The Adcom GDA 600 modification thread

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  • annihilatorgannihilatorg Posts: 14
    edited September 2011
    FTGV wrote: »
    I personally woundn't place the shortcomings of the Maudio entirely at the feet of the AKM chip since it's working in a less than ideal environment.It's basic(read noisy)on board voltage regulators are being fed from an RFI polluted switch mode supply.The power supply and analog stages following the dac chip have a large influence aswell.
    I'm currently dabblingly with an AKM AK4396 based dac that sounds quite good mated to a hi perfomance Class A output buffer and reasonably clean power supply.It's not quite the equal of my Cirrus based unit but it has a superior power supply scheme and it better manages the incoming SPDIF data.
    Fair enough. I suppose I should say I prefer using the adcom as my audio source over the Maudio card or the Marantz cd5003. I've dabbled with the idea of getting a linear power supply for the PC, a 9amp 12v linear supply can be found for only $330. :rolleyes:

    Oh, and I got my bdogs today. Too bad my ex-boss and go-to for all things solder related is out of town until the 19th. I guess I will have time to decide on which caps to get. Too bad parts connection doesn't have the +15v burson regulators anymore (at least, not the $20 versions).
  • annihilatorgannihilatorg Posts: 14
    edited September 2011
    2 questions guys:

    1) since I have the RELcaps (c542 and c545) coming in, will I have room to put the op-amp reserve caps along with the bypass caps like FTGV posted earlier in the thread (post 248)? or will I probably have to directly solder them to the opamp pins 4 and 8?

    2) parts connexion has both burson and dexa regulators on sale for the next few days (30% off i think the ad said). The burson regs are series 2 and look a bit more complex than the original shunt regulators. Would it still be this same method?
    remove: R112 and R110
    remove: c122, c123
    remove and jump: r113, r111
    (assuming i am reading the directions from post 166 and schematic correctly, jumping c122 and c123 would be unnecessary if r113 and r111 were jumped)

    ok, 3 questions...
    3) Dexa vs Burson regulator pro/cons... but I'm not going to fret over it if the burson's worked well in the past.
  • FTGVFTGV Posts: 3,654
    edited September 2011
    1) since I have the RELcaps (c542 and c545) coming in, will I have room to put the op-amp reserve caps along with the bypass caps like FTGV posted earlier in the thread (post 248)? or will I probably have to directly solder them to the opamp pins 4 and 8?
    If you parallel the bypass and larger decoupling cap as shown in the pic in post #248 you would then simply remove the stock caps and install the paralleled assemblies in thier place.Ofcourse care is needed when installing so as to observe proper polarity for the electrolytic caps.
    2) parts connexion has both burson and dexa regulators on sale for the next few days (30% off i think the ad said). The burson regs are series 2 and look a bit more complex than the original shunt regulators. Would it still be this same method?
    remove: R112 and R110
    remove: c122, c123
    remove and jump: r113, r111
    (assuming i am reading the directions from post 166 and schematic correctly, jumping c122 and c123 would be unnecessary if r113 and r111 were jumped)
    I suspect it will be identical but when I'm able to dig up the schematic I can give you a more definative answer.You might need to get creative with the mounting of the series 2 version of the regs. since they don't have pin's that mount directly in the board.
  • FTGVFTGV Posts: 3,654
    edited September 2011
    . The burson regs are series 2 and look a bit more complex than the original shunt regulators. Would it still be this same method?
    remove: R112 and R110
    remove: c122, c123
    remove and jump: r113, r111
    (assuming i am reading the directions from post 166 and schematic correctly, jumping c122 and c123 would be unnecessary if r113 and r111 were jumped)
    I found the schem. and can confirm the procedure is the same with Burson's series 2 reg's.
  • annihilatorgannihilatorg Posts: 14
    edited September 2011
    Thanks FTGV, I ordered the series 2 regs, should be about two weeks.
    In the meantime I now have:
    Power Supply:
    6 nichicon 2200uf/35v FG caps
    5 panasonic 120uf/25v FC caps
    2 nichicon 22uf/50v KZ muse caps (which will be wasted when I get the new regs)
    2 panasonic 470uf/35v FC caps

    Analog:
    2 dual-opa627 browndog adapters
    2 .022uf/600v multicap ppmfx
    2 .0039uf/600v multicap ppmfx
    2 .0027uf/600v multicap ppmfx
    4 120uf/25v panasonic FC
    4 .1uf/50v panasonic film
    2 680pf/600v RELCAP

    It's odd that with all the mods (caps, regs, opamps), I'm spending nearly twice what I spent on the DAC itself. I've got the schematics marked up and directions written up for the installer. Should be a musical weekend, eh?
  • heiney9heiney9 Posts: 24,125
    edited September 2011
    It's worth it. I love my GDA600 since I modded it. Using the same components as you. Those Multicaps take longer than normal to break in so keep that in mind. At first the unit was pretty forward, but it has mellowed out nicely. I still have to install my Burson regulators. Hopefully soon now that Fall/Winter is arriving.

