SDA compliant amps / recievers

BacchusBacchus Posts: 20
edited September 2013 in Vintage Speakers
as most here already know polk SDA speakers require a "common ground" amp. They say that MOST are common ground amps but some how I just seem to know how to pick them. Seems to me this site needs a data base of common ground and non common ground amps and receivers to make this a bit less painfull for those with newly aquired SDA speakers...

please cut copy and paste the running list and add to it. please don't post until you are sure.



non - common ground amps - don't use with your SDA's

1. Sansui B-2101 power amp
2. Sansui au-g99x integrated amp
3. adcom 7500 5ch power amp


Common Ground amps -- YAY !!! - go for it

1. Adcom gfa 555
Post edited by Bacchus on

Comments

  • boston1450boston1450 Posts: 5,927
    edited September 2013
    You can take a peek around and see other forum members signature which also may give you idea's what they are using. There may be archived threads also. The internet is a good tool GLWYS
    Randy in Maine
    CRS+ TL'd 198 tweets-RTA15 TL'd 198 tweets
    --All TL upgrades by WMG--
    Cs1000p-Yamaha-Parasound
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  • drumminmandrumminman Posts: 3,354
    edited September 2013
    Most amps are common ground these days. The safest thing to do is to contact the manufacturer of the amp you're considering and ask.

    An alternative is to measure between the negative speaker terminals with a digital VOM. You can do a search to learn how.
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
  • zingozingo Audiophile Posts: 11,610
    edited September 2013
    drumminman wrote: »
    An alternative is to measure between the negative speaker terminals with a digital VOM. You can do a search to learn how.

    Works every time.
  • SchurkeySchurkey Posts: 1,764
    edited September 2013
    The early versions of the Carver M1.0 had one channel that was inverted. The polarity was made right at the output by swapping the red + and black - caps for the speaker wire connections. Inverting one channel was a trick to get more power from the power supply on heavy bass tracks. Bass is usually recorded monophonically, even on stereo recordings. With one channel inverted, a bass transient pulled power from both the + and the - power supply capacitors equally. THESE AMPS CANNOT BE MADE COMMON-GROUND.

    Later versions of the M1.0 had both channels in phase. These M1.0s are common ground UNLESS THEY'VE BEEN BRIDGED TO MONO.

    They can be identified by the order of the red and black knobs at the output terminals. Looking at the rear panel, if the output terminals are
    Black Red Black Red the amp is an early, inverting, non-SDA-compatible unit.
    Red Black Black Red the amp is a later, non-inverting, SDA-compatible unit.

    http://thecarversite.com/yetanotherforum/default.aspx?g=posts&t=3876 especially post #6
  • drumminmandrumminman Posts: 3,354
    edited September 2013
    Schurkey wrote: »
    The early versions of the Carver M1.0 had one channel that was inverted. The polarity was made right at the output by swapping the red + and black - caps for the speaker wire connections. Inverting one channel was a trick to get more power from the power supply on heavy bass tracks. Bass is usually recorded monophonically, even on stereo recordings. With one channel inverted, a bass transient pulled power from both the + and the - power supply capacitors equally. THESE AMPS CANNOT BE MADE COMMON-GROUND.

    Later versions of the M1.0 had both channels in phase. These M1.0s are common ground UNLESS THEY'VE BEEN BRIDGED TO MONO.

    They can be identified by the order of the red and black knobs at the output terminals. Looking at the rear panel, if the output terminals are
    Black Red Black Red the amp is an early, inverting, non-SDA-compatible unit.
    Red Black Black Red the amp is a later, non-inverting, SDA-compatible unit.

    http://thecarversite.com/yetanotherforum/default.aspx?g=posts&t=3876 especially post #6

    Interesting, clever design feature- didn't know that.
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
  • SchurkeySchurkey Posts: 1,764
    edited September 2013
    Copy of e-mail received from a question about common-ground sent through the Adcom web site:

    Dear Schurkey,

    There is no common ground into the GFA 5500 model.

    You can look for GFA 555se which is higher power with common ground terminals included.

    http://www.adcom.com/products.html?page=shop.product_details&flypage=flypage.tpl&product_id=73&category_id=28

    Thank you.

    Sunil


    Everest World Co.,Ltd.

    18/8 Fico Place Building, 2nd Fl.,

    Sukhumvit 21 Rd., Wattana,

    Bangkok 10110, Thailand.

    Mob.+66 8 70035217

    ' +66 2 204 2255 | F +66 2 204 2259
  • drumminmandrumminman Posts: 3,354
    edited September 2013
    Where is Adcom made? I thought they were an American company, yet you get a reply from a person in Thailand. Outsourcing CS, or that's where manufacturing is?
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
  • heiney9heiney9 Posts: 23,730
    edited September 2013
    Adcom hasn't been made in the States for atleast a decade and a half. They have been sold a few times, not the same company it was in the early days. Not saying the gear is bad, just that the "original" Adcom is far removed from today's company. But, many similar companies suffered that fate.

    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!
  • SchurkeySchurkey Posts: 1,764
    edited September 2013
    I have four Adcom GCD-600 carousel CD changers, (two of them in operating condition, two with problems to the analog circuitry that I'm not smart enough to fix) strongly preferred over the newer but similar GCD-700 because the earlier units are Japanese rather than Chinese origin like the later units. They may not be American or North American, but at least they're from the "Free World".

    Far as I know, Adcom--like Harman-Kardon, Rotel, Parasound, newer Carver gear, and so many others, but UNLIKE Acurus, B&K, and Bryston, for example--has outsourced the actual building of components to Asia for decades if not "forever". Were the famous GFA-555s and '555 IIs made in America? I doubt it.

    The only thing that surprised me was that they freely acknowledge the outsourcing of the customer service. Perhaps Adcom is now owned by an Asian holding company.
  • zingozingo Audiophile Posts: 11,610
    edited September 2013
    Does anyone know if two OEM ICEpower modules can be strapped together to create a common ground stereo amplifier? I believe W4S amps are common ground, but their production amp does not use stock modules either.
  • oldmodmanoldmodman Posts: 745
    edited September 2013
    If you want to use a pair of monoblocks, are they common ground?

    Or does it make a difference if they are tube or transistor?

    Since they are both plugged into a "common ground" does that make them a common ground?

    Like the amps that nooshinjohn made, the Carver Statement Moniblocks, which I assume are common ground.
  • zingozingo Audiophile Posts: 11,610
    edited September 2013
    The common ground that SDAs need is that the negative binding posts between the two channels have to have continuity, and zero, or close to it resistance. Some monoblocks can have the negative binding posts "strapped together" with a piece of speaker wire or something similar to create an electrical common ground, but ALWAYS check with the manufacturer; the output device whether tube or transistor does not matter.
  • Is a Yamaha M2 a common ground amp?
  • SchurkeySchurkey Posts: 1,764
    Is a Yamaha M2 a common ground amp?
    Put an ohmmeter across the negative terminals of the two channels, and find out. Or post a schematic.
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