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  1. #1

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    Default common ground amp

    i have a pair of sda 2b that i would like to find a better used amp upgrade than the one i have now. i know it has to be common ground (still dont know what that means really) to work well with the sda, but while i am hunting for an amp, is there a way to easily tell if it is common ground or not? do certain brands run common ground, while other brands do not. i have to assume that the integra adm 2.1 amp i am using now is common ground, because it sounds pretty good. but while i have been searching for a used, perhaps vintage amp with some more power, i know if i accidently buy one that is not a common ground, i'll be screwed.

    any advise from those with more experience?
    Theater - Polk LSi15, LSiC, LSi9 speaks, DIY Sub (142.5L box, SVS plus driver, 500 Watt plate amp)...Outlaw 990 pre/pro, Carver TFM45, 2 X Outlaw M200 . Rotel RB980 . PS3, Monster 3600 power center

    2 Channel -
    Anthem Pre 2l, Jolida JD100 CD player, CAL Sigma DAC, Carver m4.0, Polk LSi9 w external modified Crossovers (thanks Trey!)

  2. #2

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    If you are looking at something that you are not sure about you can always check with the manufacturer or in a lot of cases you can check here.

  3. #3

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    most amps are common ground, so it is not as hard as it sounds, it is harder to find one that is NOT common ground. Ask here on the forum and somebody can help out I am sure.

    If you have the SDA 2B's, you can build a homemade AI-1 interconnect and then you can buy any amp you want with no worries.

    Good luck.
    Dodd - Battery Preamp
    Monarchy Audio SE100 Delux - mono power amps
    Sony DVP-NS999ES - SACD player
    ADS 1230 - Polk SDA 2B
    DIY Stereo Subwoofer towers w/(4) 12 drivers each
    Crown K1 - Subwoofer amp
    Outlaw ICBM - crossover
    Beringher BFD - sub eq

    Where is the remote? Where is the $%#$% remote!

    "I've always been mad, I know I've been mad, like the most of us have...very hard to explain why you're mad, even if you're not mad..."

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    The easiest way to tell if the amp is common ground is to take an ohm meter that is set to continuity and take one lead of the ohm meter and touch the neg terminal on the left output of the amp and take the other lead and touch the right negative terminal output of the amp and if it shows continuity you have a common ground amp,if nothing happens then you have a non-common ground amp.Basically the amp is considered a common ground if they share a ground for all the negative outputs on the amp.Hope this answers your question.

  5. #5

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    anyone know of parasound amps are common ground?
    Theater - Polk LSi15, LSiC, LSi9 speaks, DIY Sub (142.5L box, SVS plus driver, 500 Watt plate amp)...Outlaw 990 pre/pro, Carver TFM45, 2 X Outlaw M200 . Rotel RB980 . PS3, Monster 3600 power center

    2 Channel -
    Anthem Pre 2l, Jolida JD100 CD player, CAL Sigma DAC, Carver m4.0, Polk LSi9 w external modified Crossovers (thanks Trey!)

  6. #6

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    Talking Don't know

    What I do know is the Parasounds come with 3 pin plugs. If you have 3 pin sockets it will work!!!:D
    Sunfire TGP III PrePro, Sunfire Cinema Grand Signature 405wpc 5 ch. Amp, Rotel RCD-1072 CDP, Onkyo TA2600 Tape Deck, Pioneer Elite 47-A DVD, Sony 32" XBR TV, Polk RTA-8T Main Speakers, Boston VR-920 Center Channel, Boston PV-600 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers

  7. #7

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    Originally posted by ohskigod
    anyone know of parasound amps are common ground?
    Parasound Halo JC1 monoblocks? Definitely not common ground, but if one can afford the $6000 to buy a new pair, getting an in-line transformer should be no problem.
    Used Parasound HCA3500? Dual mono design with two power cords--not common ground.

