sda 2 - common grround..............

nankerphelge
nankerphelge Posts: 9
edited May 2006 in Speakers
.....................can i bridge a pair of nad 2200's to power these speakers or am i breaking the common ground amplifier rule by doing this.
Post edited by nankerphelge on
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  • BobMcG
    BobMcG Posts: 1,585
    edited March 2006
    nankerphelge wrote:
    .....................can i bridge a pair of nad 2200's to power these speakers
    Yes.
    nankerphelge wrote:
    am i breaking the common ground amplifier rule by doing this.
    Yes.

    So:
    I highly recommend you do so only with the use of a non-common ground interface (AI-1). A search will bring up a lot of info on this including how to make one. Polk CS will probably send you the schematics for one too if you ask.

    PS: Welcome to CP.
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  • nankerphelge
    nankerphelge Posts: 9
    edited March 2006
    ............i figured there had to be some way around it. does this involve modifying my existing cord or making a whole new one? also the speakers i owned in the past were sda 2 a's. the ones i am about to aqcuire are just sda 2's. beside some cosmetic differences (grills, cabinets, etc.) what is the difference?
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    Wait a sec. The only SDA 2's that one can use the AI-1 with are the SDA 2B's with S/N's greater than 14115 left channel and 14124 right channel. SDA 2's and SDA 2A's are out of the question. Neither can you tie the negative outputs together on bridged amps. So, the answer is no and yes.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • nankerphelge
    nankerphelge Posts: 9
    edited March 2006
    ok thanks. one 2200 seems to drive them no problem anyhow. i just acquired a second one recently and figured i'd use it.
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  • BobMcG
    BobMcG Posts: 1,585
    edited March 2006
    Forget my entire previous post... was thinking 2B in my mind for some darn reason. You aren't biamping them (2 or 2A) even with an AI-1.
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  • nankerphelge
    nankerphelge Posts: 9
    edited March 2006
    well if that's the case and i'm not getting the sda effect as intended then i might as well just not use the connector and then it's safe to use mono amps. correct?
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  • heiney9
    heiney9 Posts: 25,215
    edited March 2006
    If you are not using the innerconnect, then sell the SDA's. What's the point of keeping them if your aren't using them as intended? SDA's are meant to be used with the cord.
    "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 Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    nankerphelge wrote:
    well if that's the case and i'm not getting the sda effect as intended then i might as well just not use the connector and then it's safe to use mono amps. correct?
    Without the interconnect cable in place only half the speaker is actually working.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • nankerphelge
    nankerphelge Posts: 9
    edited March 2006
    ...........according to anonymouse they're not working properly with this amp and the interconnect plugged in. they seem to be, though. when i turn the balance to one side you can still hear the other speaker close up. this is as it should be, no?
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    It would seem that your speakers are working as they should with your amp.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • George Grand
    George Grand Posts: 12,258
    edited March 2006
    Okay, I'VE got a problem. The Polk Forum member who has indicated he wants to buy my NAD 2200PE amp (riglehart) is going to drive some kind of SDA 2's with it. I don't want to sell him this amp if it is NOT going to be compatible with his speakers. Could somebody PM him and see which speakers he wants to drive, and if it will work out for him? I'm also going to PM him and tell him to get in touch with this thread, and maybe anonymouse, Jesse or Bob McG.
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  • jtgranby
    jtgranby Posts: 887
    edited March 2006
    George
    I think he bought some 2.3tl's off ebay. If so he will need a common ground amp.
    JT
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  • riglehart
    riglehart Posts: 276
    edited March 2006
    I am planning on driving a set of 2.3TLs with the NAD 2200 that George Grand is ready to sell me? Do I need to find something else?

    I read the brochure on the NAD web sight and when it mentioned that it did a 180 flip on the low frequencies to even out power usage, I was a little surprised. Wouldn't this also cause your L & R channel bass drivers to cancel each other out on a "plain" set of speakers? Then again, these guys didn't fall off a turnip truck and start building amps. Here's what it says...

    <Cut From The NAD 2200 PDF on NAD's web site>
    Inverted channels for powerful bass

    The greatest power demands commonly occur at low frequencies. Bass signals are in phase (and virtually
    monophonic) in most recordings; thus when the bass waveform is strongly positive in the left channel, it
    usually is strongly positive in the right channel at the same time. As a result both channels draw current
    simultaneously from the positive half of the power supply, while the negative half sits idle. During the
    negative half of the waveform, both channels draw from the negative supply while the positive supply
    sits idle. In the NAD 2200 the right channel is internally inverted in polarity. When a bass waveform
    causes the left channel to draw current from the positive supply, the right channel draws its bass power
    from the negative supply, and vice-versa. This efficient usage halves the instantaneous drain on either
    supply, allowing much stronger bass to be reproduced without draining the supply.
    Jolida Tube
    Polk 11T, 7, 5, 5jr, 4
    Standard equip not worth bragging about.
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  • riglehart
    riglehart Posts: 276
    edited March 2006
    Here's the actual PDF...

