The Adcom GDA 600 modification thread

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  • annihilatorgannihilatorg Posts: 14
    edited November 2011
    hey guys, i decided to use the turkey weekend to install the Burson Regulators. That's all done, but I'm having issues getting any readings on my volt meter (and this is not my first time to the rodeo).

    First, concerning resistor and capacitor removal...
    U100: removed R110, bridged R111, bridged C122
    U104: removed R112, bridged r113, bridged C123

    U100 was replaced with the 78XX. This needed to be re-pinned so that ground went to pin 1 (black cable) white +out to pin 2, and red +in to pin 3.

    U104 was replaced with the 79XX and the pinout was the same from stock 1-red-ground 2-in-black, 3-out-white

    For testing, I've got the two circuit boards in a plastic tray so they don't short to each other or to the case. I didn't see any reasons in the documentation why they might need to be directly tied to ground. I figure I'll employ some velcro or something similar for the final mounting, there's plenty of room for them between the PSU board and the DAC board.

    I've plugged it into the wall and powered it on (btw, the series 2 regs have those annoying blue LEDs that everything 'techy' seems to require these days).

    Using my trusty radioshack digital meter, I'm not getting anything for voltages on J101 pin 7 or 8 when connected to ground. I'm using the green cable screw point as my ground (ground from power plug). pins 7 and 8 on J101 are the + and - 15v pins that connect to the main DAC board. I've played a bit with the pots (turned each one a half-turn) but I've not gotten any difference in voltages.

    Is there a better place to try and use for ground or a better place to find the correct output voltages? Seems like diode cr101 and cr109 might give me correct voltages on one side or the other, but I'm only getting miniscule microvolt differences on testing those.

    perplexed. :frown:
  • FTGVFTGV Posts: 3,654
    edited November 2011
    Try using the jumper at R111 or R113 as your ground probe point.
  • annihilatorgannihilatorg Posts: 14
    edited November 2011
    FTGV wrote: »
    Try using the jumper at R111 or R113 as your ground probe point.

    ah ha! yes r111 is giving me magical volts! looking at the schematic i see why. going to play with the pots and report back.

    Thanks again FTGV!

    edit: I'm reading +15.00v on pin7 and -15.00v on pin 8 using R111 and R113 as my ground. Those pots required a large number of turns from 11-ish volts to 15v. Case Re-Assembly commencing.
  • FTGVFTGV Posts: 3,654
    edited November 2011
  • heiney9heiney9 Posts: 24,125
    edited February 2012
    Okay-- components removed and jumpers in place.Since the regulators will not fit side by side unless I bend the pins,,I'll need some help here

    Is this the correct position for the lm 337 in the U 104 slot?(the one on the right.)?

    Yes, back to this. FYI I reloaded all my pics so they show up again in this thread. I had inadvertently moved them to another folder in my Photobucket account. I restored them to the original location so the links are working again.

    A local Polkie Agfrost (Jay) is getting ready to mod his, and I need to get the regulators installed so I bumped this thread ttt.

    George I have a question about photo number 4 aboove. Are the regulators mounted in this photo? Because it looks like they are in the resistor positions. Probably an optical illusion but they look out of place.

    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 Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • SCompRacerSCompRacer Posts: 7,195
    edited February 2012
    Way kewl! I love the DIY challenge of will it work better, or at all, when I am done.:twisted::cheesygrin:

    I got my second shunt PS done for my next project so there is more space available on the bench.
    Make yourself necessary to someone. Ralph Waldo Emerson

    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ & Pro 11+ * Signature Series Sonore Music Server w/Deux PS* Twisted Pear Buffalo III Dual Mono ESS Sabre32 DAC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *

  • george danielgeorge daniel Posts: 11,995
    edited February 2012
    heiney9 wrote: »
    Yes, back to this. FYI I reloaded all my pics so they show up again in this thread. I had inadvertently moved them to another folder in my Photobucket account. I restored them to the original location so the links are working again.

    A local Polkie Agfrost (Jay) is getting ready to mod his, and I need to get the regulators installed so I bumped this thread ttt.

    George I have a question about photo number 4 aboove. Are the regulators mounted in this photo? Because it looks like they are in the resistor positions. Probably an optical illusion but they look out of place.