    All other current Parasound designs? Yes, they're all common ground, but verify with Parasound customer service or a dealer if uncomfortable, especially with twin blade SDA speakers (which the 2B speakers are/were).
    1. JM Labs Electra 920.1 and CC30; MB Quart Vera Sub; Pioneer SC-57; Squeezebox Touch; Panasonic BDT-500 Blu-Ray; Samsung 52" LCD; FIOS; PS Audio Power Plant Premier; MIT S3 cables
    2. Polk SDA-SRS 2.3TL; Sonic Frontiers Line 3 SE; Classe Model 25; Marantz SA8004; Acoustech PH1P; Squeezebox Touch; Music Hall MMF7; PS Audio P1000; MIT S2 cables
    3. Polk SDA 2A; Parasound Halo JC-2 and A21; Musical Fidelity X-DAC; Squeezebox Touch; PS Audio 4.7; MIT S1 cables

  8. #8

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    http://clubpolk.polkaudio.com/forum/...+common+ground
    Here's a starting point for you. Call Polk and the amp manufacturer to double check before you fire it up (hopefully you will see no fire)! If you do go this route, make sure you use heavy gauge speaker cable for your jumper, no lamp cord. A run of the heavier Monster Cable should do.
    SDS-400, SDA-1B, SVS 20-39pc+, B&K Ref 50, Denon 2900

  9. #9

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    Originally posted by Emlyn
    especially with twin blade SDA speakers (which the 2B speakers are/were).
    the pair of 2B's I had had a pin blade interconnect.
    Dodd - Battery Preamp
    Monarchy Audio SE100 Delux - mono power amps
    Sony DVP-NS999ES - SACD player
    ADS 1230 - Polk SDA 2B
    DIY Stereo Subwoofer towers w/(4) 12 drivers each
    Crown K1 - Subwoofer amp
    Outlaw ICBM - crossover
    Beringher BFD - sub eq

    Where is the remote? Where is the $%#$% remote!

    "I've always been mad, I know I've been mad, like the most of us have...very hard to explain why you're mad, even if you're not mad..."

  10. #10

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    Originally posted by hoosier21
    the pair of 2B's I had had a pin blade interconnect.
    The pair of 2Bs I have now (Studio version) have the twin blade interconnect. My best guess is they were made in late 1988 or early 1989 from the date stamps on the drivers.

    Kind of confusing to keep track of these things. ;)
    1. JM Labs Electra 920.1 and CC30; MB Quart Vera Sub; Pioneer SC-57; Squeezebox Touch; Panasonic BDT-500 Blu-Ray; Samsung 52" LCD; FIOS; PS Audio Power Plant Premier; MIT S3 cables
    2. Polk SDA-SRS 2.3TL; Sonic Frontiers Line 3 SE; Classe Model 25; Marantz SA8004; Acoustech PH1P; Squeezebox Touch; Music Hall MMF7; PS Audio P1000; MIT S2 cables
    3. Polk SDA 2A; Parasound Halo JC-2 and A21; Musical Fidelity X-DAC; Squeezebox Touch; PS Audio 4.7; MIT S1 cables

  11. #11

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    My ADCOM GFA-7605 came with 3 pin IEC detachable power cord.

    ;)
    Panasonic TH-50PX80U Plasma HDTV
    Polk Audio RT800i (fronts)
    Polk Audio CS400i (center)
    Polk Audio F/X1000 (side surrounds)
    Polk Audio RTi6 (back surrrounds)
    Velodyne CHT-15 (subwoofer)
    Yamaha RX-V1400 (Pre/Pro)
    NAD C272 (2-ch Amp)
    Adcom GFA-7605 (5-ch Amp)
    Toshiba SD-3109 (DVD/CD player)
    Malata DVP-580 (Multi-region DVD player)

  12. #12

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    Originally posted by Emlyn
    Kind of confusing to keep track of these things. ;)
    As far as SDA models, that is an understatement.


    cfritz "If you have 3 pin sockets it will work!!!" please explain????
    Dodd - Battery Preamp
    Monarchy Audio SE100 Delux - mono power amps
    Sony DVP-NS999ES - SACD player
    ADS 1230 - Polk SDA 2B
    DIY Stereo Subwoofer towers w/(4) 12 drivers each
    Crown K1 - Subwoofer amp
    Outlaw ICBM - crossover
    Beringher BFD - sub eq

    Where is the remote? Where is the $%#$% remote!

