kramskoi
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Posts posted by kramskoi
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wow! and i thought i had it bad !...nice...and definitely check out the offerings from Mark Seaton...the man really knows his business...Hello,
I have a limit of four in my theater (no more room!). If I deceide to buy some other manufacture one has to go.Maybe this summer I might try one of Seaton Sounds new subs we will see.
rmlowz
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the 20 Hz performance will be affected by any highpass filtering be used...i would expect the RT12 to roll off much faster, given it's a 4-6th order system...if it's truly -6 dB @ 19 Hz, then i'd say that with the excursion envelope of the f113 and a Linkwitz transform coupled with PEQ, it's very possible to match the transfer function "and" SPL output at 20 Hz...
Judging by the Sound & Vision article, Tom N. found in-room spl to be 105 dB> 25 Hz and 110 Hz @ 32 Hz...no 20 Hz output numbers are given...
The f113 tested outside at 2m GP (craigsub):
Distortion is ~13% at 20 Hz but this would likely fall in-room as the fundamental gets pushed up and the spl would rise 6-10 dB, depending on the size, layout and construction of the room...hardly a cut and dried vented vs. sealed argument...
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well given the scarcity of Klipsch subwoofer reviews with subjective opinion or "objective" numbers...i would'nt hold my breath...that said, the RSW 15 has been said to be very musical for a PR design...how the RT12 will deal with a SOTA sealed subwoofer is another matter...the JL w7 has the displacement of a Tumult 15" driver...even then, these commercial designs, JL included, are limited in what they can do with a single driver...this affects ultimate extension the most and just looking at posted data from Craigsub's evaluations, it looks as though some sort of highpass filtering is being used at the bottom...the rolloff would seem to be even steeper with 12TD using passive radiators which would attenuate VLF much faster...i remember the "Under the Xmas tree shootout in 2001", which noted the lack of impact below 30 Hz compared to other offerings...knowing what i did'nt know a year ago, there is no way i would leave VLF duties to a single driver subwoofer...especially not Home Theater...not for an uncompressed, low distortion presentation...
Bl product does'nt always tell the whole story...for instance the tc3000's i use have more motor force (29 teslameters) than the LMS offerings from TC sounds...the downside to huge amounts of BL is usually a rise of inductance, which inhibits the upper bass and introduces higher amounts of flux modulation distortion...the FR also becomes less linear so more equalization is needed to flatten it...this begins to negate the advantages of the high motor force used...shorting rings can be used to combat, to a degree, this inductance rise, but they are'nt always totally effective...this is one of the reasons why the LMS series weigh so much...the gap must be made wider to accomodate the linear coil, losing force...the HUGE linearized coil adds back the motor force, but lots of copper must be used to attenuate the inductance and keep it low...
Its a very good chance that the RT12 will surpass the f113 at 20 Hz but i would'nt bet on it...the HTW7 has a huge excursion envelope (3.6 to 4" iirc) and indeed it would seem that the modified drivers would have greater thermal capacity, given the amplification which is being used...my guess is that the f113 would provide a better "sound signature"...which is the current rave of this subwoofer at the moment...JL, it seems, definitely did their homework with these subs...i'm personally waiting on the Gotham, which is more in line with the sort of implementation i currently use...even so, i plan to upgrade to LMS drivers once they are released...
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TheEar,
"Outclass,then let anyone here buld a sealed sub using the most capable 12" in the TC SOunds catalog and pit it against the f113,lets see who comes on top.
Will be very close in the worst case for the W7.I have no doubt."
Arthur
i would'nt think that you'd outclass the f113, but there are some peculiarities to note...
Tc Sounds incorporates a high-roll surround with a smaller footprint which allows more of the cone area to be used (more sensitivity)...i'm not sure if JL, with their wider surround, has increased the sensitivity for the HTW7 implementations of the Fathom and Gotham...the 13w7 comes in around 86 dB, iirc...the question becomes how much does the wider surround eat into the effective Sd of the driver...
The LMS 5400 will have the advantage in both linear excursion and max output before compression (4" VC)...and it will boast good sensitivity to boot...
While there is no BL profile given for the HTW7, i would imagine that the 32-34mm Xmax figure does'nt represent lossless BL. If we use the typical 70% BL formula, then the LMS will xmax at ~45 mm one way...with maybe 10-12mm more to xmech...no BL loss out to 38-40 mm...we must remember that, with traditional motor topologies, BL begins it's decline as soon as the driver starts moving...
I think the w7 driver uses a SGLC motor design (overhung), and though this has probably undergone rigorus FEA to maximize linearity, i'm sure it still exhibits the normal parabolic BL roll off, characteristic of the architecture...
We also don't have an inductance value for the 13w7, so flux modulation distortion is a question mark, along with frequency response linearity...
That said, i think the LMS 12 would offer some "similar" performance to the f113, provided it is implemented correctly...with a 4" VC and no BL loss at 38 mm, it should definitely set a new standard for extension and output from a 12" driver.
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the fathom and gotham series, iirc, are using enhanced versions of the 13w7, called the HTW7...looks like a beefier magnet/coil/surround implementation...i think it's excursion capability has been enhanced also...the envelope is supposedly 3.6 - 4" peak to peak...how much of that is "linear" is another matter (normal 13w7's are 32mm xmax)...perhaps they've raised the sensitivity of the driver also (from 86 dB)...also, the driver used in the fathom is different from the one used in the gotham...or so it is stated...
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[:$]Interesting,the RT-12d performs quite well,generating a max output of 110dB @ 32hz and a respectable 105dB @ 25Hz.
Versus only 106dB @ 32Hz for the f112,not good.The f113 should add 2-3dB to this figure,being at the same output as a RT-12d.Still not to my liking. I am demanding a price reduction here. [:@]
My Sunfire Signature beats these numbers @ 32hz with ease! What a joke,I am disgusted,to say the least.What is this a Tonka sub? [:$]
Wait a minute my RSW15 beats all the above at 32Hz! [:$] badly
I am going to puke....excuse me...
Ok I am back... I see after browsing thier website my Paradigm seismic 12 did 109dB at 25hz ! besting the JL f112 and RT-12d! WOW not bad for a more compact and less expensive sub!!!!