    H9

    Brock,, if we are talking about the same pic,,they are not mounted,,IIRC one went in U-104(right side) and the other in U-100,,,it's been playing for for about 20 months now.I hope this helps.
    JC approves....he told me so. (F-1 nut)
  • agfrostagfrost Posts: 2,275
    edited February 2012
    Thanks for fixing up your pix, Brock. I was rereading this thread last night and was wondering if you'd yet gotten around to installing the regulators. One of the two needed is now sold out at Parts Connexion, so if I wanted to replace those, I'd have to "get out of the boat" (sorry, George!). Perhaps the newer models might work, but that can wait.

    Rich, I'd consider signing a lease if you throw out a "For Rent" sign on that benchspace. :cool:
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Marantz DV-9500 * Modded Adcom GDA-600 DAC * Rythmik F8
    Micro Seiki DQ-50 * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
  • FTGVFTGV Posts: 3,654
    edited February 2012
    agfrost wrote: »
    . One of the two needed is now sold out at Parts Connexion, so if I wanted to replace those, I'd have to "get out of the boat" (sorry, George!). Perhaps the newer models might work, but that can wait.
    Yes the Burson series two will work(see post#424,425) but will need an alternative way for mounting the PC board since they don't mount like standard 3 pin regs. Another option would be from Belleson that Rich used in his MH.They will fit in the old reg's position.
  • SCompRacerSCompRacer Posts: 7,195
    edited February 2012
    agfrost wrote: »

    Rich, I'd consider signing a lease if you throw out a "For Rent" sign on that benchspace. :cool:

    Mod Space Available! Sign up now! We got FM down there, or cassettes with a pair of Polk 7A's with Peerless. No slumming while working, at all. (Blake has the TT. It was too much of a distraction down there).

    FTGV wrote: »
    Another option would be from Belleson that Rich used in his MH.They will fit in the old reg's position.

    Good suggestion Fred. Of course the all time good deal ain't there like with the close out Bursons. I've got some small sinks if Jay goes that route. Shouldn't be much mA draw/heat with the chip op amps. What, a few mA?
    Make yourself necessary to someone. Ralph Waldo Emerson

    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ & Pro 11+ * Signature Series Sonore Music Server w/Deux PS* Twisted Pear Buffalo III Dual Mono ESS Sabre32 DAC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *

  • FTGVFTGV Posts: 3,654
    edited February 2012
    SCompRacer wrote: »
    Of course the all time good deal ain't there like with the close out Bursons.
    Yeah that deal made it a much more attractive proposition.
    Shouldn't be much mA draw/heat with the chip op amps. What, a few mA?
    Probably only in the 50-60ma range.
  • george danielgeorge daniel Posts: 11,995
    edited May 2012
    Okay-- I promised Mike that we would get his done---let the fun begin.
    Yes-Mike it arrived safely--here we go,,stock pics first.
    JC approves....he told me so. (F-1 nut)
  • sda2mikesda2mike Posts: 3,151
    edited May 2012
    my sweet little dac! they grow up so fast, then we send them away! ha! thanks good dr. george! good idea with the pics! i've been looking forward to this for a long time!


    mike
  • FTGVFTGV Posts: 3,654
    edited May 2012
    sda2mike wrote: »
    my sweet little dac! they grow up so fast, then we send them away!
    No worries the little fella is in good hands .Uncle G will feed him a good diet of solder and have his analog stage all blinged out before sending him home.
  • SCompRacerSCompRacer Posts: 7,195
    edited May 2012
    I think I'll have one here next week to send you George.:cheesygrin:
    Make yourself necessary to someone. Ralph Waldo Emerson

    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ & Pro 11+ * Signature Series Sonore Music Server w/Deux PS* Twisted Pear Buffalo III Dual Mono ESS Sabre32 DAC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *

  • FTGVFTGV Posts: 3,654
    edited May 2012
    SCompRacer wrote: »
    I think I'll have one here next week to send you George.:cheesygrin:
    Dipping our toes into the old school R2R DAC waters are we Rich?l
  • SCompRacerSCompRacer Posts: 7,195
    edited May 2012
    FTGV wrote: »
    Dipping our toes into the old school R2R DAC waters are we Rich?l

    Jay has one (agfrost). He is suppose to bring it over after school and get some experience.:cheesygrin:
    Make yourself necessary to someone. Ralph Waldo Emerson

    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ & Pro 11+ * Signature Series Sonore Music Server w/Deux PS* Twisted Pear Buffalo III Dual Mono ESS Sabre32 DAC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *

  • agfrostagfrost Posts: 2,275
    edited May 2012
    Have you ever been experienced? :afro:
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Marantz DV-9500 * Modded Adcom GDA-600 DAC * Rythmik F8
    Micro Seiki DQ-50 * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
  • annihilatorgannihilatorg Posts: 14
    edited May 2012
    Hello to others who have done this mod. I've been listening to my modded DAC for, I dunno, 500 hours since I did the mod with the voltage regulators. And yes, it still sounds awesome.

