Archaea's Kansas City Blind Subwoofer Shootout 2012 - Page 28 - AVS Forum
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post #811 of 848 Old 12-17-2013, 01:18 PM
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Originally Posted by derrickdj1 View Post

I personally don't strive for a flat sub response even though it is very close.

Where are these measurements?
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post #812 of 848 Old 12-17-2013, 02:32 PM
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This was my comment amidst the hooplah when the thread was originally launched:
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Originally Posted by bossobass View Post


The sub comes with a 500W (rated) amp. There's a 0.55dB difference dropping to 440W (rated), so I'm not sure what fair has to do with the question.

Is there a recommended power input for the sub that's significantly higher than the 500W amp it comes with?

Are you suggesting that 0.55dB of amp headroom would have made a significant difference using the amp that comes with the sub?

With +4dB of PEQ boost at 20 Hz, then running Audyssey on top of that, either the Dayton or the iNuke would be drained with the soundtracks used in the G2G. Just not enough amp, period.

Bosso

I understand the discussion to track down the source of the bad noises/clipping, but it's really not worth the effort for me.

For those who believe that more power would have solved the problem and for those who have no signal shaping boost and use 'x' amplifier with the passive CHT stuff and claim "no problems", let's clear the air a bit with the facts.

Let's assume that Joe Owner has a 4KW burst-capable amp bridged to a pair of the CHT 18s wired to 4 ohms nominal. If Joe pops in WOTW with the sub 'calibrated' flat and the MVL = '0', what should we expect in the way of distress from such a system? With the subs anechoic response being >-30dB @ 10 Hz... not much. The signal will not clip the amps input stage, if the gain is reasonably set the amps output stage will be clip-free and the drivers will be reproducing mostly 40 Hz to cross, so no excursion worries.

Joe concludes: "My sub handles the power input and handles WOTW with no problems".

Now, let's apply a +10dB L/T boost to the signal. Where the previous scenario asked 500W peak bursts from the amplifier, the signal now demands 5000W, which the amp is not capable of, causing the clip lights to flash. And, where the driver excursion was below Xmech and now with the excursion demands quadrupled the driver is exceeding Xmech.

Now, Joe is rushing to the forums to ask "WTF?, You guys said 'No Problem', so why is my sub making bad noises?".

For every owner who posts 'no problem', there is an owner posting 'problem'. Why is that? See above.

BTW, it makes no difference if the low end boost comes from Audyssey, an outboard signal processor, or both.

Also, As I've said before elsewhere, NO class D amp should be operated in stereo mode (half-bridge configuration) for full bandwidth subwoofer amplification. <100 Hz, bus pumping is a problem. The only way to eliminate the problem is a massive cap reservoir (N/A in the Berry) or run the amp in bridged mode. THIS is my beef with the whole affair. The manufacturer of any passive subwoofer that it recommends for HT duty should know this and have documentation available warning the purchaser of this and all other potential problems when connecting the passive sub to a signal chain that begins with WOTW at reference level in ANY room. And, somehow, Arch has been blamed for it, his posts deleted, his GTG disparaged, etc., etc.

The 2 18" CHT subs have about the same displacement as a single 15" Tumult below 30 Hz. Will a single Tumult drive Arch's room at reference level playing WOTW pods emerge? No chance. It's a nice wet dream and I hate to be the alarm clock here, but please get over it. If the amp has enough juice, the driver will self-destruct. If the amp doesn't have enough juice, the boosted signal will drive the amp into clipping as it tries in vain to amplify the boosted signal to reference level. If you remove the L/T or use a HPF, you defeat the purpose of having a sealed sub.

The iNuke3K is rated @ 3KW bridged into 4 ohms. With 10dB of boost (and assuming the input signal is clean and the amps gain setting is correct), you have to be cruising @ 300W in order for the WOTW LFE hits to remain without clipping. If it clips you can lower the boost. If you lower the boost, you raise the F3 and lose the shootout because the other subs played lower. Or, lower the MVL. If you lower the MVL, you lose the shootout because the other subs are louder. If you toss the iNuke and put a K10 in it's place, you get the vac out to sweep up the pieces of your sub.

That's the whole story and there isn't more to it.
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post #813 of 848 Old 12-17-2013, 03:10 PM
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"get your vac out.." made me snort my coffee. lol
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post #814 of 848 Old 12-17-2013, 03:17 PM
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Originally Posted by sputter1 View Post

"get your vac out.." made me snort my coffee. lol

+1

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post #815 of 848 Old 12-18-2013, 01:04 PM - Thread Starter
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It was brought to my attention that Craig has asked for clarification on some meet details in the last couple days by several members here through PM.
http://www.chasehometheater.com/forum/showthread.php?t=5820

With a general inability to speak freely at CHT forums, I'll not participate in his current thread in his own domain. He'll say it's not fair that we discuss here without his ability to respond. I agree, but I'll counter with the fact I feel the same about his forums, and he is the owner and source of the frustrating censorship there. IMO - there is a reason he is talking to himself in that thread for the last few days - he's burned his bridges with a lot of people who would otherwise like to particpate in this type of learning/discussion/validating. I do not wish Craig Chase ill will. I never have. But as the old saying goes once bitten, twice shy. So no, I won't be participating on CHT forums.