SO Paradigm Seismic 12 beats the Klipsch TR-12d on very deep bass(looking at the 25hz output)!!! Hm and is more compact,same type of design,both use a 12" woofer and twin PR's. Hmmm
Now ...pass me the puke bucket [:$]
Ok I give up,ANADA or nothing. Enough toying around,time for performance that leaves these in the dust. COUGH
Excuse the typos...its late 1:15AM here... [+o(]
JL in miramar, ran a test of the f112 in a 3200 cubic feet room, in response to the test by T.N. in his 7500...10 % THD (@ 2m) (1/8 th space) as follows:
B&K mic 3" from cone center for distortion measurements/ELF trim off, ARO off, LP off, sub level to maximum
83 dB----------16 Hz
92.8 dB--------20 Hz
100.3 dB------25 Hz
maximum SPL @ 2 meters-1/8th space B&K mic at listening height
32 Hz-------112.4 dB
40 Hz-------116.2
50 Hz-------113.3
62 Hz-------117.6
average 32-62 Hz----114.9 dB
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Keep in mind that this is stated by the mfg. and will be confirmed later by a subwoofer shootout which will take place on AVS...both the f112 and dual f113's...Now i give JL props...and having heard a few high Xmax 15" designs (in 3-3.5" peak to peak range), these should deliver the goods, however, that said, single sealed drivers are usually limited in more ways than one and usually extension takes a hit...
The Gotham should present some interesting data points once it is released commercially next year...if it is allowed to run unlimited, then i'd say "keep the cats in the cradle" and look out!
We'll have to wait on the testing to tell exactly what type of limiting is being used with these subs and also what their respective roll off rates are. This will determine if they can offer the 99th percentile extension of non-commercial designs (100th being the $25K TRW rotary sub)...While the 99th percentile won't appeal to most, once you've felt VLF infrasound (< 10 Hz) at levels which are palpable (100 dB+), DVD viewing becomes a "listening event", as the full emotional impact of the scenes are delivered with bone crushing precision and frightening dynamics...
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Richard C. Heyser, "Loudspeaker Phase Characteristics and Time Delay Distortion: Part 1," J. Audio <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />Eng. Soc., vol. 17, p. 31 (Jan., 1969). Also available in the Heyser Anthology Time Delay Spectroscopy published by AES<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
H. Suzuki, S. Morita, and T. Shindo, "On the Perception of Phase Distortion," J. Audio Eng. Soc., vol. 28, pp. 570-574 (1980 Sep.). Also available in the Anthology Loudspeakers, Volume 2 published by AES
I think this is where I am going to remove myself from this discussion. And I hope that no one misunderstands my reasons.
It is a wonderful area for exploration, and it is an area where we do not yet have all of the answers at least not in a coherent form that will simply answer everyones questions in a simple manner!
But my reason for withdrawing is this. Pursuing this topic is akin to delving into chapter 356 of the Advanced Time Domain Chronicles when we are having a heck of a time getting through chapter 1 in the Basic Large and Small Room Acoustics thread.
And just as it is difficult to get a handle of the latest string and TOE theories without a basic grasp of quantum electrodynamics, we are necessarily going to run into a problem here without a good grasp of the basic time domain concepts as well.
I wish it were possible to just skip over the more mundane aspects in order to arrive at a simple three sentence answer that can be understood with just a simple non-technical understanding. Maybe it can be done. But I know that I cant!
In response to the idea that horns necessarily exhibit lower group delay My gut is that the answer is both yes and no. The fact that a horn diaphragm undergoes less movement in space due to its efficiency in its generation of an acoustic signal would suggest that its group delay will be less than a dynamic transducer such as a LF woofer. But then we also get to deal with the apparent acoustic origin such as that in a constant directivity horn which appears to be located (and measures thusly) further out in the throat of the horn. And to make issues even more complex, this acoustic origin varies with frequency. Thus we have a degree of complexity over correlating the two concepts in at least some variants of a horn.
My other concern is that this topic (like many others) is difficult to discuss in words. Words arent the native tongue for such phenomena, and I am loath to jump into the math that does more accurately describe such behavior and it is guaranteed to drive everyone away! And I suspect that includes even those of us who are proficient with the tools. And I say this as I know I certainly want to avoid going there! Topics such as negative time, and pre-causal stimuli describing acoustic behavior that happen before we apply a stimuli will be confusing enough as the basic concepts of measurement are presented without introducing the confusement of math!
My recommendation is to maintain an open mind regarding this topic, and to refrain from jumping to any quick conclusion based upon ANY marketing claim you may read!
And again, my agenda is to encourage folks to begin to pursue an understanding of the basics of acoustics as they are rendered via the perspective of the time domain, as that is both the rabbits hole and the entrance to the looking glass through which a simultaneously confusing and utterly fascinating and enlightening journey enhancing your current level of understanding will really begin! But please be realistic! For while this journey will resolve many questions that have been heretofore shrouded by limitations in the traditional approaches, there will also be new challenges and new questions that will be raised with new quests to be solved. But from my perspective, that is precisely what currently makes acoustics such a fascinating areafor unlike many other areas of study where most of the really tough issues were addressed a hundred years ago and most modern challenges simply consist of plugging a few values into well behaved models and equations, acoustics is still a relatively unknown frontier with yet still many regions to be explored and better understood. And if one only avails themselves of the current tools, you will realize that we are in the modern renaissance of acoustic study.
OK, well my soapbox is getting pretty rickety, so I had best be quiet.
I have also attached a discussion from the ProSoundWeb Smaart posting regarding phase. There is a mixture of both confusion and clarity within, and I will leave you to wade through it. After all, what else would you be doing on a beautiful fall weekend? ;-)) My unsolicited suggestion is to forget this stuff and to get out and enjoy!!!
thanks MAS...enjoyed the posts...and point taken!...*wink
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Good layman's term description, Im of the same opinion as Doc on the time delay issue...these are time-domain issues, and to say that they arent interrelated would be a bit premature IMO...They are ABSOLUTELY related! a constant delay through the signal envelope "is" desirable Rather, it is acceptable, but it is not ideal. We are dealing with the tolerances of the ear, the gross limits of perception and the broad area of psycho-acoustics. If we had better (read ideal) transducers the entire signal component of an infinitely short impulse would be reproduced in an infinitely short period identical to the input. In other words, the transform would be unity. would be produced but here we are talking about delay in the 2-4 msec range in the higher frequencies and anywhere from 10 to 100msec in the lower bass range down to 10 Hz... I will defer on this, as we are also entering into the realm described by the Haas, or more accurately, the Henry Precedence Effect.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
it is my thinking that the "room" is the great equalizer in all this. If we agree that the basic loudspeaker is a high pass circuit, passing the highs and rolling off the lows, would this "temporal shift" be more noticeable in an anechoic chamber? How much is the "room" masking the issue? The critical range is the early first order reflections of the Lre field. This becomes important in establishing what is referred to as the initial time delay (or more correctly, the initial signal delay) gap. This is a period where the signal arrival processing is anechoic.
