SUBFEST 2011-HuskerOmaha and Desertdome's Subwoofer Showdown - Page 8

Yeah, a lot of the time stamps seemed strange.


It does have a strong burst around 30Hz, but this should help you visualize better. I've scaled and chopped each graph to show the 0-20Hz regions of each one after another. You can see better which has more effects down there:

I couldn't find the answer re-skimming the thread...what amp was used to power the caps?

Nice job to all who participated and Husker for hosting.

Ron

Ron, EP4000.

Post five excerpt:

Configuration:
I’ll speak to the Cap config because people may be wondering since it is a passive setup and there are no common setups that everyone recommends. The Cap pair was being powered off a single EP4000 amp. 1 Cap on L channel, 1 Cap on R channel, using a single parralled input, and running at 2ohm stereo. The EP4000 amp’s HPF was disabled, and no HPF was engaged via desertdome’s EQ. The clip limiter was engaged - I know some people say a clip limiter limits dynamic range and prefer to have it off, but with unknown equipment sourcing the amp it’s probably best to have the clip limiter on for a test like this. This choice may have adversely affected the scores, and I like the clip limiter off at home – but oh well. The amps gain knobs were maxed out. I doubt we were hitting clip levels during our normal testing based on my experience with this setup at home and the fact that Greg’s room and my room are roughly the same cubic feet (though all the amps were in a closet and I wasn’t able to watch the amp to verify). Greg measured around 120dB during the loudest demo scenes we played – specifically in the unranked ad hoc Open Range movie material that Jeff and Mark asked to show with multiple shotgun blasts. The volume for this scene wasn’t increased until we found the limit, but rather just arbitrarily set a few notches higher for this scene. I know that isn’t the Cap’s limit on the single EP4000 because the Cap pair plays 125dB at the listening position on repetitive bassline dubstep music at my house while just tickling the single EP4000 clip lights – so figure we had at least 5dB more of steady continuous RMS power before we ran out of amp powering the cap pair. Then add 6dB more spl PER sub if you choose to utilize a more robust amp because the EP4000 only supplies about 800 watts RMS of the 4,000 watt RMS rating on the Cap driver. If I’m doing the math right and we threw in a HPF - effectively we could have tripled the cap pair’s subwoofer volume levels and still had clean sound. Impressive when you consider the other subs were already at or finding their limits. Some will say a sanity check needs to be employed here --- and I will concede. Do you need to triple your volume when you are at these types of sound pressure levels already? ….well no… but a few extra clean dB of that bass line you can feel really appeals to me!!! I would have liked to run all the demo material as hot on bass as we ran the open range material, but just dialed back the mains to something close to what we were actually listening to save our ears from being overwhelmed with highs.

Thanks for the info and the outstanding explaination.

Do either of you feel there is an amp that would be a "step up" in terms of eeeking out the caps performance (esp. relative to the low end (under 15 range)? Or does the EP4000 match perfectly to the cap's utmost capabilities?

Archaea, 4000w over 800w would probably get you another 4-6dB, to triple perceived volume you'd need +30dB.

Or 4 million watts.

Those were from my own internal notes which I had sent to HuskerOmaha. That is actually the timestamp used of the Scubasteve Blu-ray Demo. I import each m2ts file separately into my HTPC. For the GTG we decided on Friday night to use the DTS audio of the DVD. The clip used is from 10:08 - 11:25. This is from when the guys go to save the china until the boy gets the wood in his arm.

I've not read anything myself to suggest that EP4000 amp has any noteworthy rolloff at lower hz frequencies. Certainty not below the 20hz tuning frequency of the Caps at the meet. The EP4000 generally underpowers the captivators at all frequencies - but would not limit the caps any more than another more powerful amp below tuning frequency. With a significantly higher powered amp you'd most likely need engage a high pass filter at 19hz-20hz to keep the driver from over excursion below the cabinet's tune.

What I would do with a pair of passive Caps is try an FP10000Q ($785 + shipping). I believe you can then do 2 x 4200w in 8ohm. Add a MiniDSP to pull down the upper end -9dB and add a 18-19Hz HPF.

Thanks BBB!
You wouldn't happen to have the waterfalls for WOTW and BFD would you? Be interesting to compare those too.

fuzzy math right...

it's generally accepted that quadroupling wattage doubles output --- more or less.