    But, has anyone gone back and re-checked their Burson regulators for voltage changes after extended periods / burn-in? I've not had a chance to pop the case back open again, but am thinking about looking at it this weekend. Might be paranoid, but I always think something might be wrong when it has been modded. I'm not hearing anything noticeable, just wondering.

    ps and only slightly unrelated - for computer audio sources, get a linear supply if you can. It makes insane differences in analog, and I'm going to wire up my PC that's hooked up to the adcom this weekend to one as well. Not sold on it making a difference in digital transmission, but it's something to check. I got two acopian VA12H1300 supplies from ebay for a steal and have one hooked to my headphone system.
  • sda2mikesda2mike Posts: 3,151
    edited August 2012
    well the good doctor george told me, my dac is on it's way back to me!!! george didn't just take a handful of parts and slap em in there..nope, he tried different combos of parts...burned them in...listened...tore some out...listened some more...until he was satisfied with the results! i can't wait to hear it this weekend! george is what this club is all about! stand up guy helping others...just for the fun of it!

    thanks george
    mike
  • heiney9heiney9 Posts: 24,125
    edited August 2012
    Do tell us George D, which parts did you swap in and out and what were your impressions.

    Mike, If George did the work you know it's done correctly.

    Details people................we need details!

    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 Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • sda2mikesda2mike Posts: 3,151
    edited August 2012
    i think after several different combos of brands, george settled on sonicaps...with the recommended brown dogs...count on me posting my impressions..;)
  • heiney9heiney9 Posts: 24,125
    edited August 2012
    The only two brands I ever found that supply the exact value caps around the dac chips are Sonicap and Multi-cap the values are odd at .022uF; .0039uF and .0027uF. The PS can use a few different brands, that's why I need details. :cheesygrin:

    I chose the Multi-caps because they were less expensive and seemed to get really good reviews.

    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 Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
  • sda2mikesda2mike Posts: 3,151
    edited August 2012
    i'm sure when george signs on again, he'll update you:cheesygrin:
  • soundfreak1soundfreak1 Posts: 2,829
    edited August 2012
    BTW george this is a thanks from one of my gpod friends, i sent this thread to owr tech amd je did theod on his 600 and they were bpth gobsmacked by the improvement. Enough so that my teck bought a 600 to do for himself. And the parts are in fory 700, cant wait to get it in to be done. So thanks from both pf them!
    Main Rig:
    Krell KAV 250a biamped to mid/highs
    Parasound HCA1500A biamped to lows
    Nakamichi EC100 Active xover
    MIT exp 1 ic's
    Perreaux SA33 class A preamp
    AQ kingcobra ic's
    OPPO 83 CDP
    Lehmann audio black cube SE phono pre, Audioquest phono wire (ITA1/1)
    Denon DP-1200 TT. AToc9ML MC cart.
    Monster HTS 3600 power conditioner
    ADS L1590/2 Biamped
    MIT exps2 speaker cable
  • DrenisDrenis Posts: 2,872
    edited August 2012
    BTW george this is a thanks from one of my gpod friends, i sent this thread to owr tech amd je did theod on his 600 and they were bpth gobsmacked by the improvement. Enough so that my teck bought a 600 to do for himself. And the parts are in fory 700, cant wait to get it in to be done. So thanks from both pf them!