Keeping the phase shift as minimal as possible seems to contradict the practice (by some) of crossing over mains to the subwoofer at frequencies appreciably lower than 80-100 Hz...for example, 40 Hz, which would add twice the group delay of an 80 Hz crossover...cross lower and it becomes even worse...
Aaaaa. Here I will disagree in the sense that you can align the gross signals between transducers in time to a degree and this limitation is due primarily to what is referred to as cosine error and this is also the primary force' behind the concept of co-axial driver development. Additionally, with most transducers, the rate change of phase is not necessarily a constant throughout the frequency range. And as this varies with transducer type, I am hesitant to make any over-reaching pronouncements here.
Of course, the biggest question is always "when does it become audible"? That is the $64,000 question. Another perhaps even more important aspect is when does it become grossly apparent, and when does it become subtly apparent!
okay MAS..."uncle"...i have'nt much to add here...
I'm still in the infant phase with most of these advanced sound concepts...the driving force behind most of my curiosity is subwoofers...the what, when, why and wherefore of any and everything pertaining to them...there's a slow focus with all the hazy generalizations/myths that persist in the audio community...i guess the learning curve depends on your desire to uncover the ultimate truths.
These concepts become important from a design and integration standpoint, with the room weighing in as a "major factor" in total system synthesis...as such, one needs to be wary of all mitigating factors which inhibit said integration.
I guess that "gross signal alignment between transducers" would be a DSP issue? Or could we manage it manually with the appropriate software and a laptop? How many HT enthusiasts actually undertake what "seems" a painstaking process of precise time alignment between all channels? This delay compensation would give us something close to the unity you stated, no?
In any event, i look forward to an increasing knowledge of the "deviled" details of sound reproduction...Thanks for the great posts...
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Maybe I can take a swing at explaining group delay in a way that may help one be able to more clearly visualize what is going on.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
We often talk of a signal arrival time. Take for instance, the Direct signal, Ld, in a room. If we envision a broadband impulse (click) of an infinitely short duration (hey, it's my fantasy where such things exist), we can imagine the entire signal arriving at a finish line at the same precise instant. It is this time differential between the time of origin and the time of arrival that is commonly referred to as 'time delay'.
But in fact, the entire impulse signal does not arrive at the same instant. Rather, it's arrival is spread over a small period of time. And it's behavior during this time distribution (referred to as 'phase') is what is focused upon in 'group delay'.
Remember the comic books and Sci-fi shows where a character moves incredibly fast? Remember how the special effects folks created this effect by showing the character stretch and blur into a character wider then if he were standing still? Well, that is how the actual signal travels. The different frequencies that constitute the impulse signal do not all arrive at the same time. There is a stretching a distribution in time regarding the propagation of the frequencies that constitute the impulse. This distribution (stretching) of the impulse over a finite period of time, and whether the stretching is uniform and contiguous or broken into pieces is what is commonly referred to as 'group delay'.
Now, if the stretching is contiguous, and the blur is a well behaved blur with uniform stretching, and all of the adjacent frequencies arrive in order, only just a little out of time (out of phase), then all is well and good as long as the blurring is well behaved and evenly distributed at the same rate over the frequency bandwidth and not stretched too far. Thus our cartoon super-hero arrives in one piece.
But, if the blurring is not uniform, if parts of the frequency composition are stretched in time (the rate of the change in phase) significantly more than other parts (imagine looking at yourself in a fun house mirror), or even more significantly, if the total frequency band pass constituting the impulse is broken into pieces and these various pieces arrive spread over different non-contiguous times, each acting as separate discrete signals (as often happens with a passive speaker crossover), there is a temporal smearing that becomes apparent in the perception if the 'change in the degree of stretching' is great enough or if the differing arrival times of the discrete packets are great enough apart. In this case, our super-hero is in trouble. He has become stretched out of proportion, or worse, he has broken into several pieces, and we enter the realm of Humpty Dumpty - as this uneven behavior becomes audible.
Now the exact limits of the unevenness of the stretching (the phase) and the exact limits of this separation delay for discontiguous 'bandpass packets (pardon the abuse of language here) that are noticeable have yet to be detailed as finely as we might like. But this issue of temporal smearing is a fundamental issue in Dick Heysers work.
I hope that my poor description allows you to have a better idea of the order of magnitude difference between the basic arrive time of a signal considered as a whole (the time delay), and this same signal magnified and looked at as a continuum (the group delay).
good layman's term description, i'm of the same opinion as Doc on the time delay issue...these are time-domain issues, and to say that they are'nt interrelated would be a bit premature IMO...a constant delay through the signal envelope "is" desirable but here we are talking about delay in the 2-4 msec range in the higher frequencies and anywhere from 10 to 100msec in the lower bass range down to 10 Hz...
it is my thinking that the "room" is the great equalizer in all this. If we agree that the basic loudspeaker is a highpass circuit, passing the highs and rolling off the lows, would this "temporal shift" be more noticeable in an anaechoic chamber? How much is the "room" masking the issue? especially larger rooms, with their reverberant sound fields.
Or perhaps our ear/brain learning has compensated for this phase shift between high and low frequencies...over many years of less than perfect acoustic reproduction.
Keeping the phase shift as minimal as possible seems to contradict the practice (by some) of crossing over mains to the subwoofer at frequencies appreciably lower than 80-100 Hz...for example, 40 Hz, which would add twice the group delay of an 80 Hz crossover...cross lower and it becomes even worse...
Of course, the biggest question is always "when does it become audible"?
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In a small room I'd probably go with a sealed system too [
]Btw, what is an LLT alignment?
first of all...i apologize if i come off a little confrontational...not my intention...i'm still a baby with all this stuff...while i do think that sealed is a potent performer in small rooms, it would'nt necessarily be the best way to go in larger rooms...here the LLT is perhaps the best option, although it will also require multiple drivers and substantially larger cabinetry...this becomes more feasible with the larger space involved...if you can get your wife or s.o. to accept these monster sized enclosures, you can give sealed enclosures a real run for their money...
That said, this design will naturally fall outside the mainstream for output and extension.
LLT subs are usually tuned between 12-16 Hz, with enclosure sizes of about 250-300 liters per driver...so you can see that using multiple drivers really chews up real estate.
The design is run without highpass filtering so this requires amp limiting the driver(s) for infrasonic protection...this is one of the drawbacks to the system, but if you use enough drivers it becomes less of a problem. Care must still be taken with infrasonic material though.
