Unstrap those amps for your SDA's

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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited December 2010
    TOOLFORLIFEFAN wrote: »
    So why am I experiancing better sound without the strap??
    I went at it again with the adcom tonight and you can clearly hear the difference without the strap using the AI cable..

    This question came up before:
    schwarcw wrote: »
    One compelling question remains, why do you get overall better sound when you place all that electrical hardware in place of a single ground strap? I would think the more copper that is added to the signal path, the result would be a deminshed sound quality. How does adding all that material improve the sound quality? The scope and your ears don't usally lie, but why?
    DarqueKnight wrote: »
    There is actually less electrical hardware with the AI-1. When you use a pin/blade cable and strap, the SDA signal is gounded through the amplifier's ground...and comes with all the electrical noise in the amplifier's ground path.

    The AI-1 isolates the SDA signal from the amplifier's ground path, therefore you get a potentially cleaner signal.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • mole'
    mole' Posts: 3,160
    edited December 2010
    TOOLFORLIFEFAN wrote: »
    I should also say I unstapped my Adcom GFA-5802 as well and I still could not beleive how much the strap took away from the clarity in sound. I personally think this is the one cable Polk should have available for the SDA enthusiast.

    Yea I know they could make one, a better one at that but not all people have the skills to do so..

    tell me more about these cables?

    i still dont have my 5802 strapped. but im running my 2.3TLs without the SDA cable for now
    mole'
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  • audio_alan
    audio_alan Posts: 770
    edited January 2011
    I'm considering adding another amp to my setup (Pioneer Elite, pre-out to an Adcom 555mkII, to my SDA-SRS's). I currently have my sights on another 555mkII.

    According to DarqueKnight's post above, I won't be able to AI-1 my SDA-SRS's because their serial numbers are too low (1124 and 2311). So, would my only option be to strap the Adcom negatives together? Would the end result be worth the additional $250 investment?

    Or should I just get a set of SDAs that have higher serial numbers, so I can AI-1 them? :biggrin: (Seriously, this isn't out of the question...).
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  • heiney9
    heiney9 Posts: 25,165
    edited January 2011
    Don't run bridged stereo amps in mono for SDA's first of all; and 2nd of all IIRC you can't strap bridged stereo amps when run in mono.

    What is the issue you feel you need two amps instead of one?

    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 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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  • heiney9
    heiney9 Posts: 25,165
    edited January 2011
    audio_alan wrote: »

    Or should I just get a set of SDAs that have higher serial numbers, so I can AI-1 them? :biggrin: (Seriously, this isn't out of the question...).

    Why? What is the underlying issue you feel you need to go out and buy a pair that can use the AI-1? If it's to run a pair of bridged stereo amps in mono..............forget it, not the worth the effort or hassle and not recommended even if you have the AI-1 in place.

    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 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: 50,567
    edited January 2011
    IIRC you can't strap bridged stereo amps when run in mono.

    That is correct.

    The only way to run those would be in a bi-amp configuration with the grounds strapped. Although, the sound quality will suffer when strapped.
    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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  • audio_alan
    audio_alan Posts: 770
    edited January 2011
    heiney9 wrote: »
    Don't run bridged stereo amps in mono for SDA's first of all; and 2nd of all IIRC you can't strap bridged stereo amps when run in mono.

    What is the issue you feel you need two amps instead of one?

    H9

    Ok, I didn't know that you can't strap bridged stereo amps running in mono. Regarding the reason why - why do any of us make tweaks? Hopefully to get even better sound... and more power! :biggrin:

    I guess I'll scrap that idea. Thanks for the quick response and educating me on that. I'm thinking my next frontier should a nice tube amp anyway. I just happened to spot a 555mkII and thought I'd poll the forum to see if it was worth it...
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  • heiney9
    heiney9 Posts: 25,165
    edited January 2011
    I see, so no real issue. Tube amps are nice :biggrin:

    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 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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  • audio_alan
    audio_alan Posts: 770
    edited January 2011
    heiney9 wrote: »
    I see, so no real issue. Tube amps are nice :biggrin:

    H9

    Yeah, no real issue, just bored. haha

    According to the specs, the Adcom 555mkII is rated at 800 watts bridged mono into 4ohms. That sounds better than 325 wpc into 4 ohms stereo (since the SDA-SRS's can handle up to 1000 watts each). But I didn't realize the limitations that you pointed out...
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited January 2011
    audio_alan wrote: »
    I'm considering adding another amp to my setup (Pioneer Elite, pre-out to an Adcom 555mkII, to my SDA-SRS's). I currently have my sights on another 555mkII.

    According to DarqueKnight's post above, I won't be able to AI-1 my SDA-SRS's because their serial numbers are too low (1124 and 2311). So, would my only option be to strap the Adcom negatives together? Would the end result be worth the additional $250 investment?

    Or should I just get a set of SDAs that have higher serial numbers, so I can AI-1 them? :biggrin: (Seriously, this isn't out of the question...).

    The AI-1 Non-Common Ground Amplifier Interface was designed to be used with some SDA's that use the pin/blade interconnect cable. Therefore, the original SDA SRS, which uses a blade/blade interconnect cable, cannot be used with the AI-1.

    The "SDA SRS" mentioned in the chart in post #48 of this thread does not refer to the original SDA SRS, but rather the SDA SRS 1.2, SDA SRS 1.2TL, SDA SRS 3.1TL, SDA SRS 2.3TL, and SDA SRS 2.3.

