Adcom GFP-750

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  • audiocr381ve
    audiocr381ve Posts: 2,588
    edited February 2012
    I'm leaving to pick it up in an hour! The new B&K amp comes in tomorrow. I have my amp figured out, my preamp, now for the last piece of the puzzle, the DAC.
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  • FTGV
    FTGV Posts: 3,649
    edited February 2012
    audiocr381ve wrote: »
    I'm leaving to pick it up in an hour! The new B&K amp comes in tomorrow. I have my amp figured out, my preamp, now for the last piece of the puzzle, the DAC.
    Looks like your piecing together a nice system.
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  • FTGV
    FTGV Posts: 3,649
    edited February 2012
    heiney9 wrote: »
    The main thing is if you aren't using the balanced connections and the balanced input is missing the jumpers the pre-amp won't sound right using single ended (RCA) connections until you get the jumpers in place. You will have an impedance mis-match that will sound pretty bad. Muffled, lower output, etc.
    Have you tried it without the jumpers Brock?Typically the jumper would short the inverted half of the input to ground so it won't be an open conduit for noise.The impedance on the non inverted half used for the single ended input shouldn't change.
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  • heiney9
    heiney9 Posts: 25,165
    edited February 2012
    Yes, I have and it was muffled and noisy and low output. Not ideal at all. I was just giving a heads up because typically if the seller has used the balanced inputs the jumpers get misplaced. I am only talking about the cd input. A work around if the jumpers are missing it to use a different input. The input marked CD is the only balanced or unbalanced input, so choosing another input like TUNER would be a work around for single ended use if the jumpers are missing.

    H9
    "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 Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • heiney9
    heiney9 Posts: 25,165
    edited February 2012
    http://www.adcom-usa.com/userguides/gfp-750-ug.pdf

    Refer to page 4, #10 bullet point

    H9
    "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 Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • FTGV
    FTGV Posts: 3,649
    edited February 2012
    Thanks,unfortunately they don't state the reason,be it noise immunity(likely),gain..Since I see the stated input impedances are 47k ohm unbal and 94k ohm bal.indicating 47k across each half(=94k) so impedance shouldn't be an issue without the jumper.


    Note. I'm just curious about this kind of thing not being argumentitive.
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  • heiney9
    heiney9 Posts: 25,165
    edited February 2012
    It is a good question Fred. If I have a chance I'll pull the pins and report back. I admit I only listened once w/o the pins in place, back when I bought it. At the time I had an Adcom GDA700 dac which was balanced so I used the balanced cd inputs for awhile. I don;t know why they need to be in place, they just do.

    If I have time this weekend I'll take a listen with the pins removed.

    H9
    "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 Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • RickTfromAZ
    RickTfromAZ Posts: 122
    edited February 2012
    heiney9 wrote: »
    Does it do it in the Summer when humidity is high? Or just the Winter when you are more likely to get/give a shock. I ground myself this time of year before touching any gear, because it can be badd juju if you don't.

    H9
    I've only had the balanced IC's about a month. I'm sure that it's a winter, low humidity thing.
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  • FTGV
    FTGV Posts: 3,649
    edited February 2012
    heiney9 wrote: »
    If I have a chance I'll pull the pins and report back... I don;t know why they need to be in place, they just do.
    Cool I would be interested in the result.As mentioned I suspect it's a precautionary step to reduce the likelihood of noise pickup through a floating input.
    RickTfromAZ wrote: »
    I've only had the balanced IC's about a month. I'm sure that it's a winter, low humidity thing.
    You get winter in Arizona:question:
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  • audiocr381ve
    audiocr381ve Posts: 2,588
    edited February 2012
    FTGV wrote: »
    Looks like your piecing together a nice system.

    That's literally the first time anyone has said that to me around here. I'm grinning from ear to ear, check out my review that's up already.
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