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  1. #1

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    Default ADCOM GFA-555 mod

    Ben or others,
    I've only been able to find limited details on the ADCOM mods that are possible. I am trying to understand the shunt capacitor (??) mod a little better to consider if I should give it a shot.

    Skill Level: I have limited experience soldering on a board, but am otherwise perfectly mechanically capable. I used to have a very deep knowledge of electronics, but haven't used it since my senior year in college, so let's consider it almost gone from my brain. But...with some explicit explainations to start with, I'm sure I can ask enough questions to make sure I understand and don't screw things up.

    So... What kind of mods can be easliy done to the GFA-555 and what are the benefits of the mod.

    Also... Are the mods easily reversable if I don't like the results?

    Thanks
    HT
    RTi70 mains
    CSi30 center
    RTi28 Rears
    Velodyne CHT-12
    H/K AVR-247
    ADCOM GFA-7000
    Samsung PN58B860
    Playstation 3

    2-Channel
    Polk Audio LSi15's
    Rotel RCD-1072
    Nakamichi CA-5 Pre
    ADCOM GFA-555
    Signal Cable Analog II IC's
    Signal Ultra Bi-Wire Speaker Cables

  2. #2

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    From what I have done the mods are simple on the shunt caps on the big caps. Use a 12uf or so cap on top of the main PS caps. An audio grade cap like the Dayton's is fine. Also you may want to add a 1uf cap in the mix. The big caps are designed to hold a lot of currant. If you add smaller caps the detail is slightly better. Also on the input boards are a few fusible resistors that are not the best for signal path. Shoot me a PM, and I can tell you what resistors to replace. I am going to do the mods myself finally on my own amps. GV27 has pointed me in the right direction concerning replacing signal path R's;)
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  3. #3

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    Default

    I've been curious about this myself. I'm planning on getting an Adcom 555 in the near future, once my HT is rounded out. I've heard a little bit about the mods that people have done to them, but haven't really been able to find any solid info about them either.
    The nirvana inducer-
    APC H10 Power Conditioner
    Denon DVD-2910 universal player
    DPA The Little Bit Three DAC
    Yamaha P-300 turntable/TCC TC-750 phono preamp
    Acurus L10 preamp
    Adcom GFA-545 power amp
    PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Type 4 speaker cables
    Audioquest Sidewinder IC's
    Audioquest Black Mamba IC's
    Signal Cable Analog II IC's

  4. #4
    GV#27
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    I think Ben has a schematic so he can tell you if there are any coupling and feedback caps that may need replacing/upgrading aswell.

  5. #5

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    Ben, could you shoot me an email about the mods as well? I got a GFA-555MKII a few weeks back that I want to mess with. Lol.

  6. #6

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    Quote Originally Posted by GV#27 View Post
    I think Ben has a schematic so he can tell you if there are any coupling and feedback caps that may need replacing/upgrading aswell.
    I have most of the diagrams:)
    Quote Originally Posted by Ender View Post
    Ben, could you shoot me an email about the mods as well? I got a GFA-555MKII a few weeks back that I want to mess with. Lol.
    You have my number no? Shoot me an email.
    Take care.
    Ben
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  7. #7

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    Also guys.............do a search at DIYAUDIO.com and you will find several long threads on mods for those Adcoms.
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30; Eastern Electric Mini Max; Adcom GDA600; MIT S3/Z Pc; SDA 1C; Squeezebox; Tubes add soul!

  8. #8

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    Quote Originally Posted by heiney9 View Post
    Also guys.............do a search at DIYAUDIO.com and you will find several long threads on mods for those Adcoms.
    Thats wheere I learned my stuff;) Again a few naughty resistors, and the cap mods can go a long way. I said it before and I will say it again. Thanks H9 for pointing me in the right direction. NP, and Chris have taught me much!
    Ben
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  9. #9

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    Quote Originally Posted by heiney9 View Post
    Also guys.............do a search at DIYAUDIO.com and you will find several long threads on mods for those Adcoms.
    Thanks!
    HT
    RTi70 mains
    CSi30 center
    RTi28 Rears
    Velodyne CHT-12
    H/K AVR-247
    ADCOM GFA-7000
    Samsung PN58B860
    Playstation 3

    2-Channel
    Polk Audio LSi15's
    Rotel RCD-1072
    Nakamichi CA-5 Pre
    ADCOM GFA-555
    Signal Cable Analog II IC's
    Signal Ultra Bi-Wire Speaker Cables

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