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Tempest reviewed and compared to the Mass 2012..

Discussion in 'Archived Threads 2001-2004' started by TerryC, Feb 25, 2001.

  1. TerryC

    TerryC Stunt Coordinator

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    After a couple weeks of the Tempest being my primary sub I'm ready to give my impressions, read on if you're interested. I decided on making it a comparison between the Tempest and the Mass as I'm sure many are interested in seeing a direct comparison of two highly thought of drivers. Please be aware that this review is mostly comparing two complete sub designs not specifically the drivers as the design has as much to do with the output as the driver.
    Design specs:
    Tempest
    8.5ft3
    fb=20hz (3 X 4" PVC by 26.3" long)
    Group Delay at 20hz (26.84ms WinISD) (30.71ms LspLab)
    Vent Mach (0.03 WinISD) (8.35ms LspLab @19Hz)
    F3 is 22.6hz.
    Price-$140.00
    Adire Audio
    The enclosure is a "test mule" sub, I plan to use this to test many different variants in the future as the only thing holding it together is tons of easy to remove hot glue and a couple of partially nailed in finishing nails! I'm amazed it held for the Max SPL tests but it did!
    Here are a couple of pics at the finished test sub: http://terryctheater.tripod.com/tempsidejpg.jpg http://terryctheater.tripod.com/temptop.jpg http://terryctheater.tripod.com/tempbottom.jpg
    Mass design is:
    4.18ft3
    Fb-19.033hz(1 X 4" PVC 19" long)
    Group Delay at 20hz is (32.48ms WinISD) (38.86ms LspLab)
    Vent mach is (0.16 WinISD) (12.1ms LspLab @ 18hz)
    Driver Cost-$299 http://www.audiomobileinc.com
    Frequency sweep and Max SPL test:
    Mic placed 6 feet away from sub at my listening seat, used my Mackie M-1400 as the power amp. http://terryctheater.tripod.com/masstempspl.jpg
    Red-Mass 2012 at my listening seat, level matched with low SPL
    Pink-Mass 2012 at my listening seat, unrestricted MAX SPL output
    Blue-Tempest at my listening seat, level matched with low SPL
    Green-Tempest 2012 at my listening seat, unrestricted MAX SPL output
    In this test it is easy to see at low volumes the two are almost the exact same frequency wise at my listening seat. When the volume gets turned up you can see the Tempest easily betters the Mass by 3.1dB at 20Hz and a little more in the rest of the spectrum.
    Theater listening:
    On the Lost in Space sub killer test, my new lower tuned Mass bottoms ever so slightly or at least reaches it's suspension limits during two parts of the opening sequence. With the Tempest it makes it by without a fuss which is a very big accomplishment and goes along with the engine builders term-"there ain't no replacement for displacement" meaning cubic inch motor size.
    Overall at normal theater listening levels I'd say it's a dead heat between the two, I think I'd be hard pressed to pick one or another in a blind test, they're that close. At reference volume with the sub channel +4db in my open concept house which makes for one big 10,000ft3 plus living space the Tempest does a better job because it can play the loudest passages without any hick ups when the mass just ever so slightly falters. BTW-the lower 19hz tuning over the 23hz original tuning on my mass sub really cleared up a bigger hick up on the Lost in Space test.
    Music listening:
    As for music, I was being really critical and I spent a great deal of time comparing different types of music to see how the subs compared. I have heard many times that a 15" driver is not as quick as a 12" driver, usually its the motor strength that plays into this statement and not the actual driver size but I'm not here to debate reasons I only wanted to see how these two compared.
    To my surprise they were very, very similar, both hit hard and fast as expected. Another expected was there wasn't any sort of boominess in either. If I had to pick one that kept up more with my Paradigm Studio 100 mains it would have to be the Mass and only by a very slim margin. This is my first experience on aggressively listening for tightness, it was only as I was writing this and pulling up GD numbers that I realized that the GD results for the Tempest is higher above 25hz or so and that could be the reason for me hearing a slight delay?
    Either way it was a very close test and one I had to do about 10 times back and forth on a Rage against the machine song (name of song escapes me) that had super fast bass and very large dynamics that let me actually hear the difference. I can only describe the difference as a sort or muddier sound as the bass lagged or followed the mains a very tiny bit. But I need to stress I'm being very critical hear, without doing back to back comparisons I would not have noticed it.
    Here is the Spectra graph on the Rage song that shows how close frequency wise they were. Please note this graph can not show GD so don't try to see it. http://terryctheater.tripod.com/masstempmusic.jpg
    Red-Mass 2012 at my listening seat
    Blue-Tempest at my listening seat
    As you can see, as far as frequency response goes with music sources, one would be hard pressed to hear a difference between the two such as one being more boomy or played lower than the other.
    Conclusion:
    This was a very easy test as I love both subs and also a very hard comparison to do as both subs are of almost equal performance and will do any owner proud. In the end though if you have the space, $140 to get this kind of performance is a super tough bargain to beat. In fact, the more I think about it, it's practically impossible considering it's only $140! I think it all comes down to how much you want to spend and how big can you realistically go. Whatever you answer for those two questions should be your decision maker and thankfully to Audiomobile and Adire we have a solution for both.
    Terry
    PS- Ask away if you have any questions that I didn't touch on, I'll be happy to answer. Dan, if you'd like to have me run a specific test for you I'm more than happy to.
     