Over the audible range, it supposedly mimics the characteristics of a sealed enclosure but, because of the abnormally low tuning, it allows you to extend lower than a comparable sealed unit. Group delay is quite high at the lowered tuning point, but falls to inaudibility in the muscial range so it is nothing to worry about...in theory of course.
In summary, it is supposed to mimic the sealed box in the audible range and extend the Fb of the system to a lower level than normal vented or sealed designs...and you keep massive midbass output with the multiple drivers. A best of both worlds solution for all.
This design is not without drawbacks though, as i mentioned in previous posts...markedly reduced midbass output, distortion limited output below Fb, size, port velocity (audibility), elevated 20-30 Hz distortion and possible bottoming above Fb, cabinet colorations and port resonance issues...although if carefully designed, a lot of these concerns can be marginalized...it is a sound theory and has been put into practice by various DIY'ers like me...and with good results. Granted we have'nt seen one tested head to head, those who've built them swear by the output and musicality.
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You're opening a can of worms with that question!
As I understand it, for a fixed diameter piston the lower it plays, the further it needs to travel in order to "create" the frequency. You could almost think of group delay as the time it takes for the driver to produce that note. I hesitate saying that because I know it's wrong, but I don't know how else to describe it (which probably means I don't understand it correctly).
I do know that a google search brings up crap loads of debates on the issue. The "audibility of group delay - round 5, start!"
I too would be intersted in a good explanation.
This is a very good,simple description. When a cone/piston has to travel say 4" to produce a given note a say X dB the group delay will be much higher than say the same note produced with a 4mm travel and Y dB. In a perfect world there would be no group delay and full range,point source would be the summum of perfection.In the real world the engineers have to work to minimize group delay or at least keep it in check,if I may say.
Also more travel means recuperation time,the woofer's cone/piston does not reach its central position as fast when under full excursion as it does at moderate levels where the cone has little travel.
basically, a driver in an enclosure is a high pass filter...allowing the highs to pass and rolling off the lows...with any highpass filter, decreasing frequency brings increasing time delay/group delay (the delay between two differing frequencies, i.e. 10 and 100 Hz)...past a certain point it becomes audible...it is "generally" accepted that group delay becomes noticeable between 1 and 2 cycles of the frequency being reproduced...the allowed limit gets higher as frequency decreases...for example, 20 Hz = 20 cycles per second, or one cycle every .05 second, or 50 ms...so the onset of audible delay @ 20 Hz would be between 50 and 100 ms, or 1 - 2 cycles...at 10 Hz it would increase to 100 and 200 ms...
If we use the phase adjustment on subwoofer plate amps as an example...why do two frequencies canel each other? It is because they are both arriving at different times (out of phase) to the listening position, cancelling rather than reinforcing one another...by adding or reducing delay, one can cause the frequencies to sum together...with this example we can see that reducing the amount of time delay between frequencies allows a closer approximation of the intended sound signature...the different frequencies arrive virtually simultaneously, reducing the "time smearing" effect.
The shallower the rolloff (highpass filter), the least amount of phase shift over the passband...and if this also represents time delay the way i think it does, then we should strive to keep this delay as small as possible, in the interest of the most cohesive reproduction of sound.
That said, all this becomes moot, however, once you factor in room acoustics...this is what lots of mfgs. conveniently forget when pushing for sales...a ruler flat frequency response means nothing once placed in a particular room...the loudspeaker is then at the mercy of a myriad of reflections cancelling and reinforcing various frequencies throughout its range...
I'm no EE, but group delay, phase shift, and impulse response are all related to a degree, and all will affect the final presentation in the time domain.
I don't pretend to have this all figured out...this is a "very" tricky and confounding subject...one in which i feel uncomfortable responding to...so take the above with a grain of salt and do your own independent research...the axiom, "rely but verify", definitely applies here...
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We're talking about "AC" signals, not "DC". The concepts of "leaking" at DC do not apply to periodic waves. Air doesn't "escape" through the port unless it's a "high" frequency where the wavelengths are small enough that it doesn't see a trapped lumped mass of air (and at 12 feet, the wavelength of 90Hz so I don't think we have anything to worry about).
For what it's worth, I wasn't actually suggesting to use a 1Hz tuning. Nor would I ever suggest the use of ports below 25Hz in a "small" enclosure (whatever that means). It was meant to be an exercise at plugging through the math and looking at the behavior of one variable (or if you're lazy dropping numbers in a model). All the factors that attribute to transient response will be "identical" about 1/2 octave above the tuning frequency (gotta get outta the pass band of the port). Identical is a loosely defined term (as are all the other words in quotes), but for all practicality it is identical. I would challenge anyone that feels differently to provide objective reasons.
but what are the implications as far as size of enclosure, port resonance in the passband, wall flex, standing waves, port velocity, etc....this enclosure would have to be "much larger and heavier".
When using passive radiators none of this is an issue, but that's not the point I want to make. The reason I bring this up is because you rejected the original premise because you didn't feel it feasible to accomplish with ports. The practicality of a concept is a mute issue when discussing the behavior of single variables. All audio is a system of compromises, but it is up to the designer to decide when things aren't practical. I agree that it's important to be practical, but it just adds to the confusion when that is used as grounds for an argument.
Allow me to present an example to illustrate the point. I have seen a lot of IB / Sealed systems that rely on room gain that start pooping out at around 15Hz with some output down to 10Hz. EQ is often used to flatten out this response, which doesn't increase the maxSPL capabilities of the system...it just effectively reduces the output at higher frequencies to match the peak at the lower frequencies. To get 6dB more output down low, one would need to double up on drivers and amplifier power. This also requires the cabinet to double in size as well. If you're already running 4 drivers in two cabinets and pulling 8000W, then doubling up is extremely expensive. An alternative would be to use about 8 PR's, which would also free you up from the EQ. The cone unloads below the tuning frequency, but this can be easily controlled with EQ. It's important to note that ports/PRs introduce about the same level of group-delay as EQ on a sealed system - basically affecting the transient response in the same way. The only downside I see to this kind of approach is that the cost of 8 PR's is rather expensive and the cabinets often need to be a touch bigger to account for the lower efficiency of PR's. And usually the extra costs could have been spent on better drivers in the first place (and then you could just add PR's to the better drivers) [
]I wonder how many people have had the chance to directly compare Sealed and Ported systems with similar frequency responses. Another trippy concept to throw out there is that the transient response of a system is also contained in its frequency response - I still don't believe it, but that's what the profs tell us in our signal processing classes...
first of all...8000 watts is hardly needed, just add more drivers...if i add a second 2x15 unit and amplifier, using my current driver choice...i'm looking at 130 dB (30 Hz) at 3.5 meters and output around 110 dB at 10 Hz (10 % 3rd HD limited)...it would be unbearable to listen for an extended period of time...2- 24" cubes would stay well hidden in my theater space...this (PR) design presents a steeper rolloff (below the notched Fs of the drone) and therefore worse transient response than a ported system...using two overlapping shelving filters or a Linkwitz Transform circuit (actually improves group delay a bit) would allow group delay to remain below the levels of vented and pr systems...