    http://207.228.230.231/info/NAD_2200.pdf
    Jolida Tube
    Polk 11T, 7, 5, 5jr, 4
    Standard equip not worth bragging about.
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    That's an unusual set up. If you're not having any problems driving your SDA 2's with the same amp, then I don't see where you'd have a problem driving the SDA 2.3TL's either. One nice thing about the 2.3TL's is that you can make an AI-1 interconnect cable and run any amp(s) that you want.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • nankerphelge
    nankerphelge Posts: 9
    edited March 2006
    i don't know. i know when i bought my original sda 2's the 2200 was the amp that the local hifi shop sold me to use with them. i used this amp/speaker combination for years and thought it sounded really good. i lost those sda 2's and nearly everything else i owned in a nasty divorce. managed to hang onto the 2200, though. i recently had a chance to acquire a pristine set of sda 2's locally and certainly do plan to drive them with this amp again. if i'm missing something by using this amp then i must have a tin ear. i just don't know now after hearing all this the past few days i don't know what to think. i'm certainly no expert on polks or amplifiers, i just thought that they sounded pretty good together. thanx to all.
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  • riglehart
    riglehart Posts: 276
    edited March 2006
    Just to clarify. I am the guy who bought the 2.3TL on ebay. They aren't even here yet. I have an 80 watt yamaha rx-v850 with preouts that I am looking for an amp for. I don't think it will cut the mustard by itself.
    Jolida Tube
    Polk 11T, 7, 5, 5jr, 4
    Standard equip not worth bragging about.
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  • riglehart
    riglehart Posts: 276
    edited March 2006
    Is there an A1 connector schematic somewhere? This is the second time it has been mentioned. I was also considering bi-amping these.
    Jolida Tube
    Polk 11T, 7, 5, 5jr, 4
    Standard equip not worth bragging about.
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    So, you don't actually have any SDA speakers right now. I was under the impression that you were using the SDA 2's right now with said amp. Also, you need to call your new speakers by the proper model number, SDA SRS 2.3TL, in order to receive the proper info. The bottom line is, if in doubt build the AI-1 and you'll have no worries with the SDA SRS 2.3TL's.

    The search function is your friend.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • BobMcG
    BobMcG Posts: 1,585
    edited March 2006
    Jesse, this did a bit confusing didn't it?

    Ok lets try to get this straightened out.

    nankerphelge / SDA-2s: If you have powered an identical pair of SDA-2s in the past for quite some time with a NAD2200 with no problems I don't see why you should start having them now. The SDA-2s and 2As need to be run with common ground amps to avoid damage to the amp and or drivers. Apparently this amp, although being a bit unusual in design, isn't causing problems with the 2s. You cannot run 2s, 2As and certain early versions of the 2Bs with an AI-1 so using two bridged to mono amps is out.

    ringlehart / SDA-SRS 2.3s: To be safe, you could make use of an AI-1 with these speakers. Here is a PDF on the construction of one.
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  • George Grand
    George Grand Posts: 12,258
    edited March 2006
    Rob,

    You're first in line for this amp IF you decide to go with it. I can see how the answers provided so far may have confused more than clarified. Good thing I only spent about an hour today getting the amp halfway boxed up for shipping huh?

    It's just a bit more than a LITTLE confusing Bob. To tell the truth, I can't believe the SDA's were as successful ($) as they were with this kind of handicap. I'm not aware of too many other speakers out there that have amplifier specific qualifications as these SDA's. I'm very, very happy to be a Carver Amazing/AR-9 owner now.
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  • riglehart
    riglehart Posts: 276
    edited March 2006
    I'm going to make the AI-1 cable. I only have one question now. Does this cable solve all of my problems? Meaning, can I put any darn amp I want on them after I have the magic AI-1 cable? Or, do I still need the old one for a common ground amp.
    Jolida Tube
    Polk 11T, 7, 5, 5jr, 4
    Standard equip not worth bragging about.
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    riglehart wrote:
    I only have one question now. Does this cable solve all of my problems? Meaning, can I put any darn amp I want on them after I have the magic AI-1 cable?

    Yes, it's the answer to all amps, stereo, bridged, dual mono or mono blocks.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • George Grand
    George Grand Posts: 12,258
    edited March 2006
    I appreciate the help from EVERYONE in straightening this out.
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  • riglehart
    riglehart Posts: 276
    edited March 2006
    Me too. Thanks.

    I am still trying to find an AI-1 schematic. My searches here (and google) haven't taken me to any hard documentation. I have a message into polk support.
    Jolida Tube
    Polk 11T, 7, 5, 5jr, 4
    Standard equip not worth bragging about.
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    http://www.polkaudio.com/forums/showthread.php?t=6670&highlight=SDA+AI-1

    Post #2
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • riglehart
    riglehart Posts: 276
    edited March 2006
    Me too!! Thanks all.
    Jolida Tube
    Polk 11T, 7, 5, 5jr, 4
    Standard equip not worth bragging about.
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  • HBombToo
    HBombToo Posts: 5,256
    edited March 2006
    F1nut wrote:
    http://www.polkaudio.com/forums/showthread.php?t=6670&highlight=SDA+AI-1

    Post #2

    Jesse
    Just making sure that this also works with the 2B's? Of the 3 listed isolation transformers, is there a preferred transformer?

    Henry
    ***WAREMTAE***
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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    Let us know how things work out.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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  • F1nut
    F1nut Posts: 50,753
    edited March 2006
    Henry,

    Big Ted had a problem with one of them, but I do not recall which one. He posted a thread on the subject somewhere in here. Shoot him an email.

    The AI-1 will only work with the 2B's which have serial numbers greater than 14115 left channel and 14124 right channel.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

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