Velodyne Digital Drive Plus 18 (DD18+) Subwoofer Review

[pbc]

Hi Steve what is the sub to the left of your pb13u? Btw...I know that rack was replaced with one of your dual opposed av15's so you ain't doing so bad in the sub department...

P'Digm Servo 15v2...

 

[DS-21]

What's funny about this thread is that there's so much whining about the price, but only one person it seems even read the review. Or at least this passage.

"I have scaled the 2 graphs as closely as possible for comparison. The black line is the raw measurement from the M30 with no smoothing and the pink trace is the same measurement with 1/3rd octave smoothing. Looks rather different eh? The black trace is +/-13.4dB from 15-150Hz. Even with 1/3rd octave smoothing the pink trace is still +/-6.4dB over that range. I had thought that adding the smoothing would better reconcile the two but it still doesn’t match up that well. Even more curious is the fact that many of the main features from the two measurements do not seem to match up. The Velodyne chart indicates a dip at 45Hz instead of the obvious peak. Again at 30Hz there is a bulge in output instead of a dip. Down below 20Hz the Velodyne software indicates a rising response, but my personal rig indicates a large drop off. Very odd indeed. I’m not really sure what to make of this. It almost seems as if the response as reported on the graph inside of the Velodyne software is offset ½ of an octave. Again both microphones were in the same position within ½” of each other. Certainly there can be differences attributable to the different test signals used and the way the data is presented but these seen here are rather large. If you do use the internal EQ of the DD+ series the manual method is by far the best option in my estimation."

Clearly, the feature set of this sub is outstanding. But there seems to be a glitch in the code somewhere. One that doesn't seem to have been there in the old Velodyne systems that used a TV screen to display measures. (Or at least the SMS-1, can't speak to the DD-series subs.)

I don't know if that should "disqualify" it, given the feature set and obvious performance. But it seems to be an actual issue, not just a price tag.

 

[gene]

What's funny about this thread is that there's so much whining about the price, but only one person it seems even read the review. Or at least this passage.

"I have scaled the 2 graphs as closely as possible for comparison. The black line is the raw measurement from the M30 with no smoothing and the pink trace is the same measurement with 1/3rd octave smoothing. Looks rather different eh? The black trace is +/-13.4dB from 15-150Hz. Even with 1/3rd octave smoothing the pink trace is still +/-6.4dB over that range. I had thought that adding the smoothing would better reconcile the two but it still doesn’t match up that well. Even more curious is the fact that many of the main features from the two measurements do not seem to match up. The Velodyne chart indicates a dip at 45Hz instead of the obvious peak. Again at 30Hz there is a bulge in output instead of a dip. Down below 20Hz the Velodyne software indicates a rising response, but my personal rig indicates a large drop off. Very odd indeed. I’m not really sure what to make of this. It almost seems as if the response as reported on the graph inside of the Velodyne software is offset ½ of an octave. Again both microphones were in the same position within ½” of each other. Certainly there can be differences attributable to the different test signals used and the way the data is presented but these seen here are rather large. If you do use the internal EQ of the DD+ series the manual method is by far the best option in my estimation."

Clearly, the feature set of this sub is outstanding. But there seems to be a glitch in the code somewhere. One that doesn't seem to have been there in the old Velodyne systems that used a TV screen to display measures. (Or at least the SMS-1, can't speak to the DD-series subs.)

I don't know if that should "disqualify" it, given the feature set and obvious performance. But it seems to be an actual issue, not just a price tag.

The SMS-1 has never been an accurate measuring device. It's a crude approximated measurement system which I've noted in our SMS-1 review and my DD15+ review.

I've even written about this in an article:
Audio Measurements: The Useful vs. the Bogus in Consumer Audio — Reviews and News from Audioholics

That doesn't take away from the very useful manual setup capabilities of this sub which exceed virtually everything else on the market. I've never run across any sub with an auto-EQ system that consistently produced beneficial results. Most auto-EQ's in receivers suffer the same fate and involve manual tweaking and a good measurement system to get them right.

 

[DS-21]

The SMS-1 has never been an accurate measuring device. It's a crude approximated measurement system which I've noted in our SMS-1 review and my DD15+ review.

Gene, the issue you seem to have with the SMS-1 based on your linked post* has nothing to with the bug Josh, through his extraordinarily thorough review process, seems to have discovered in the DD18's software. The only real issue with the SMS-1 is that it doesn't include everything needed to take a proper measurement of the primary listening position. For that one needs to spend the extra coin for their MIC-5 to get a proper spatial average at the listening position. Or use an outboard measurement system such as FuzzMeasure Pro, and move a single mic through 5-6 spots at the primary listening position, and then average the graphs in software.