In the end, unless you are using an EBS/LLT type alignment, it just makes since, once headroom is taken care of, to use a sealed alignment...fewer drawbacks...the F6 bandwidth will be much wider with a 6 dB/octave or less roll off (with less system ringing)...with drivers sporting up to 4" peak to peak excursion capability, these sealed systems can run unhindered by high pass filtering, with no fear of destroying the driver with infrasonic material...a first order system should'nt sound the same as a 5th or 6th.
Most sealed subs without highpass filtering will couple perfectly with smaller rooms, negating the need to add boost below 20 Hz, unless one wanted to implement a house curve...my on room exhibits this characteristic...room gain negates roll off down to 10 Hz and this is measured, not theoretical...personally, i see vented and pr systems as more output than extension oriented...ultimate extension anyways...and then there's the sound signature...i guess we'll just have to "agree to disagree" here...i''ll defer that i'm a little biased, with my current implementation of a sealed subwoofer in a smaller room...in "some" cases, the simplest solution is often the best.
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Doc, I will take issue with one aspect of the carte blanche claim above, not with the intent to rebut your information, but simply to try to present a bit of balance to it with regards to a few variables............
I'm in the middle of a lab at the moment, but wanted to playfully rebutal that you can avoid all those issues by using a better driver [
]Or on a more serious note, you can still maintain the exact same acoustic damping as a sealed system above the tuning point. As a crazy example, take a normal sealed enclosure and thow in a 1Hz tuned port (I'd say 0Hz, but the model falls apart at DC). The port really only affects the system right at the tuning frequency and below. This should make sense when you consider that there are losses in any cabinet that could essentially be considered as very low tuned ports. Also, the acoustical damping is greatest in the region immediately surrounding the port - and the driver barely moves at all.
In the analogy I was going to make, but stopped cuz it was 2am and I figured it was time to go to bed, was that you can slide the tuning up from 1Hz until you're boosting the failing output of the sealed system - essentially using the the port as an EQ at the bottom corner of the extension. Throw in a peaking 2nd order high-pass filter and now you don't sacrifice anything from the sealed system - you just end up spending more money for marginal gains.
Btw, the effects of the room to which I was referring wasn't the modal structure, but rather the behavior below the last mode where the reflections are always in phase and result in constructive interference. I've been wanting to do some experiments comparing flat extension down to 10Hz in a small room to flat extension down to 10Hz outside. So many people refer to "pressurizing the room" which is really a pet peave because SPL = pressure. It is my hypothesis that the room will have some issues that only show up in the time-domain, based on the fact that the output boosting reflections take time to arrive at the listening position.
Speaking of science crap, I better get back to this CPU I'm building... [
]yes, theoretically, like i said with the LLT, you can lower this tuning point (with enough drivers and enclosure space) to 1 Hz but what are the implications as far as size of enclosure, port resonance in the passband, wall flex, standing waves, port velocity, etc....this enclosure would have to be "much larger and heavier"...to each his own here...personally i think there are too many "potential" drawbacks in both audible artifacts and enclosure size/construction to realize this system in a typical setting...and i do think that acoustic suspension is a more stable system, as far as driver protection is concerned...
acoustic damping being "exactly" the same as a sealed enclosure is questionable, given enclosure size, electrical and mechanical damping of the drivers themselves...the summed acoustical damping should be a factor of all of these combined no?...and if the sealed enclosure has losses, then it would seem that the vented enclosure would have as much or more losses...even the amount of polyfill will vary this acoustic damping, with heated air from compression presenting the driver(s) with a stiffer air spring. Lots of variables to the equation...
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Sealed vs. Ported is an issue I've been mulling over for a long time now without any definitive answer. Theoretically, you can take any sealed system with flat response and add a port to increase the output where the driver naturally rolls off. So from one perspective, a ported system can always trump a good sealed system. But the issue of diminishing returns quickly comes into play.
Ultimately I think it comes down to the particular situation at hand. The room has such a large impact on the low frequency performance of a system.
Doc, I will take issue with one aspect of the carte blanche claim above, not with the intent to rebut your information, but simply to try to present a bit of balance to it with regards to a few variables .
Given the example where all things are kept constant, by properly porting a sealed box, you can extend the low frequency extension and efficiency of the speaker just as Mike has accurately mentioned.
But if the focus is on a subwoofer, one must address the desired LF cutoff frequency of the sub. As one goes lower in frequency you approach the free air resonance of the driver and the free lunch of increased efficiency and low frequency extension offered by a reflex/ported enclosure is in danger of 'being eaten'.
In a sealed box you maintain significant mechanical damping - a significant factor in tight defined LF transient response, whereas in a reflex loading the speaker is totally undamped at its free air resonance! It is literally flapping in the breeze with only the negligible electromotive damping is provided by the amplifier (not to mention the speaker's mechanical excursion limit! [
]) which is MANY orders of magnitude less than the mechanical damping afforded by the air in a sealed enclosure.Very Generally speaking, and with all other variables being equal, given that you are employing an optimally designed cabinet of either topology providing for tuning to the desired LF cutoff frequency, you can get away with using a reflex configuration in a sub where the LF cutoff is in the >30 Hz arena. And this is quite common in SR applications where the LF extension is not that extreme. But if you are expecting response much below this region as you approach the free air resonance of the driver, I personally would opt for the less efficient but much improved transient response offered by the acoustic suspension (sealed) enclosure loading. In this region, the increase in efficiency of the reflex loading is not as important as the accuracy afforded by the increased transient response. After all, the issue of effciency and the availability of low cost amplifier power, just like the change in availability in low cost memory capacity over the past 15 years, is no longer an issue. And I am politely ignoring the issues involved in the brick wall filtering required to prevent the LF extension from approaching the free air resonance region of a reflex enclosure used for subwoofer applications.
