SQ & output of a Tumult VS a Contrabass & a few Contrabass questions

Discussion in 'Home Theater Projects' started by James W. Johnson, Jan 14, 2004.

  1. James W. Johnson

    James W. Johnson Screenwriter

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    I know the Contrabass is not necessarily a DIY subwoofer although kits have been offered in the past but it seems I have met a few Contrabass owners here in the past.

    By days end today or tomorrow I should have a tracking number for my Contrabass subwoofer. I found a deal that I could not refuse so I jumped on it.

    I was just about to pull the trigger on a Tumult subwoofer though so now I will wonder what I am missing ,likewise if I went with a Tumult I would wonder what I was missing with the Contrabass. The Contrabass deal will most likely never happen again though so I had to go with it and as
    a bass enthusiast I will feel more complete having tryed out a Contrabass.

    How will the output of a Contrabass compare with a single Tumult?
    I was going to seal the Tumult in around 3cuft and based on what I have read about it I am fairly confident that this subwoofer would be very satisfying for both music and movies.
    How does the Contrabass perform in the music department?

    Lastly , I am putting the Contrabass in my 8.5' x12' HT room , as I understand it I am going to have to EQ the heck out of it and buy an amplifer that can drive anything.
    What is a good amp and EQ for the Contrabass?
     
  2. ThomasW

    ThomasW Cinematographer

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    HTF member GM, Greg Monfort either has or had Contrabass bins. You might look him in the members list.

    Normally I'd say your room is too small for the size of the Contrabass cabinets, but that may not be the case given your 'Bass Pig' cabinet design.

    As for which is 'better' Contrabass vs Tumult, probably only Mark Seaton, or Dan Wiggins is in a position to say
     
  3. Greg Monfort

    Greg Monfort Supporting Actor

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    >By days end today or tomorrow I should have a tracking number for my Contrabass subwoofer. I found a deal that I could not refuse so I jumped on it.

    ====

    ServoDrive or DIY unit? New/used? If used, by whom, and for how long? The reason I ask is because that while they can take quite a bit of abuse, once the belt system gets worn it must be completely replaced. If the motor is in tough shape and needs replacing, then you're looking at ~the cost of a Tumult, or at least that was the replacement cost back in the late '90s. The cone 'drivers' and PRs are fairly bulletproof, so short of someone carving up the surrounds, they should be OK.

    If DIY, some were assembled wrong due to a lack of info initially, others had cabs with the wrong offsets due to an error in the drawing provided and some folks just respaced everything to make it work, putting additional load on the belt system.

    ====

    >I was just about to pull the trigger on a Tumult subwoofer though so now I will wonder what I am missing ,likewise if I went with a Tumult I would wonder what I was missing with the Contrabass. The Contrabass deal will most likely never happen again though so I had to go with it and as a bass enthusiast I will feel more complete having tryed out a Contrabass.

    I was going to seal the Tumult in around 3cuft and based on what I have read about it I am fairly confident that this subwoofer would be very satisfying for both music and movies.
    How does the Contrabass perform in the music department?

    ====

    Assuming it's in good condition, the only subs that I'm familar with that can begin to compete SQ wise is a huge basshorn or extreme IB such as TW's. I haven't seen the distortion specs or auditioned a Tumult, so can't offer any opinions on it, but I would be surprised if any point source driver can compete that's not compression loaded.

    The CB OTOH has such low distortion that one guy over on HTT described it as 'overly dry'. According to Tom Danley, they normally only fail in use because the FOH engr. will keep boosting them to destruction since he's listening for the perceived loudness/distortion limit he's used to hearing when tonally balancing a typical vented woofer stack.

    This I can believe. Being used to low distortion horns, folks tend to listen to them quite a bit louder than a typical cone/dome speaker. Still, in playing with mine, I seriously damaged the structural integrity of my house with a pair and some pipe organ music, but not once did I hear any of the 'doubling', power compression, etc., typical of high output subs.

    Its lack of a point source's 90deg phase shift makes blending to a sealed or EBS system perfectly seamless.

    ====

    >How will the output of a Contrabass compare with a single Tumult?

    ====

    The CB is ~92dB eff. and I've been told it can handle 2kW for a short period of time with no compression or non-linearity down to Lastly , I am putting the Contrabass in my 8.5' x12' HT room , as I understand it I am going to have to EQ the heck out of it and buy an amplifer that can drive anything.
    What is a good amp and EQ for the Contrabass?

