The Adcom GDA 600 modification thread

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  • heiney9heiney9 Posts: 24,125
    edited June 2010
    I finally got my regs today. Not sure, but it may be awhile before I install them.
    "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 June 2010
    davide256 wrote: »
    Would it be a reasonable trouble shooting step to remove the reg at u100 and see if i can then adjust to a -15 voltage?
    No,they are independant of each other so adjusting one will have no affect on the other.
    Also checked intersection of CR107, CR105, -7v to ground, would have thought it should be 0.
    You should get + 5 V across CR105 and -5v across CR107,the intersection between them should be 0v
    (ground).
  • FTGVFTGV Posts: 3,654
    edited June 2010
    davide256 wrote: »
    Also note that when I first started adjusting the voltage was -24
    I assume you mean U104 ,at what point were you taking the measuement from?
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    FTGV wrote: »
    Yeah it's a head scratcher,the voltages on the stock reg's would have to be correct as long as the right resistors were installed.


    Is yours still singing?

    Is it-- yeah man.;):D
    JC approves....he told me so. (F-1 nut)
  • davide256davide256 Posts: 50
    edited June 2010
    FTGV wrote: »
    Yeah it's a head scratcher,the voltages on the stock reg's would have to be correct as long as the right resistors were installed.


    Is yours still singing?

    Ok, its been a bit of a pain but I finally figured out the Burson reg replacing the LM317 is bad. Went to radioshack, bought a stock 317 and now my voltages are correct and the aggressive quality is gone. This has temporarily forced me into a right/left A/B comparison between stock reg and the Burson reg. The burson reg definitely passes more high frequency information but with less distortion... makes the stock reg sounds like its shy cousin. Will be ordering another burson reg tonite, may just order some higher quality resistors for the outputs while I'm at it (R530, R531)
  • FTGVFTGV Posts: 3,654
    edited June 2010
    davide256 wrote: »
    Ok, its been a bit of a pain but I finally figured out the Burson reg replacing the LM317 is bad.
    I would hope PC would repalce it free of charge.
    Went to radioshack, bought a stock 317
    I suggest that anyone doing the mod keep the old parts just in case.
    This has temporarily forced me into a right/left A/B comparison between stock reg and the Burson reg.
    :confused:There is no left and right,both regs feed the opamps of each channel.
  • davide256davide256 Posts: 50
    edited June 2010
    FTGV wrote: »
    I would hope PC would repalce it free of charge.I suggest that anyone doing the mod keep the old parts just in case.:confused:There is no left and right,both regs feed the opamps of each channel.

    hehe, now i do feel dumb ( and worried that Ive found yet another totally unrelated problem :( ) Time to flip cables and see whether the difference
    stays with the speaker or follows the signal.

    BTW I also put in a lower capacitor value at C120, as FTGV said it didn't change anything with the signal but it did eliminate the audible transformer hum.
  • davide256davide256 Posts: 50
    edited June 2010
    ok, looks like the left tweeter on my Maggie 1B's is degrading as the treble difference stays left with speaker cables reversed. Keeping my fingers crossed the 1.7's show soon its been 3 months waiting for delivery. Kind of cool in a way, with the stock DAC or Genki output the treble transients weren't challenging the speakers enough to reveal the weakness. FGTV sent me a question, heres the back serial number, watch out for quality control issues if your serial number is close to mine.
  • FTGVFTGV Posts: 3,654
    edited June 2010
    davide256 wrote: »
    ok, looks like the left tweeter on my Maggie 1B's is degrading as the treble difference stays left with speaker cables reversed. Keeping my fingers crossed the 1.7's show soon its been 3 months waiting for delivery. Kind of cool in a way, with the stock DAC or Genki output the treble transients weren't challenging the speakers enough to reveal the weakness. FGTV sent me a question, heres the back serial number, watch out for quality control issues if your serial number is close to mine.

    Thanks. With all the issues you have been having I was just wondering:) Maybe yours was a friday build ?


