bi-amplification vs. bridging

scottyjacks
scottyjacks Posts: 19
edited January 2005 in 2 Channel Audio
I have a pair of SDA 2.3tl's being driven by an Adcom GFA-555. I guess I'm thinking these things need more juice and am considering adding a second amp. The 2.3 manual shows the bi-amplification wiring schema and does not even address bridging. I see the 555 rated at 600w as bridge mono @8ohm.
What is going to get me the better sound on these speakers?
Scooter
Post edited by scottyjacks on
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  • organ
    organ Posts: 4,969
    edited January 2004
    Check out the bi-amping thread by Steveinaz father down. If I had to pick between the two I'd rahter do vertical bi-amping than bridging.

    I don't really see the point in bridging. Yes, the power will increase but the speaker impedance is dropped by half and distortion increases.

    Maurice
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  • steveinaz
    steveinaz Posts: 19,538
    edited January 2004
    Originally posted by scottyjacks
    I have a pair of SDA 2.3tl's being driven by an Adcom GFA-555. I guess I'm thinking these things need more juice and am considering adding a second amp. The 2.3 manual shows the bi-amplification wiring schema and does not even address bridging. I see the 555 rated at 600w as bridge mono @8ohm.
    What is going to get me the better sound on these speakers?

    The quick answer is that usually bi-amping renders better quality than bridging--but NOT always. There are too many variables involved to make that distinction....

    ...more importantly....

    What is leading you to believe they are underpowered? Are you getting audible distortion or clipping? If you're wanting more power because of clipping problems, I would consider selling the existing amp and buying a single, more powerful amplifier. If you want 85% of the "effect" of vertical bi-amping, then just bi-wire the speakers, using good quality speaker cable.

    Bi-amping is a very expensive solution to your problem--IMO, your money is better spent on a single (used maybe?) high power/high quality amplifier. Your ears and wallet will thank me later...

    another solution (I personally don't recommend):

    Bridge your existing amp and run your L/R woofers in "mono" as there is very little detectable seperation information in the lower frequencies, and purchase a second amp to run the L/R mid/high sections (in stereo)...but again, this is a compromise, in the name of saving money...
    Source: Bluesound Node 2i - Preamp/DAC: Benchmark DAC2 DX - Amp: Parasound Halo A21 - Speakers: MartinLogan Motion 60XTi - Shop Rig: Yamaha A-S501 Integrated - Shop Spkrs: Elac Debut 2.0 B5.2
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  • Manamp
    Manamp Posts: 71
    edited January 2004
    And yet another solution is to upgrade the 555 like this: :D

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3070061305
    If you are not judgemental, you don't care enough.
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  • F1nut
    F1nut Posts: 50,662
    edited January 2004
    Very important issue with your idea of bridging, you will need a AI-1 interconnect cable between the speakers as the amps will become mono blocks at that point. You can in some cases connect a heavy gauge speaker wire between the negative output posts on the amps, but not always.

    I'm with Steve, "your money is better spent on a single (used maybe?) high power/high quality amplifier."
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • madmax
    madmax Posts: 12,434
    edited January 2004
    Originally posted by steveinaz
    another solution (I personally don't recommend):

    Bridge your existing amp and run your L/R woofers in "mono" as there is very little detectable seperation information in the lower frequencies, and purchase a second amp to run the L/R mid/high sections (in stereo)...but again, this is a compromise, in the name of saving money...

    Actually you have some misconceptions to deal with here. The SDA's have a bass/mid section and a high frequency section. Everything up to the very high treble would be mono. Also, there would be no SDA response. The center image is about all you would have.

    madmax
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
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  • steveinaz
    steveinaz Posts: 19,538
    edited January 2004
    Your right MadMax, I had completely forgotten about the "SDA" thing...
    Source: Bluesound Node 2i - Preamp/DAC: Benchmark DAC2 DX - Amp: Parasound Halo A21 - Speakers: MartinLogan Motion 60XTi - Shop Rig: Yamaha A-S501 Integrated - Shop Spkrs: Elac Debut 2.0 B5.2
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  • amulford
    amulford Posts: 5,020
    edited January 2004
    I have to concur with Steve and F1, if you don't feel you are getting what you want out of the amp you are using, consider searching out something pre owned. I have found this to be the ticket. There are some very high quality amps around, and the prices are reasonable.
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  • scottyjacks
    scottyjacks Posts: 19
    edited January 2004
    Thanks - I guess the reason behind this has to do with the relative "warmness" of the sound - I have plenty of volume.

    In reading other threads about the 2.3TL's - I got a feeling the consensus was that you really should be driving them at 50% or more of the rated wattage - which would mean sending 375w to each channel.
    Scooter
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  • scottyjacks
    scottyjacks Posts: 19
    edited January 2005
    I'm back, and I now have another question - the speakers came with bass brackets and spikes. I've always used the spikes, as I'm not a real fan of putting holes in walls for no great reason.

    What's the consensus? The question stems from what I consider to be lackluster low end on these speakers. At 150lbs a piece, I cannot imagine needing a sub to get that.

    Is there any definitive test to make sure these are set up optimally? They sit in a "great room" with a high ceiling, and I've had to resort to using an EQ to equalize the room. I get a lot of flack from some purists using an EQ, but without it, I end up running too much juice to the speaker and the high end shuts down until I lower the volume - so I'm doing something else wrong....

    Finally, is there anyway to troubleshoot these things to make sure they are operating properly. I'm the second owner and have had them since probably 1988-89. Is it as simple as speaker on/speaker off?
    Scooter
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  • F1nut
    F1nut Posts: 50,662
    edited January 2005
    Use the Bass Brace, it keeps the cabinet from moving. They are so tall that the mid drivers actually move the top of the cabinet resulting in sloppy bass. Also, move the speakers close to the back wall. I have mine at 5.5" from the wall.

    If you're tripping the polyswitch (tweeter protection) it could be two things, not enough power or the polyswitches are worn out. Are you still running the Adcom amp? Do you have the SDA interconnect cable hooked up?
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • scottyjacks
    scottyjacks Posts: 19
    edited January 2005
    Yes, I still have the Adcom - still in 200w mode.
    Seriously thinking my preamp is the/one source of problem - old Yamaha c-60. I ended up throwing my old BSR equilizer in the loop - the pink noise generator/microphone helped me equalize what has to be a sonically challenging room (great room, 15ft ceilings). NOw I don't need nearly the volume to get a decent sound, but I have to think I'm introducing a ton of noise.

    Yes, the interconnect is still there, but I'm at a loss to generally verify if it's making any difference connected or not.

    Thanks, I will look into pulling off the spikes and using the brace, I seem to remember the documentation saying not to use both.
    Scooter
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  • F1nut
    F1nut Posts: 50,662
    edited January 2005
    A couple of suggestions, study the manual for ideal set up info. You have some high end speakers, you need to feed them with some high end gear. As they say, garbage in....garbage out.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • reeltrouble1
    reeltrouble1 Posts: 9,312
    edited January 2005
    Bridging has worked perfectly for me, I hear no distortion with the NAD's, a quarter turn on the volume results in a SPL that is quite loud but clean in my room. My results have been clean warm sounding power making the 1C's sing marvelously.
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