1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

impedance ohms

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by mgh0001, Sep 8, 2005.

  1. mgh0001

    mgh0001
    Member

    Joined:
    Sep 5, 2005
    Messages:
    483
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    trafford, manchester
    Ratings:
    +3
    i have 2 power amps and 2 4ohms speakers

    each power amp in normal mode can handle 4ohms rated
    each power amp in btl (bridged biamping) mode can handle 8ohms rated

    if i was to put one 4ohm speaker with one power amp and the other 4ohm speaker with the secong power amp. could i have each power amp on btl mode, considering it is rated at 8ohms with four set of speaker wire to two speakers per amp.

    Can Anyone Help?
    cheers, mike
     
  2. Reiner

    Reiner
    Active Member

    Joined:
    Jul 16, 2000
    Messages:
    3,315
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    61
    Location:
    Germany
    Ratings:
    +13
    Sure it's biamping mode and not bridged mode (which makes sense since you mention BTL *) )?

    In biamping mode there is no change to the impedance the amp can handle, but in bridge mode the impedance that the amp can handle usually doubles.

    You can biamp the speakers using four set of wires, but the amp must not be switched to briged (BTL) mode then. Obviously for biamping you need to split the L and R input signal so they can be fed to the two amplification stages of each power amp.

    *) BTL = bridge-tied load
     
  3. mgh0001

    mgh0001
    Member

    Joined:
    Sep 5, 2005
    Messages:
    483
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    trafford, manchester
    Ratings:
    +3
    howdo, reiner. thanks for your reply. yes btl does mean bridged. i have corrected this typing error in my starting statement
    cheers, mike
     
  4. Steve.EX

    Steve.EX
    Active Member

    Joined:
    Oct 17, 2001
    Messages:
    3,096
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    68
    Ratings:
    +69
    Mike.

    Without going into specifics, in the case of your amps (i say this as you have stated that they say: 8 ohms minimum bridged") their internal design is such that in bridged mode the amp (for want of a better term) "see's" only half of the speakers impedance.

    So it "see's" an 8 ohm speaker as a 4 ohm load
    It will see a 4 ohm speaker as a 2 ohm load, which is a mighty struggle for all but the crazy American(ish) poweramps. It is also presumed that this is a nominal figure and the speaker's impedance will actually drop lower!
    There are a few amps that will run @ 1 ohm continuously, but they generally have power supplies and output devices that are akin to Battersea power station.
    Your amp will just give up and die in a very short space of time.
    As a footnote i am not at all convinced that bridging an amp offers anything in quality terms, infact i have always been of the opinion that it is in fact marginally worse.
    I would bi-amp if i were you.

    Steven
     
  5. Nic Rhodes

    Nic Rhodes
    Well-known Member

    Joined:
    Mar 23, 2001
    Messages:
    17,133
    Products Owned:
    0
    Products Wanted:
    1
    Trophy Points:
    133
    Location:
    Cumbria
    Ratings:
    +1,277
    I am not sure I know any quality advantages re bridging. I do know several for biamping. Bridging does give more power but as Steve has explained at quite a cost. Biamping doesn't have these limitations.
     
  6. mgh0001

    mgh0001
    Member

    Joined:
    Sep 5, 2005
    Messages:
    483
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    trafford, manchester
    Ratings:
    +3
    thanks for all your replies. of those intrested, i use 2 "sony ta-n9000es" power amps and a "sony ta-e9000" control amp.
    cheers, mike
     

Share This Page

Loading...