The Adcom GDA 600 modification thread

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  • davide256davide256 Posts: 50
    edited February 2011
    Trying to remedy "digititus" on violins and aggressive edge on combined female vocalists. The Genki analog out reduces this compared to the Adcom mod output but loses high frequency sheen/air. Toying with buying a Dlink III since it has an upgrade path with Cullen and touts its design as addressing this issue.
  • FTGVFTGV Posts: 3,654
    edited February 2011
    Well I suspect it's a system synergy thing or you might have some high frequency oscillation's.Though this is unlikely if you have the opamps bypassed properly.You might try rolling some different opamps in there and see if you can find one with a softer presention in the treble that would be more to your liking.
  • davide256davide256 Posts: 50
    edited February 2011
    actually I've done the full upgrade in this thread, and have enjoyed since about May last year. But with my speaker upgrade to MG1.7's there is no mercy shown to bad inputs. While experimenting with the Music Streamer II I did get some relief by upsampling to 96khz and as bit depth improved the problem disappeared ( as did imaging). So I'm not entirely certain that the problem is equipment so much as 44.1khz recording limits. Examples of recordings that exhibit this

    Norah Jones - Come Away With Me
    Dixie Chicks - Taking the Long Way
    KT Tunstall - Eye to the Telescope
    Michael Jackson - Thriller
  • davide256davide256 Posts: 50
    edited February 2011
    BTB i did buy a PS Audio Jewel power cable and use with the Adcom, definite improvement in base and percussive transients. So will be buying a few more and adding IEC connectors to my CJ-PV10A, and MC modded Hafler.
  • davide256davide256 Posts: 50
    edited February 2011
    decided based on echidnas comments to buy some better cables... always been a skeptic when it comes to digital cables. Bought some Monster cable M850 digital cables (both RCA and toslink). The toslink was an immediate improvement over the cheaper THX toslink cable I was using into an Oppo DV970, reducing or eliminating sizzle and clarifying snare drum whacks. Comparing the RCA out of the Oppo, it didn't eliminate sizzle as well but power design could easily account for difference.

    As to remaining edge on vocalists, will see what happens later this week as I alter pre and amp to IEC connectors and upgraded power cables all around, including transports.
  • davide256davide256 Posts: 50
    edited March 2011
    echidna, 100uf is a pretty big value, are you sure you don't mean pf?

    At this point I have completely replaced all my cables, using some Analysis Plus Oval One
    and Audioquest Black Mamba II from Audio Advisor.... the old cables were 90% of the glare issue and what edge remains I'm fairly certain is the Hafler amp. What's really surprised me is that I now prefer the Linn Genki analog out to its digital output through the Adcom DAC.
  • george danielgeorge daniel Posts: 11,992
    edited June 2011
    This was a fun mod,,mine is still working well.
    JC approves....he told me so. (F-1 nut)
  • heiney9heiney9 Posts: 24,124
    edited June 2011
    Mine sounds incredible. Thanks again to you and Fred. Still have to install the Burson rectifiers. Probably in the Fall/Winter when I actually have some time.
    "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!
  • Poee7RPoee7R Posts: 903
    edited June 2011
    Same, I havent installed the Bursons yet either. But the dac gets airtime everyday, really dig this little black box now. Think I may even try some Auricaps in it, really liked em in my old preamp.

    Regardless if I find something I like better, Im thinking the Adcom will stay stay forever. Thanks again to Fred and George, I blame ya both. :tongue:


    Dave
    Once again we meet at last.
  • heiney9heiney9 Posts: 24,124
    edited June 2011
    Just be aware the Auricap leads won't fit in the pcb and IIRC, they don't have values available. The REL Multicaps were the only one's I felt comfortable the leads would fit and they were snug.

    Of course you can probably "rig" something up, but to the best of my knowledge only the small Sonicaps or REL would fit as stock as well as having the proper values. If I could have done Auricaps, I would have............best budget coupling cap going, IMO.

