Subwoofer shootout in Ultimate AV (1 Viewer)

[Bhagi Katbamna]

Great article by Keith Yates in Ultimate AV(the new name for Stereophile Guide to HomeTheater). He compared the Revel, Wilson Watchdog, Kleiss, and Genlec Powered subs. What really stood out and represents a real change for the magazine is the measurements he performed. I really liked the dynamic compression measurements and thd at 100,105,110, and 115dB. Check it out if you can.

 

[Mark Seaton]

FYI, this was part 1 of a 3 part report. 4 more subwoofers to come in each of the next two issues.

For those interested in the testing and review methods, Keith Yates wrote up a description which is posted on the SGHT website:

Measurements & Meaning: Way Down Deep

Keith Yates is also not your tyipcal reviewer. He is primarily a constultant who designs some of the highest performance home theaters I know of. His website isn't very up to date, but you can find some background here: www.keithyates.com

Disclaimer - I'm not totally impartial here - watch for next month's issue.

 

[frank manrique]

quote:

"Keith Yates is also not your tyipcal reviewer."

Well, at least he doesn't use words like "pace and rhythm" and other such idiotic attempts to describe aural perceptions by the high-end audiophile lunatic fringe...

"Disclaimer - I'm not totally impartial here - watch for next month's issue."

Oh, oh!

It'll be good to finally see how your subs perform under rigurous tests, Mark...

-THTS

"...hi, my name is Frank...and am an SVS bassaholic..."

 

[Bhagi Katbamna]

And, he stated that the term "fast bass" is an incorrect term.

 

[John F. Palacio]

Bhagi says:

I like him already!

 

[Craig Chase]

It will be interesting to see what Ed's review on the PB2-Ultra looks like against the AV Review. I am keeping the AV issue handy for comparison purposes... looks like good stuff.

And for those of you who do not like the term FAST bass, I am coining a new term... TRAD (Transient Response, Attack and Decay)... That is what is actually being heard. Take a poorly designed subwoofer, and no matter what you do, nor how good the upper octaves of the attack are, a kickdrum will sound like a thud, not a thwack. That is because the subwoofer in question cannot respond quickly enough to replay the signal it receives correctly.

The first guy who tries to tell me all subwoofers have the same TRAD will be banished forever to AVS.

Fair enough ?

 

[John F. Palacio]

I thought the "upper octaves" would be reproduced by the mains? Not the sub.

So go ahead and banish me!

 

[Craig Chase]

A good portion of the attack portion of a kickdrum is reproduced by the main speakers, as its frequencies are above those of the subwoofer, while the subwoofer actually reproduces the fundamental, listen to a kickdrum with the mains off, and you will hear what I mean...both the upper frequencies AND the fundamentals have to be presented by drivers with excellent transient response...

You are now exiled...

 

[Jason Brent]

.....Craig has spoken......

"You are fired!"

 

[Craig Chase]

Or... John can bring beer and pizza... and stay...

 

[Jason Brent]

I'll take a large cheese please...

 

[Edward J M]

I haven't read these reviews. I'd like it if you kept them for me, Craig - thanks.

Dynamic compression: I usually run my FR sweeps at 100, 105, and 110 dB. Dynamic compression is really a combination of power compression, port compression, and mechanical limitations of the woofer suspension. Eventually the curve will start to compress in the bottom octave, signaling the onset of this phenomenon.

I prefer to ground plane at 2 meters - if the weather cooperates. In upstate NY, that's an iffy proposition. Otherwise I have a spot in my room that pretty closely mimics GP from a FR standpoint.

Naturally, the THD data will be radically different inside at 1 meter vs. outside at 2 meters. The PB2-Ultra will not ever be GP'd - too expensive, too nice of a finish, and too heavy.

Also, when I ran THD on the PB2-Ultra I switched to 5% above 25Hz because the higher frequencies would have approached 130+ dB at 10% at 1 meter in room - thanks but no thanks.

I will drop this tidbit: Normally I don't measure THD at the listening position but I couldn't resist checking 20 Hz at the seat with the PB2-Ultra. I chickened out at 114 dB @ 20 Hz @ the listening position and THD still handn't hit 10%. "Room lock" was really starting to occur, where the room sets up in a strong sympathetic resonance and everything that wasn't bolted or glued down was moving. Can the PB2-Ultra do Reference Level bass at the seat with less than 10% distortion? You bet.

 

[Craig Chase]

Ed - Basic Testing was:

1. Outdoors
2. One Meter
3. Distortion when audible, no % applied, though distortion levels were measured.
4. max SPL from 20 to 80 HZ

For example, the Genelec HTS6 managed about 115 dB outside at one meter/ 20 Hz... very impressive, though it is $9950.

