1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

New Orange Isobaric design bass cabs?!

Discussion in 'Amps and Cabs [BG]' started by dannybuoy, Mar 25, 2009.


  1. dannybuoy

    dannybuoy

    Aug 3, 2005
    England
  2. Gintaras

    Gintaras

    Dec 11, 2004
    Kent Island, Md.
    the 2x10 looks like what I need when my wife and I hit to road in an RV for extended times. I wonder if the new Terror Bass amp is really small.
     
  3. The Bass Terror is the same size as the Guitar one. So "Small is a relative thing" ...
     
  4. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Isobarics have the advantage of a using a smaller box for a given frequency response than a standard alignment. BUT...an isobaric 2x10 will only have the same output capability as a standard 1x10 in a larger box. It won't have the output capability of a standard 2x10; 6dB less, to be exact.
     
  5. If you wire the isobaric pair in Parallel, you gain +3dB over a single driver due to the reduced impedance.
    The typical 2x10 gets +3 from the parallel wiring, and the second +3 from the bass mutual coupling with the second cone.
    The isobaric trades the second +3dB gain for the 50% volume reduction.

    I speculate that isobaric adds a fourth component to Hoffman's Iron Law, i.e. "Expensive".
    In a Loud + Low configuration, you can also get Small by using Expensive (double drivers = double price).
     
  6. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Supporting Member Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    bgavin, the voltage sensitivity gain from impedance reduction is shared between the two drivers, only one of which sees the outside world. So broadband, you don't even get +3 dB. You just break even, except for in the bass region, where the second woofer does effectively increase the output. The limiting factor will still be the outer woofer's X-max, which is what Bill was referring to.

    Isobarik loading obeys Hoffman's iron law. Box size is reduced but so is net efficiency, because half the wattage (Hoffman relates to power, not voltage) is going to the inner woofer.
     
  7. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    No violation. Low, yes. Small, yes. Loud, no. Isobarics were popular in hi-fi decades ago when drivers with high Qts and Vas made five cubic foot and up cabs de rigeur to get below 40 Hz. Going isobaric cut the net cab volume in half by halving net Vas. But as system Vd remained that of one driver net output remained that of one driver, and yes, you had to pay the price of two drivers to get that smaller box size. Lower Qts smaller Vas drivers rendered the isobaric alignment obsolete, Orange's use of it now is puzzlement. :confused:
     
  8. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    I thought the bass one was smaller, being as it does not have power tubes or their attendant large transformers.
     
  9. Acquistapace

    Acquistapace

    Feb 28, 2009
    From what I've seen, it still has preamp tubes, which may attribute to its' similar size. That, and its' use of a similar form factor to cut costs.
     
  10. Not really.

    Let's use the Delta 15LFA as a ridiculous example.
    The 15LF requires 22 cubic feet to hit 29 Hz at 95 SPL.
    This is a typical Loud + Low + Large configuration.

    Adding the second 15LF as Isobaric makes it Expensive.
    Loudness remains unchanged. Loud before, loud after.

    The end result is Loud + Low + (50% Smaller + Expensive).

    Moved into the present, the Omni15 could be made 50% smaller using an isobaric pair of 3015LF.
    The loudness remains the same as the single driver. Only the size is cut down.

    Yes, isobarics were popular decades ago.
    Ditto for bass horns.
    Both are still good ideas.
     
  11. Rickett Customs

    Rickett Customs

    Jul 30, 2007
    Southern Maryland
    Luthier: Rickett Customs...........www.rickettcustomguitars.com
    Isobaric you say?

    Bah, I did that about 5 years ago with 4- 10"s and a 15. Matter of fact, you could call it an Iso-vent. 15 was ported out of the front at the bottom and the 4 10's were sealed. Nothing new.
     
  12. i really could use a big orange "fridge" 8-10. it would suck to cart around but once you got it to the gig you'll be glad it there. anyone know how to get them?
     
  13. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I think you're getting your sums wrong. Isobaric costs 6dB in true sensitivity and the paralleled drivers only get you 3dB back in voltage sensitivity. Hoffman's still rules! ;)

    If you made an Omni 15 with an isobaric pair then although the max displacement limited output would remain unchanged you would need four times as much power to get there yet your thermally limited power handling would only be doubled.

    Alex
     
  14. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Close. With isobaric voltage sensitivity remains unchanged, but since the impedance is halved the power draw is doubled. So you get the same output with a smaller box size, but you need twice the amp size to get it, and twice the driver cost. If your priority is maximum extension and output from minimum box size and you don't care about price then there's something to be said for isobaric, but only then. As always there's no such thing as a free lunch.
     
  15. Agreed. Doubling the driver cost is certainly no free lunch.
    I added "Expensive" to the postulates because this is a viable way to reduce the box size of a given Loud configuration.
    Limited amplifier power is of no concern today, so I don't care about the power draw.
    My focus is entirely on reducing the box volume while preserving bass extension.

    I'm currently building prototypes for a 10 and 15.
    I'll take full measurements, and know for sure whether it is viable or not.
    I have a number of indoor venues where a single 3015LF at 450w would be much too loud, and too big, so a modest amp won't pose a problem.

    The -6dB reference is comparing an isobaric to a system with two drivers.
    This is accurate, but a two-driver box is 2x larger than the single box, and 4x larger than the isobaric.
    My intent is starting with a single driver box and reducing it 50% without sacrificing bass extension.
    My Olson, Dickason, and D'Appolito texts are all mum on isobarics, so I have to find out for myself.
     
  16. DukeLeJeune

    DukeLeJeune rational romantic mystic cynical idealist Supporting Member Commercial User

    Nov 24, 2008
    Princeton, Texas
    Owner & designer, AudioKinesis; Auth. mfg, Big E (Home Audio only)
    bgavin, starting on page 49 of the 7th edition of Loudspeaker Design Cookbook, Dickason describes isobaric, or as he calls them "compound", woofer systems. If you don't have a copy let me know and I'll send the information to you.
     
  17. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Keep in mind that it won't be a 50% size reduction. It's 50% net volume, exclusive not only of the second driver but also the plenum chamber required to connect the two. I've seen articles about isobarics in old issues of Speaker Builder, like from the 80's. Can't remember by whom.
     
  18. greenboy

    greenboy

    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Could be: John Cockroft, Chris Edmondson, or Bill Schwefel. Maybe some others too.

    Even if you do clamshell, if you plan on not having the outer driver hanging out in easily damagable territory, the cab size goes up quite a bit.
     
  19. True.

    I'll run it against the simplest box design to see if the size is actually that much different.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.