Naturally these limits are factors in properly designing a complete LF speaker 'system', regardless of the topology utilized, so a combination of various interactive factors are involved. So it is not really possible to say which is by definition 'better'. Rather you must evaluate the total system design. But all things being equal - the same driver, and an enclosure with the only difference being whether it is optimally ported or sealed - for the best accurate LF extension regardless of efficiency, my money will head for the sealed enclosure. It is hard to have tight defined bass response with an undamped speaker [
]But as regards which speaker topology will have the greater effect on room modes?... Again, generally speaking, as both speaker topologies are low Q (directivity) transducers, neither speaker topology matters as much as the room geometry and the total amount of LF acoustic energy being generated within the room (and to a lesser degree speaker placement). So I would not worry about the cabinet topology when evaluating the subwoofer with respect to room modes. You will get to worry about the room modes after you select your sub regardless of the speaker topology! [
]ah the old sealed vs. ported battle...the vented subwoofer really comes into its own in large rooms, where soundwave propagation/diffusion is the chief characteristic of the space...with these large rooms come long dimensions. Because of this, as the room dimensions get larger, the frequency at which room gain begins, falls lower and lower. This limits the amount of help from the room and puts the onus on the driver system for ultimate low frequency output...combine this with the 5th to 6th order roll off in the response (depending on the high pass filter rate), and the sub is too far down before room gain can pick it up...
Now their are ways to combat this with EBS or LLT alignments tuned to very low frequencies, however, these require much larger enclosures (~300 liters (12 cu. ft.)for a single 15" driver), larger ports, heavier construction and bracing...
With these extremely low tuning points (12 Hz in some instances) you move group delay down to frequencies where it won't be noticeable. This "supposedly" more closely mimics the sound signature of sealed subs...this is debatable of course...There is a price to pay with this approach though...
First, you reduce midbass output and increase the possibility of bottoming the driver "above" the tuning point...there's also added distortion in the 20-30 Hz range because you've moved the contribution of the port to a lower frequency, thus the driver has to make up for this decrease in port output...
Second, depending on the size of the enclosure and porting, you are adding the risk of port resonance falling into the audible band of the subwoofer
Third, port velocity above 17 m/s becomes a serious concern, adding audible artifacts to the sound signature at higher levels of output.
Fourth, the cabinet must be extremely well built to combat enclosure colorations, wall flex, vibrations, and standing waves...
Finally, the subwoofer usually would need to be amp limited to protect the driver from the rapid unloading of such a low frequency tune...otherwise you are back to the extreme roll off mentioned above...
Normal vented subs tuned in the 20-25 Hz range, exhibit good midbass output and low frequency extension, a compromise of sorts.
That said, EBS/LLT alignments are probably the best bet for VLF in large, high ceiling, multiple entry rooms. If the sacrifice in midbass output is acceptable, you can achieve lower extension and better transient response, albeit at the cost of a huge enclosure...
In larger rooms, because of the early roll off of sealed designs, it takes multiples to achieve the VLF of EBS "and" Butterworth alignments, for that matter. Again, we are talking < 20 Hz here, not midbass output, at which sealed subs excell.
The compensation (highpass) circuit of the Ultra2, i would guess, is a trimming of the VLF to reduce peaking in that region, thereby flattening the response...it is also causing earlier and steeper rolloff in the response.
In summary, it is difficult to effectively couple the subwoofer to a large room and it takes a considerable amount of displacement to pressurize it, which, in turn, increases the cost of the subwoofer system.
The sealed subwoofer reaches the zenith of its power in the small "pressure mode" rooms, where inadequate diffusion of soundwaves causes the room to become overloaded. Because of the smaller dimensions, room gain starts earlier and is much more pronounced than larger rooms.
Here it is possible to negate the earlier rolloff with the earlier onset of room gain, producing a coupling of the subwoofer to the room, culminating in flat frequency response to very low frequencies, depending on how well the room seals.
The low frequencies tend to be well below what is possible in larger rooms...down to 10 Hz in most cases...one need only add additional subs for the desired output and the system is set for some "very" impressive performance.
With dual driver, single cabinet units, one can improve on this and allow the sub to roll off at 5-6 dB per octave, really improving the amount of infrasonic impact delivered. This would be the closest one could come to an Infinite Baffle sound signature, assuming one does'nt see fit to punch holes in living room walls.
Here you have the best of all possible worlds...lowest group delay, flat frequency response to infrasonic regions, minimal phase shifting and excellent VLF "and" midbass theatrics...a lethal combination.
In summary, IMO, it is doubtful that a comparable vented system in a larger room, can deliver the impact of the smaller room with its pressure mode characteristics.
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Ok. This is interesting stuff but there is another possibility I would like to explore. I knew someone who had a Definitive Trinity sub for sale but I was a little late and it is gone. I have located another. An 18" footprint 34" tall with 2000w, two 14" drivers and four !4" radiators. Literature says 128 db at 20hrtz and 116 db at 16hrtz. What do you think? Kramoski your sub looks awesome but I have niether the time nor talent to build my own sub.
Tom
the enclosure was designed by me, but built by someone else...
I'll say this about the Trinity Signature...it looks extremely formidable but there is no objective tested data that i could find online...some mfg. claims are a little on the optimistic sides...i'm sure it has stupendous output, given 2 drivers and 4 radiators, i have to wonder what the consequent group delay and rolloff would be and how good it would sound with music selections...just looking at the claims, falling 12 dB between 20 and 16 Hz denotes a "very" steep attenuation of VLF response...at this falloff rate, your midbass would have to be very high to realize this below 20 Hz output...i don't think that this subwoofer would couple well to a room at all, even smaller rooms...just my opinion...objective testing of FR, compression, output at varying distances, impulse response analysis, etc. would go a long way toward revealing a "true" picture of performance...
i don't wish to be a cynical skeptic, just that i like to see tested numbers on subs...subjective opinions are just that...subjective opinions...
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kramskoi: I have saw post on TCSounds forum, but didn't realize it was you. Coupla questions. Is the enclosure CNC cut? Would two enclosures at half the volume perform as well. Two 100 lb. enclosures might be a little more manageable.
Raiderno CNC, but the enclosure was built by a local high-end audio store...for about $385...i wanted this thing to be indestructible and dead silent...and that it is...they also built me a 3.3 cu. ft. cabinet with 3" baffle 1.25" walls and 4 internal braces...this weighs in at around 125-150 lbs. with the driver added...they just built them, the designs on both were mine...cabinet flex, resonance, vibration, etc. etc....nil!
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kramskoi: What TC set up are you using? Which drivers, amp, enclosure size and porting? ThanksThe Revel B15 is a great subwoofer,capable of solid deep bas soutput and is very "musical" not adding boom or other unwanted audible colorations.