Here is the context of the thread currently - in case it is deleted or modified.


I want to address his six questions and one statement in post 5.

1. The pair of 18's were driven by an Inuke 3000 in stereo mode.
Basically true - dual mono mode as shown in the first three post setup screenprints.

2. Measurements have been taken on the Inuke that show it starts clipping at 282 Watts into an 8 ohm load.
Measurements have been taken that show it producing higher scores in other tests, I'm not going to argue this one - I have no way to validate.

3. For a pair of drivers, this means the drivers would get 564 watts total before clipping sets in.
I don't have means to validate.

4. The listening tests were done with typical volume levels between 108 and 118.1 dB for the pair of 18's.
118.1 dB was the 'peak' ominimic number. Not the max. IMPORTANT NOTE: The peak SPL number didn't come from the music listening section. Recall we turned up the volume to -4 main listening volume for the last two clips - but all other clips were at -10dB main listening volume. The SPL numbers thus will be unreliable to get any meaningful data out of. In the back of the room where we measured the 'peak' spl measurements it is 5-7dB less than the blind voting seating area as retested here:
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/390#post_21532431
However we recorded peak values on the omnimic, and it was later determined and I was corrected that we shouldn't have used 'peak' values on omnimic. We should have used 'max' numbers, which are significantly lower. This discussion was pretty thick through the thread, and it was agreed upon that the max numbers were the numbers that would have aligned with the traditional SPL meter. What were the 'max' numbers? No one knows? What were the max numbers in the listening area? No one knows.
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/570#post_21841359
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/600#post_21845862
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/600#post_21845654
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/630#post_21870257
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/660#post_21870566
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/600#post_21845459
http://www.avsforum.com/t/1402885/weighting-measurement-with-omni-mic#post_21849189


5. The listening distance was 5.2 meters from the subwoofers.
No. The subs were 6-9 feet from most listening positions, and these are the same seats that the five Audyssey calibrations for each sub were done as shown in the video in the first few posts. The tiles are 1 foot squares for reference. Remember the average frequency response captures were an average of the 12 chairs in comparison.

What the SPL discussion should all boil down to is during our blind audition our simple and documented setup procedures tell you at what SPL the subs should have been asked to play. The music section was all at Audyssey calibrated -10dB from the main listening positions with each sub turned up 3dB as attached to sub 1 and sub 2 output on the Onkyo TX-NR1007. The movies were all played back at this volume too, with the exception of the last two tracks which were played back at -4dB main volume for each demo.



Craigs other statement in that CHT thread:
"The analysis as done by Archaea was the poor performance was due to the subwoofers bottoming out using the Inuke in stereo mode."
No. My sole hold out observation on the matter is that there were no clip lights observed during the music section, thus the iNuke amp wasn't at its limits during the music section ---- therefore the music section in particular are valid scores for the CHT subs. Since the clip lights never engaged for the music section, the remaining discussion, as it relates to bottoming only centers on one clip -- the Realm of Excursion 100hz - 20hz sine wave sweep (original file linked a few posts above) as it was played during the music section. The amp was clipping during the movies section, and I never denied a clipping amp wasn't possibly limiting the peak performance of the CHT subs during the dynamic sections.

As best I could tell at the time, AND still as best as I can confirm currently in our amp only retests earlier this week - documented in the last couple pages the amp was not clipping for the music section. So the outstanding discussion is that we encountered bad noises on the 20hz note for this subwoofer during the demos at -10dB on the main volume (with the 2 Onkyo sub channels both boosted 3dB) on three different days (with and without Audyssey), and never encountered evidence of amp clipping during ANY of the music section demo material at those standardized volumes. That is to say - the CHT subs earned their own musical blind test score without any negative influence from the amp chosen - again as best I understand.