    You have a pair of 1.7 's on order.Nice.
  • sm88sm88 Posts: 353
    edited June 2010
    Might be getting a 600 locally for cheap, so I'll be attempting this. Any chance for a "minimalist" version of the upgrades? Such as just the op amps and perhaps some but not all of the capacitors? I mean to leave out any change that does not make an improvement for the cost, unless it is really all worth it
    Current System:
    Paradigm Signature S2 v2
    Conrad Johnson MF2500
    Wyred4Sound DAC2
    Audioquest Black Mamba II


    For Sale:
    3x Wilson Cub's
    Conrad Johnson MF2500
  • heiney9heiney9 Posts: 24,125
    edited June 2010
    You could just do the power supply caps and the Op-amps. Use the sockets for the Op-amps it make life a whole lot easier. The rest of the stuff isn't hard just time consuming and you need a little bit of skill and few proper tools. The Op-amps involve the most work because of the reserve caps recommended and really needed. The rest is just removing/replacing some caps.

    The largest cost by far are the Op-amps. The caps are fairly cheap if you don;t have to buy a minimum amount. Just be careful if you stray to far from the cap model numbers mentioned because space will be an issue so if make 100% sure they will fit, both in the physical space and the size of the leads. The holes in the pcb are very small and really can't be enlarged.
    "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 June 2010
    sm88 wrote: »
    Might be getting a 600 locally for cheap, so I'll be attempting this. Any chance for a "minimalist" version of the upgrades? Such as just the op amps and perhaps some but not all of the capacitors? I mean to leave out any change that does not make an improvement for the cost, unless it is really all worth it
    Yes IMO upgrading just the opamps would provide the biggest sonic gains.
  • sm88sm88 Posts: 353
    edited June 2010
    I almost hope this doesn't turn out awesome so I don't regret the AVM 20 I bought a few weeks ago! I'll let everyone know my experiences with the mod, already have the tools so unless it is a pain to desolder shouldn't take too much effort
    Current System:
    Paradigm Signature S2 v2
    Conrad Johnson MF2500
    Wyred4Sound DAC2
    Audioquest Black Mamba II


    For Sale:
    3x Wilson Cub's
    Conrad Johnson MF2500
  • FTGVFTGV Posts: 3,654
    edited June 2010
    sm88 wrote: »
    I almost hope this doesn't turn out awesome so I don't regret the AVM 20 I bought a few weeks ago! I'll let everyone know my experiences with the mod, already have the tools so unless it is a pain to desolder shouldn't take too much effort
    Have fun and if you have any questions ask away.
  • heiney9heiney9 Posts: 24,125
    edited June 2010
    sm88 wrote: »
    I almost hope this doesn't turn out awesome so I don't regret the AVM 20 I bought a few weeks ago! I'll let everyone know my experiences with the mod, already have the tools so unless it is a pain to desolder shouldn't take too much effort

    Ha....Ha you are in for a treat if you do the full mod (sans the regulators). They are a PITA to desolder, not too difficult, just time consuming to get every tiny bit of solder out of the holes otherwise the new parts won't fit :p.
    "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 June 2010
    This looks tempting,the question is are they counterfits.As they say if it sounds to good to be true then... http://cgi.ebay.ca/2-pcs-Dual-BB-OPA627-SOIC-DIP-Adaptor-/200474962780?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2ead3d2b5c
  • FTGVFTGV Posts: 3,654
    edited June 2010
    FTGV wrote: »
    This looks tempting,the question is are they counterfits.As they say if it sounds to good to be true then... http://cgi.ebay.ca/2-pcs-Dual-BB-OPA627-SOIC-DIP-Adaptor-/200474962780?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2ead3d2b5c


    OK didn't see that they are actually used parts.
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    heiney9 wrote: »
    Ha....Ha you are in for a treat if you do the full mod (sans the regulators). They are a PITA to desolder, not too difficult, just time consuming to get every tiny bit of solder out of the holes otherwise the new parts won't fit :p.

    A desoldering tool with the suction bulb is a necessity.
    JC approves....he told me so. (F-1 nut)
  • sm88sm88 Posts: 353
    edited June 2010
    FTGV wrote: »
    OK didn't see that they are actually used parts.

    Would these be worth trying, by chance? So long as they are tested to be working i'm not against spending $25 instead of $50, isn't like they'll be in worse condition than the old DAC itself.

