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post #181 of 380 Old 02-06-2007, 10:03 AM
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Originally Posted by SteveCallas View Post

There were a handful of Avalanche 18 x 4 IBs being made in '05, and now there are MJ18 x 4 IBs being made as well. Again, never claimed to have heard them. Subjective sound quality hasn't come up yet in this thread, I'd prefer not to bring that into the mix as well, that's its own can of worms

So how do you know they aren't capable of high level single digit output? I'll ask again: Do you base that opinion on measurements taken with Radio Shack SPL meters?
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post #182 of 380 Old 02-06-2007, 10:20 AM
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Originally Posted by SteveCallas View Post

When the bulk of the frequency range on a sweep is centered around say 85db, and then there is a 6db drop below 20hz, claiming the +/-3db point iss at 82db is pretty weak. The spl is being cut in half, it's fairly significant.


A single LLT isn't designed to be flat into single digits, where did you come up with that idea from? Just as when someone wants to be able to play at moderate to spirited levels into single digits with a sealed sub, meaning multiple drivers, the same would be needed with a LLT, in addition to plenty of volume. This idea of wanting to stay flat to the single digits with the ability to play at spirited levels is not something that will be accomplished with a a couple drivers, we're talking a relatively large scale project, like the 10 driver Dayton HiFi 15 design that was being talked about a while back. Even then, the depth one can stay flat to in the singel digits is going to be hindered by electronics rolloff. Again, it's not a simple undertaking, if it were, everyone would be flat to 3hz with 120db capability already A LLT is designed to get the most impact - the best all around performance if you will - from each driver, allowing reference or near reference (depending on the driver) levels into the low teens while maintaining great accuracy in the musical range from just one. The majority have not experienced powerful infrasonics in movies by means of a bass reproduction system that can stay flat into the low teens and still be able to play at very spirited levels. For each ported to sealed counterpart, we're talking ~6db more headroom down low, extending flat FR lower.

My measurement was made with RoomEQ Wizard, a calibrated soundcard, and a digital RS meter using Sonnie's calibration file - if you don't want to believe it, you don't have to Nichol and Jon have pretty wide open rooms to the rest of their homes and their own responses with identical subs are reasonably flat to 11-12hz.

You should check out the FR graphs at avtalk

http://www.avtalk.co.uk/forum/index....t=0&rid=0&SQ=0

the dashes on the FR charts say it all...if the FR is "centered" on 85 dB, that would mean the FR peak is 88 dB and 6 dB down or +-3 dB is 82 dB...

all i can say about a digital RS meter is that the number of calibration files vs. model numbers are increasing, this denotes a certain unreliability with regards to accurate FR sweeps...it seems hit or miss with QC...don't take my word for it, just check out the shack...that's why a calibrated microphone, not an SPL meter, presents a better option...

I simply made an observation about the LLT graphs...i'll leave the "vigorous" defense of what an LLT can and can't do to you...if the sub is'nt designed to extend into single digits then perhaps some of the observations offered in the TRW paper have some merit...perhaps the "waveform" distortion, or "destructive cancellation" theory has some teeth...i'm not saying it's fact but it bears investigation...independent investigation...

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post #183 of 380 Old 02-06-2007, 11:14 AM
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Lets assume the TRW is the best subwoofer to finish off the debate.

1. Most people don't meet criteria for this installation.
2. Most people don't want to fork over $25k for one.
3. Most people can fit traditional subwoofer designs in their sound room.




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The perfect setting for things to come......

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post #184 of 380 Old 02-06-2007, 11:16 AM
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Originally Posted by Richard Mayer View Post

You've seen? You mean you've seen some crappy Rat Shack measurements?


Do notice that his mic correction file doesn't go below 10 Hz. He haven't also calibrated his sound card/measuring chain. Those two alone can have a huge effect on roll-off you see below 10 Hz. Correct those and I'll bet his response will be MUCH flatter below 10 Hz.