As to affecting their whole demo session - I long ago, in fact on the Friday night before the meet when I told the sub owner and the three other pre meet setup observers that some aspect to the setup as we pre test demoed them was was a problem because they were making bad noises, and that I expected none of the other subwoofers auditioned that next meet day would make. This prediction bore out in truth. Yet, the sub owner blessed the setup, communicating to me and overheard by others present that the subs sounded the best he'd ever heard them sound and he would prefer to risk a few bad noises for the benefit of the overall better sound. He decided not to use the Dayton amp, not I. I only setup the iNuke as a possible option for him to consider at first, he made the call. I was trying to help. Sunday's post meet testing showed Tesseract67's decision to be a good move in both of our opinions. This has been discussed over and over and over. I'm at the point where this whole bench 'guessing' should be dropped and ultimately the subs retested in person if the conversation is to come to any conclusion. Retested on the same amp in my same room and same source equipment - otherwise we gain little. Outside of recreating the original scenario again - what else can be done? I know Tesseract has family in the KC area. If he is agreeable, when next he comes to this area I offer to meet with him for some final testing. I have several different amps available to me at this point, either that I own, or could borrow from local friends. The Crown XLS-5000, the iNuke DSP 3000, an EP4000, an IP7500, a CV-5000, an iNuke 6000, and probably Tesseract67's Dayton amp if he still has it. We can power those subs by several manner of amps and see if the situation changes based on the amp at the volume levels we originally used which created the problem.

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post #816 of 848 Old 12-18-2013, 02:49 PM
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IIrC, those were the subs that were returned by that fellow (I forget his name) to CHT and subsequently bought by Tess.apart from the original owner being very displeased with the finish and nail holes, I think he made some comments about the sub making some kind of noise presumably from pushing the diver using his hand as I don't seem to recall him ever actually running it. On a side note, Back when there was much discussion over the sealed subs actual measurements and CHT indicated they would send a sub to Josh for testing, I was quite surprised that the sub that actually was sent was the vented prototype and not the sealed unit. A pity as this might have cleared up many issues.

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post #817 of 848 Old 12-18-2013, 04:06 PM
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We spent a lot of time to come around to the initial point that reopened this thread: I simply stated that the amp was not setup correctly. One of the forum members stated that no class D amp should be used in stereo mode. This has been an informative discussion and educational. A take away message is to be cognitive of the setup requirements when using a pro-amp and what is really happening when using PEQ or other types of EQ on top of autocalibration. It is my belief that any PEQ be done after autocalibration. This may preserve more headroom in the system and not affect as many of the things done during the autocalibration.

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post #818 of 848 Old 12-18-2013, 04:15 PM - Thread Starter
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Quote:
Originally Posted by desertdome View Post

HuskerOmaha and I measured the stock Dayton SA1000 amp vs a Face F1200TS amp using a close mic on the dual opposed MFW-15 drivers. The Dayton amp had the bass boost on and subsonic filter off. There was no high pass filter in place for either amp. We also measured the Dayton amp with the bass boost off, but inadvertently deleted the measurement later on.


You can see that on the Dayton the bass boost is giving about a 3 dB boost at 25. According the the manual, the boost is a PEQ with a 3 dB gain and 1.4 Q at 25 hz. Below 16 Hz, the Dayton amp is dropping lower than the Face amp and is down 4 dB at 10 Hz. With a 1.4 Q/25 Hz PEQ, the Dayton should start boosting at 60 Hz and finish the boost at 10 Hz.


The blue line is the Dayton and green is the Face.
LL
This old post is interesting given the discussion on the weaker subjective impressions of the Dayton amp during Sunday's retest. If this rolloff is universal to the Dayton amp it may explain why the Dayton was a CHT recommended paring with the 18.1 subs, and amps with less rolloff, like the EP4000, sounded 'bad' with the 18.1 drivers as mentioned by several CHT forum members and discussed/quoted a few posts back. That's a big if, and perhaps not relevant, but I find it interesting given the discussion of late. If the amp rolls off another 4dB WITH the bass boost engaged on the Dayton over a randomly compared Face amp. Then it could possibly explain why users with the Dayton have less reason to complain about bad noises at or around 20hz, it may also effect Audyssey's decision to boost bass at or around 20hz or not based on the - dB points Audyssey or other room correction software takes into account if no Parametric EQ is applied before Audyssey is run. Obviously this is no sort of conclusive evidence, but just a discussion point.

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post #819 of 848 Old 12-18-2013, 04:24 PM - Thread Starter
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Quote:
Originally Posted by derrickdj1 View Post

We spent a lot of time to come around to the initial point that reopened this thread: I simply stated that the amp was not setup correctly. One of the forum members stated that no class D amp should be used in stereo mode. This has been an informative discussion and educational. A take away message is to be cognitive of the setup requirements when using a pro-amp and what is really happening when using PEQ or other types of EQ on top of autocalibration. It is my belief that any PEQ be done after autocalibration. This may preserve more headroom in the system and not affect as many of the things done during the autocalibration.

Derrickdj1 would you play the sine wave listed in post 777 on just your pair of sealed 18.1 subs at home (no mains, no 18.1VS subs), and see how they sound at -10 with the subs each 3dB hot from your typical MACC calibration.
http://www.avsforum.com/t/1387178/archaeas-kansas-city-blind-subwoofer-shootout-2012/750#post_24077201

Ignoring everything - room size, frequency response, amp config, lack of Audyssey, room gain --- everything applicable -- just humor me and play the clip. See at what level you start encountering what you would consider bad noise on the bottom note of the sine wave. I'm morbidly curious.