    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 September 2011
    any highly-skilled polkies out there willing to mod the 600 for those of us who would be over our heads???
  • george danielgeorge daniel Posts: 11,994
    edited September 2011
    just how far do you want to take it?(the mod)
    JC approves....he told me so. (F-1 nut)
  • annihilatorgannihilatorg Posts: 14
    edited September 2011
    Quick disassembly note...
    1 - top of the unit: remove 3 small Allen wrench screws
    2 - Bottom of the unit: remove the 2 left and 2 right side black screws
    3 - Back of unit: remove one black screw that holds the cover in place
    4 - Slide off the top cover (dunno if anyone else had this, but mine had two black slabs of some type of rubber installed on the top of the cover, it looked non-oem and made removal incredibly difficult)
    5 - front of unit: pull off the 2 black knobs
    6 - bottom of unit: remove 4 screws holding faceplate
    6.5 - remove leads from front signal lock LED on audio board. Remember where those leads went!
    7 - remove faceplate
    8 - back of unit: remove 8 (i think) black screws that stabilize the RCA and such jacks in place.
    9 - pop off the power supply cable between the boards
    10 - pop the AC cable connector off of the power supply board
    11 - remove screws for power supply
    12 - remove power supply
    13 - remove screws for audio board
    14 - remove audio board making sure to clear the 'push' clip on the XLR connector from the hole.
  • sda2mikesda2mike Posts: 3,151
    edited September 2011
    far enough that i would reccomend it to others...i wanna be blown away;)
  • annihilatorgannihilatorg Posts: 14
    edited September 2011
    Another note: when getting the caps for c122 and c123... get the muse ES (bi-polar), not the muse KZ (polar) like I did. Whoops!

    But these are removed anyway if you pickup different +/- 15v regulators.
  • heiney9heiney9 Posts: 24,125
    edited September 2011
    Hey Fred if you are out there which one of these will work in place of the OPA627's I put in? Since I added sockets will the DIP models plug-n-play without any other modifications? I bought the brown dog's from Cimmaron and IIRC each channel has (2) OPA 627's specially monuted like these http://cimarrontechnology.com/single-to-dualop-ampadapterpn020302.aspx

    so I'm not sure if Burson has an eqivalent.

    http://www.partsconnexion.com/opamp_burson.html

    FYI, If these fit I'll have a pair of Burr Brown OPA627's for sale.

    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!
  • george danielgeorge daniel Posts: 11,994
    edited September 2011
    Well,if there is any interest,,I can bring mine to PF,if it's gonna get some airtime.
    JC approves....he told me so. (F-1 nut)
  • FTGVFTGV Posts: 3,654
    edited September 2011
    Since you have the sockets you'll want the dual's with DIP header.One minor mod is required.
  • annihilatorgannihilatorg Posts: 14
    edited September 2011
    It's all done, powered up and playing some music already. Guess that means my installer didn't blow it up.

    so, for the burn in I have:
    44.1/16 FLAC files on nas -> foobar on audio pc with asio plugin-> ASIO SPDIF output from audiophile 192 -> modded adcom gda-600 -> pro-ject headbox II -> sennheiser hd595
    Not exactly your super tube amp setup with high silver content cables, but for this purpose it should serve me well over the weekend.

    I can see what everyone was saying about the directness of the audio. Elton John's Your Song was amazingly clear, but perhaps over detailed. Just need to let it play for a while I guess, but it's already a much cleaner and open sounding dac.
  • FTGVFTGV Posts: 3,654
    edited October 2011
    Another consideration Brock,if you install the Burson's you will need to add some heatsinks to those LM317/337 regulators because the Burson's require a higher current draw from them so they will get hot.Or better yet get those Burson regulators in there.

    Also since they sit up rather high I would double check that you will have enough clearance under the top cover with them installed.
  • heiney9heiney9 Posts: 24,125
    edited October 2011
    FTGV wrote: »
    Another consideration Brock,if you install the Burson's you will need to add some heatsinks to those LM317/337 regulators because they require a higher current draw from them so they will get hot.Or better yet get those Burson regulators in there.

    Also since they sit up rather high I would double check that you will have enough clearance under the top cover with them installed.

    You read my mind Fred, I was going to ask you about the regulators because Rich said his get much hotter now that he runs those Burson Op-amps. Also I was going to measure the height because again Rich said they are quite tall and top heavy. Thanks again. I'm still contemplating whether the extra $$$ is worth it. I suppose if I could sell the dual BB OPA627 modules to help fund the Burson's it might be worth it. I'll wait and see if they run a sale on the Burson Op-amps in the next couple months. I'm in no hurry.

    Do you have another source for Burson Op-amps? Those in your DAC look sweet, IIRC, you made those yourself?