I've attached Art's in-room frequency response (Mark posted it some time ago). It goes only down to 10 Hz, but are you seriously suggesting it will drop like a rock below 10 Hz?

right, here is the calibrated FR, though the ecm8000 only has correction down to 10 Hz...looks like -4 dB @ 8 Hz was pretty much on my initial measurements...



it would be pretty easy to attenuate the midbass a little and fit 7 Hz inside a 6 dB window...making it 7 Hz +-3dB...even so, the ecm8000 correction under 10 Hz is unknown...but i'm guessing, by the slope, 2-4 dB at 7 Hz...that would put even 6 Hz inside the 6 dB window...fascinating

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post #185 of 380 Old 02-06-2007, 11:20 AM
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Quote:
Originally Posted by thylantyr View Post

Lets assume the TRW is the best subwoofer to finish off the debate.

1. Most people don't meet criteria for this installation.
2. Most people don't want to fork over $25k for one.
3. Most people can fit traditional subwoofer designs in their sound room.


good points on your past PM...i enjoyed it...perhaps we could revisit this at a later date...thanks, martin

"Frequency response is NOT efficiency response."

 

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Klipsch RB-35's surround

Acoustech HT-65 center

Cerwin-Vega CV-2800

 

Subwoofer

B&C 21SW152-4  [21" critical-Q]

 

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post #186 of 380 Old 02-06-2007, 11:27 AM
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Originally Posted by SteveCallas View Post

I didn't touch the sealed sub's rolloff, that's just what it became after adding the necessary EQ boosts.

An appropriate Linkwitz transform or stacked shelving filter + PEQ is the preferred, but not the only method. The differences vs what you posted are very significant and quite audible.

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4-8db/octave of room gain still means you'll need to be adding 8-4db/octave of boost in order to stay flat, and then you'll also need to account for electronics rolloff. No, I haven't even seen any system have a flat FR down to DC at spirited levels, let alone heard one. The 4x15" IBs or even 4x18" IBs I've seen don't come close to staying flat to DC at moderate to spirited levels. If you know of some, point me in that direction please.

No one has said such systems would be flat to DC. Early on catapult made and example as a reality check made of what it would take to produce DC if we actually had an entirely air-tight room.

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Kramskoi, looks like you are reasonably flat to 9hz with a little more than a 24db/octave rolloff below that. So I'm not really sure what you are claiming here. The ultra low stuff in that scene is centered around 3hz I believe.

Even with my calibrated microphone there is some VLF roll off. There are microphones that can be flat to ~1Hz or so. My own system is reliable to near 6Hz and I've cross referenced it with Bruce Thigpen's system which he has gone to great lengths to calibrate to very low frequencies. I would be hugely surprised if the kramskoi's measurement doesn't include some inherent roll off in the measurement system. While some like to point to the very lowest content in every case, stop grouping everyone's oppinions as one. The point is that there is in fact energy to very low frequencies, and there are systems that are reproducing this to varying degrees down to the 5-12Hz range. Many have agreed that they have observed notable subjective improvements with such systems. It isn't just about SPL, but the entire mix of qualities in signal reproduction that we suspect is responsible. Or at least that's my own suspicions.

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And I've asked you to post such measurements before, as you've claimed a couple sealed 15" woofers will be flat into single digits in most rooms. When you have, the response is definitely not flat into the single digits. We must have a different idea of what flat into single digits means.

I'm not quite the response-nazi that Bosso is (think Seinfeld soup-nazi). I also have used quite a few different measurement systems and methods. "Flat" is a useless definition for a measured frequency response without some stated or implied tolerance window. Is "flat" +/- 0.5dB? +/-2dB? +/-5dB?

I've referred to this before in posts that the idea of "flat" at low frequencies is a bit of a moving target, especially in relation to higher frequencies. The acoustics of a room can HUGELY affect the subjective observation of what a "flat" magnitude response sounds like. Floyd Toole has made public comments that early on a big problem they had with the JBL Synthesis systems in using their EQ and measurements for level setting was that between larger, lossier rooms and small, rigid spaces, they were finding a variance of up to 10dB for what subjectively sounded like the same relative ballance of bass.