    Would be pretty great to get all this together for less than $150, going to hinge on the sale of my Anthem I suppose
    Current System:
    Paradigm Signature S2 v2
    Conrad Johnson MF2500
    Wyred4Sound DAC2
    Audioquest Black Mamba II


    For Sale:
    3x Wilson Cub's
    Conrad Johnson MF2500
  • dacboydacboy Posts: 23
    edited June 2010
    I was looking at this seller a few weeks ago. Seems legit as they seem to have good feedback from past buyers, and sells a lot of audio related parts, are they real OPA627's...? Perhaps contact some of the past buyers.

    http://cgi.ebay.com/Two-2x-Mono-Dual-OPAMP-2x-OPA627-NE5532-OPA2604-/300433407893?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item45f339ff95
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    I was hesitant to purchase from e-bay--I got mine here



    http://cimarrontechnology.com/pre-mountedcomponents.aspx
    JC approves....he told me so. (F-1 nut)
  • FTGVFTGV Posts: 3,654
    edited June 2010
    sm88 wrote: »
    Would these be worth trying, by chance? So long as they are tested to be working
    The price is tempting,the SOIC-DIP adators alone would probably be worth it but they don't say how they test them.Also they have had atleast three heat cycles of solder-desoldering.
    'm not against spending $25 instead of $50,
    The Brown Dogs are $50ea and you'll need two.George (and others) have had excellent results with the OPA627's which are premium devices but there are other less expensive good performing alternatives like the LM4562.They may not give you quite the same level of improvements but should IMO be an upgrade vs the stock opamps.
  • FTGVFTGV Posts: 3,654
    edited June 2010
    A desoldering tool with the suction bulb is a necessity.
    +1 I find I get the best results using a good solder pump.
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    Never get out of the boat.:cool:
    JC approves....he told me so. (F-1 nut)
  • FTGVFTGV Posts: 3,654
    edited June 2010
    dacboy wrote: »
    I was looking at this seller a few weeks ago. Seems legit as they seem to have good feedback from past buyers, and sells a lot of audio related parts, are they real OPA627's...? Perhaps contact some of the past buyers.

    http://cgi.ebay.com/Two-2x-Mono-Dual-OPAMP-2x-OPA627-NE5532-OPA2604-/300433407893?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item45f339ff95

    Hard to say if they are legit 627's and he doesn't specify if they are used but at $25 per pair might be worth a try.You could always reuse the adaptors.
  • FTGVFTGV Posts: 3,654
    edited June 2010
    Never get out of the boat.:cool:
    Well going with the Brown Dogs does eliminate the unknown.;)I have a fair amount of experience with the LM4562($6ea) so feel fairly confident in recommending it if he can't swing the $100 for the 627's.
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    FTGV wrote: »
    Well going with the Brown Dogs does eliminate the unknown.;)I have a fair amount of experience with the LM4562($6ea) so feel fairly confident in recommending it if he can't swing the $100 for the 627's.

    he,he,Now hear this,,,, as always,,I defer to you. Guys,,Fred walked me thru this entire process of modding mine,,so my response to something unfamilar to me is gonna be,,NGOOTB,, but in all seriousness,,listen and obey what Fred says,,,cause "he knows".That is all.:)
    JC approves....he told me so. (F-1 nut)
  • sm88sm88 Posts: 353
    edited June 2010
    FTGV wrote: »
    Well going with the Brown Dogs does eliminate the unknown.;)I have a fair amount of experience with the LM4562($6ea) so feel fairly confident in recommending it if he can't swing the $100 for the 627's.

    I thought the link that George provided was $50 for a pair of them, so it would actually be two of those sets?
    Current System:
    Paradigm Signature S2 v2
    Conrad Johnson MF2500
    Wyred4Sound DAC2
    Audioquest Black Mamba II


    For Sale:
    3x Wilson Cub's
    Conrad Johnson MF2500
  • george danielgeorge daniel Posts: 11,994
    edited June 2010
    sm88 wrote: »
    I thought the link that George provided was $50 for a pair of them, so it would actually be two of those sets?

    Yes 49.00 x 2
    JC approves....he told me so. (F-1 nut)
  • heiney9heiney9 Posts: 24,125
    edited June 2010
    So George how does it sound with the new regs?
    "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!
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