    "I've always been mad, I know I've been mad, like the most of us have...very hard to explain why you're mad, even if you're not mad..."

  13. #13

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    The regular 2 vertical pins with the round one that goes underneath. (ie 3 pins) It might not be the correct terminology, but whadaya want I'm not an electrical engineer!:D I'm sure there is one on this board, get the right term from them!;)
    Sunfire TGP III PrePro, Sunfire Cinema Grand Signature 405wpc 5 ch. Amp, Rotel RCD-1072 CDP, Onkyo TA2600 Tape Deck, Pioneer Elite 47-A DVD, Sony 32" XBR TV, Polk RTA-8T Main Speakers, Boston VR-920 Center Channel, Boston PV-600 Subwoofer, Polk DSW 400 Subwoofer, Polk FXi-3 Surround Speakers

  14. #14

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    anyway i can get some feedback as to how to build the interconnect i need to not have to worry about common ground. i'm assuming it will involve speaker wire, but where do i get the connectors to attach to the wire (and of course, which connectors are they)?
    again, thanx in advance for the help.
    Theater - Polk LSi15, LSiC, LSi9 speaks, DIY Sub (142.5L box, SVS plus driver, 500 Watt plate amp)...Outlaw 990 pre/pro, Carver TFM45, 2 X Outlaw M200 . Rotel RB980 . PS3, Monster 3600 power center

    2 Channel -
    Anthem Pre 2l, Jolida JD100 CD player, CAL Sigma DAC, Carver m4.0, Polk LSi9 w external modified Crossovers (thanks Trey!)

  15. #15

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    someone mentioned above that just had to build the cable and that is it, but dont i need to do something to the speaker to get the new connector to fit?, i'm referring to the A1-1 cable mentioned by hoosier
    Theater - Polk LSi15, LSiC, LSi9 speaks, DIY Sub (142.5L box, SVS plus driver, 500 Watt plate amp)...Outlaw 990 pre/pro, Carver TFM45, 2 X Outlaw M200 . Rotel RB980 . PS3, Monster 3600 power center

    2 Channel -
    Anthem Pre 2l, Jolida JD100 CD player, CAL Sigma DAC, Carver m4.0, Polk LSi9 w external modified Crossovers (thanks Trey!)

  16. #16

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    cfrizz, I am not taking you to the mat on this, but the AC power cord's plug, has little to do with the common ground or non-common ground issue we are talking about:)

    ohskigod, tell us, is your interconnect the blade blade or pin blade? If it is blade blade, you are stuck with common ground amps only, no modification or fabrication of the AI-1.

    If you have the pin blade type of interconnect, look at the file I attached.


    good reading
    http://clubpolk.polkaudio.com/forum/...&highlight=AI1

    http://clubpolk.polkaudio.com/forum/...highlight=AI-1

    Julian Hirsch reviewed the SDA-1 in the Dec 82 issue of Stereo Review

    "Removing the grille reveals an array of six drivers and a large,
    12-inch, flat "cone" passive radiator for the bass drivers. There are
    actually two separate speaker systems, sharing a common bass section,
    within each SDA-1 cabinet. They are designated the "stereo" and the
    "dimension" subsystems. Like previous Polk speakers we have tested,
    the SDA-1 bass section uses two 6-inch cone drivers located about
    midway up the front of the speaker board above the passive radiator.

    "Above each bass driver is a driver of similar size that handles the
    frequency range from 125 to 2,500 Hz, and above these are two newly
    designed 1-inch dome tweeters with light plastic domes driven by
    low-loss "litz wire" voic coils. The left and right midrange driver
    and tweeter each make up a subsystem, the two being isolated from each
    other acoustically and electrically.

    "In operation, the two speaker cabinets, a mirror-image pair, are
    placed (typically) about 6 to 8 feet apart and at exactly equal
    distances from the rear wall. For best results, the listener should
    be seated equidistant from the speakers, whch should form an angle of
    about 45 degrees with the listener. In each cabinet the innermost
    pair of drivers forms the "stereo" system and the outermost drivers
    the "dimension" system.