Anyone reading with a CHT 18.1 sub please do the same. Report back.

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post #820 of 848 Old 12-18-2013, 05:11 PM
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Quote:
Originally Posted by Archaea View Post

It was brought to my attention that Craig has asked for clarification on some meet details in the last couple days by several members here through PM.
http://www.chasehometheater.com/forum/showthread.php?t=5820

Retested on the same amp in my same room and same source equipment - otherwise we gain little. Outside of recreating the original scenario again - what else can be done? I know Tesseract has family in the KC area. If he is agreeable, when next he comes to this area I offer to meet with him for some final testing. I have several different amps available to me at this point, either that I own, or could borrow from local friends. The Crown XLS-5000, the iNuke DSP 3000, an EP4000, an IP7500, a CV-5000, an iNuke 6000, and probably Tesseract67's Dayton amp if he still has it. We can power those subs by several manner of amps and see if the situation changes based on the amp at the volume levels we originally used which created the problem.[/COLOR]

The bottom line: The Dayton amp is what was shipped with the subs at the time. Bridged into 4 ohms: 950W (rated) and the iNuke3K into 8 ohms, stereo: 300W/CH = 600W (measured NOTE: This was a 20 Hz sine wave into a 4 ohm resistive load). That's exactly a difference in headroom of 1.996dB. Does anyone who may still be interested in this CHT baloney actually believe that would have made a difference?

Is CHT actually saying the results would have been different had the bridged Dayton been used, or is he saying the subs actually require a 2000W amplifier (a la iNuke3K bridged into 4 ohms)?

I think most every member of this forum feels you've gone above and beyond, the questions have all been addressed.

If the owner of CHT really wants further data he can send a pair to Josh with the Dayton Amp that came with the pair tesseract (and many others) bought.
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post #821 of 848 Old 12-18-2013, 06:10 PM
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Archeae the sine wave play fine on just the two SS 18.1's in my system. No bad noise, no clip indicator lighting up and minimal power use (195 watts roughly). The test is of a very short duration. Well, I think we have beat a dead horse back to life and killed it again since it is impossible to recreate the past. Time for me to get back to some of the other thread and have some fun.smile.gif

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post #822 of 848 Old 12-18-2013, 09:37 PM - Thread Starter
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Derrickdj1, thanks for testing, can you continue test? At what main volume (assuming reference calibration) in your room do you encounter the beginnings of bad noises from the sealed 18.1 drivers on the bottom end of the sine sweep with the INuke in the preferred bridged configuration with a four dB boost at 20Hz programmed into your iNuke DSP and both subs individually running +3dB hot compared to the mains? If you only have a single sub out on your AVR, run it six dB hot from the mains for the test. Please test with MACC off and 100Hz crossovers. I'm curious at what main volume level you start to hear the noise even with all the ridiculous variables in place.

I noticed something else. I read your setup iNuke setup thread...
http://www.chasehometheater.com/forum/showthread.php?t=5774

My Onkyo TX-NR1007 has an early/first/alpha version of multisubEQ. It's basically the same thing as the Onkyo TX-NRxxx8 models with multisubEQ, but it doesn't finally ping and eq the two subs together and knock the overall combined sub levels back down to 75dB. So Audyssey calibrates both sub1 and sub2 to 75dB individually and applies EQ, but when both are playing it's now a bit hot and louder than reference. This is discussed in the Onkyo thread. That was fixed in the xxx8 models from Onkyo where the two independent sub outs were finally pinged and eq'ed together after being eq'ed individually. Thus in your setup guide - you say calibrate both to 73dB. That's a slight difference from the way my AVR works. In our test both would have been 75dB and then each channel was added another 3dB.

And one final note. I don't believe you have to apply manual PEQ post Audyssey for best sound results. In my experience it doesn't matter. Apply it before or after and it works/sounds the same -- at least as this relates to minor changes. That's my experience.

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post #823 of 848 Old 12-18-2013, 10:47 PM
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I can and can't believe this has come around again.

We can't exactly recreate the scenario.

It happened.

I had fun though. Archaea when are you coming up and swapping subs?
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post #824 of 848 Old 12-18-2013, 11:14 PM - Thread Starter
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Craigs posted a new response in post #8 of the thread on the CHT forums..
http://www.chasehometheater.com/forum/showthread.php?t=5820

Most of this has already been discussed elsewhere.
Here is one example.
http://www.chasehometheater.com/forum/showpost.php?p=85133&postcount=46

If anyone thinks I said the amps never clipped for anything - they didn't at all read through this thread. Not much else I can say about that - except recommend they go back and reread. I freely offered this information, and it was discussed a lot through the thread. I only said the amp didn't clip for the music section.