    ====

    It depends on what motor is in it. If it's a SD unit, then any quality amp that can handle a 2 ohm load AFAIK, but check with SD to be sure. If it has the 0.89 ohm motor that many used in their DIY units, then basically you either need an amp rated to DC, such as the old Crown DC300, or use an autoformer to impedance match to a higher resistance amp. Mine had the 0.89 ohm motors and I drove them with a well used QSC USA 900 amp till it popped. It lasted for a lot longer than I expected it to, so if they're still building them like they used to, QSC would seem a good choice.

    As for EQ, I haven't kept up with what's available so don't know if there's an EQ unit that goes down to
     
  4. James W. Johnson

    James W. Johnson Screenwriter

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    ServoDrive or DIY unit? New/used? If used, by whom, and for how long?
    >>>>>>>>>>

    Its a new , never used unit from when the company was called Intersonics. I am not sure what the whole story is but he had 4 and never used 2 of them. Me and another fellow worked out a deal on both of them.
    They are unfinished birch which used to be an option...
    I'll probably finish mine with Formica or something.
    Mark Seaton was nice enough to do a little research on them and he thinks they are legit units.



    Assuming it's in good condition, the only subs that I'm familar with that can begin to compete SQ wise is a huge basshorn or extreme IB such as TW's. I haven't seen the distortion specs or auditioned a Tumult, so can't offer any opinions on it, but I would be surprised if any point source driver can compete that's not compression loaded.

    The CB OTOH has such low distortion that one guy over on HTT described it as 'overly dry'. According to Tom Danley, they normally only fail in use because the FOH engr. will keep boosting them to destruction since he's listening for the perceived loudness/distortion limit he's used to hearing when tonally balancing a typical vented woofer stack.
    This I can believe. Being used to low distortion horns, folks tend to listen to them quite a bit louder than a typical cone/dome speaker. Still, in playing with mine, I seriously damaged the structural integrity of my house with a pair and some pipe organ music, but not once did I hear any of the 'doubling', power compression, etc., typical of high output subs.
    Its lack of a point source's 90deg phase shift makes blending to a sealed or EBS system perfectly seamless.
    >>>>>>>>>>>

    That is exciting! These days SQ is way more important to me that output is, its sounds like the Contrabass will blend well with my Klipsch Reference speakers.





    It depends on what motor is in it. If it's a SD unit, then any quality amp that can handle a 2 ohm load AFAIK, but check with SD to be sure. If it has the 0.89 ohm motor that many used in their DIY units, then basically you either need an amp rated to DC, such as the old Crown DC300, or use an autoformer to impedance match to a higher resistance amp. Mine had the 0.89 ohm motors and I drove them with a well used QSC USA 900 amp till it popped. It lasted for a lot longer than I expected it to, so if they're still building them like they used to, QSC would seem a good choice.
    >>>>>>>>>>>>>>>>>>>>>>>>
    I am not sure what motor Intersonics used in theses, but I am pretty sure the other fellow in this deal with me who spoke with Mark Seaton said they are around a 3 ohm load.




    As for EQ, I haven't kept up with what's available so don't know if there's an EQ unit that goes down to
     
  5. Seth_L

    Seth_L Screenwriter

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    I'm going to buck the trend and say that a PR'd Tumult in about 7-8 cu ft should equal the SPL of a single contra. However, the Tumult will take several times the power to do it.

    I've heard a Contra, and my own single Tumult with PRs and the Acoustic Visions Everest (2 Tumults). They all sound very good and can play very loud.
     
  6. James W. Johnson

    James W. Johnson Screenwriter

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    Greg, do you know of any websites where I can chat with other Contrabass owners? It does not seem like there are very many here or at AVS and I know there are none at HTT.
     
  7. ThomasW

    ThomasW Cinematographer

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  8. Greg Monfort

    Greg Monfort Supporting Actor

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    >I'm going to buck the trend and say that a PR'd Tumult in about 7-8 cu ft should equal the SPL of a single contra. However, the Tumult will take several times the power to do it.

    ====

    Dunno, the numbers I have say it won't, but have no way to prove it. Are you implying that the Tumult is very conservatively rated and can heat sink enough power to hit its Xmax? At a glance it looks like ~4.8kW into the Tumult puts it over the top of another's claimed peak for the CB.

    ====

    >I've heard a Contra, and my own single Tumult with PRs and the Acoustic Visions Everest (2 Tumults). They all sound very good and can play very loud.