    "The left and right speakers are connected to the amplifier in the
    usual manner. The amplifier MUST have a common ground between its
    left and right output terminals. (Most amplifiers meet this
    requirement; check your amplifier's instruction manual for warnings
    about the use of external speaker switches or accessories that require
    an output circuit with a common ground.) A special cable, supplied
    with the SDA-1, interconnects the two speakers. In the left speaker,
    the dimension section carries the L - R signal, while in the right
    system it carries the R - L signal (the inverse of the L - R signal,
    180 degrees out of phase with it).

    "When the speakers are installed correctly, the output of the
    "dimension" speaker section on each side is delayed by the period
    needed for it to cancel the sound reaching the ear on that side from
    the opposite channel's "stereo" section. The actual operation of the
    Polk SDA system is somewhat more involved and depends to a
    considerable degree on the Hass (precedence) effect, which causes the
    earliest arrival of a sound to establish its apparent direction of
    origin.

    "Most of the specifications for the Polk SDA-1 speaker system, as
    listed in its instuction manual, deal with its driver and crossover
    characteristics. However, the manual does state that the midrange
    drivers operate as fourth-order vented systems, with their small vent
    openings located just above and between the drivers. The rated
    impedance of the system is not given in the usual manner, but its d.c.
    resistance is rated at 5 ohms. The recommended price of the Polk
    SDA-1 is $850 each, but they are normally sold only in pairs at
    $1,700."

    To measure the frequency response, the speakers were driven
    individually as ordinary speakers, with no connection between them.
    The smoothed and averaged room response was within +/-2.5 dB from
    about 150 to 12,000 Hz. There was a tweeter resonance at about 13,000
    Hz, which created an output peak of about 5 dB at that frequency. The
    overall in-room response was +/- 4.5 dB from 20 to 20,000 Hz.
    Sensitivity is a high 95 dB SPL measured at 1 meter when driven by
    2.83 volts of band-limited pink noise. The electrical impedance
    measured on a single system was a minimum of 5 ohms in the vicinity of
    100 Hz and varied between 5 and 12 ohms over the full audio range.
    When operating as a normal system, the music may cause the amplifier
    to "see" a load as low as 2.2 ohms, although Hirsch states that it is
    unlikely to load any reasonably good amplifier or receiver unduly.

    "Briefly, a properly installed pair of Polk SDA-1 speakers produces a
    broad, precisely defined sound stage, not only between the speakers,
    but extending appreciably beyond the speakers, but extending
    appreciably beyond the laterally as well. The effect is very similar
    to that achieved by all-electronic imaging systems [such as Carver's
    Sonic Holography, or QSound-encoded material --Darryl], although the
    exact position is not quite so critical with the Polk speakers.

    "The sound of the Polk SDA-1 is beautifully balanced, with a total
    lack of bass heaviness, in spite of its psychoacoustic manipulations
    and the fact that it reaches an octave or so deeper into the low bass
    than many speakers of similar size. Under some conditions we found
    that it sounded a little bright or crisp, probably because of the
    tweeter peak at 13,000 Hz, but this was usually evident only in a
    direct A-B comparison with a speaker system lacking a peak at that
    frequency."
    Attached Files
    Dodd - Battery Preamp
    Monarchy Audio SE100 Delux - mono power amps
    Sony DVP-NS999ES - SACD player
    ADS 1230 - Polk SDA 2B
    DIY Stereo Subwoofer towers w/(4) 12 drivers each
    Crown K1 - Subwoofer amp
    Outlaw ICBM - crossover
    Beringher BFD - sub eq

    Where is the remote? Where is the $%#$% remote!

    "I've always been mad, I know I've been mad, like the most of us have...very hard to explain why you're mad, even if you're not mad..."

  17. #17

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    My previous posted link goes to an individual that had the blade/ blade interconnect. Read it thouroughly, it has more to do with which amp you run than the interconnect termination between the SDA's.

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