I found kwarney saying we did try bridged mode on Friday night's pre setup testing with the iNuke, but it wasn't favored by the sub owner, nor one of the other meet guests who left early for his hotel that night. I had completely forgotten about that. Here is his post. I admit, some of the finer meet details aren't fresh in my mind after two years. We setup and played with quite a bit of stuff on Friday night in preparation for the Saturday meet.
http://www.chasehometheater.com/forum/showpost.php?p=85132&postcount=45

I never said anything about the peak SPL levels being captured at the "lowest tones" either. I think Craig is mixing up two posts. What I was trying to convey is that the SPL levels being captured were on some of the toughest tracks available. The sine wave playback in the music section wasn't anywhere near those SPL levels. I tried to point out we didn't know at what frequency the SPL peaks were captured, but this one of my posts Craig deleted - this deleted post is addressed in the second link above. Ultimately we've determined the SPL level captures using the omnimic 'peak' values are pretty meaningless data. We should have used the 'max' values, but even if we'd captured max values - the distance to the back of the room where the mic was at the control station affected the values, as did the room response. Even then we don't have any determination as to what frequencies those peak SPL levels were captured. Furthermore - those values would have represented the two movie clip peaks when we were auditioning each sub at -4 on the main AVR volume, and not the vast majority of the rest of the movie clips played at -10, or all the music section, (which included the 100hz to 20hz sine wave) played at -10.

Finally the Chase 18.1 subs were up against quad MFW-15 drivers in two dual opposed boxes, with a modified Dayton amp, not just a pair at this g2g.
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post #825 of 848 Old 12-18-2013, 11:21 PM - Thread Starter
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Quote:
Originally Posted by HuskerOmaha View Post

I can and can't believe this has come around again.

We can't exactly recreate the scenario.

It happened.

I had fun though. Archaea when are you coming up and swapping subs?


Hey, look who's still alive!!!

I'm pretty decided on just adding subs and not trading or selling off my caps. I just like them too much, and they are especially handy for quick grab and go to meets, or barbeques g2g's in the park. I may still work out a timeframe where we can trade them out for a while - just for a change of pace --- but I want them back. wink.gif

I bought a set of four of the new Dayton ultimax 18" drivers that should ship in Feb. With the black Friday special four of them were $966 shipped. I can cancel my order at anytime before they ship and not be charged, but at this point I think they'll make nice near field transducers or something to play with.

You become active again in the hobby?

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post #826 of 848 Old 12-18-2013, 11:37 PM
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Originally Posted by Archaea View Post

Hey, look who's still alive!!!

I'm pretty decided on just adding subs and not trading or selling off my caps. I just like them too much, and they are especially handy for quick grab and go to meets, or barbeques g2g's in the park. I may still work out a timeframe where we can trade them out for a while - just for a change of pace --- but I want them back. wink.gif

I bought a set of four of the new Dayton ultimax 18" drivers that should ship in Feb. With the black Friday special four of them were $966 shipped. I can cancel my order at anytime before they ship and not be charged, but at this point I think they'll make nice near field transducers or something to play with.

You become active again in the hobby?


I just don't get it. This meet has been dissected more than most - was attempting to do something most hadn't yet at large GTG. And it gets rehashed now?

Is the sub in question even being produced in that exact configuration anymore? I guess I'll have to go look.

There were so many facets and issues to the subsequent fallout - it wasn't just the debate over what was interpreted to be or not to be "clipping",

I'm still alive - like I said, I had to step away for a while. Picked up road biking/triathlon. Did a race. Was fun. Building a house in 6 months. Will have a dedicated theater. Now I can start nerding out again. Might be a couple years (several if wife wins) until the theater actually gets done.

If you are up for it, I can just bring the subs and amps down with me next time we go to Parkville to visit family. You can have them and fix my air leak and test whatever to your hearts content all summer until next Christmas.

Good luck on this resurrected thread.
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post #827 of 848 Old 12-18-2013, 11:45 PM - Thread Starter
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That'd be cool. I'd fetch them from you in Parkville for sure. I could bring them back long before summer - as I'd likely start missing my caps. Our KC audio enthusiast community has really come together over the last couple years and there's a lot of varied equipment around these parts. We do stuff pretty regularly in small groups now, and have a lot of small meet ideas coming up.
http://www.avsforum.com/t/1496367/kansas-city-area-home-theater-meets-and-movie-night-events

You also need to come down and check out the new Dolby Atmos AMC Prime theater. It's all that and a bag of chips!
http://www.avsforum.com/t/1506209/amc-prime-theaters-dolby-atmos-guitammer-seat-transducers-reclining-electronic-leather-seats

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post #828 of 848 Old 12-19-2013, 01:15 AM
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I don't understand the need to discuss this any further. Bossobass said it all. We have t/s specs of driver for modeling and near field responses.

http://www.avsforum.com/t/1321030/official-chase-home-theater-owners-thread/630#post_23885657

We also have the driver manufacturer Eminence saying that the Xmax is 11 mm.

