Lab12 vs Shiva

Discussion in 'Home Cinema Building DIY' started by BK Electronics, Apr 13, 2003.

  1. BK Electronics

    BK Electronics
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    At this moment I am well oiled, but I have to bring up something that really bugs me and I cannot normaly talk about. You all rave at the Shiva, but it is my guess that none of you have actualy measured its Th-Sm. Well in my position I have well documented its parameters so can someone explain to me why the Lab 12 is rated at 400W with a 160 oz magnet and the Shiva is rated at over 650W with a 60oz Magnet????

    Remember Bl is like Litres to an engine. bigger magnets bigger magnetic fields bigger BL

    I know thats not the be all and end where magnets are concerened (close tolerence air gaps and all) but the Shiva has a 60oz Mag the Lab 12 160oz?????

    Your comments are welcome
     
  2. nathan_silly

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    Ah poo. (see my DIY thread)

    I noticed the weedy magnet today whilst looking through the Shiva white paper - (my Volt driver is more meaty)
     
  3. GaryG

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  4. micb3rd

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    My next sub project will most likely envolve a Lab 12, I am very intersted in your comments about the woofer.

    Manget size does not allways effect power handleing there are subwoofers with huge magnets but terible power handeling and suboofers with small magnets and high power handeling.

    Compairing the 400rms to the 650 rms does not really work, most of the time these figures are a general a guideline and are totally dependent on the size and type of enclosure used.

    Powerhandling in my opinion is a measure of a speakers performance before either power compression of the driver within x-max limits or driver execding the x-max limits and 9 times out of 10 bottoming the driver into its back plate.

    The Shiva and lab 12 have very simular sensivities but the Shiva does have about 2.8mm more potential x-max over the lab 12, but the lab 12 does have a shade more cone area (SD) about 25 cm more.

    They are fairly simalar drivers, in looking at enclosure models for both these drivers they are pritty close.
     
  5. BK Electronics

    BK Electronics
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    If you use the published specs the two drivers model near identical. I hadn't seen a Shiva untill last week, and up against the Lab 12 there is no comparison. After seeing the spec I thought the Shiva would be monster, but it's not. I was a bit disapointed by it.

    Im going to run my Shiva in, then measure its Th-Sm I'll do the same with a Lab12 it will be interesting to see how these figures will model.
     
  6. micb3rd

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    Are so you have both, may I ask what enclosures and amplifier power you are using?

    I would be intersted in any information you can give me, I would appreciate it.

    Regarding the Lab 12 what kind of power does it need to perfrom in a small to medium room?

    Will it run well on a solid 150 rms or does it require closer to 300 rms?
     
  7. BK Electronics

    BK Electronics
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    I have tried the Lab12 in a 50 Litre sealed enclosure with LRC. It was -6dB at 20Hz. Using a 50 Litre enclosure, allows the speaker to be run at higher power levels below resonance without the drive unit reaching max excursion.

    I was using a 500W amplifier but never had it turned up.

    I think 150 watts will work fine, but it's always nice to have a little to spare, even if you dont use the available power the added headroom gives better dynamics
     
  8. micb3rd

    micb3rd
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    LRC? I assume you are talking about Linkwitz-Riley Transform Circuit.

    Is that -6db in room or semi anechoic responce.

    I am not sure weather to go for larger enclosure ported or use a smaller sealed enclosure and use a LT.
     
  9. Ramius

    Ramius
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  10. BK Electronics

    BK Electronics
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    micB3rd, The response was semi anechoic, as for type of enclosure I think it needs to be about 140 Litres for a reflex cab, but then I suppose the 150W would be more than adequate.

    Ramius. I have read Toms posts on the forum before, but I must of missed those. Thanks a lot. Boy does he know his stuff
     
  11. Ramius

    Ramius
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    Yeah, Tom Danley is a true genius.


    Cheers
    Boris
     
  12. micb3rd

    micb3rd
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    Intersting read Ramius, those lab horns do sound like a lot of fun and that have some crazy in room output, pity the size of them is pritty prohibative to custom rooms only.


    Dan Gleebles could you requalify a question of mine erlier, did you use a Linkwitz-Riley Circuit to transform the responce on your 50 liter sealed LAB 12 subwoofer or did you run it plain.

    Thanks

    MB.
     
  13. BK Electronics

    BK Electronics
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    I used a Linkwitz riley transorm, I have an Excel program that works out the component values you dial in a few parameters about the driver and the box it's in, tell it what the new resonant freq you want and Q and hey presto it comes up with the values you need.
     
  14. micb3rd

    micb3rd
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    Well I just modeled the Lab 12 in WinISD.

    I quite like the look of a 103 liter vented alignment tuned to 23.5 hz, this gives me a port 4.02 inch wide and 13.75 inches long.