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I give them a fair shake, but I can't take things seriously when it's suggested that a couple sealed 15s will stay flat to DC in most rooms. I haven't seen anything like that in ANY room, let alone most rooms. I'm trying to be realistic about this stuff, but many sealed afficionados seem to be living in some kind of make believe world. Take a new look at the many sealed projects completed on here and other sites in the past couple of years, most start rolling off ~20hz even after EQ. Your own subs Mark, in the installs I have seen, dropoff around 6db below 20hz, then slowly taper off. Yet all these FRs I see just get a pass for some reason, like we're not looking at the same thing.

Ok, I agree with that. If a house curve is a distortion though, any type of a rolloff is also a distortion, whether it be shallow or steep. I'd just like to see bosso be consistent about that. To the point though, what we're talking about here is being flat to a lower frequency and having a steeper rolloff, or rolling off sooner but being less steep. If the goal is to be flat to the lowest frequency, and the rolloffs are already occuring in the infrasonic ranges anyway (meaning potential ringing isn't very detrimental), the first option would better suit the goal.

Keep your arguements separate. Bosso was the one saying house curves are bad. This is one area where he and I dissagree. You are also forgetting a few important relevant factors when looking at the responses of systems like Art's and the others I've posted. Those systems are in dedicated rooms and are expected and capable of playback at higher main volume levels than many generally listen to. You also cannot see the relative ballance with the main speakers and are failing to keep the points on the response curve in perspective with the rest of the frequency range.

The response curves were concious decisions, as it is easy to make the response measure flatter in those displays. If the system was rarely,if ever, listened to above -5dB from calibrated reference, some of those curves likely would have had more relative 10Hz level. In the context of most of the systems, the ~10Hz level is in fact quite close to the relative level above say 150-200Hz. In my experience it is quite easy to discern a shelving of the response below 20-40Hz by even 2dB. In the setup process I first achieve a response curve that is appropriate for the subwoofers and what I expect to be desireable based on measurements and experience. After that I get to listening and make finer adjustments in the overall level and general shaping of the response. For a wide variety of reasons, I usually deviate from ruler flat.

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I understand that a higher order rolloff will result in more GD, but is the difference between the two systems being discussed meaningful? Again it gets back to in room FR. Flatter lower or rolling off sooner but less shallow. As for your second point, now we're talking about in room GD, and that's a different topic. Like I said before, GD in and of itself I could care less about, it's the in room FR that matters most. If a system has a less than 12db/octave rolloff that it can maintain, it should have a nice in room FR that stays reasonably flat to DC with great GD. Please show me such a system in existence, I've never seen one.

Many rooms will have some added losses below some single digit low frequency, and as you well know, many electronics start a roll off in the 3-10Hz range. Such roll off is present with a vented or a sealed system. The coupling to the room will usually result in a shallow roll off at some low frequency, combined with a softer overall knee of the electronics. This most certainly will have a better group delay profile than a vented sub with a much sharper corner below it's tuning frequency.

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post #187 of 380 Old 02-06-2007, 11:27 AM
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Quote:
Originally Posted by thylantyr View Post

Lets assume the TRW is the best subwoofer to finish off the debate.

1. Most people don't meet criteria for this installation.
2. Most people don't want to fork over $25k for one.
3. Most people can fit traditional subwoofer designs in their sound room.


true....at the same token, to be precise, "most people" fall into the $400-$500 sub range. Just goto Audiogon and look at some of the "high end" HT setups and multi-channel music rooms, and you will see thousands upon thousands on electronics and front channels, only to have slapped a polk/yamaha/klipsch sub, or a PB10 or ST-2 at best.

amazing that the "average" enthusiast will leave the subwoofer as the last piece of the budget, when in fact, it should be at near the top of the list...........albeit, I may have a skewed viewpoint :P
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post #188 of 380 Old 02-06-2007, 11:29 AM
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Originally Posted by kramskoi View Post

good points on your past PM...i enjoyed it...perhaps we could revisit this at a later date...thanks, martin

I wish people would place this much effort as seen in this thread, with discussions
on high performance > 80hz sound reproducton.