    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!
  • FTGVFTGV Posts: 3,654
    edited October 2011
    The OPA627's are very good so it's hard to predicted the level of improvement the Burson's would afford.I'm not aware of any other sources for them,the ones I'm using were pulled from another piece of equipment that was otherwise non functional.
  • annihilatorgannihilatorg Posts: 14
    edited October 2011
    Wanted to say thanks again for posting this modification guide. After nearly 72 hours of burn-in, this thing is getting smooth. Listening to Dire Straits - Brothers in Arms, Peter Gabriel - So, Vienna Teng - Inland Territory, Allison Krauss with Union Station - Paper Airplanes... Incredible.

    I want to hear it compared to something like a $1000 standalone player (like a marantz sa8004/3). But I must say that I do like the Burr-Brown sound. Laid back? Dark? dunno... I don't speak audiophile. But saxophones and harps seem pretty hard to recreate digitally and these do a damn good job to my ear.
  • FTGVFTGV Posts: 3,654
    edited October 2011
    Congrats,and enjoy.
    Did you get the Burson reg's in also?
  • Joe08867Joe08867 Posts: 3,935
    edited October 2011
    reported^^^^^^
    WOW!

    That's like working your way through Katie Perry in order to get to Rosie O'Donnell.
  • SCompRacerSCompRacer Posts: 7,190
    edited October 2011
    heiney9 wrote: »
    .....Rich said his get much hotter now that he runs those Burson Op-amps....H9

    Oh yeah, the Burson HD's pull 19mA each and I have three, so it was like a 400% increase in power draw compared to the OEM op amp chips. My main power regulator sinks are at 133F/56C now. I never measured them before the mod, but I do know from poking around in there they never got this warm. Still looking for sinks that will fit, or ones I could cut down. I've never seen any of the big name modders install larger sinks to address that increased heat with my 25.3 DAC either. Basically, they just use physically larger power supply filter caps.
    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 October 2011
    Whats the height and width of the stock heatsinks Rich? Wakefield make something similar in lengths up to 2.5" http://ca.mouser.com/ProductDetail/Wakefield/677-20ABP/?qs=wT7LY0lnAe2M82a53sTbdw%3D%3D
  • SCompRacerSCompRacer Posts: 7,190
    edited October 2011
    Hey George, I don't think you will mind the deflection since it pertains to something that could apply.

    Fred, they are 16mm x 40mm (5/8" x 1 & 9/16") with 4mm between them. I can go up to 65mm (2.5") high. I can go 20mm (3/4") to either side. Probably have to do some surgery on larger sinks, cutting them at the edges where they meet. A little file job on the bottom of the wider sinks would clearance them off the board traces.

    The MUR860 diodes I plan to install would block the left sink, unless I bend the leads favoring the front of unit.Attachment not found.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 *

  • davide256davide256 Posts: 50
    edited October 2011
    Guys a question. I've done some playing around with the Nichicon Fine Gold caps in some of my other gear. On the Hafler DH-200
    PA-3D board and on the boards for the Oppo-Dv970HD I replaced all standard bipolar caps with Nichicon Fine Gold/Muse. In both cases what I found was that was a mistake in the power vs signal section. In the audio path the Fine Golds gave a truer harmonic spread for overtones. But in the power section the Fine Golds compressed dynamic range... ie the stock power supply side caps had better burst behavior. Now the GDA-600 PSU doesn't seem to have that issue, dynamics/transients are excellent with Nichicon fine gold in the PSU. Is that because of the Burson regulators?
  • SCompRacerSCompRacer Posts: 7,190
    edited October 2011
    I don't get why the FG's would work in good one power application and not the other. I'm sure Fred would know. My DAC (Music Hall 25.3) was supplied with Nichicon FG's as power supply filter caps in four locations and no problems with dynamics. Burson does use Elna caps in their clock and has recomended Elna caps be used as HD op amp power supply caps. Elna Silmic II's to be specific. I was going to install six Elna's until Fred pointed out that the Panasonic FC's already in place are not shabby at all. Thanks for the help Fred!
    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 October 2011
    SCompRacer wrote: »
    I don't get why the FG's would work in good one power application and not the other.
    Nor do I assuming the values are not undersized.
  • annihilatorgannihilatorg Posts: 14
    edited October 2011
    FTGV wrote: »
    Congrats,and enjoy.
    Did you get the Burson reg's in also?
    They are sitting next to my computer right now... not in the device. I wanted to let it burn-in and see how it changes when the regs are installed. I am a little concerned that my DAC may have a better power profile than my amp with these mods (marantz pm5003). I'm not sure if it will make as big a change. Guess I need to finally get that pm-11s1 from my friend.
  • starkillerstarkiller Posts: 2,647
    edited October 2011
    Did I miss the answer to the question about having a Polkie do the mods for those of us who can't even use a glue gun?:mrgreen:
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  • davide256davide256 Posts: 50
    edited October 2011
    partsconnexion is selling the old Burson regulators at $20/$25.

    http://www.partsconnexion.com/regulator_burson.html
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