  2. Jack Gilvey

    Jack Gilvey Producer

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    Thanks Terry, excellent job. I guess ,based on the Tempest having about 3db more max output in this case, that a dual-Tempest sub would have been even further ahead of that FSR-15! I'm gratified to see these results, as I've got two Tempests on the way (destined for an IB,though).
    How did you determine when "max output" occured, bottoming? And how much power was being delivered on each case?
    It appears that the vent mach for the Mass is much higher than that for the tempest...might compression account for the lower max SPL?
    If you tune lower,I think you can push GD in the audible range even lower,at the cost of some output.
    Thanks,
    Jack
    ------------------
    http://content.communities.msn.com/i...&ID_Message=40
    I prefer to listen to my music in its Original Aspect Ratio: Stereo.
     
  3. TerryC

    TerryC Stunt Coordinator

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    Jack,
    "Thanks Terry, excellent job. I guess ,based on the Tempest having about 3db more max output in this case, that a dual-Tempest sub would have been even further ahead of that FSR-15!"
    You bet!
    "How did you determine what "max output" was,bottoming? And how much power was being delivered ion each case?"
    As far as max output, I just turn up the volume until the results don't go any higher at the loudest frequency.
    I start the sweep at a lower volume and see where the loudest peak is. In the case of this sweep its 70hz.
    I then keep running the sweep up to the 70hz mark and keep turning up the volume until it won't go any louder. Having 1400watts on hand gives me that option. [​IMG] All the lights dimmed when doing this test as the amp is drawing so much power. When I stop the test all the lights go back to normal. I have great power in a new neighborhood too!
    There comes a point where the driver has reached its limits and it won't go any louder, at that point all the driver would be doing is dissipating the excess power as heat. I back off about 2db and record the sweep.
    As for the rest of the frequencies I just leave the volume at that level and record the sweep ready to press mute if the sub starts to bottom or whatever. I'm not sure if I kept turning up the volume at lower frequencies such as 30hz if it would read any louder at those frequencies or if I did individual frequencies for max SPL such as Tom Nousaine does???? DanW, TomV, ThomasW, GregM any ideas?
    Either way I'd guess it wouldn't make "much" of a difference in the results?
    "If you tune lower,I think you can push GD in the audible range even lower,at the cost of some output."
    Yes you are right. I'm not completely sure it was group delay I was hearing as the difference is so small. It could be the mass of the driver, the motor or other issues. But it was so hard to hear I wouldn't even think it's cause for concern.
    Terry
     
  4. Greg Monfort

    Greg Monfort Supporting Actor

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    >I'm not sure if I kept turning up the volume at lower frequencies such as 30hz if it would read any louder at those frequencies or if I did individual frequencies for max SPL such as Tom Nousaine does???? DanW, TomV, ThomasW, GregM any ideas?
    ====
    Once the VC heats up, thermal compression sets in and that's all she wrote. [​IMG]
    WRT any 'muddiness', while it's not obvious in the in-room response, the Tempest is a much higher Qb than the Mass, which is shown in the greater group delay. Drop Fb to ~18Hz, and I think it will be a dead heat without sacrificing any LF impact.
    BTW, thanks for the report. [​IMG]
    GM
    ------------------
    Loud is beautiful, if it's clean
     
  5. Patrick Sun

    Patrick Sun Moderator
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  6. TerryC

    TerryC Stunt Coordinator

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    Thanks for the response guys. The design was actually the one Dan Wiggins told me to make do to the nature of HT. Not much goes below 20Hz and tuning lower makes you loose some upper end.
    I'm going to try a Max SPL single 20Hz tone and after 10min another 25hz tone tomorrow after work to see how they come out.
    About the GD issue, it's so small of an issue that I wouldn't even bother re-tuning it. Is more than adequate for my tastes. The term muddiness was maybe incorrectly read. The bass is not muddy in the least bit, just has a very, very, very slight linger to it when compared to my mass sub.
    Greg, you think a stronger motor might have some play on this issue. The reason I suspect it might is the GD difference is only a couple of M/S and I have a hard time believing that we can hear that small of a difference?
    Terry
     