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post #189 of 380 Old 02-06-2007, 11:38 AM
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Agreed thylantyr,

Of course we have debates like this over subwoofer devices that are relatively simplistic in operation compared to a >80Hz loudspeaker. That requries too much reasearch and thought, and unfortunately there isn't that much to read that doesn't conflict with everything else written.

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post #190 of 380 Old 02-06-2007, 12:24 PM
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Originally Posted by Richard View Post

So how do you know they aren't capable of high level single digit output?

Again Richard, I didn't say anything like that. I'm talking about staying flat into these single digits, not just being able to produce output in them. If the goal is just trying to produce output in them, being satisfied with a rolloff, by all means, go sealed. If the intent is to stay flat as low as possible, not worrying about the rolloff profile in single digits, for a set number of suitable drivers, it would be easier going ported because of the additional headroom.

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Originally Posted by kramskoi View Post

the dashes on the FR charts say it all...if the FR is "centered" on 85 dB, that would mean the FR peak is 88 dB and 6 dB down or +-3 dB is 82 dB...

Technically that may be how it's done, and if you consider a steady 6db drop to still be flat, more power to you. I'll agree to disagree.

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Originally Posted by Mark View Post

The point is that there is in fact energy to very low frequencies, and there are systems that are reproducing this to varying degrees down to the 5-12Hz range. Many have agreed that they have observed notable subjective improvements with such systems

To play devil's advocate, what were they coming from before, and after how intensive an installation? How much of the improvement they are experiencing is from being able to play into the teens reasonably flat as compared to single digits at 10-20-30db down? Comparing something to nothing is a no brainer, but your same logic can be applied to higher frequencies. Back before infrasonic capability was the norm, would you rather have been flat to 20hz with a steeper rolloff or start rolling off at 35hz with a more shallow profile? The hearing sensitivity curves tell us that we become less sensitive as frequency lowers, so at least staying flat would be a reasonable goal. When you make it a subjective issue citing individual preference rather than an issue of accuracy, it becomes gray area, as everybody will like something different. There are people who don't like any infrasonic capability. That conversation will only get so far, and we end up in this continuous loop like we are now.

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Those systems are in dedicated rooms and are expected and capable of playback at higher main volume levels than many generally listen to.

I didn't link to that graph, just responded to it. If I'm not mistaken though, he's using four of those subs plus some built in woofers in the walls, yes? I'd think that would level out the playing field between his system and a more typical one with only one of those subs. Point I'm trying to make yet again is that it seems to be underestimated in this thread the amount of air moving capability it takes to be able to stay flat into the single digits while being able to play at spirited levels. Again, if it were easy, we'd all be flat to 3hz with 120db capability.

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Many rooms will have some added losses below some single digit low frequency, and as you well know, many electronics start a roll off in the 3-10Hz range. Such roll off is present with a vented or a sealed system. The coupling to the room will usually result in a shallow roll off at some low frequency, combined with a softer overall knee of the electronics. This most certainly will have a better group delay profile than a vented sub with a much sharper corner below it's tuning frequency.

Again, we're talking about infrasonic rolloffs vs FR linearity and low end headroom. Accuracy will side with the latter, whereas you might cite some individual preference for the former. I have a series of interesting blind tests I would like to participate in regarding this preference you cite. I will make an effort to visit someone with an apporpriate sealed system to eventually conduct these tests and report my findings.
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post #191 of 380 Old 02-06-2007, 12:31 PM - Thread Starter
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Ok, I agree with that. If a house curve is a distortion though, any type of a rolloff is also a distortion, whether it be shallow or steep. I'd just like to see bosso be consistent about that.

I will say this one more time, so pay attention. After this, I will just say something rude to you when you bring it up.

First, a rising level/decreasing frequency, in room curve can easily be corrected, whereas a ULF roll off is due to the limitations of the subwoofer, which cannot easily be corrected.