We also have the driver measured in a large bass reflex alignment and on Ricci's amp it was driver distortion limited to 100 hz.


The time to discuss this midwoofer's performance at the meet is gone and passed. Sorry Archaea, I won't be testing or discussing this any further.
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post #829 of 848 Old 12-19-2013, 02:40 AM
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wOriWS

We just got home from a big family wedding so let me ask my wife tomorrow for clearance to be gone for awhile. I might only have time to go to one place though and I need to bring those fabric samples over to Luke's. I want to have both of you take a look at my basement before I do anything in case you have some more ideas. I will be on vacation this week so any day will work.

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post #830 of 848 Old 12-19-2013, 09:29 AM
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Originally Posted by Luke Kamp View Post

I don't understand the need to discuss this any further. Bossobass said it all. We have t/s specs of driver for modeling and near field responses.

http://www.avsforum.com/t/1321030/official-chase-home-theater-owners-thread/630#post_23885657

We also have the driver manufacturer Eminence saying that the Xmax is 11 mm.

We also have the driver measured in a large bass reflex alignment and on Ricci's amp it was driver distortion limited to 100 hz.


The time to discuss this midwoofer's performance at the meet is gone and passed. Sorry Archaea, I won't be testing or discussing this any further.

I agree. I really think you guys need to start discussing (dissecting?) Jeff's upcoming speakers now. I rely on Archaea's and the KC gang's reviews of JTR products!

I have been staring at the T8-LP's in my living room and wondering if I should be staring at 228 or 212's instead...
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post #831 of 848 Old 12-19-2013, 09:53 AM
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Quote:
Originally Posted by Luke Kamp View Post

We also have the driver manufacturer Eminence saying that the Xmax is 11 mm.

We also have the driver measured in a large bass reflex alignment and on Ricci's amp it was driver distortion limited to 100 hz.
If the same driver used at the GTG was in the sub measured by Ricci, then I would probably say the Xmax is 19 mm.
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Originally Posted by databass.com 
The xmax of the driver is listed as about 19mm one way with a recommended power rating of about 800 watts. In use the driver would produce this much stroke but the xmech seems to be at almost the same point as the useful excursion and the surround and/or suspension seemed to be the most limiting factor. The driver exhibits a soft bottom behavior because of this. Also this driver probably has the softest suspension system that I have encountered. This combined with what seems like a generous amount of motor force and a relatively low amount of moving mass give it a rather good sensitivity. It is not a very expensive driver but certainly seems to have the money spent on the correct areas to improve and optimize its performance while keeping costs reasonable.
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post #832 of 848 Old 12-19-2013, 01:48 PM
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Sweet someone send the sealed alignment off to Ricci. Unfortunately we don't have a means to do Klippel testing or cea 2010 here and nobody has the sub or any desire to get one unless someone is willing to lone. I have no idea how much power the driver can handle to reproduce clean 20 hz or below in a small sealed enclosure. Nobody here has one to test so I won't be testing or discussing this any further as I stated. I simply can't add anything that hasn't already been stated at least a dozen times.

What we did was a one day shootout with a bunch of subs. The owner decided to try the inuke the way Archaea had it set up for his subs. He set it up and liked it better than his dayton amp on Friday and went with it. You were there on Friday DD I wasn't, why didn't you tell them not to run the darn amp 8 ohm stereo? I wasn't there so can't comment on the reasons this configuration was chosen.

I knew nothing about the sub or amp and once it was hooked up by the owner during meet I asked Archaea "how is it being powered?" He stated, "8 ohm stereo on my inuke with some dsp" and I said "oh dear, why?" He said "that is how the owner tested them and wanted them to be run." I said "not what I would recommend for the setup and the sub should be run with the amp it is being sold as a package with." It wasn't my subwoofer or GTG so I just let the pieces fall where they may. Looking back pulling out a pistol and holding the meet hostage while I rewired and properly configured the damn thing would have been a much easier proposition than putting up with this crap 2 years later.

kma100
Get the JTR 212, they are good constant directivity design with low cross from the very nice BMS compression driver. I would get them if you can handle the size in a living room. If not I like the 228's better than the T8's myself.
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post #833 of 848 Old 12-20-2013, 01:55 AM
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This thread kind of reminds me of the Hunger Games. It would be fun to repeat this blind shootout without Audi C and more potent amps. I can see it now; Archaea's Kansas City Blind Subwoofer Shootout 2014: Catching Fire.