    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: 11,992
    edited June 2011
    +1 on the caps,,the Burson's were not too bad,,and yes-- a huge thanks to Fred,for without his guidence/support I would have never been able to finish this project.
    JC approves....he told me so. (F-1 nut)
  • Poee7RPoee7R Posts: 903
    edited June 2011
    Getting the value's right may be a pita. But luckily I thought ahead (for once) when doing this initially and saved all of the clipped leads from the Sonicaps because of the pcb opening size. Not a perfect fix, but could always just go from pcb to lead, then lead to new cap lead, if ya get my drift hah. Had to do this with my Acoustats, try to fit the lead off of a 100uf poly into a pcb hole made for a 100uf electrolytic, not happening.

    I agree with you about the Auricaps, there is just something special that they do, they sound much more natural than others if you would. And the decay... it really is scary good. Notes hang and disappear perfectly, almost too perfect perhaps. But yeah I really dug em in my old custom pre, the Auricaps realy made the difference for me.


    Dave
    Once again we meet at last.
  • heiney9heiney9 Posts: 24,124
    edited June 2011
    I have Auricaps stock in a couple of my tube pieces and really like them. I actually stopped at Parts Express in Ohio on the way back from Ricardo's (we went to Polk Fest last year) and picked up some other Auricaps to install in another tube piece of gear, saved a little on shipping since it's not too far from Ricardo's house.

    Good idea on saving the leads.............now good luck finding the values.

    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!
  • Poee7RPoee7R Posts: 903
    edited June 2011
    Seems you are right. Those value's are unobtainium.

    Looks like it may be time to try something new, if I can find the right size's.


    Dave
    Once again we meet at last.
  • FTGVFTGV Posts: 3,654
    edited June 2011
    Good to see you gents still enjoy the fruits of your labours.
    Poee7R wrote: »

    Regardless if I find something I like better, Im thinking the Adcom will stay stay forever.
    With those ingredients I would expect it to compare very favourably with some of the newer generation DAC's.So unless your starting into the Hi rez download game replacing it with a newer unit might be more of a sideways move than an upgrade.
  • george danielgeorge daniel Posts: 11,992
    edited June 2011
    Poee7R wrote: »
    Seems you are right. Those value's are unobtainium.

    Looks like it may be time to try something new, if I can find the right size's.


    Dave

    Sonicap has a sale going--thats where I got mine from(Sonicaps fit just fine)
    JC approves....he told me so. (F-1 nut)
  • Poee7RPoee7R Posts: 903
    edited June 2011
    Fred no question about it, its staying. Actually planning a move to Australia next year, my wife asked about which electronics Im going to take/ship there, I told her the little black box with the red light on it, aka the Adcom. May ship speaker's also (LSi9's), but looks like electronics arent to hard to come by.

    George I have the Sonicaps in it now, just really dig Auricaps in other components, so thought I would givem a try. Doesnt look like that'll happen though.


    Dave
    Once again we meet at last.
  • FTGVFTGV Posts: 3,654
    edited June 2011
    Poee7R wrote: »
    Actually planning a move to Australia next year, my wife asked about which electronics Im going to take/ship there, I told her the little black box with the red light on it, aka the Adcom.
    Wow Dave moving down under,that will be a big change.I understand it's an amazing place,however I believe their AC is 240 volt.Should be no problem for the Adcom though.Looking at one of the pic's of the power supply I can see there are a pair of jumpers that can easily be desoldered and repositioned to convert it to 230/240 volt operation.
  • Poee7RPoee7R Posts: 903
    edited June 2011
    Yes their voltage is 240. Im glad you brought it up, was going to ask in a pm at some point haha. Thanks


    Dave
    Once again we meet at last.
  • FTGVFTGV Posts: 3,654
    edited July 2011
    Your welcome,if you take a look at the pic's of the power supply Brock posted in post #74 on page 3 you'll see two brown jumpers in the R100 and R102 positions.By removing both of these then adding one to the R101 spot will make it 230/240 ready.You might also want to reduce the fuse amperage to roughly half the value.
  • FTGVFTGV Posts: 3,654
    edited July 2011
    echidna wrote: »
    FTGV and Poee7R I imported my dac from the US last year and converted it to 240v as described....
    A genuine Aussie eh.There are not many if any others from down under on CP AFAIK.You must have really wanted a 600.:smile:
    Other things to note are normal beer (super) is 5% alcohol,
    Thats the same as regular beer in Canada also.That stuff south of the border is more akin to Donkey wizz than beer.:tongue:
  • megasat16megasat16 Posts: 3,534
    edited July 2011
    echidna wrote: »
    most important we drive on the other side of the road.