  7. Mark Seaton

    Mark Seaton Supporting Actor

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    Mark Seaton
    Terry,
    I would be suprised if we could really differentiate between a woofer with a "stronger" motor than another as long as the final system response is not very high Q or bumped in nature. I would venture a guess that the VERY slight differences you noted could be related to the distortion charateristics of each driver. It would be interesting to do some good comparisons of IM distortion and THD at various drive levels between the 2 subs. With the TC-Sounds drivers like the MASS 2012, there are a few mechanisms which *could/should* lower IM distortion some, and the underhung motor design would have different overload charateristics. Specifically the spectral nature of the distortion should be different. Now the age old question that becomes very tough to define is "how audible are these types of differences or does it even matter at all?" Finally, it could be an effect related to what looks like slightly smoother in room response from the MASS.
    Mark Seaton
     
  8. Jack Gilvey

    Jack Gilvey Producer

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    Then again,it might not necessarily be driver/motor differences at all. An interesting comparison would be to have both with the same Qb, as Greg suggested. Might take care of the slight linger heard from the tempest. (I know it's slight,Terry, but it's an interesting point you brought up. [​IMG])
     
  9. DanWiggins

    DanWiggins Second Unit

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    Terry,
    Thanks for the data! I surmise from the 3+ dB output advantage of Tempest, you're happy? [​IMG]
    A few things to consider:
    1. The box size I gave you was to maximize SPL (and from the results, it looks like it did that quite well... [​IMG]). As I understood, you wanted to wanted to see what these two drivers can do when tuned for max SPL, so that's what I gave. For better sound quality, I'd definitely agree with Greg and Patrick about tuning lower. Tune for 16-18 Hz, should audibly tighten the sound. You will lose around 1.2 dB SPL output, but you'll still be ~2 dB more output than the 2012. And should have at least equivalent sound quality, if not better.
    2. I know this will probably come up quickly, but box size. I'm sure some will point out that the Tempest box was nearly twice as big as the 2012 box. Solution? Run an Isobaric pair of Tempests. Still lower cost ($280 retail versus $299 retail), and the box sizes can be exactly the same (4 cubic feet for either solution). And you keep the output advantage, too. Plus have higher power handling for less power compression. So, for those looking for a small box solution, an iso pair of Tempests would have lower cost, same size box, and higher SPL potential than a 2012.
    3. Motor strength. Remember, BL is NOT the measure of motor strength! Qes is. Given that, Tempest actually has a stronger motor than the 2012 (0.39 versus 0.44).
    BL is only one aspect of the motor strength. You need to consider Mms and Re as well. BL by itself is meaningless; it's only when combined with these other parameters that it really has meaning. Kind of like looking at the bore of a piston in an engine. By itself, bore is meaningless. It's bore times stroke times number of cylinders that gives you total potential. But then there's the intake, fuel delivery, exhaust, etc. that determine the actual performance of the engine. For a driver, motor strength is the Qes, because it takes into account all the aspects that govern how much actual force you get out from the driver.
    If you want high BL, take a Tempest and wire the voice coils in series. Now you have a BL of 28.4! Of course, the Qes is still the same, because Re has quadrupled along with the doubling of BL... It's Qes that's important, and not BL by itself.
    Anyway, I think you measurements are quite high quality; I really appreciate your willingness to do this, and post the results. You've done a wonderful job, and I'm sure it's going to be of great benefit to DIYers on this and other forums.
    Thanks again,
    Dan Wiggins
    Adire Audio
     
  10. Greg Monfort

    Greg Monfort Supporting Actor

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    Hi Dan, I see you got here before me and covered all the salient points. The only thing I would like to add is that when critical listening comparisons are to be made for music, then matching alignments as close as reasonable is required for them to be valid.
    Looks like you've come up with another great bang for the buck! [​IMG]
    Now if you would just get those 18" PRs going...... [​IMG]
    GM
    ------------------
    Loud is beautiful, if it's clean
     
  11. TerryC

    TerryC Stunt Coordinator

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    I ran the max SPL 20hz and 25hz tones and they made zero difference to the results. So I figure this test is a good representation on what these subs are capable of within most frequencies.
    Terry
     