Second, I will accept either distortion over not having the option to reproduce those frequencies at all. This is a separate issue that you are trying to twist into an argument point, to which I reply...nice try.

Third, to say that a roll off is distortion, whether it's shallow or steep is like saying THD is distortion whether it's 1% or 100%. Again, if you have a choice, which would you prefer?

Lastly, on the subject of 'house curve', you won't find a more consistent stance than my own, to the point of being referred to as a 'response nazi', which BTW, is the best one ever and I fell off the chair laughing at when I read it.

House curve is appropriate in a 'house', which is a live concert venue, and addresses the limitations of human hearing for the listening pleasure of the live audience (many assumptions here as to the quality, or lack thereof, of the knob jockey).

Recorded music already has the house curve applied, unless the recordist was deaf.

Boosting the subwoofer in relation to the rest of the in room, sine wave induced FR is an all too common mistake that comes from years of conditioning by listening to grossly distorted bass.

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This may be a big reason why so many people "crank up the bass" desperately trying to simulate the missing peaks without being aware of how they went missing.

This is definitely one of the reasons, and a good point.

Bosso
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post #192 of 380 Old 02-06-2007, 12:42 PM
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Originally Posted by bosso View Post

Again, if you have a choice, which would you prefer?

You're simplifying it a bit. You don't just choose the rolloff profile - if that were the case, of course I'd chose 2nd order. The choice between infrasonic rolloff profiles come at the cost of free headroom and linearity without needing EQ.

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First, a rising level/decreasing frequency, in room curve can easily be corrected, whereas a ULF roll off is due to the limitations of the subwoofer, which cannot easily be corrected.

That's really beside the point. It is what it is, you call one a distortion and the other not because the latter isn't as easily corrected. I'll agree to disagree here as well, and I'll call both the housecurve and the rolloff profile preferences, not distortions.
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post #193 of 380 Old 02-06-2007, 12:43 PM
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Originally Posted by SteveCallas View Post

Again Richard, I didn't say anything like that. I'm talking about staying flat into these single digits, not just being able to produce output in them. If the goal is just trying to produce output in them, being satisfied with a rolloff, by all means, go sealed. If the intent is to stay flat as low as possible, not worrying about the rolloff profile in single digits, for a set number of suitable drivers, it would be easier going ported because of the additional headroom.

I know the difference between ported and sealed systems, no need to repeat that.

I just want to know how do you know large IB system (let it be 4x18") isn't capable of staying flat into single digits? How many have you measured with calibrated tools?
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post #194 of 380 Old 02-06-2007, 01:01 PM
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I just want to know how do you know large IB system (let it be 4x18") isn't possible to stay flat into single digits? How many have you measured with calibrated tools?

he doesn't. It's all speculation at this point.

hell, even a 4 x15" IB with relatively mild EQ and no L/T applied had flat to 10, at which point I would not feel 100% confident that the measuring equipment calibration (mic, etc) was accurate in the single digit range:



hell, even dual 2x15" mini-IBs have potentially flat to single:




speculating by looking at classic rolloffs is just hilarious.
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post #195 of 380 Old 02-06-2007, 01:10 PM
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Originally Posted by bossobass View Post

Lastly, on the subject of 'house curve', you won't find a more consistent stance than my own, to the point of being referred to as a 'response nazi', which BTW, is the best one ever and I fell off the chair laughing at when I read it.

Bosso

Hey Bosso,

I'm glad you saw the humor in it. "No bass for you!!!"

There needs to be some entertainment while beating our heads against the proverbial brick wall...

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post #196 of 380 Old 02-06-2007, 01:16 PM
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Originally Posted by ssabripo View Post

he doesn't. It's all speculation at this point.

hell, even a 4 x15" IB with relatively mild EQ and no L/T applied had flat to 10, at which point I would not feel 100% confident that the measuring equipment calibration (mic, etc) was accurate in the single digit range:

hell, even dual 2x15" mini-IBs have potentially flat to single:

speculating by looking at classic rolloffs is just hilarious.