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post #834 of 848 Old 12-20-2013, 03:08 AM
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"We also have the driver manufacturer Eminence saying that the Xmax is 11 mm."

not really following this one, just happened to pop in for a moment and saw reference to eminence and xmax. on many of their drivers, they spec xmax the very old school (conservative) way of overhang only. to get to the 70% bl or 10% distortion number it would be a little higher, perhaps adding 1/3 of the gap height. then depending on a variety of things, "usable" might be another few mm.

its the same way with the drivers in the submersive. the official xmax spec isn't consistent with their performance. same thing with several of the Dayton drivers, particularly the 460ho.

based on the distortion numbers, which are pretty good for the cht, it seems to have something approaching 20mm usable excursion.

not defending or supporting anything here...just noting xmax isn't a well defined specification (there are at least 5 ways* used to measure it and all are reasonable imho).


* overhang, overhang + 1/4 gap, overhang + 1/3 gap, 70% bl, 10% thd
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post #835 of 848 Old 12-20-2013, 07:47 AM
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Originally Posted by LTD02 View Post

"We also have the driver manufacturer Eminence saying that the Xmax is 11 mm."not really following this one, just happened to pop in for a moment and saw reference to eminence and xmax. on many of their drivers, they spec xmax the very old school (conservative) way of overhang only.
Eminence has used Klippel analysis to determine xmax on all of their drivers since 2004. Models that existed prior to 2004 were re-measured and new data sheets issued with the Klippel 10% THD xmax spec.

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post #836 of 848 Old 12-20-2013, 11:19 AM
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Yeah, it appears Craig has finally come to terms with reality and is admitting the specs acquired from Eminence are indeed accurate:
Quote:
Guys ... Let us look at three drivers. We have CHT-18 Gen 1, which to date is the only 18 we have had in our 18 inch subwoofers. Then we have our new CHT-18 Gen 2, which will be shipping in January, 2014. Finally, we have the Submersive.

In this post, we will look at the supplied specs from Eminence on all three drivers. Each of these specs comes directly from Eminence. After the Eminence specs are posted, we will discuss the actual useful excursion of each driver.

CHT-18 Gen 1

FS: 21.4 Hz
X-Max: 11.1 mm
QE: .28
QT: .27
BL: 21.12 Tm
SD: 1169 cm^2

Submersive

FS:22.9 Hz
X-Max: 14.29 mm
QE: .34
QT: .32
BL: 18.73 Tm
SD: 823.7 cm^2

CHT-18 Gen 2

FS: 20.7
X-max: 14.29 mm
QE: .31
QT: .29
BL: 30.18 Tm
SD: 1169 cm^2

I have had lengthy conversations with one of the lead engineers at Eminence. Many of these conversations were centered around driver excursion in the realm of home audio subwoofers.

This engineer specified that our 18 inch driver had useful excursion of about 19.5 mm. He also specified the Submersive's driver has a useful excursion of about 21 mm.

Our new driver, even though its Eminence spec sheet X-max of 11.1 mm has increased to 14.29 mm, is still about a 19.5 mm excursion driver in the way excursion is thought of in home audio products.

We are not going to gain much, if any, in useful output over the old driver. The improvements will largely be in terms of lower distortion all the way to its excursion limits.

The Submersive driver represents the longest throw 15 inch driver (and overall longest in any size) that Eminence produces.

The two generations of CHT-18's represent the longest throw 18 inch driver Eminence produces.

In terms of sheer clean air movement, the drivers look like this when driven to the clean excursion limits:

Submersive 15: 1729.5 cm^3 (Single driver - a Submersive system will have 3459 cm^3)

CHT-18 (Gen 1 or Gen 2): 2279.1 cm^3 (Single driver)

The real revelation to me here is the admission of yet another Chase deception.

Two years ago, nearly to the day, I PMd / emailed Craig about the response of the sealed 18, specifically the steep roll-off which did not match with the expected specified response that existed when I purchased the sub. I did a close-mic which showed a response drastically different than the claimed spec at the time. I also measured one of the drivers and sent him a few of the T/S parameters to show that both the modeled response of a measured driver and the close-mic itself matched fairly well and were both drastically different then what he had claimed and also presented in a myriad of fudged simulations or botched measurements.

So what does he response to this with?

"Your info regarding the T/S parameters is incorrect. You have the wrong Fs."

To back up his position on my "incorrect" Fs, he sent another PM:

"I had the driver measured by Paul Appolonio. Paul designs drivers fo a living, and he has access to a multi-million dollar set up with the company for whom he works full time. He measured two of the drivers, and got numbers that were quite close.

I trust the accuracy of Apollonio's tests. He is a professional, and was taking the measurements as he was also making a pitch to get me to have him source a driver for us. In other words, it was in his best interests to show our driver in a bad light. As Paul IS a true professional, he merely took the measurements and sent me the results."


I looked back today to see what Fs I had measured back then and had sent him to see how far off they were. It was 21.53 Hz.