    Drunk post? :lol:
  • SCompRacerSCompRacer Posts: 7,195
    edited August 2012
    agfrost wrote: »
    Have you ever been experienced? :afro:

    You're experienced now, solder-slinger! Post them pics! :cheesygrin:
    Make yourself necessary to someone. Ralph Waldo Emerson

    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ & Pro 11+ * Signature Series Sonore Music Server w/Deux PS* Twisted Pear Buffalo III Dual Mono ESS Sabre32 DAC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *

  • SCompRacerSCompRacer Posts: 7,195
    edited August 2012
    Wait, I have one! I hope your pics turned out better than mine.....:rolleyes::cheesygrin:

    Attachment not found.
    Make yourself necessary to someone. Ralph Waldo Emerson

    Salk SoundScape 8's * Audio Research Reference 3 * Bottlehead Eros Phono * Park's Audio Budgie SUT * Krell KSA-250 * Harmonic Technology Pro 9+ & Pro 11+ * Signature Series Sonore Music Server w/Deux PS* Twisted Pear Buffalo III Dual Mono ESS Sabre32 DAC * Heavy Plinth Lenco L75 Idler Drive * AA MG-1 Linear Air Bearing Arm * AT33PTG/II & Denon 103R * Richard Gray 600S * NHT B-12d subs * GIK Acoustic Treatments * Sennheiser HD650 *

  • agfrostagfrost Posts: 2,275
    edited August 2012
    SCompRacer wrote: »
    Wait, I have one! I hope your pics turned out better than mine.....:rolleyes::cheesygrin:

    That one looks quite artsy, actually.

    Well, after a few(ish) months of foot-dragging I finally made it over to master tradesman SCompRacer's house to start my soldering apprenticeship. I even had most of the parts needed for the mod! I'd been thinking about it for so long I was certain that I had all my caps in hand, but found out at the last moment that I was missing a handful (The 2200uF Nichicon FGs and the 470uF Panny FCs) for the power supply. As such, the full modding will be done in two parts.

    What I did bring to the modding party was a Hakko 808 desoldering device, which has a trigger-actuated pump that removes solder through a hole in the iron's tip. It's a pretty nifty tool, but there were still several holes in the PCBs that weren't easily willing to be cleaned out. Rich has a patient hand, fortunately, and the mod went smoothly if slowly.

    The main difference in our approach compared to the previous documentations (especially those of George and Brock) was how we installed the two "local power supply reservoir" caps for each opamp: Both George and Brock mounted the two 120uF Panny FCs on the underside of the board. Please read and view the description/pictures of Brock's posts 115 & 116 on page 4 of this thread to see how they mounted these caps. I decided to try to do the same task in a different manner, one which Fred (FTGV) suggested would work as well in words/pictures in post 248 of page 9 of this thread. At the time the soldering iron was hot, I was actually working from a months-old recollection of the pictures from that post as the forum disappearing-photo bugaboo was still in effect. The key thing (just as with the other method) is to make sure that the polarity of the two 120uF caps is correct with respect to pin #4 (neg) and pin #8 (pos) of the opamps.

    Here's two shots of the analog board: The first half-completed, the second after completion.

    Halfdoneanalog.jpg

    AnalogComplete.jpg


    So how does it sound? Well, in a word it sounds great. Right off the bench it sounded really, really good and I've had it running for 80+ hours and my rig sounds better than it ever has before. I'm super happy to have done this and I'm looking forward to completing the job with the last few power-supply caps that I now have in hand. If replacing them makes additional audible improvement, well, I guess I be that much more happy!

    Special thanks to all those that have made this possible: Rich for his workshop, experience and steady hand (and for razzing me at every opportunity until I committed to a date to get this done), George and Brock for documenting well both how to do this mod and for making it clear how pleased they were with the results; and finally to Fred, for sharing your knowledge and insight--your generosity is noted and appreciated!

    I'll snap a couple pics of the other board when I get around to completing it--don't hold your breath, school starts this coming week!

    Jay
    Jay
    SDA 2BTL * Musical Fidelity A5cr amp * Marantz DV-9500 * Modded Adcom GDA-600 DAC * Rythmik F8
    Micro Seiki DQ-50 * A hodgepodge of cabling * Belkin PF60
    Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0
  • soundfreak1soundfreak1 Posts: 2,829
    edited August 2012
    No drunk post (regretablely) using phone big thumbs small keys and sometimes to lazy to edit typo's. LOL sorry bout that chief. Will be less lazy in the future!
    Main Rig:
    Krell KAV 250a biamped to mid/highs
    Parasound HCA1500A biamped to lows
    Nakamichi EC100 Active xover
    MIT exp 1 ic's
    Perreaux SA33 class A preamp
    AQ kingcobra ic's
    OPPO 83 CDP
    Lehmann audio black cube SE phono pre, Audioquest phono wire (ITA1/1)
    Denon DP-1200 TT. AToc9ML MC cart.
    Monster HTS 3600 power conditioner
    ADS L1590/2 Biamped
    MIT exps2 speaker cable
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