Need help connecting two Adcoms together?

biffbuntainbiffbuntain Posts: 1
I need help hooking up an Adcom GTP500 to an Adcom GSP560 ? Can one of you knowledgeable and courteous gentlemen help a needy newcomer?
Post edited by KennethSwauger on


  • LegenderLegender Posts: 451
    Nice update Ken. like this wording much better.
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  • KennethSwaugerKennethSwauger Moderator Posts: 6,538
    It kind of reminds me of an old Vietnam era joke about an Armed Forces Radio interviewer and a battle hardened GI.
    "And the house you live in will never fall down
    If you pity the stranger who stands at your gate" G.Lightfoot
  • JstasJstas Posts: 13,663
    Uhhhh....the GTP-500 is a stereo pre-amp.

    The GSP-560 is meant to be an add-on amplifier to make a stereo a surround sound system. It's a processor and an amplifier in one. It needs a stereo signal and a secondary amplifier to power the front stereo speakers.

    You need a stereo amplifier for it to work because all of the surround processing is handled by the GSP-560. But you can't cheat it and use the GSP-560 as a stereo amplifier. The internal processor prevents it and isn't set up that way.

    What you'll need to do is run the output RCA cable from the GTP-500 pre-amp that would normally go to your stereo amplifier and run it to the labeled input jacks on the back of the GSP-560.

    Then from the GSP-560, you run another RCA cable from the labeled Front output set to your stereo amplifier.

    Then you wire the center channel speaker and surround channel speaker to the respective speaker outputs on the GSP-560 and your separate stereo amplifier runs your front speakers, left and right, as typical.

    However, the best you are going to get out of this is Doby Pro-Logic, a format that is now 20+ years old and very dated. Also, it is not Pro-Logic II so the rear surrounds are not discrete, they are basically left and right channel information on time delays and such to create a surround sound effect.

    That's fine and all but an old Pro-Logic processor that isn't Pro-Logic II may not be able to process modern day digital surround encoding. So it's possible that when watching a modern movie through an old Pro-Logic receiver/processor, you will be missing a significant amount of the program information from the center and surround speakers.

    This is further exacerbated by the fact that this set up you have here is meant to enhance an existing component stereo (meaning, not a stereo receiver or integrated amplfier). So even if you have the latest 4K Blu-Ray encoded for 7.1 surround sound, this setup is only going to manage the stereo channels and create a center channel signal and surround channel signals by processing them out of the stereo signal. It will ignore the center and surround encoded channels that are part of the information on the disc or in the streaming content. It's technically not multi-channel surround sound. That's why it's just called Pro-Logic and not like 3.1 or 5.1 or 7.1 or whatever. The numbers indicate the number of discrete channels with the .1 being the subwoofer channel that is typically a low-pass filtered channel.

    That's not to say this is a bad deal. I just don't know what your intent here is. It has a cool/historical factor and can be useful for stuff like a kid's video game system or a garage/workshop rig or something if it falls short of your surround sound expectations. At the same time, though, to a rookie in the HT game with not a ton of spare cash, these are often very attractive due to price and unscrupulous sellers that will tell you anything to get the item moved at any price. They often have them because it was a "package deal" and they couldn't buy just the cash-cow GFA-555 or something.

    So if you don't want to or can't afford to go a different route right now, you should go pick up an Adcom GFA-535, Adcom GFA-535 Mk ii (means mark 2) or an Adcom GFA-5300 for your stereo amplifier. Unless you have some kind of crazy huge stereo speakers, one of those will not break your budget and will be able to sufficiently drive a pretty wide range of speakers. The GFA-535/535 Mk ii are older amplifiers than then series that you have here but they are sought after because they perform. The GFA-5300 is the same idea as the 535's but reviewers all said that it fell short of the model it replaced (i.e.: the GFA-535 Mk ii). But it's like comparing a Ferrari to a Maserati. That said, the GFA-5300 will have similar aesthetics to the gear you already have so if you want it all to match, go for that one.

    All 3 go for anywhere from $75 in rough but functional shape to $250 for a unit in prime condition. You can get a middle of the road unit for $100-$150 easily.
    You're just jealous 'cause the voices don't talk to you!
  • JstasJstas Posts: 13,663
    I guess I missed something.
    You're just jealous 'cause the voices don't talk to you!
  • F1nutF1nut Posts: 39,998
    About ten minutes of your life.
    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."

  • tonybtonyb Posts: 29,329
    I thought John gave a well detailed and informative response. Yet the OP disappeared. So yeah.....ten minutes of your life flushed. Oh well, crap happens, not the first time and certainly won't be the last.
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  • mhardy6647mhardy6647 Posts: 18,422
    About ten minutes of your life.

    On the other hand, he may have invested his ten minutes much more wisely than did I mine.

    "It's like watching a roomful of people who couldn't get through college algebra discussing the flaws of quantum physics theory. I guess it could be fun, but it's ultimately a waste of time." -- seen on audiokarma

    "Some amps run on self bias, some amps run on fixed bias. But his amps run on confirmation bias." -- seen on audioasylum

    "Writing about hifi is like dancing about architecture" -- paraphrasing some wag (possibly Frank Zappa)
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