Portable shop/test Amp

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xschop
xschop Posts: 4,702
edited March 2022 in DIY, Mods & Tweaks
Nothing like a smoked amp to get a project motivated....

My tech-repaired Onkyo A8190 burned a resistor or something in the same amp board as before, so I'm retiring that one from shop duty.

Building this all-walnut slide box for the shop as it is powerful enough with a 36V, 5Amp DC power block....

Still haven't decided what size volume knob to attach,

Here's some billet for you F1....

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Don't take experimental gene therapies from known eugenicists.

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  • F1nut
    F1nut Posts: 49,802
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    Billet...good. Green speaker cable...bad.
    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

  • xschop
    xschop Posts: 4,702
    edited March 2022
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    Must be an optical illusion. It's 14g OFC copper and not made in Wuhan. I did burn a couple sheaths with the soldering iron.

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    Don't take experimental gene therapies from known eugenicists.
  • F1nut
    F1nut Posts: 49,802
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    Damn if it doesn't look oxidized in the first pic.
    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

  • xschop
    xschop Posts: 4,702
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    Wouldn"t doubt it as wifey was using workbench to spray teal green on photo frames while amp board was out on bench.
    I'm going to have to get crafty and find a flexible tube to connect knob to volume pot shaft as it is soldered off kilter from the MIC factory.
    Don't take experimental gene therapies from known eugenicists.
  • F1nut
    F1nut Posts: 49,802
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    This might be what you need.
    https://usa.banggood.com/Machifit-4-or-6-or-8mm-Shaft-Coupler-Coupling-Nylon-Plastic-Motor-Encoder-CouplerCNC-Parts-p-1457567.html

    That was one quick example. There are other sites that sell similar. Avoid the metal ones as they do not have as much flexibility.
    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

  • mhardy6647
    mhardy6647 Posts: 33,046
    edited March 2022
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    The chemistry of acid catalyzed oxidation of copper is the same in China and in Deutschland.
    Heck, even in outer space!

    B)
  • xschop
    xschop Posts: 4,702
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    I'll trust the Cu purity of the Deutschlanders over the Cu chimeras from Wuhan. The intramolecular galvanic activity of the impure Cu is MUCH higher when electrons start flowing.
    Don't take experimental gene therapies from known eugenicists.
  • skrol
    skrol Posts: 3,339
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    Just adds a little coloration to the sound.

    I was wondering if that neat little box needs some ventilation? Seeing the fan and heat sink, it must generate some heat but it has no where for air to flow once you slide the lid on.
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • xschop
    xschop Posts: 4,702
    edited March 2022
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    I got knob mounted by using the outer sheath from a coaxial cable and a spline wood dowel. Fits nice and snug and flexes just right.

    Well, interesting note is I ran this board for over an hour or more with knob volume half way, and the fan never kicked on (this was not mounted in walnut box last weekend). It was plenty loud and clear on the shop speakers to overcome any machinery in background. The cooling fins/radiator were very warm to the touch but not burning hot. That was with 36v 5A power supply that I may make standoffs to mount inside box as it fits with lid closed and 1/2" speration from fan/radiator. (Will this introduce noise into amp?) With either power supply hooked up separately, I get almost dead silence at tweeter-ear proximity.

    Today with 24V 3A laptop brick at knob half volume, does not have the same bottom end bass grunt, but also doesn't even barely warm up....

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    Also to note, I've been playing FLAC files on my LG G7 phone that has a (quad-DAC?) and I cannot tell sound quality difference between it or the Onkyo CD player that I have at home matched to the rebuilt Onkyo A8017. Even the 320KBps thru the G7 sounds excellent either on Onkyo amp or this D-class amp.




    Don't take experimental gene therapies from known eugenicists.
  • xschop
    xschop Posts: 4,702
    edited March 2022
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    I added some thermal paste, because factory shipped both these 7498e amps without any on their chips. The fins actually are warming up now much quicker. Just been playing the snot out of this on the 5B's and it doesn't sound half bad. Will take this contraption back to the shop speakers however.

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    Cleaned up the drilled spots for the power and signal cords...


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    Post edited by xschop on
    Don't take experimental gene therapies from known eugenicists.