The $2500 Kleiss did 110 dB, for a $2500 subwoofer, THAT is impressive.

Each subwoofer also seems to be a great sounding unit...

 

[Mark Seaton]

Ed - take a look at the link I posted above. Most of the details of the testing are in there. Keith did measure at 2m outdoors, and subtracted 6dB to get more familiar 1m numbers. 1m can be still a little too close for fully representative measurements on larger speakers, especially something like the Genelec. I'm not sure what method you are sweeping your sub with at the increasing levels, but one unique bit is that Keith's TDS sweep with the TEF 20 was a very slow linear sweep of 35 seconds long which will show a little more compression than a faster sweep.

One nice thing about having outdoor measurements as a equal ground of sorts is that anyone can measure a subwoofer in their room, then measurement outdoors at the same exact drive level and determine the effect of the room which will be the same for 95% of the subwoofers out there when placed in the identical location. Readers need to remember that in most moderate size rooms,

 

[Edward J M]

Wow - kick ass measurement methodology - something to study and learn from.

Yes, at 1 meter sometimes the driver and port/PR outputs from larger units will not all properly sum for the FR testing; 2 meters is best for that.

I'm using the quick sweep function, which is much faster than the TEF 20 unit. It definitely won't show the dynamic compression as well as a slower sweep will.

It's cool to compare the FR and THD numbers for GP vs. indoors. I ran a full GP test of the SVS PB1-ISD I recently reviewed in the $600 shoot-out report. I didn't include those numbers in the review, but it was nonetheless interesting to compare the two data sets.

 

[Edward J M]

Craig, I'll never know for sure unless I dragged the PB2-Ultra outside (which won't happen).

But looking at the in-room data sets for both the PB1-ISD and the PB2-Ultra, and the GP data for the PB1-ISD, I can get a fairly good idea of how the PB2-Ultra would perform in a GP environment.

Looking over the numbers, I wouldn't put it past the PB2-Ultra to hit 115-116 dB @ 20 Hz @ 1 M GP.

Ed

 

[Craig Chase]

Ed _ It looks like I will have to get Tony over here with his measuring equipment and run some ground plane on the B4+ ...

 

[Edward J M]

You can check with Tom V, but IIRC from his posts during the B4+ development phase, he was hitting somewhere in the neighborhood of 125 dB @ 25 Hz @ 2 meters ground plane. He had to use a 5,000 watt Crown amp to hit 10% THD at certain frequencies.

Depending on the frequency, even with the K2, you might run out of amp power before the B4+ hits 10%.

Please don't test the B4+ at 15 Hz with all ports open. Please DO run THD across the board in a few different states of tune, though. It's important to evaluate the impact of plugging a port both in the lowest octave AND at higher frequencies too.

In my testing of the PB2-Ultra, I found that the 20 Hz tune was probably the best overall combination of output and extension. The 20 Hz tune almost matched the 25 Hz tune in sheer output at all frequencies above 22 Hz. And the 20 Hz tune kept pace down to 18 Hz against the 16 Hz tune.

 

[Mark Seaton]

I know everyone gets excited to see "how loud can it go," so they can pound their chests, but while interesting and part of the total picture, this is the test I find the least insightful or valuable. The series of long sweeps at increasing levels and the resulting compression graphs are some of the most telling details. Combined with the distortion plots they tell quite a story. This is the best depiction of what is going on with a dynamic, program input. IOW, it doesn't matter how loud a subwoofer gets at a given frequency if it compresses heavily; you won't be able to get it that loud. Likewise, complex scenes have to ride through the signals that send the sub into higher distortion. If a high level 25Hz signal sends a sub into heavy distortion, it doesn't matter if a sub has less than 2% distortion above 40Hz, EVERYTHING else coming out at that time will be distorted.

From my reading and interpretation, these figures most closely correlate to Keith's listening impressions. While there will always be room for more measurments and data, for an easy to read and concise set of measurements, they are quite useful and telling.

I'm still digesting the program spectrogram plots. There are some very interesting blips and streaks on some of the products which I need to give some more thought to.

 

[Wayne Ernst]

Just bumping this thread up from the basement ...

Today, I picked up the latest issue of Ultimate AV from my local bookseller. This issue is the "July/August" issue and features part #2 of the subwoofer review.

For those who have read through part #1, I'm sure, like me, you are looking forward to this second part. However, when I purchaed the issue, I realized it was the July/August issue which means that part #3 won't reach us until the latter part of August, which seems like a very long time from now.

Enjoy!

[Edit]: I should have also pointed out that 4 subs are tested in this issue. Among them are the Adire Sadhara and the Contrabass subs.