  12. Jack Gilvey

    Jack Gilvey Producer

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  13. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    1)how the hell could you build a *iso-tempest* using half the overall box volume AND tune down to 16-18hz?(dixie straw porting?)
    2)the mass12 would have at least 3dB more clean output capability down low with 2 flared fours
    3)Audiomobile almost always has *b-stock* mass12s(returned/or a scratch on the magnet) in the $225 range
    4)once you factor in shipping costs for the $299 mass12 compared to 2 of the tempests $140---it's a push. So while either option(single mass 12/ iso tempest)would lead to great bass...I wouldn't try to convince yourselves of any great savings by going with either option.(in fact, it's almost certain the *iso* enclosure would cost you much more to build...time/money wise!)
    5)there's plenty of respected folks who DO consider *BL* to be important. Ask Deon B. his POV, or go look over the TCSounds website. Thilo(from TC) is considered the absolute *man* for driver design, and his website spends a bit of time explaining some of the features on many of their drivers...including high motor strength UNDERHUNG drivers!
    The mass12 motor is Thilo's design btw.
    Sometimes I hear *BL* isn't important, and underhung drivers have inherent flaws because of the BL curves during excursion.
    Then I see TOM NOUSAINE gushing over the high BL/underhung driver from TCsounds(mass12) saying it's the best 12" driver he's ever reviewed,measuring >19mm of CLEAN xmax each way,the longest stroke he EVER measured.(and TN has reviewed HUNDREDS if not thousands of subwoofer based products)
    Interesting cross section of opinion(s) vs. real world data?
    TV
     
  14. Jack Gilvey

    Jack Gilvey Producer

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  15. Bob Sorel

    Bob Sorel Stunt Coordinator

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    In regards to the "iso-Tempest" idea, I just keep thinking about a quote that someone once posted when I was trying to use Pro musical instrument drivers to build a subwoofer:
     
  16. Matt Overpeck

    Matt Overpeck Auditioning

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    Hello?
    quote:
    "Motor strength. Remember, BL is NOT the measure of motor strength! Qes is. Given that, Tempest actually has a stronger motor than the 2012 (0.39 versus 0.44).
    "BL is only one aspect of the motor strength. You need to consider Mms and Re as well. BL by itself is meaningless; it's only when combined with these other parameters that it really has meaning. Kind of like looking at the bore of a piston in an engine."
    "By itself, bore is meaningless. It's bore times stroke times number of cylinders that gives you total potential. But then there's the intake, fuel delivery, exhaust, etc. that determine the actual performance of the engine. For a driver, motor strength is the Qes, because it takes into account all the aspects that govern how much actual force you get out from the driver."
    -----------------------------------------------------------
    Dan,
    With all due respect, what are you talking about? I must concur with TV's thoughts on this. I would suggest you either choose your analogies better or do some further research on how an 'I-C engine' works.
    To compare 'Beta product' (BL) to the piston diameter of engine (an static diamention of an inanimate component in the reciprocating mass), is just bizarre. To say "Bl by itself is meaningless" would invalidate the consenus opinon that BL^2/Re is a very useful measure of a motors strength.
    To use the "piston bore" analogy would be like saying that the diameter of a speaker magnet fails to tells the whole story of the driver's capability -- no kidding?
    BL is more like HP or torque, in that it represents a key measurement of the applied force available in the motor.
    But as they are dynamically related, they should be viewed as collectively.
    By the way, according to DUMAX tests on production MASS units and those done by Vance Dickason for CAE, the Qes on the MASS 2012 respectively is, .45 (proto in CSR was .43) and .49 -- so your analogy and your facts are rather flawed.
    While Qes is certainly an important element, to make it the 'crown jewel' is just absurd. We have a new driver line coming out, and it has both high BL and a Qes about 50% greater then the Tempest or Shiva (or the MASS), but I can assure you, it does not represent the motor is "stronger" then the MASS.
    In fact, as BL increases, as you increase the magnetic structure, so does Qes. They are related, as is torque and HP and should be examined together, not in isolation, as you appear to imply in regards to Qes.
    I can think of several excellent drivers, which have extremely powerful motors, featuring very-high BL, yet have modest X-MAX and low Qes. Do these subs have "less powerful" motors then your subs? I think not.
    In transducer design, 'tradeoffs' represent the defacto reality, and increasing the 'gap' raises BL, but reduces the overhang or X-MAX. If the Adire drivers had any less gap, the BL would fall further, but the X-MAX would increase. Would that be a better driver? NO.
    To focus on and tout only a few select specs, that you favor, to support your products performance (like Qes and
    X-MAX), while attempting to discredit the importance of others, such as Bl, counterdicts your analogy, as the composite results of any motor, are determined by a number of interrelated factors.
    To attempt to support the notion that Qes is the definitive
    measure of a motors "strength" is just nonsense, and to attempt to mislead the forum members to that conclusion, is both absolutely not accurate and is a great disservice to them. There is a word for that...
    Disinformation...
    Later,
    Matt Overpeck
    President
    Audiomobile
     