Look at what he's now admitting the true spec is:

21.4Hz

How anyone can take a word that comes out of this man's mouth seriously I'll never know; but I'm sure there's one born every minute.
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post #837 of 848 Old 12-20-2013, 11:25 AM
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Originally Posted by LTD02 View Post

"We also have the driver manufacturer Eminence saying that the Xmax is 11 mm."

not really following this one, just happened to pop in for a moment and saw reference to eminence and xmax. on many of their drivers, they spec xmax the very old school (conservative) way of overhang only. to get to the 70% bl or 10% distortion number it would be a little higher, perhaps adding 1/3 of the gap height. then depending on a variety of things, "usable" might be another few mm.

its the same way with the drivers in the submersive. the official xmax spec isn't consistent with their performance. same thing with several of the Dayton drivers, particularly the 460ho.

based on the distortion numbers, which are pretty good for the cht, it seems to have something approaching 20mm usable excursion.

not defending or supporting anything here...just noting xmax isn't a well defined specification (there are at least 5 ways* used to measure it and all are reasonable imho).


* overhang, overhang + 1/4 gap, overhang + 1/3 gap, 70% bl, 10% thd

Where do you get the SubMersive data to determine what's consistent with anything?

Where do you get the data to determine the CHT THD numbers are "pretty good" and what exactly does that mean?

Xmax has been defined for decades. "Old school"? It's always been the maximum linear excursion. That's what Xmax stands for. Has nothing to do with overhang, which is a physical parameter only.

There's no driver manny I'm aware of, past or present, that underestimates its linear throw. With all due respect to Josh, he doesn't measure Xmax and guessing by whatever guesstimate method he uses makes for a good read but is hardly a worthwhile metric, especially since Josh puts every driver in the same box.
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post #838 of 848 Old 12-20-2013, 01:01 PM
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Correct...I do not measure xmax. I don't have a Klippel which is really the only way I trust any xmax spec and that is assuming the Klippel test was done right. Otherwise the coil overhang is a good estimate if a bit conservative many times. When I mention excursion specs they are usually just a best guess from looking at the excursion with the driver in free air and listening for mechanical distress and offsets in the cone movement which can be seen with a piece of white tape on the cap. If anything my estimates of this should be considered as ballpark at best and +/-5mm at least. The xmax specs on the driver page are all manufacturer supplied numbers. I generally only note whether the driver seems able to meet the manufacturer spec or not. Also worth mentioning is that by the time a driver starts to sound/appear non linear to me subjectively is probably well past where a Klippel test or other distortion threshold would have limited the stroke. Clearly a far better judgment of useful stroke than any of my subjective notes is provided by the distortion and maximum output measurements.

I have seen a few drivers that were conservatively rated such as the Dayton RS18 which was listed at the coil overhang of 12.75mm but 3rd party Klippel testing came back with 16mm, some other Dayton products and a few pro style woofers have also been but that is only because they were using the simple coil overhang method without any fudge or Klippel testing. These are few and far between though, the majority of the long stroke drivers have xmax exaggerated quite a bit in my opinion. Most of them will physically move that far but that doesn't mean it is output worth listening to.

Another SS18 debate...In my notes after testing the VS18.1 I noted that the xmech of the driver appeared to be right around 20mm or so where the surround appeared to be completely stretched out. (see the notes above for how innaccurate that spec may be). Drivers do not sound good at all when bumping against mechanical limitations. Take that for what it is worth.
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post #839 of 848 Old 12-20-2013, 01:21 PM
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Cool, so now Jon Lane's in on the action throwing out insults from the 60's:

"Whoever this kook is he's also claimed it's deceptive to call a 21.40Hz Fs a 21.53Hz Fs.

-A difference of less than 0.1%, or well inside the measured specification of probably any pair of drivers ever made."


Yes Jon, that's the point. If you weren't so busy tripping over yourself to post the math that is painfully obvious to anyone who's ever looked at numbers before, you'd realize that Craig was the one claiming my measurements were wrong because my Fs of 21.4Hz was less then 0.1% different than the actual specification from Eminence. rolleyes.gif

Edit: Looks like Craig's decided to delete Jon's post and give him a talking to.

You really can't write this stuff. It's incredible. tongue.gif
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post #840 of 848 Old 12-20-2013, 01:28 PM
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If you weren't so busy tripping over yourself...

-which, I certainly did, obstruction being the intent around here. Bravo. Of course, I caught and deleted that remark when, after sifting this unmitigated barrage of unanswerable nonsense, it dawned on me that that's precisely its point.

It'll teach me not to engage on this level.
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Originally Posted by nfraso View Post

Edit: Looks like Craig's decided to delete Jon's post and give him a talking to.

You really can't write this stuff. It's incredible. tongue.gif

Edit: see above. No, you really can't make this stuff up, nfraso.

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