    Add to that most important list is how you folks greet "Good-die Mite" as in "Gooday Mate" to the tourists on the street. I almost punch the guy and broke his nose first time I was greeted. Joking of course :biggrin:
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
  • Poee7RPoee7R Posts: 903
    edited July 2011
    Thanks echidna, Im trying to prepare for alot. My wife and I were in Brisbane (where she is from) for a month, beautiful place.

    Gonna be a wild ride.


    Dave
    Once again we meet at last.
  • FTGVFTGV Posts: 3,654
    edited July 2011
    megasat16 wrote: »
    Add to that most important list is how you folks greet "Good-die Mite" as in "Gooday Mate" to the tourists on the street. I almost punch the guy and broke his nose first time I was greeted. Joking of course :biggrin:

    Did he have a really big knife and answer to the name Dundee?
  • megasat16megasat16 Posts: 3,534
    edited July 2011
    FTGV wrote: »
    Did he have a really big knife and answer to the name Dundee?

    The guy looked like Chuck Norris. I almost think he is an Aussie version of Chuck. :tongue:
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
  • megasat16megasat16 Posts: 3,534
    edited July 2011
    Poee7R wrote: »
    Thanks echidna, Im trying to prepare for alot. My wife and I were in Brisbane (where she is from) for a month, beautiful place.

    Gonna be a wild ride.


    Dave

    Dave,

    The land of Aussies is a very beautiful place with a very nice Sunset in the evening. Fish are aplenty and they makes excellent wine too. I can only envy you to be moving there. Is that a permanent move or a temp stay?

    Good Luck!
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
  • Poee7RPoee7R Posts: 903
    edited July 2011
    Haha Im not big on fish and I dont really drink, but my wife enjoys both. Its a permanent move, not sure if we'll live in Brisbane the entire time, as I would like to see alot of the country. May end up buying an RV or ute (truck) and camper or something of the sort, and take a long, long drive. My father-in-law did something similiar when he was younger, and the stories he has to tell are awesome. Would love to have the same sort of memories when the time comes to look back.

    Kinda a big roll of the dice. But thats where the fun is, we dont have any kids and sold the business a while ago, gonna play it by ear and see what happens. Have long term goals of living in Europe also, so this is another step in that sense.

    No place is safe. :wink:


    Dave
    Once again we meet at last.
  • megasat16megasat16 Posts: 3,534
    edited July 2011
    Dave,

    I don't know when you are moving (in a couple of months?) to the land down under but here is the video made for the land down under. Nice tunes to go with the funny video.

    http://video.search.yahoo.com/search/video?p=men+at+work+down+under

    James
    Trying out Different Audio Cables is a Religious Affair. You don't discuss it with anyone. :redface::biggrin:
  • annihilatorgannihilatorg Posts: 14
    edited August 2011
    Hi guys, I just picked up one of these DACs today used for a couple bucks. This thread is one of the deciding factors to me dropping the cash for it.

    Upon the first few listens, I do like the sound. I had two previous 'main' analog audio sources... A marantz cd5003 and an maudio audiophile192 pci card in a tiny passive computer case. I'm using the SPDIF output from the audiophile192 to run the DAC. (FLAC on a NAS + foobar2000 + ASIO plugin + maudio spdif out)

    My initial impression is that I like the adcom better than the onboard AKM dac on the audiophile192, which I liked better than the Cirrus Logic set in the marantz.

    But, I can tell that this is a little conjested (much like the sound blaster Xfi before opamp and power cap swaps)

    I'm going to be picking up these BurrBrown ops and the caps. Gotta say that I'm excited to get working on it.
  • FTGVFTGV Posts: 3,654
    edited August 2011
    Hi guys, I just picked up one of these DACs today used for a couple bucks. This thread is one of the deciding factors to me dropping the cash for it.
    Congrats, sounds like you got yourself a good deal on a 600.As for the mods I believe George and the two Dave's think it a worthwhile endevour.
    My initial impression is that I like the adcom better than the onboard AKM dac on the audiophile192, which I liked better than the Cirrus Logic set in the marantz.
    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.
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