  17. John E Janowitz

    John E Janowitz Second Unit

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    Both Dan and Matt have valid arguements here. BL by itself is not a valid means for comparison. Wiring a DVC woofer in series doubles the BL as Dan said, however this does not mean you have increased the motor strength. You need to take into account the Re of the driver as well. For years, the equation of BL^2/Re has been used to compare motor strenghts, however it has been found that this equation is also flawed. There is another factor or constant that needs to be included in there. On the other hand you cannot simply compare to motor directly by looking at the Qes value either.
    The other issue to look at is that a stated BL value for a driver is the peak BL value for the driver AT REST. What is much more significant than the peak value is the rate of decrease in BL as the excursion is increased. Typically an underhung design excells in this field up to the point where it reaches Xmax(gap-VClenght / 2). At that point, the VC begins to ride out of the gap, and the BL decreases very sharply. In contrast, an overhung design typically decreases more sharply at first, but it has a more constant rate of decline as it surpasses Xmax, because there is more coil in the gap.
    For a comparison we can look at BL vs X DUMAX curves for both an underhung motor design, and an overhung design. Dan and Matt should find these fairly familiar. Keep in mind that you need to look at the blue lines in the graph which are the actual measured BL data. The purple lines are just the curve fit to aproximate the measured data.
    First is the overhung design:
    [​IMG]
    Then here is the underhung design:
    [​IMG]
    The underhung woofer has somewhat of a peak at the rest position, and a much more gradual rate of decline in BL with increased excursion than the overhung design. This is until it gets to the point where the VC rides out of the gap and then it takes a sharp drop. The overhung design has more of a flat spot in the BL curve at and around rest, with the rate of decrease getting larger with increased excursion. Both designs have their advantages and disadvantages, but i won't get into that here.
    My point is to shed a little more light on what Dan said as far as BL itself being meaningless. This is absolutely true, not only for the fact that Re also needs to be factored in, but because the BL value of a driver is only at the rest position. You also need to look at the rate of decrease in BL as it moves throughout it's excursion.
    John
     
  18. DanWiggins

    DanWiggins Second Unit

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    John,
    What do you know... We're in agreement... [​IMG] BL by itself is really not important. One can wire voice coils in series and double BL. Has the motor strength increased? Nope. But BL doubled. I think that simple fact right there shows that BL is NOT the measure of motor strength.
    I personally believe that Qes is a better measure, because it does factor in things like the mass of the motor, as well as the Re of the motor.
    Matt,
    My analogy may have been flawed, but I still stand by it. As far as the specs, I'm sorry if I got them wrong; I guess I used Qts in place of Qes. The Qes of the M2012S4 is actually 0.46 based upon http://www.audiomobileinc.com/massspecs.htm, and is not 0.44 as I posted above.
    Perhaps then, in the interest of spec accuracy, the SPL at 1W, 1m for the M2012S4 should be checked? It's listed at 89 dB, but I think it should be closer to 86 dB. Is that perhaps a 2.83 Vrms sensitivity instead?
    Tom,
    How to tune 4 cubic feet to 18 Hz? Your middle sized sub is what, around 110L net? That's right around 4 cubic feet. How do you tune it to 20 Hz? I'd use the same techniques for tuning to 18 Hz, just that the vent would be about 20% longer (based on a 10% drop in Fb, since Lv is inversely proportional to Fb squared).
    I thought you were always one on the "more displacement is a good thing" kick. A single Tempest provides 38% more linear displacement than a MASS 2012. In this case, an iso pair of Tempests would provide 38% more linear displacement than the single MASS solution, use about the same size box, and have about the same cost.
    To everyone else,
    I'm sorry if I stirred up the bees. I guess posting my thoughts and opinions isn't welcome on this site, even if they are basically supported by others here (in this thread, Greg Monfort and John Janowitz being the most notable ones).
    Dan Wiggins
    Adire Audio
     
  19. Jack Gilvey

    Jack Gilvey Producer

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  20. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    >>>Tom,
    How to tune 4 cubic feet to 18 Hz?>>I thought you were always one on the "more displacement is a good thing" kick. A single Tempest provides 38% more linear displacement than a MASS 2012. In this case, an iso pair of Tempests would provide 38% more linear displacement than the single MASS solution, use about the same size box, and have about the same cost.
     

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