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  1. #1

    Member Sales Rating: (3)

    Join Date
    Jul 2001
    SDA SweetSpot

    Post My SDA Bi-Wire/Bi-Amp Adventure

    Page 7 of the SDA SRS 1.2TL owner’s manual states:

    “The SRS is equipped with two sets of inputs to facilitate bi-amplification or bi-wiring….This enables the system to achieve greater dynamic range with lower distortion.”

    I am sure this was true back in 1989 when the manual was written. I wanted to see if it was still true today.

    Reference Configuration

    Denon DCD-1650AR CD Player (modified)
    Adcom GFP-750 preamp
    Adcom GFA-5802 power amp
    2-meter pair of Monster Z200i XLR interconnect cable (preamp/power amp)
    1 meter pair of Monster Z200I RCA interconnect cables (cd/preamp)
    10 foot pair of Monster Z3 speaker cable with medium gold spade connectors.
    Polk Audio SDA SRS 1.2TL Speakers with upgraded crossover components and Cardas CCGR-S binding posts.

    Listening notes were made with respect to sound quality, sound stage dimensions, and image placement within the soundstage. Diagrams were drawn of the relative locations of instruments within the soundstage. Four Tiptoes aluminum isolation cones were used under each power amp.

    Bi-Wired 5802

    The Adcom GFA-5802 has a second set of binding posts for bi-wiring. I used a second set of Monster Z3 speaker cable with medium gold spade connectors.

    I didn’t like this at all. There was a bright haze over the entire frequency spectrum. The bass became thinner and had less impact. Images in the soundstage were shifted two feet to the left. Although the overall sound was brighter, the high frequency detail and clarity was slightly diminished.

    Bi-Amped GFA-5500 on high frequencies/GFA-5802 on low frequencies
    The Adcom GFP-750 preamp has two sets of RCA output jacks for bi-amping. Monster 1 meter Z200i interconnects were used between the preamp and power amps.

    This was a disaster. The highs became dark and muddy (very noticeable loss of detail and clarity). The soundstage width and depth shrank significantly. Imaging was confined to the area between the speakers.

    Single GFA-5500

    Replacing the GFA-5802 and Monster Z200i XLR interconnects in the reference configuration with a GFA-5500 and Monster Z200i RCA interconnects caused a noticeable loss of bass impact (slam) and overall detail. It didn’t sound bad, just not as good compared to the GFA-5802.

    Bi-Amped GFA-5500 on high frequencies/GFA-5500 on low frequencies

    This was much better than the GFA-5500/GFA-5802 combo and the single GFA-5500. These were not subtle improvements. Bi-amping with two GFA-5500’s sounded close to the reference configuration with one GFA-5802. I am assuming the “muddy” sound I heard with the GFA-5500/GFA-5802 combination was due to mismatches in input impedance and power rating. The gains of the two amplifiers are the same. The GFA-5802 is 300 watts/channel compared to the GFA-5500’s 200 watts/channel.

    I did not notice any improvements in soundstage dimensions and imaging when going from the single GFA-5500 to the bi-amped GFA-5500 configuration.

    Although I liked the sound of the bi-amped configuration with two GFA-5500s much better than the GFA-5500/GFA-5802 configuration, I still did not like it better than the sound of the single GFA-5802.


    GFA-5802s can be obtained on the used market for $750-$850. The good results I received with the bi-amped GFA-5500 configuration leads me to believe that there might be some noticeable sonic improvements in going to a bi-amped GFA-5802. I don’t know if it would be $750 to $850 worth of difference though. Maybe the local Adcom dealer will let me “borrow” a GFA-5802 to test my theory.;)
    Last edited by DarqueKnight; 05-16-2003 at 08:27 PM.
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
    "Knowledge, without understanding, is a path to failure."~DK

  2. #2

    Member Sales Rating: (1)

    Join Date
    Jul 2001
    FL 320


    How did I miss this thread? That was a great post. Very informative about your experience. I also took a look at your systems and it looks awesome! You're a hardcore SDA fanatic!

    Have you considered vertial bi-amping with the 5500's?

    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**

  3. #3

    Member Sales Rating: (0)

    Join Date
    Jul 2001
    Livingson, Montana


    I have a surround system with 1.2s in the front and 2.3s in the rear. I just bi-amped the 1.2s with a consecutive #ed pair of PSE Studio IV amps rated at 190 watts per channel. Previously I had been running just one of the amps on the front. I noticed a bit of an improvement in the sound after bi-amping. Almost everything about the sound is better although not by some incredible amount, I would not undo the bi-amp. I think that If you want to bi-amp these speakers it is a good idea to have marching amps.


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