*The "problem" you identify is limited resolution due to 1/3-octave smoothing. But in the modal region that isn't really a big deal. Perhaps 1/6 octave resolution would be marginally better, but anything higher than that really just has people chasing nonexistent "problems." Especially if they rely on single-point measurements instead of a proper spatial average. Before you throw the quote from Dr. Toole at the bottom of your linked article into the mix please note that his own bass measurements in Sound Reproduction are considerably smoothed, often to as low as 1/4 octave or only slightly finer than the SMS-1's display. See Toole, at 55-6, 145, 186, 232, 235-6, 247.)

What Josh deduced is a 1/2-octave shift in the display has absolutely nothing to do with measurement resolution. It's a software bug, pure and simple. Hopefully one that's fairly easy for Velodyne to fix and push out a firmware update to correct.

Again, here's the relevant quote, truncated for clarity:

I had thought that adding the smoothing would better reconcile the two but it still doesn’t match up that well. Even more curious is the fact that many of the main features from the two measurements do not seem to match up. *** It almost seems as if the response as reported on the graph inside of the Velodyne software is offset ½ of an octave.

The SMS-1, and presumably the ur-DD subs, don't have that issue.

That doesn't take away from the very useful manual setup capabilities of this sub which exceed virtually everything else on the market.

Funny, nobody disagreed with that, at least assuming you don't consider a closeout ur-DD series Velodyne sub "on the market"

(Though of course if one needs a separate measurement system to get good results anyway, that begs the question of why the EQ should be onboard instead of in a dedicated unit such as a miniDSP or Berry DCX...)

I've never run across any sub with an auto-EQ system that consistently produced beneficial results. Most auto-EQ's in receivers suffer the same fate and involve manual tweaking and a good measurement system to get them right.

With the caveat that I haven't heard the one system that might actually be worth something, JBL's BassQ, agreed. None of the other autocal systems even make a pretense of being able to properly set up modern subwoofer systems (i.e. ones that employ multiple varied units around the room to smooth modal region response and boost overall efficiency in the first-mode region). I hope somebody soon makes a automated subwoofer processor that's worth something, based on an iterative process such as Harman's SFM or Geddes' methods. I'll buy it (at least assuming it's not at a Krell/Levinson price-point) even though I'm perfectly capable of setting things up manually, just for the time savings and to support that rarest of things in modern audio: actual thought applied to real problems.

 

[Warpdrv]

Wow...People really get bent out of shape over subwoofers.

Exactly what I was thinking....

Spec Whores.....


In the infamous words from The Joker… “Why So Serious?”

 

[Ricci]

Exactly what I was thinking....

Spec Whores.....


In the infamous words from The Joker… “Why So Serious?”

LOL... Pat my extensive assumption based napkin calculations have proven that I have 0.5dB more 20Hz output capability from my sub system than you do with yours and I have this winisd screen shot as proof.

 

[Ricci]

On a more serious note which DS-21 brings up, I have never used an SMS-1 so I can't comment on it but the thought that perhaps it is based on the same software and performs the same did enter my mind. Again I have never used one though.

I thought that the Klipsch EQ built into the SW-311 did a decent job. It won't handle more than one position though and has other shortcomings.

 

[pbc]

Speaking of the SMS-1 software, an upgrade/feature add-on would be the ability to remove the smoothing, or at least lessen the amount used in the standard graphs. Though I guess that would eliminate the awesomely smooth "post" response, and render the marketing ads more or less useless.


Reminds me of the AS-EQ1 "post response", which essentially looks like this ...


________________________________________________
20hz...................................................................80hz

 

[gene]

Gene, the issue you seem to have with the SMS-1 based on your linked post* has nothing to with the bug Josh, through his extraordinarily thorough review process, seems to have discovered in the DD18's software. The only real issue with the SMS-1 is that it doesn't include everything needed to take a proper measurement of the primary listening position. For that one needs to spend the extra coin for their MIC-5 to get a proper spatial average at the listening position. Or use an outboard measurement system such as FuzzMeasure Pro, and move a single mic through 5-6 spots at the primary listening position, and then average the graphs in software.

*The "problem" you identify is limited resolution due to 1/3-octave smoothing. But in the modal region that isn't really a big deal. Perhaps 1/6 octave resolution would be marginally better, but anything higher than that really just has people chasing nonexistent "problems." Especially if they rely on single-point measurements instead of a proper spatial average. Before you throw the quote from Dr. Toole at the bottom of your linked article into the mix please note that his own bass measurements in Sound Reproduction are considerably smoothed, often to as low as 1/4 octave or only slightly finer than the SMS-1's display. See Toole, at 55-6, 145, 186, 232, 235-6, 247.)