Buying dual Klipch THX subs will mostly add very deep bass output.As the B15 is a monster down to 30hz and quite potent down to 20hz.
Question is,are you satisfied...fully satisfied with its deep bass output in your room? If YES no upgrade needed,if no try a pair of Klipsch THX subs.
Arthur
Let me try to answer that. I needed to set the Revel sub to +12db and the ultra mains to -7db on my receiver to make the explosion of the Keep wall in LOTR sound the way I thought it should. To really rumble. Is this because of the high efficiency of the ultras? Still, I don't know if I am getting that feel it in the chest impact so many reviewers talk about. I do feel some vibration in my chair. Another thing I need to know is how do you know when you are driving a sub to hard. Should that be a concern? I don't think I am near that yet but how do you know?
Tom
Not good.The B15 is not enough sub for your needs.My mains are at 0dB,center at -3dB,sourrounds at -4dB and subs at -12dB and not even half way on the units! And the bass is simply THERE when called upon.
You need to try two THX subs,these will best the B15 by a solid 10-12dB down deep.If this is still not to your liking,you know TC Sounds has a super sub composed of two cabinets and two Crown amps capable of filling all rooms except stadiums($7000).
I would get a much more capable subwoofer(s).Start by giving the Klipsch THX a spin in your house.
I would love to. It is only the $$$ stopping me. THX's two subs and amp don't come cheap. I would have to win the lottery to go the TC Sounds & Crown route. In my most recent post I was just saying that for the time being I could acheive better results in the smaller room without breaking the bank. It could be the place to go for movies and serious music listening and the great room fo regular tv, sports, chick flicks and etc. On the other hand it does seem a waste to under use those thx fronts center and surrounds that way. They deserve better. A solid 10-12 db down deep huh. Will that be enough? I guess it is obvious I am undecided what to do really.
with the THX pair you're going to get a fair amount of output but you won't get the extension that really brings out DVD's like WOTW...with more selections encoding infrasonics, you need not only massive output but excellent extension also...the THX pair is probably tuned too high for this, and the 4th order roll off won't help either...
a nice high-end 2x15 (or 2 units) sealed that is allowed to rolloff at 6 dB/ octave "and" keep massive midbass output is the ticket here...you should strive to couple the sub to the room and maximize extension...if you think below 16 Hz does'nt matter i can email you spectrals of various movie clips to prove otherwise...i guarantee you that a tc-3000/lms-5400 based dual 15" like the one i built would impress in that small room...with a Qtc. of .450...the attack is violent and the decay rapid...almost an infinite baffle sound signature and in a 6 cu. ft. enclosure, which is quite a small footprint for a 2x15" subwoofer...the lightning,pods and especially the laser scene in WOTW produces absolutely visceral impact and NO FLAB...i sincerely doubt that you could get 105 dB @ 12 Hz (5% 3rdHD) at 3.5 meters from a pair of THX 12" subs...
The problem with the vented subs is the 4th order rolloff, with it's consequent group delay and unloading issues...if a high pass is used, this become much worse (5th or 6th order in some cases)...rapid rolloff, increased impulse response, ringing...i.e. transient response...you have to protect the driver (from unloading) below the tuning point, so this is mandatory for commercial vented subs...
The problem with sealed is worse...you won't find too many sealed subs without a high pass filter installed...for instance the Pardigm servo15 rolls of at 20 dB octave because of it's filtering and has nothing to offer as far as true infrasonic output...don't make the mistake of equating output with extension...two different animals entirely.
i have all the sub details here:
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The Revel B15 is a great subwoofer,capable of solid deep bas soutput and is very "musical" not adding boom or other unwanted audible colorations.
Buying dual Klipch THX subs will mostly add very deep bass output.As the B15 is a monster down to 30hz and quite potent down to 20hz.
Question is,are you satisfied...fully satisfied with its deep bass output in your room? If YES no upgrade needed,if no try a pair of Klipsch THX subs.
Arthur
Let me try to answer that. I needed to set the Revel sub to +12db and the ultra mains to -7db on my receiver to make the explosion of the Keep wall in LOTR sound the way I thought it should. To really rumble. Is this because of the high efficiency of the ultras? Still, I don't know if I am getting that feel it in the chest impact so many reviewers talk about. I do feel some vibration in my chair. Another thing I need to know is how do you know when you are driving a sub to hard. Should that be a concern? I don't think I am near that yet but how do you know?
Tom
Not good.The B15 is not enough sub for your needs.My mains are at 0dB,center at -3dB,sourrounds at -4dB and subs at -12dB and not even half way on the units! And the bass is simply THERE when called upon.
You need to try two THX subs,these will best the B15 by a solid 10-12dB down deep.If this is still not to your liking,you know TC Sounds has a super sub composed of two cabinets and two Crown amps capable of filling all rooms except stadiums($7000).
I would get a much more capable subwoofer(s).Start by giving the Klipsch THX a spin in your house.
I would love to. It is only the $$$ stopping me. THX's two subs and amp don't come cheap. I would have to win the lottery to go the TC Sounds & Crown route. In my most recent post I was just saying that for the time being I could acheive better results in the smaller room without breaking the bank. It could be the place to go for movies and serious music listening and the great room fo regular tv, sports, chick flicks and etc. On the other hand it does seem a waste to under use those thx fronts center and surrounds that way. They deserve better. A solid 10-12 db down deep huh. Will that be enough? I guess it is obvious I am undecided what to do really.
with the THX pair you're going to get a fair amount of output but you won't get the extension that really brings out DVD's like WOTW...with more selections encoding infrasonics, you need not only massive output but excellent extension also...the THX pair is probably tuned too high for this, and the 4th order roll off won't help either...
a nice high-end 2x15 (or 2 units) sealed that is allowed to rolloff at 6 dB/ octave "and" keep massive midbass output is the ticket here...you should strive to couple the sub to the room and maximize extension...if you think below 16 Hz does'nt matter i can email you spectrals of various movie clips to prove otherwise...i guarantee you that a tc-3000/lms-5400 based dual 15" like the one i built would impress in that small room...with a Qtc. of .450...the attack is violent and the decay rapid...almost an infinite baffle sound signature and in a 6 cu. ft. enclosure, which is quite a small footprint for a 2x15" subwoofer...the lightning,pods and especially the laser scene in WOTW produces absolutely visceral impact and NO FLAB...i sincerely doubt that you could get 105 dB @ 12 Hz (5% 3rdHD) at 3.5 meters from a pair of THX 12" subs...