Yeah, that's just what I mean. And when you measure right in front of the manifold, there's zero room gain.
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post #197 of 380 Old 02-06-2007, 01:24 PM
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Originally Posted by Mark Seaton View Post

Hey Bosso,

I'm glad you saw the humor in it. "No bass for you!!!"

There needs to be some entertainment while beating our heads against the proverbial brick wall...


The similarities are scary!

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Originally Posted by ssabripo View Post

hell, even dual 2x15" mini-IBs have potentially flat to single:

And at what levels do you think that system is capable to while maintaining such linearity? That Rythmic sealed sub that was brought to Chuck's house could be made flat to 10hz, possibly lower as well, yet it bottomed hard on an 85db sweep. Yet again, the amount of air moving capability necessary to stay flat to single digits while being able to play at spirited levels is being underappreciated in my opinion.

I can keep this up forever, but no progress is really being made. Different strokes for different folks, guess we'll have to leave it at that. To the original point of this thread though, a lot of that information was incorrect.
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Intermission



http://studio-nelson.com/images/yourbase.JPG

http://www.addletters.com/pictures/s...20n3ver%20w1ll.



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Originally Posted by SteveCallas View Post

And at what levels do you think that system is capable to while maintaining such linearity? That Rythmic sealed sub that was brought to Chuck's house could be made flat to 10hz, possibly lower as well, yet it bottomed hard on an 85db sweep. Yet again, the amount of air moving capability necessary to stay flat to single digits while being able to play at spirited levels is being underappreciated in my opinion.

Well, that isn't very difficult to calculate. Four 15" RL-p's: Sd=3200 cm^2, Xmax=25mm. Add an average 8 dB/oct. room gain starting at 30 Hz. Note that I didn't add any boundary gain, these are 1m free-space numbers.

Code:
Freq.    SPL
5 Hz    112.4 dB
10 Hz   116.5 dB
15 Hz   119.5 dB
20 Hz   120.5 dB
Quote:


I can keep this up forever, but no progress is really being made.

We know, we know...
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post #201 of 380 Old 02-06-2007, 02:16 PM - Thread Starter
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Quote:
Originally Posted by Mark Seaton View Post

Hey Bosso,

I'm glad you saw the humor in it. "No bass for you!!!"

There needs to be some entertainment while beating our heads against the proverbial brick wall...

Agreed, and well done

Ssab...superb follow-up

Bosso
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post #202 of 380 Old 02-06-2007, 02:20 PM
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Quote:
Originally Posted by SteveCallas View Post

And at what levels do you think that system is capable to while maintaining such linearity? That Rythmic sealed sub that was brought to Chuck's house could be made flat to 10hz, possibly lower as well, yet it bottomed hard on an 85db sweep. Yet again, the amount of air moving capability necessary to stay flat to single digits while being able to play at spirited levels is being underappreciated in my opinion.

I can keep this up forever, but no progress is really being made. Different strokes for different folks, guess we'll have to leave it at that. To the original point of this thread though, a lot of that information was incorrect.

in the face of cold hard facts, you still persist in whatever...i posted a 10 Hz SPL at THD and i'm pretty sure it's 17% @ 107 dB ...high enough to be audible...look at the sweep i did 3 hours ago...look at the lightning strike graphs...all proof of the SPL and linear ability of a properly integrated sealed sub...Rythmic, smithmic, compare your delusions to a 2x15 like was mentioned...not to a sub bottoming on an 85 dB sweep...you WILL keep this up forever, it is your modus operandi...some sort of twisted, synaptic, feedback-loop...

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Quote:
Originally Posted by Richard Mayer View Post

Well, that isn't very difficult to calculate. Four 15" RL-p's: Sd=3200 cm^2, Xmax=25mm. Add an average 8 dB/oct. room gain starting at 30 Hz. Note that I didn't add any boundary gain, these are 1m free-space numbers.