What Josh deduced is a 1/2-octave shift in the display has absolutely nothing to do with measurement resolution. It's a software bug, pure and simple. Hopefully one that's fairly easy for Velodyne to fix and push out a firmware update to correct.

Again, here's the relevant quote, truncated for clarity:



The SMS-1, and presumably the ur-DD subs, don't have that issue.



Funny, nobody disagreed with that, at least assuming you don't consider a closeout ur-DD series Velodyne sub "on the market"

(Though of course if one needs a separate measurement system to get good results anyway, that begs the question of why the EQ should be onboard instead of in a dedicated unit such as a miniDSP or Berry DCX...)



With the caveat that I haven't heard the one system that might actually be worth something, JBL's BassQ, agreed. None of the other autocal systems even make a pretense of being able to properly set up modern subwoofer systems (i.e. ones that employ multiple varied units around the room to smooth modal region response and boost overall efficiency in the first-mode region). I hope somebody soon makes a automated subwoofer processor that's worth something, based on an iterative process such as Harman's SFM or Geddes' methods. I'll buy it (at least assuming it's not at a Krell/Levinson price-point) even though I'm perfectly capable of setting things up manually, just for the time savings and to support that rarest of things in modern audio: actual thought applied to real problems.

Wow there is a lot if misinformation in this post but I will try to address the main issues here.

1/3 octave is NOT sufficient for doing any sort of room correction or analysis. The SMS-1 system is more like 1 octave than it is 1/3rd, but lets assume its 1/3rd for the moment. Taking a high resolution measurement and smoothing it to 1/3rd octave is NOT the same thing as making a 1/3rd octave measurement. Dr. Toole does much higher resolution measurements and then smooths them for easier understanding in his book. I know this b/c I spoke directly with him on this topic when writing one of my earlier articles.

When a measurement is taken with such low resolution, it can easily miss a higher Q null or peak. This is most likely why the SMS-1 measurement is off from Josh's and the same issue we discovered prior to Josh's measurements. Their system hasn't changed or evolved since the SMS-1 which I noted in my DD15+ review.

Velodyne reasoning is their auto-eq and measurement system is more of a layman room correction. A pro installer will use an external measuring device to manually calibrate the sub.

I suggest reading Dr. Floyd Toole's book on Acoustics which discusses the very topic of room measurements and calibration. You need at least 1/12th octave resolution to do any sort of accurate low frequency room correction which the SMS-1 simply cannot do.

 

[gene]

Speaking of the SMS-1 software, an upgrade/feature add-on would be the ability to remove the smoothing, or at least lessen the amount used in the standard graphs. Though I guess that would eliminate the awesomely smooth "post" response, and render the marketing ads more or less useless.


Reminds me of the AS-EQ1 "post response", which essentially looks like this ...


________________________________________________
20hz...................................................................80hz

The Audyssey measurement displays from their system is equally if not more useless than the measurement display of the SMS-1. The Audyssey displayed measurements are theoretical so actually they are worse.

The reality is consumers like to see smooth graphs. As Colonel Jessup used to say "You can't handle the truth"

This is why most of the major print magazines display 1/3rd octave measurements with 120dB scales. Smooth lines make consumers happy, and manufacturers happy.

 

[Ricci]

Gene is that correct? Re: SMS-1 and 1/3rd octave data collection for the measurement?

 

[96cobra10101]

So much crying about money. Why can't anyone just let products (whether it is speakers, cars, watches, whatever) stand for themselves and forget the price tag? Maybe not everyone can afford them, but who cares? Let them be what they are whether they're affordable or not. Why would I buy a rolex when a timex from walmart works better?

Because a Rolex is Baller, a Timex is Wal-er.

 

[gene]

Gene is that correct? Re: SMS-1 and 1/3rd octave data collection for the measurement?

Velodyne has always been very vague about this. They claim they purposely smooth the measurements to 1/3rd octave to make it easier for the average consumer to understand. Personally I believe their measurement system is simply limited in resolution to take anything better than 1/3rd octave. Regardless, the only way one can make reliable measurements and calibration is to do exactly what we do, measure with at least 1/12th octave. I measure at even higher resolution and smooth to 1/12th for bass and 1/6th for high F, when reporting in a review or tech article personally.

I was hoping with the computer interface they would have increased measurement resolution but it simply never happened

 

[DS-21]

Wow there is a lot if misinformation in this post but I will try to address the main issues here.

I guess serious thought is "misinformation" to the guy who wrote that "toppled-MTM's don't suck so bad despite what people who can hear think, and how closely that tracks their abysmal measured performance, really, I promise" article...

1/3 octave is NOT sufficient for doing any sort of room correction or analysis. The SMS-1 system is more like 1 octave than it is 1/3rd, but lets assume its 1/3rd for the moment.