    ====

    Yeah, I believe all these are so extreme that it's more about SQ than peak SPL in a HIFI/HT app.. The true test for these is an outdoor prosound app.. It would be interesting to see how the Tumults fare on the CB's 'home turf', though it's understood that it wasn't designed specifically for it. [​IMG]

    ====

    >Greg, do you know of any websites where I can chat with other Contrabass owners? It does not seem like there are very many here or at AVS and I know there are none at HTT.

    ====

    There's always the basslist (DIY speakers) gang that bought the kit and the Live Audio Board or other prosound forum.

    GM
     
  9. Seth_L

    Seth_L Screenwriter

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    According to the numbers on the CB I've seen 114dB @ 16Hz. My Tumult can do >114dB all the way down to about 16Hz according to the simulations. Granted it takes a lot more than 200W to do so, but it does get more SPL.
     
  10. Greg Monfort

    Greg Monfort Supporting Actor

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    OK, you forced me to actually go look up the ratings. [​IMG] 114dB/16Hz is its continuous rating. [​IMG] It's official peak rating is 'almost' 2 acoustic watts/16Hz/m, or 'almost' 123dB, which is beyond the Tumult's Xmax, and forget it handling the power requirements.

    Someone from SD will have to explain what 'almost' means, but what I can say to a certainty is that two in my open room that measures no gain down to 120dB) with only 500W/16Hz and literally 'brought the house down'.

    Regardless of whether the Tumult can match SPLs or not, if it can reach >114dB/16Hz with any degree of SQ similar to the CB it's quite a bargain. After all, the last price I saw for the CB was $3k........

    GM
     
  11. Jack Gilvey

    Jack Gilvey Producer

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    Wouldn't the output near 16Hz of both subs (Contra/Dual-PR Tumult) be limited by the Vd of a pair of 18" passive radiators? I had assumed that, in an alignment where a Tumult could push dual PR to their limit, output near Fb would be comparable. It's not, I see, so there's something I'm missing as usual.
     
  12. Evan Lee

    Evan Lee Stunt Coordinator

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    Seth L,

    Who ever owns the Everest that you heard, could you ask them to post some numbers on it. For months we have heard reviews and measurements fro the B4+, but I cannot recall the Everest being discussed in any thing other than a theoretical manner. I (and I am sure many others) would like to know just what the Everest can really do. I am glad to hear that someone actually owns one so we can finally get some measurements. Heck, if Kyle R. would post his own data that would satify my curousity.
     
  13. James W. Johnson

    James W. Johnson Screenwriter

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    Evan, if you know me then you know that I will certainly push the hell out of my Contrabass and will post the numbers I get in my room and outside my house. [​IMG]


    Right now I am just trying to figure out what exactly the Contrabass can take without moving too far into the abuse category, I dont want to buy too little nor do I want to waste a huge amp on it.
    According to ServoDrive specs the Contrabass can only take 200watts continuous yet it seems everyone I have come across with one has fed theirs alot more.



    Lets see you B4+ numbers. [​IMG]
     
  14. Kyle Richardson

    Kyle Richardson Screenwriter

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    Seth heard it at CES with only 500 watts total (250 per Tumult). I think even he will agree that even 500 watts was impressive although it was in a very small room.

    I have not posted actual numbers for a couple reasons. One, I personally hate to get into the numbers game because it can vary so much from person to person, test to test unless done under the same conditions such as Tom Nousain's tests. If people want to contribute to the funds to ship the Everest to Nousaine and back I'm all for it [​IMG] Thats also why I have not released any groundplane measurements either, again they can vary quite a bit unless done with the same mic, same hardware, etc. Sure, even I will agree that is fun to benchrace products but as we have all seen before nothing really comes about from it.

    Second, I can post some in room SPL numbers but the results I may obtain in my room will almost certainly vary from those obtained in your room and if I post, for example, 125dB at 25Hz and the customer can only obtain 120dB at 25Hz I dont want them to be upset because they cannot reach the same numbers.

    So thats why I do not post any max SPL numbers, not that I'm trying to hide anything, but more to prevent any grief and controversy.
     
  15. Noed*B

    Noed*B Extra

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    Thats also why I have not released any groundplane measurements either, again they can vary quite a bit unless done with the same mic, same hardware, etc.

    __________________________________________________ ____
    Kyle,

    It is possible to post relevant number that can be used for comparison. We all have access to the one universal which gives us the abillity to compare numbers from test to test; out door groundplanes. If you describe your test set up, the test conditions, use an accurately callibrated microphone, then the information you post is relevant and can be used for comparative data.
     