    Some of the early SDA 1C's used a blade/blade cable, but these speakers were actually a pin/blade design. Polk used up the left over blade/blade sockets and cables from the SDA 1B before they began to use the pin/blade sockets and cables in the SDA 1C.
    audio_alan wrote: »
    According to the specs, the Adcom 555mkII is rated at 800 watts bridged mono into 4ohms. That sounds better than 325 wpc into 4 ohms stereo (since the SDA-SRS's can handle up to 1000 watts each). But I didn't realize the limitations that you pointed out...

    325 clean watts sounds way better than 800 grimey, dirty, distorted watts. I have owned several GFA-555 Mk II's and I currently have one in my rig at work. The sound quality of the amp deteriorates considerably when it is used in bridged mode due to the cumulative effects of adding the noise and distortion of both channels together. I would use a bridged GFA-555 MK II in a nightclub or auditorium type audio system, but never in a two channel system.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • audio_alan
    audio_alan Posts: 770
    edited January 2011
    ^^^^ Great info, thanks DarqueKnight!

    Sounds like I better stay with my one 555mkII for now. I'm happy with the setup, but sometimes more performance is just around the corner. Not in this case, it appears...
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  • chandler9a
    chandler9a Posts: 878
    edited January 2011
    So I am going to ask the "obvious to most but not to me" question, please bare with me.

    My father has a set of SDA 1.2TL's and we are running TWO NAD 218thx amps on them, one for the highs and one for the lows. We did this to add power that we "assumed" was needed and it definitely accomplishes that.

    My question is, is this a good thing or does it take away from SDA sound in general?
    In reading some of the posts above and others I have seen on powering SDA's this way, I am getting the idea that either its not necessary or maybe just counter productive for this type of speaker. I understand that it can come down to personal taste but I was wondering what some of you more experienced guys had to say.

    To be honest, I would like to see just ONE super quality amp on these babies but due to cost we just added another amp that we got for a ridiculous price. Maybe in the future.

    Thanks for any input guys, I'm learning a lot!
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited January 2011
    The process of bi-amping will not diminish the SDA effect. The quality of the amplifier used on the low frequency section will have an effect, particularly its high current capability, will have an effect.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • chandler9a
    chandler9a Posts: 878
    edited January 2011
    Thank you DK, I will inherit these some day so I was just wondering.
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  • newrival
    newrival Posts: 2,017
    edited January 2011
    DarqueKnight wrote: »
    The "SDA SRS" mentioned in the chart in post #48 of this thread does not refer to the original SDA SRS, but rather the SDA SRS 1.2, SDA SRS 1.2TL, SDA SRS 3.1TL, SDA SRS 2.3TL, and SDA SRS 2.3..

    so to be clear, no AI-1 for my SRS's??
    DarqueKnight wrote: »
    325 clean watts sounds way better than 800 grimey, dirty, distorted watts. I have owned several GFA-555 Mk II's and I currently have one in my rig at work. The sound quality of the amp deteriorates considerably when it is used in bridged mode due to the cumulative effects of adding the noise and distortion of both channels together. I would use a bridged GFA-555 MK II in a nightclub or auditorium type audio system, but never in a two channel system.

    DK, do your comments on the quality of the 555 mkII's apply, in your opinion, to the original (Nelson Pass design)?

    Ive heard many people say this, and have witnessed poor quality myself, However it was with speakers that spend some time below 8ohms. However, I found the amps to be quite spectacular when bridged mono into 12-14 ohm speakers. I found in this situation they were quite adept at presenting the full range that I couldn't coax from any other "mid-fi" amps at my disposal. Have you ever used the amp in this situation? To my ears, they sounded very refined indeed
    design is where science and art break even.
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  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited January 2011
    newrival wrote: »
    so to be clear, no AI-1 for my SRS's??

    No.
    newrival wrote: »
    DK, do your comments on the quality of the 555 mkII's apply, in your opinion, to the original (Nelson Pass design)?

    I have not heard the original GFA-555 in bridged mode, just the Mk II version.
    newrival wrote: »
    Ive heard many people say this, and have witnessed poor quality myself, However it was with speakers that spend some time below 8ohms. However, I found the amps to be quite spectacular when bridged mono into 12-14 ohm speakers. I found in this situation they were quite adept at presenting the full range that I couldn't coax from any other "mid-fi" amps at my disposal. Have you ever used the amp in this situation? To my ears, they sounded very refined indeed

    I have only used bridged GFA-555 Mk II's with SDA SRS 1.2TL's, so I don't know how they would sound with other speakers.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
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  • On3s&Z3r0s
    On3s&Z3r0s Posts: 1,013
    edited January 2011
    Sorry to pile on, but this seems to have turned into the thread to get your AI-1 questions answered... The picture from the AI-1 manual says that *all* 2B's require a crossover mod. The ser nos. on mine are higher than given, and I'm going to be doing the TL modification and putting in new binding posts for the SDA cable on the cabinets. So I guess the only thing I need to worry about is whether the AI-1 is compatible with the TL mods. Has anyone run the 2B TL's with an AI-1 or otherwise know that this is kosher?
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  • Toolfan66
    Toolfan66 Posts: 17,248
    edited February 2011
    Another update if you crazy tweekers give a crap!!!!!!

    I have been a TOOL fan for quite some time now, and I have failed to listen to them since I have built this BIG little Black Box, Lets just say that building the Dreadnaught is the baddest thing to happen to these SDA's!!! Well that and Tubes!!:tongue: But without the Dreadnaught it was lacking to say the least,and again it also makes the GFA 5802 sound like a much bigger animal!!

    Just about everything I play has much better extension on the front stage, it is absolutely incredible..

    UNDERTOW freaking KICKS ****!!!!!:cool:

    Strapless Baby!!!!!That is all, just chillin to the best band to ever step up on a stage!!
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