Code:
Freq.    SPL
5 Hz    112.4 dB
10 Hz   116.5 dB
15 Hz   119.5 dB
20 Hz   120.5 dB

This is a great example. Obvious to most of us. Conservative at that.

There is also the fact that only an escaped mental patient would listen to a system that is calibrated flat to 20KHz at these levels. It bears mentioning that, at lower levels, the subwoofer described above could easily be calibrated flat to 5Hz at 110dB.

I've actually done that with 2X15", the graph of which I posted several times over the past couple of years.

Bosso
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post #204 of 380 Old 02-06-2007, 02:35 PM
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Originally Posted by bossobass View Post

This is a great example. Obvious to most of us. Conservative at that.

There is also the fact that only an escaped mental patient would listen to a system that is calibrated flat to 20KHz at these levels. It bears mentioning that, at lower levels, the subwoofer described above could easily be calibrated flat to 5Hz at 110dB.

I've actually done that with 2X15", the graph of which I posted several times over the past couple of years.

Bosso

I have that graph saved. I've attached it for Steve.
LL
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post #206 of 380 Old 02-06-2007, 03:24 PM
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Originally Posted by kramskoi View Post

you WILL keep this up forever, it is your modus operandi...some sort of twisted, synaptic, feedback-loop...

Correct.

With SC we have a person who's formed the classical textbook definition a 'fixed' belief system. The web, books, papers, etc., have all been 'mined' for data that reinforce the belief. The fact that the supporting data is lifted out of context, and or doesn't actually relate directly to the topic, is of no importance to a person looking to reinforce a fixed belief system.

In the scientific world a person making claims regarding the characteristic of something, has the burden of proof for those claims. Here the situation is reversed, and it's up to others to prove the "beliefs" wrong. This is of course a fool's errand.

Attempting to interact in a logical manner with someone having a fixed belief system is pointless/futile. It's much like trying to debate either side of a discussion about the existence or non-existence of God. An impossibility....

From "The Hitchhikers Guide to the Galaxy"

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post #207 of 380 Old 02-06-2007, 04:11 PM
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Quote:
Originally Posted by SteveCallas View Post

And at what levels do you think that system is capable to while maintaining such linearity? That Rythmic sealed sub that was brought to Chuck's house could be made flat to 10hz, possibly lower as well, yet it bottomed hard on an 85db sweep. Yet again, the amount of air moving capability necessary to stay flat to single digits while being able to play at spirited levels is being underappreciated in my opinion.

I can keep this up forever, but no progress is really being made. Different strokes for different folks, guess we'll have to leave it at that. To the original point of this thread though, a lot of that information was incorrect.

I should really take ThomasW's advice, as it's not much use to argue an amoeba position. The only constant in your arguements is the repeated implication or conclusion that the large ported box is the best thing since sliced bread.

I'm curious how long before you "discover" the 6th order bandpass, as all of the things that have to happen to allow a large ported box to work enable a bandpass to work. You also have much more flexibility in achieving whatever target response you are after.

Getting back to the matter, you've been using the term "spirited levels" as a qualifier a few times. Exactly what are "spirited levels" in your context? Having worked with pro systems that deliver more than 140dB as well as micro-subs/speakers where 105dB is impressive, I have a good idea of how I believe a system needs to behave to comfortably reproduce a given playback level given an intended use. Let's remember that we're talking a out sound delivered to the listener, not out of the subwoofer. What measurements should a system be able to deliver to a listener in order to deliver "spirited levels?"

Mark Seaton
Seaton Sound, Inc.
"Make no little plans; they have no magic to stir men's blood..." Daniel H. Burnham
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post #208 of 380 Old 02-06-2007, 05:11 PM
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Originally Posted by Mark Seaton View Post

Getting back to the matter, you've been using the term "spirited levels" as a qualifier a few times.

Do you really want to go there?