The problem with the vented subs is the 4th order rolloff, with it's consequent group delay and unloading issues...if a high pass is used, this become much worse (5th or 6th order in some cases)...rapid rolloff, increased impulse response, ringing...i.e. transient response...you have to protect the driver (from unloading) below the tuning point, so this is mandatory for commercial vented subs...
The problem with sealed is worse...you won't find too many sealed subs without a high pass filter installed...for instance the Pardigm servo15 rolls of at 20 dB octave because of it's filtering and has nothing to offer as far as true infrasonic output...don't make the mistake of equating output with extension...two different animals entirely.
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I Robot-- at around 52 minutes in the tunnel under attack by the robots...visceral rumbling!!! as the robot carrier moves towards spooner's car...
War of the Worlds --the lightning scene and pods...very impressive at 120 dB...this is a sub killer, most subs won't get near reference level...4 Hz information in this scene! The best subwoofer demo IMO...The laser scene is violent and vicious...maniacal...
Master and commander ---chp 4...strong 28-35 Hz information
SWII AOTC---first fly by
Black Hawk Down-- firing Irene... 7-18-32 Hz signal
Flight of the phoenix --the phoenix gets buried...impressive
The Incredibles...the moon crush at 22 Hz scene...wow!...this whole DVD smokes for low bass...
The Haunting (DTS)... the cold scene and 22 Hz knock
Finding Nemo ----darla taps the tank
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Looking at the specs,a single unit(TC Sounds ANADA)should outperform dual Klipsch THX subs with little problems.Dual stacked/side b side should rival any extravagant and costly box(non IB) desin on the market.
Now we need testing,and A/B comparos against the twin Klipsch THX/SVS dual TV12 Ultra/Velo DD18/Paradigm Servo Signature.
I am interested to see the SPL,linearity and above all COMPRESSION and THD relative to output.Nice to know a sub can best 120dB at 20Hz,now knowing it will do this with minimal compression and low THD is the icing on the cake.And lets see how linear they are across their operating freq. range and how linear they remain once they start to be pushed to thier limits(mechanical and/or thermal).
These are the most serious atempts so far,nobody else offer a sub with a driver so capable(at any price)!
with minimal Le/flux modulation distortion and considering the massive voice coil, i don't think that you'll be able to "hear comfortably" this unit, as a whole, when it reaches the level of compression. These driver are supposed to sport a sensitivity of around 90 dB, so they'll get quite loud.
I switched off the behringer eq on my 2x15 tc-3000 sealed, and was recording 125 dB @ 2 meters from the sub (30 Hz range)...and this is amp limited with 89/92 dB sensitivity...the LMS will have much more linear Vd and power handling...the 38mm given is linear, not 70% BL that is usually stated with normal VC designs...probably around 45mm i would guess for 70%...
As bad as the Ananda is, two opposite firing LMS 18" in a sealed 6.5 cubic feet with a first order rolloff will get to 10 Hz with ease, especially in smaller rooms...and the output may end up being a wash...this is what i'm modeling right now...and it's looking sweeter and sweeter the more i look at it...could probably be done for $3k...
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DrWho and kramskoi already said it. For $15k you could equal those results with standard equipment or a nice IB. All 3 would probably take up similar real estate.
But after a time you really are just adding to the ego (which I don't have a problem with). Some others would spend $20k+ on just making their HT room look like the Starship Enterprise.
To each his own.
But partially back to the original topic, I'm still curious how the differences would sound between the Klipsch option I mentioned and the Ananda. Both equal in price ($4k). I know tuning would be a factor, but I'm also curious what the output comparison would look like.
*edited for CAS
i don't know what your Klipsch option is, but the ultra2 sub pair with 1000 watts probably won't be a match...100 mm peak to peak on the two 15" radiators and 4" peak to peak on the driver (38mm linear)...these drivers have high electrical damping and extremely low Le, coupled with the Linear coil and massive amounts of copper (71 lb. driver), this "may", i'm not saying it is, but it may be best 15" driver on the planet, bar none. They'll command some serious juice but they should impress. An 18" pair should even more potent.
*Now maybe one would compare to the ultra2 system...went back and found your idea earlier in the thread...that would be an interesting comparison...i like the Klipsch pair in that case*
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First
There are plenty of CD's with information well below 30Hz,a good few I have will make subs capable of a true 16Hz with little compression cry.
To say music contains little below 40hz is knowing a tiny portion of what is out there,like i've said,you can find recordings with sub 16Hz material! Pipe organs can reach for the abyss of human hearing,with ease.Some bass electronic tracks have subsonic bass(below 30Hz).
I saw the fan "subwoofer" it is grosly overpriced as it is made in minute quantities and they know they have a niche market.Where the buyer is ready to spend 12K or more on a subsonic device.
I have no doubt these dual TC Sounds beasts with the matching Crown amps will be the last subs even some of us bass maiacs will ever need(and this in larger rooms). Now TC Sounds is a company deserving some major respect,all performance and looks to match! These guys know sub bass and I am buying from them,be damn sure.The pair and the two amps.
Yes you can do better (IB sub)and habe a "sub" capable of infra subsonics down to where you can count the frequeny (10 Hz and below).But lets be reslistic a solid 16hz is damn good,considering the output these will be capable in a mid-sized room!
point taken...but most bassheads want it all...myself included[
]...once you have enough headroom, like the TRW guy, the only improvement is extension. It's down there and does add to the experience. -
Kramskoi, do you own one of them "fan" subs? I would be curious to see some intermodulation distortion measurements. I am skeptical that it can do multiple frequencies at the same time with low distortion based on the premise of its function. Though if you're cranking out 120dB at that low of frequency I don't think distortion is much of a concern (since the fundamentals aren't even audible).
I think cost considerations come into play as well...for $12k I think you could achieve that output with an insane IB.
don't own one, of course, but you're right about infinte baffle, however, this guy mentioned that the 120 dB is conservative and that the fan held THD up to around 125 dB...even at 1Hz...going to take a lot of cones to do this cleanly, not to mention space...my sub rolls off at 6 dB octave and i get 105 dB at 12 Hz at 5% 3rd HD...to keep this level of THD and add 15 dB would cost me 5 more 2x15...7 more to get to 125 dB, that's 16 cones...and you still have the rolloff...considering it costs 1300.00 to build each enclosure, it comes out to "almost" the same...the kicker to this is the amount of wattage the fan uses...150 watts!
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problem is not everyone has the room for infinite baffle
you're right Jay...and not everyone has over $12k to drop on one!...very impressive nonetheless...it's amazing that the guy calls a 2x18" Wilson XS plus two watchdogs "anemic"...wow!
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