    My next setp it to try and simulate a small box and play with some LRC values.

    I currently use a slighly modified IPL Acoustics SW2 for bass diuties, I am happy with my current bass output but I may have to build a new sub in May to see what a beast this LAB 12 can be.

    Dan Gleebles what subwoofer/s do you use in your home setup?
     
  15. BK Electronics

    BK Electronics
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    micb3rd,

    iv'e been asked this one by MuFu on the forum chat and I answered quite cheekely anyone that I want, due to where I work and my position I usually get to try the subs before our customers do. I'm not running a sub at the moment waiting to test a new sub in the next couple of weeks.

    The wife hates sub woofesr or any deep bass, I can sympthise with any forum member in this situation. The only sub she liked was the Pro50 because of it's size, my favourite from the subs we make is the Classic 300 this is about 80L (Guesstamate) 12"
    isobaric with a 300W mosefetamp.
     
  16. MuFu

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    You should make her watch Howard Stern's film, "Private Parts". :p ;)

    MuFu.
     
  17. micb3rd

    micb3rd
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    May I ask where you work Dan?
     
  18. BK Electronics

    BK Electronics
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    LOL that might just change her mind, only problem is she would need a HGS 18:devil:

    MB, I work at BK Electronics which is sort of why I'm looking at the Lab 12 Vs Shiva Vs AC12SW4 in 50L enclosures. I measured the Th/Sm of both the Lab 12 and Shiva last week using the Daasl3+ system we have at work, using the extra weight added to the cone method. Using these ThSm not the published spec I modeled them both using ACPro and WinIsd the Shiva modeled sightly better than the lab 12.

    When I eventualy get my test cabinets I can then mesure the actual response and distortion

    Tom
     
  19. micb3rd

    micb3rd
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    Shiva VS AC 12 VS Lab 12 sounds like fun to me (interesting fun no less).

    My I ask why you are using 50 Liter enclosures?

    Is it because of a desired Q of around 0.7?
     
  20. BK Electronics

    BK Electronics
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    Yes, partly due to the Q and also the fact that we should be able to use a 250W amplifier without exceeding maximum excurtion at 20Hz.
     
  21. micb3rd

    micb3rd
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    That 250 watts flat with no boost/EQ or LRC?

    So would a MF 300 or a BSB 300 would be fairly ideal for a 50 liter sealed with LAB 12?
     
  22. BK Electronics

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    It doesnt matter if the 250W represents a flat output or is 250W with Eq. all that really matters is that the limits of the driver are not exceeded

    Both the Lab12 and Shiva will need a bit of Eq LRC to get them producing good output at 20Hz. Flat they will measure -13dB at 20Hz so I expect they need about 6dB LRC. This will mean the amp will run at about 50W in the region without Eq and then the Eq ramping the power up to compensate for the frequency roll off of the speaker. So maximum SPL would be about 104dB and at 20Hz approx 98dB

    The Lab12 will run out of excursion at about 200W the Shiva about 270W. The MF300 will run the full 300W into the Shiva as you would parallel it's two voice coils for 4 ohm the MF 300 Would run 220W into the Lab12's voice coil as it is 8 ohm. A bit more power than is needed in both instances but the headrooms always nice to have.

    What I will do when I eventualy get my cabinets is to run them up close to the maximum SPL at 20Hz and measure the distortion, on paper the Shiva should win as it has a larger Xmax but we will see.
     
  23. micb3rd

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    How much does LRC cost?

    I am starting to play with the XLS file "linktranadv29.13.xls" I will have to see what it is like.
     
  24. BK Electronics

    BK Electronics
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    The components in a LRC circuit are very cheap no more than a couple of quid, theres more components in the +/- 15V PSU you would need to supply the op amp. if you want, you can email me and I can send some circuits that may help
     
  25. RichardH

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    Also for LRC circuits have a look at Rod Elliott's site - also has a spreadsheet for download.
     
  26. micb3rd

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    Dan how things?

    Any more progress or information on the Shiva/LAB12 testing?
     
  27. GaryG

    GaryG
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    If you don't fancy building an LT circuit you can get a top quality one from Marchand Electronics. A bit expensive but very flexible, all the parameters are adjustable and the sound quality is fantastic.

    www.marchandelec.com/wm8.htm
     
  28. BK Electronics

    BK Electronics
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    No further foward with the testing, still waiting for the cabs. I havent forgot the circuits for you either, they are on a floppy disk ready to email, but the disk is on my desk at work.

    As soon as I get my cabs I'll post my findings.
     
  29. micb3rd

    micb3rd
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    Thanks a lot for the update Dan, cheers for the link Gary G.
     
  30. micb3rd

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    Hello Dan long time no speak, has the project moved along at all?

    I was wondering if you had done any more tests with the LAB 12.

    Regards.

    MB
     

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