+4x wattage = 6dB per sub x 2 = 12 db + at least 5dB from what we auditoned at Omaha to the max I've measured in my similar room in KC (limit of EP4000).

~120dB + ~12dB (for wattage increase) + ~5dB for headroom remaining on single EP4000.

that adds up to 137dB for a pair of Captivators absolutely and completely maxed out?

probably tooo fuzzy.

I do recognize that it is said humans often require more than an actual doubling of sound to recognize sound as doubling. Some do use the figure as high as 10dB for that magic number where we actually perceive sound as doubled - but the actual scientific number is 6dB right?


as to the zillion watt subwoofer - if you met KCNitro07 at the meet you'll know he is working on that design! He told swarny and I ALL about it. hahah

Yup. Lab Gruppen clones would be a significant step up in power.

Well it depends on what you're after I guess. The scientific number is +10dB if we're talking about perceived (by our ears) doubling of loudness, +6dB if you're talking about doubled sound pressure.

Sound pressure (SPL) is something we measure, +6dB is where it doubles. Loudness (volume) is what our ears hear, +10dB is where that doubles.

Out of curiosity I put some specLab captures of the demo scenes that your GTG used HERE .
Time stamps were included in the name description of the image in 6 digits.
I'm not sure if these captures match what you demo'ed in GTG, hope that helps

Any proof? Actual research, not "I tested it on X people". Would love to read documented research papers on this if there is one. A link would be appreciated.


Win!

+ Infinity

The numbers vary based on the frequency involved. Measured in dB, a double at 1 kHz (FM baseline frequency) is not the same as a double at 10 Hz!

That might be cherry picking comments and a bit out of context. Given more exposure and comparisons, when there isn't any trade off in output capability by using plenty of subs, I have yet to see a case where someone says, "Please cut off that deep extension for me!" Harman has done the most study on such things, and the general trend is as bosso suggests, but even holding to a +/-3dB window you can make a system sound dramatically different below ~100Hz.

What I was referring to was largely a matter of what strengths and especially weaknesses will be most obvious to one listener vs. another. IMO the ownership biases come more into play with the written defense of the ratings after the fact here and not while making the rankings.

Link to documentation (illegal)

True, but then again for bass frequencies the FM curve flattens at ~100dB.

I wasn't describing anyone in particular, but you certainly overlap with such a group.

At all but lower levels you will be able to hear a difference between sealed and ported design as all of the behavior with respect to level change is different. I fully expect that sufficient sealed sub capability and the right response shape at the listening position would have you questioning your absolute preferences.

The Orbit Shifter would probably be a better first point in between for you and one you'd probably really like.

Damn....after reading this thread I wish I was able to be in town to lug them in. Sigh.

the topic of listener preferences to measured results has been studied extensively. at the end of these two articles are references to 80+ studies.

http://www.aes.org/tmpFiles/elib/20111027/5276.pdf

http://www.aes.org/tmpFiles/elib/20111027/5270.pdf

Once you (at least for me anyway) begin to realize that doubling the wattage adds just 3dbs of output I was very much "ok" adding a $300 amp that would give me "just" 2k watts continuously (who knows what kind of peaks it delivers), knowing full well I'd be talking about 4,000 watts just to gain 3dbs!

I already hit 120+dbs in my room, but I understand there are larger rooms and more insane folks out there so keep chasing those w's!

James

(Hand Raised) yep thats me! i can get 115db at 20hz at the MLP over 120 a little higher, but I want close to 100db's at 5, over 110 at 10, and over 120 at 20 plus the benefit sealed and more displacement.

The LG10000Q will handle 2100 watts x4 to get me there

I'm sure you're looking for "Harmon tested it on X people", but I find the results of this GTG to be pretty good evidence. Or, maybe you saw something in the results that stood out more so than what I did?



This GTG/Demo was discussed in a thread at AVS:

http://bassment.wordpress.com/2006/0...rotary-woofer/

I believe Keith Yates was there, and I'm pretty sure Seaton was as well. You might want to ping them if you're really interested in the subject. I found it to jive very well with my own experiences.

Bosso

When you move from the 80 phon curve to the 100 phone curve, the numbers show that the 20 dB difference at 1 kHz equates to the 8 dB difference at 20 Hz.

The fly in the ointment is that for the vast majority of the population that tradeoff is required.