs output.

4. The guys who are SURE they can hear bass in stereo on CD's have vivid imaginations, are gullible, and therefore probably own Wilson Watt/Puppies, too.

5. The guys who are SURE they can hear bass in stereo on LP's are hopeless romantics, because - I got bad news for you - it ain't there. Even Direct Disk recordings have to be mixed down properly through the board so you can play the damn thing back. Here's a quote from a basic LP mastering text,

"Why is it so important for mixes to be mostly in phase and the bass being in mono?

If the mix is in phase (mono), the cutter stylus will move from left to right - if the mix is out of phase (stereo) it causes the stylus to move up and down. Too much up and down movement (out-of-phase) will produce a groove that's too shallow or interrupted. This will cause the playback needle to jump, especially the bottom end is very critical. If the bass is in stereo, the cutter stylus will leave the surface of the record – the plate will be unusable."

6. And last - They guys who ACTUALLY CAN hear stereo bass have HUGE HEADS - so their ears are far enough apart that the long wavelengths present enough phase shift. Of course, these guys can't use traditional headphones, and the large head has very negative WAF.

Au contraire, the tone of my last post was intended to put some reality into the guys who were bashing Truthseeker personally without offering one shred of backup other than their own unique "experience". And they still aren't, other than the "magical human ear" theory - which is far less plausible than the "magic human imagination" theory, formerly known as the placebo effect, or the out-of-phase sound effect.

The 65 Hz crossover point was custom chosen for me to match my speakers by Velodyne themselves at LOWER than the stock sub's point. And obviously it's not an infinite slope crossover so my mains are operating well below 65hz. The stock Velodyne DD-18, by the way, has a fixed, built in high-pass at 80hz. But I guess there's people here who know more than the Velodyne engineers.

Quick quiz - Do you know how low 65 hz. actually is? It's the very LOWEST note on a cello or a BASS trombone. Tenor trombone's lowest is 82 hz. The very lowest note written for a human bass voice is the same. Low E on a Guitar is also at about 82hz. Timpani - 87 hz. The very LOWEST note an acoustic double bass or bass tuba can possibly play is about 42 to 44hz. And nearly all the notes played even on double bass or tuba are above 63 hz and up to 300 hz. They're not down there banging the low E in every measure.

So what kind of bass are you all talking about? Exactly what instruments or pieces of music sound so much better in "stereo" bass? Organ and Tuba duets?

First of all - I'm not saying there's anything WRONG with having two subs. It may make placement (which is the REAL issue people should focus on with subwoofers) easier in some rooms. And yes, I did have two smaller 12" Velodynes before I sold them to go with a single larger one, which I keep in a slightly off center position - not in a corner.

The reason you have the potential for multiple subs for movies is because some DVD's may place bass tracks in multiple locations - intentionally WAY out of phase for FX purposes - not for music. You can hear that because two sub channels may be mixed 90 degrees apart. But we (at least I) haven't been talking about DVD/Home theater, which I have no interest in. Perhaps I should have been more specific.

As people have said above, the STEREO location of a piano, for your example, even at the 27.5hz Low A comes from the ample myriad of higher pitched overtones that ONLY arrive through the mains. Good subwoofers (if set up properly) playing NORMALLY recorded music, especially on LP - which is all I listen to - are fed no recognizable stereo information through the crossover to transmit. It isn't there unless intentionally placed by the engineer using digital delay effects - like done in a DVD.

In a true musical stereo recording, the pure bass frequencies cannot arrive at the mics far enough out of phase to be audibly placed - only the overtones can. Even in what is called an "exaggerated separation"/ "ping pong" effect by engineers, 2 stereo mics are placed maybe 10 feet apart with a 3rd one in the center. Even assuming the lows aren't later panned to the center during mixing (which they are), the TRUE bass might be out of phase enough to jump a needle from the groove, but still not enough for you to guess where it's coming from.

re: "Both subs responded at different times depending on who was playing. Apparently there are recordings with the lowest notes in stereo on some cds." Or, as you said earlier, "I can put my hands on each driver simultaneously and feel them vibrate at different times on the same tracks."
- - - - Of course you can! Nobody said the recorded signals to both channels are identical - but that doesn't at all mean if you had your eyes closed (and didn't already know the music) you could point to where the bass is coming from.