Interesting claim. You do realize that a 1-octave measurement would from 5-200 Hz would consist of all of 6 data points (5, 10, 20, 40, 80, 160), right?

Taking a high resolution measurement and smoothing it to 1/3rd octave is NOT the same thing as making a 1/3rd octave measurement.

While that is true, you've provided no evidence to support your position. Saying that a firm is "very vague about this" is not information.

I have compared my SMS-1's output to 1/3-octave smoothed measurements using FuzzMeasure, taken with the same mic that has not been moved. My conclusion from those comparisons is that the system is accurate enough to make pulling out the mic preamp, etc. not worth it. The SMS-1 (assuming the MIC-5 is also used) is easier to use. (Incidentally, these days I only use my SMS-1 for measurement. The processing side of the device is just too limited; it cannot even individually adjust level and phase for its three outputs. So I measure with the SMS-1 fed by a MIC-5 with a configuration to properly take a spatial average at the listening position*, adjust the levels/delays/PEQ with a miniDSP, and then put the SMS-1 and MIC-5 back in the closet)

*A representative configuration for a proper spatial average at the listening position looks like this, minus the kittens:

Notice that I am taking a spatial average around one listening position, not trying to use flawed single-point measurements to average multiple spots.

Velodyne reasoning is their auto-eq and measurement system is more of a layman room correction. A pro installer will use an external measuring device to manually calibrate the sub.

That's all quite silly. For one thing, if it were true, why would Velodyne offer the MIC-5 kit? They're not exactly targeting consumers with that, now are they?

A more reasonable inference is the lazy person will throw on the auto-EQ, and the more interested person will, using the measurement system Velodyne provided with the sub, manually adjust the parametric EQ.

I suggest reading Dr. Floyd Toole's book on Acoustics which discusses the very topic of room measurements and calibration.

I believe Dr. Toole has only written one book, Sound Reproduction. At least, that is the only book that comes up in an Amazon search for "Floyd Toole."

Had you read my post with a modicum of care, you would have noted that I provided cites from that very book.

You need at least 1/12th octave resolution to do any sort of accurate low frequency room correction which the SMS-1 simply cannot do.

If you want to chase phantom problems, be my guest. But while you waste time to no audible benefit, I'll be enjoying the music thank you very much...

 

[Matt34]

DS-21,

This isnt the avs forum where posting like an *** is the norm, especially when addressing the owner. Next post like the one above will get your posting previldges suspended.

 

[Ricci]

Anyone want to let me borrow an SMS-1...

 

[Sputter]

Having measured my subs via SMS and then measuring with REW there was a wide difference between the two graphs, enough for me to use REW for measuring and SMS to apply filters based on REW.

SMS does what's supposed to do in it's limited scope, I found REW to be more accurate. I only found that out by doing my own comparisons in my own room.

I would say that some rooms might be tougher to get a flat response, therefore the difference between SMS and REW would increase. Conversely, the easier room could be a closer match to what SMS and REW 'sees'.

YMMV

 

[mike c]

DS-21,

This isnt the avs forum where posting like an *** is the norm, especially when addressing the owner. Next post like the one above will get your posting previldges suspended.

but but, he probably knows more about subs than all of audioholics put together. he doesn't even need actual experience with subs.

i don't post on avs anymore because of this subwoofer BS, everything's just too serious.
i chose AH because discussions were more respectful. it's sad these know it alls have spilled over here.
subwoofer discussions just attract them like flies to ...

 

[pbc]

I think what DS may be saying (it's fun putting words into people's mouths), is that 1/3 Octave is enough from a measurement perspective to adjust for what matters.

I.e., I believe, 1/3 Octave corresponds to 12.5 Hz, 16 Hz, 20 Hz, 25 Hz, 31.5 Hz, 40 Hz, 50 Hz, 63 Hz, 80 Hz, 100 Hz, 125 Hz, 160 Hz, and so on.

Chances are, you're not going to go in and manually try to correct very narrow peaks or dips in response and therefore 1/3rd "may" be enough from a measurement/correction persective since sure, we can all look at a line with more resolution but at what point are you chasing things you can't fix?

However, looking at the above, once you get to the 31.5 - 40hz, then 40hz to 50hz, I would start to wonder what is happening in between.

Would be interesting to know whether the SMS-1 is in fact measuring at a higher resolution and presenting the FR at 1/3 Octave, or measuring at 1/3 octave as well.

 

[Sputter]

but but, he probably knows more about subs than all of audioholics put together. he doesn't even need actual experience with subs.

i don't post on avs anymore because of this subwoofer BS, everything's just too serious.
i chose AH because discussions were more respectful. it's sad these know it alls have spilled over here.
subwoofer discussions just attract them like flies to ...

Piling on isn't cool either.