If so you'll discover the meaning of any term or descriptor SC creates is subject to change anytime it suits his needs (it's harder to hit a moving target). The whole intent of his discussions or the creation of terms is to keep the focus of attention on him. That's why he creates terms like "spirited" or "woofage". It's not to be cute, it's to maintain him as the focus of attention. That's the point of 5400+ posts, being the center of attention

A normal person who's built one sub in their life and has a very modest home audio system doesn't take a 20yr old sub design, rename it, and give it "magic" performance characteristics. Someone desirous of attention does this...Then they engage endless debate about it with people like you, bosso, Dennis H, et al.

So as is usually recommended in situations like this "Don't feed the trolls"...

I'm going to sit back and wait for Mr. American Gladiator's reaction to the last handful of posts. Now that control has been removed from him, it will be interesting to see how he attempts to manipulate the situation in an attempt to regain control. It can be predicted, but I won't spoil the fun by spelling it out in advance.....
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Well, I see you guys have been keeping up the good fight after I wimped out and quit in disgust last night. The sad thing is I think Steve's basically a bright guy but he's got himself in a spot where he's staked out a position and he'd rather argue than consider the notion that he might be wrong and could learn something if he listened to those with more experience/knowledge. Too bad his ego is bigger than his desire to learn.

Dennis H
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post #210 of 380 Old 02-06-2007, 05:50 PM
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Quote:
Originally Posted by Kramskoi View Post

in the face of cold hard facts, you still persist in whatever...i posted a 10 Hz SPL at THD and i'm pretty sure it's 17% @ 107 dB ...high enough to be audible...look at the sweep i did 3 hours ago...look at the lightning strike graphs...all proof of the SPL and linear ability of a properly integrated sealed sub...Rythmic, smithmic, compare your delusions to a 2x15 like was mentioned...not to a sub bottoming on an 85 dB sweep.

107db at 10hz with 17% THD from two high excursion 15" drivers. That's pretty good, but with the additional headroom porting provides, more could be achieved with less power, though in much more volume than your current enclosure. It all comes back to this infrasonic rolloff profile vs additional headroom and linearity.

Quote:
Originally Posted by bosso View Post

There is also the fact that only an escaped mental patient would listen to a system that is calibrated flat to 20KHz at these levels

The goal of increased headroom isn't always necessarily to put it to use, as you very well should know, more headroom means less stress on the drivers and less distortion.

Quote:
Originally Posted by Thomas View Post

With SC we have a person who's formed the classical textbook definition a 'fixed' belief system

Correct, because until I see some logic or evidence to change my opinion (I base my opinions on such), the increased headroom and linearity that a port provides seems to be a better alternative to a less steep infrasonic rolloff. When one describes the goals of an accurate bass system, linearity, low distortion, and headroom are typically near the top. By adding a port, you are gaining in those areas down low, right where they are needed the most. It also brings about some negative side effects, but in the infrasonic regions, the negative side effects are easily outweighed by the benefits. Now instead of debating these points, you will go on to harrass me, say the volume required is too much, quote somebody, and so on and so forth.

Quote:


has the burden of proof for those claims

My claims are nothing extraordinary, it's just common sense. There's not really anything to prove there, you just have to change your thinking a bit. If you really don't grasp it, take a look at the difference in FR and low end headroom in someone like Ryan's system after starting with two sealed subs and moving to a dual driver LLT. He's now flatter down low with more low end headroom while using less power. He couldn't play the pods emerging scene in WotW as loud as he can now with as much low end impact without clipping or bottoming the two sealed subs. Again, it's not really some extraordinary claim I'm making, it's pretty simple stuff. The extraordinary claim that I am hearing from the other side is that two 15" drivers can stay flat to single digits while playing at spirited levels - and I'll touch on "spirited levels" next.

Quote:
Originally Posted by Mark View Post

Getting back to the matter, you've been using the term "spirited levels" as a qualifier a few times. Exactly what are "spirited levels" in your context?

If you want me to assign a number to it, taking redirected bas sinto the mix, I'd say 112-113db is a good representation. That's the output capability I try to set as a baseline when helping someone design a sub.

Thomas, I hope my responses lived up to your expectations old buddy
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