  16. Kyle Richardson

    Kyle Richardson Screenwriter

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    Deon,
    This is true, but with a passive sub the amplifier will always be the variable and a large variable it is too. Heck, at higher SPL levels I've seen even "calibrated" mics vary by a bunch. Compare results from an Audio Control to a Linear X and I'm sure we'll see a difference.
     
  17. Seth_L

    Seth_L Screenwriter

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    This is correct. I heard it at CES. It was very nice sounding. It's tuned a bit higher than my single Tumult at home, but the sound is very similar. The few tracks from the 5th Element soundtrack were very cool.

    Tumult based subs with PRs are the only subs I've heard that rival the CB in terms of clean sound with scary output levels.
     
  18. Marshall Joyner

    Marshall Joyner Auditioning

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    Everest in general would be difficult if not unfair and impossible to get good measurements outside (I'd think) from the simple fact that the PR's are not on the same face as the drivers... and half of the PR's are on opposing sides of the enclosure all together...making even 2 measurments STILL unfair to the Everest....(dividing output of the PRs on measurments in terms of dbs would be bogus) ...

    But what do I know...I'm just a crash test dummy for woofers..

    I was impressed with Everest, but not shocked like others that were so amused that it was only operating on 500w (250 per driver) ...thats what i drive my personal Tumult with at home... a single 250w plate amp...and it tries to destroy the house...Tumult does NOT need alot of power to do the job...

    Good job on the Everest Kyle...it looks good and feels even better... extreme clean output down way low.....and had the balls to flex the walls when it was time to get stupid too...
    Love it... too bad i can't afford it LOL.
     
  19. Noed*B

    Noed*B Extra

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    Deon,
    This is true, but with a passive sub the amplifier will always be the variable and a large variable it is too. Heck, at higher SPL levels I've seen even "calibrated" mics vary by a bunch. Compare results from an Audio Control to a Linear X and I'm sure we'll see a difference.
    __________________________________________________ _______

    Kyle,

    (My apologies for taking so long to answer, as it happens I've been busy taking in depth distortion measurements and evaluating a ton of competitive product, and am crazy busy so don't have a lot of time to sit at my desk. The front side of product development is massively man hour intensive, and I don't have any idle time)

    Obviously, different boxes, different woofers, different amplifiers, etc will give different results. Any difference from set up to set up will affect the 'comparability' and yes even microphones used (IF you approach their SPL limits, or the test gear isn't set up correctly, or the mics aren't accurately calibrated), and the measurement gear and test setup. Agreed.

    However, if you were to measure 1/3 octave test tones with your set up, sub, amp combo, etc... and detail your test set up, It's likely that I could take the same driver, box and tuning, and similarly capable amplifier (provided there is no on board equalization differences / I am assuming most DIY do all their equalization outside of the amplifier) use my equipment and come up with similar data. It may not be exactly the same, but there WILL be a strong enough resemblance that you could compare them, and in that respect there is some relevance to the data. Remember the largest distortion component in an acoustic system IS the driver (and or port/PR). Distortion from electronics, or in the test gear itself are going to be buried by the driver and ports (or passives) distortion (Unless there is a gross error somewhere in the chain). The distortion components generated WILL be similar, and you'll be able to 'make a comparison'. OR if you've not got the gear to test, then Joe Schmo who just bought THAT driver from you can say to himself, Hey. If I used exactly what he did to get that, I can reasonably expect to achieve similar results. In this respect then, posting real measurements IS valid.
    _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _

    Everest in general would be difficult if not unfair and impossible to get good measurements outside (I'd think) from the simple fact that the PR's are not on the same face as the drivers... and half of the PR's are on opposing sides of the enclosure all together...making even 2 measurements STILL unfair to the Everest....(dividing output of the PRs on measurements in terms of dbs would be bogus) ...

    But what do I know...I'm just a crash test dummy for woofers..
    __________________________________________________ ______

    Marshal,

    In the case of the Everest, measure with the mic aimed at the drivers, then at the passives, then average the two curves. I do this with EVERY subwoofer I measure whether passive or ported if any radiator is not directly aimed at the mic. and do it all the time. It's a simple procedure, just takes a little longer. Virtually any professional grade measurement device used in the industry has the ability to average curves, it's a necessity to any mass production environment. Indeed I average a hundred or more curves to set the window of tollerance for our QC department on our assembly lines...
     
  20. Kyle Richardson

    Kyle Richardson Screenwriter

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    Yes, it would be quite easy to for somebody to replicate the FR graph with a different amplifier as long as not filters were being used and similar test methods used, but I was under the assumption we were talking about max SPL/THD numbers and thats where it starts to get tricky to replicate.
     

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