Anyway, I give up on this one... there's no argument that defeats the Magic Ear theory.

re: Bumblebee flight

From Straightdope.com:
"The basic principles of bumblebee flight, and insect flight generally, have been pretty well understood for many years. Somehow, though, the idea that bees "violate aerodynamic theory" got EMBEDDED IN FOLKLORE."

From David Wilkinson of Quarksoft:
"bringing two wings flat against each other and then moving them apart, very strong vortices were produced which could generate unexpectedly large lift. The earlier "disproof" was based on an inadequate model but THE STORY HAS AN INSTANT AND LASTING ATTRACTION TO THE NON-TECHNICAL MIND."

'Nuff Said.

re: Spacekadet's original post -

Well, since I don't know much about DVD/Home theatre I just called Velodyne tech support directly - and they completely agreed that there should be no "stereo" advantage in having 2 subs. He stated that, even for home theater, the only advantage of 2 subs is, depending on the room, having a smoother response curve attainable across a very wide or deep seating area. He specifically reiterated that the frequencies emanating from a DD-12 or DD-15 are completely non-directional for movies or music. I'd trust the manufacturer more than some Audiogon knowitalls (like me, for example).

He also said that the bass output from one DD-12 is about the same as two DD-10's, so it's (IMHO) an insane waste to buy 2 DD-10's at $2,000 each instead of one DD-12 at $2400, or one DD-15 at $3,000.

Hey - it's just been slow at work, and I enjoy a good debate. You don't think I totally believe all this stuff do you? :) Despite everything I said - I DO keep my sub to the Right of center which is where all the low register instruments are - the cellos, double basses, tubas, etc. of the orchestra is - just in case it does make a difference.

UPDATE - This may be some explanation for the discrepancy in opinions here. Last night I experimented a bit with a 40 hz test tone to see if I could hear where it was coming from. This wasn't scientific since I knew where it was, but I'm pretty sure at LOW and MODERATE volume I couldn't "hear" it's location.

HOWEVER - above a certain fairly loud volume point, I think I could FEEL where it came from, literally - through my clothes. This makes sense (I think) - the primary pressure impulses are hitting your body from a specific direction, and you pick it up more on that side than on the other, just like wind blowing at you.

And the volume is important - just as it's much harder to tell the direction that a light breeze is coming from than a stiff wind is hitting you from.

It's possible that your brain can integrate the directional information felt by your overall body with the non-directional ear input, so that you think you are "hearing" it from there - or in essence ARE hearing it.

I then played some LOUD rock/blues with electric bass, probably centered around 65 hz or so, which I remembered being way over to the left side. I sent it through my main speakers ONLY and concentrated on what was happening. (CD was Joe Louis Walker - Great Guitars)

I could "tell" (not necessarily "hear") that the bass was from the left, and I'd guess it was a combination of feeling the impulses bodily and the higher overtone cues. But the next step would be to try it with the single sub crossed over high enough to really exclude the mains from the lower frequencies and see if the bass "imaging" suffered. Unfortunately the sub now has a custom fixed crossover point mated to my speakers and I can't do that easily :(

In addition, I'm giving the sub away to my cousin this weekend and won't have one for awhile. WAF issues - my wife wants me to get one (or two) of the smaller long-throw cube types.

But my guess is that both sides of this argument have merit depending on SPL and source material:

--At high enough SPL the brain may incorporate information that DOES NOT COME FROM THE EARS, and insert it into the brain's locatization algorithm. I'm not sure if this is anything normally considered in acoustic theory.

--In addition, of course, the source material actually has to have stereo bass - which as we've discussed before is virtually non-existent on vinyl lp's. So for vinyl people like myself, two subs is a total waste. For CD it may be desirable depending on how loud you listen and how much source material has the true bass frequencies actually mixed to one side. And for DVD it probably should be a good idea.