are bridged amps common ground?

analog97
analog97 Posts: 328
edited October 2007 in Vintage Speakers
I have 1.2TL's and am considering bridging two 125 W Parasound amps, using one for each channel. This will give me about 300W for each channel. BUT, although DARQUENIGHT gave a great explanation of a common ground amp, I am confused about using two bridged amps. Maybe to achieve a common ground, I have to tie both chassis together? Help, please!! The last thing I want is to blow up my precious Polks. TIA.
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  • analog97
    analog97 Posts: 328
    edited September 2007
    Each amp is a 2-channel stereo, 125W per channel. It is bridgeable per the manual.
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  • analog97
    analog97 Posts: 328
    edited September 2007
    The manual says bridging is good for 8 ohms, no problem. But, you did remind me to re-think the connections. I will not be using the bridged amps to power the lows and highs separately. Rather, each amp will power one speaker. BUT, I still gotta get 2 Y's to split the pre-amp outputs. Thanks again for your assurance and help.
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  • Systems
    Systems Posts: 14,873
    edited September 2007
    analog97 wrote: »
    Maybe to achieve a common ground, I have to tie both chassis together? Help, please!!
    With the amps in bridged mode you CANNOT tie the neg speaker terminals together.When the amp is bridged it is no longer common ground.In other words the negative terminals are not at ground potential(when unit is bridged).
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  • analog97
    analog97 Posts: 328
    edited September 2007
    GV#27:

    OK. I hear you. You are saying it is OK, as long as I do NOT tie the bridged amps together?
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  • Systems
    Systems Posts: 14,873
    edited September 2007
    analog97 wrote: »
    GV#27:

    OK. I hear you. You are saying it is OK, as long as I do NOT tie the bridged amps together?
    Correct, unless the 1.2tL is an SDA design?If so you cant use the bridged amps with them.You could use a non bridged bi amp setup like Lasereath is using.
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  • analog97
    analog97 Posts: 328
    edited September 2007
    Geepers. I have Polk SDA SRS 1.2TL's. So, now you are saying that I can't power each individual speaker with a bridged amp? Rather, I must use the configuration by Lasareath to use a classic "bi-amp" configuration?
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  • Systems
    Systems Posts: 14,873
    edited September 2007
    OK sorry for the confusion I will try to explain it better.You cannot tie the neg speaker terminals of bridged amplifiers together to make them common ground regardless of which speaker you are using.
    However SDA's require the use of an amp with a common ground.Bridged amps are not common ground therefore eliminating them for use with SDA's.

    Does that help?
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  • F1nut
    F1nut Posts: 50,734
    edited September 2007
    Of course, you can build an AI-1 and then you can use any non-ground amp(s).
    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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  • Systems
    Systems Posts: 14,873
    edited September 2007
    I should add that in a non bridged set up like Lasereaths the amps will be common ground.
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  • F1nut
    F1nut Posts: 50,734
    edited September 2007
    Another thought for you to consider, bridged amps may net you more power, but they also net you more distortion.
    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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  • analog97
    analog97 Posts: 328
    edited September 2007
    F1, you have raised an excellent point. What I am really trying to achieve is to really "light up" my 1.2TL's without breaking the bank. Maybe this is a pipe dream. I am listening now to my 125 W Parasound stereo amp driving the 1.2TL's. I also have an Anthem (close to 200W per channel) awaiting a fuse replacement, but that's not really that much more. Ideally, it seems to me about 500W per channel would be ideal, but these are an arm and leg to buy. What are the alternatives that most 1.2TL-owners are using? I have seen a few posts, like Hearingimpaired's 300W Adcom monoblocks, etc. But I just wonder what that would be like because I have not heard anyone's large Polk speakers except mine. Thanks for the thought. PS: the big Polks even sound great with 125W!!
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  • F1nut
    F1nut Posts: 50,734
    edited September 2007
    Figure out which of your amps has more current, that's the one 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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  • analog97
    analog97 Posts: 328
    edited September 2007
    OK. Thanks again. Seems the answer for me is to use the 2 Parasound amps in the bi-amp configuration as outlined by Lasareath. All I need is more speaker wire, bananas and a couple Y's. Apparently, bridging each amp to mono and powering one SDA with each amp will violate the "common ground" principle. Thanks!:) :)
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  • F1nut
    F1nut Posts: 50,734
    edited September 2007
    I'm getting around 600 Watts per channel. I cant put it up past 3 on my receiver or it gets really painful

    The gain in the pre amp section is too high if that's the case.
    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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  • michaeljhsda2
    michaeljhsda2 Posts: 2,185
    edited October 2007
    My Crown XLS 602 amplifier in bridged mono has an output of 1200 watts at 8ohms. Does this mean that I can use 1 amp for each speaker without needing an AI-1 cable? thanks Here is a link to Crown's website http://www.crownaudio.com/amp_htm/xls.htm I have 1.2 TL's btw.
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
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  • Systems
    Systems Posts: 14,873
    edited October 2007
    michaeljhsda2 wrote: »
    My Crown XLS 602 amplifier in bridged mono has an output of 1200 watts at 8ohms. Does this mean that I can use 1 amp for each speaker without needing an AI-1 cable? thanks Here is a link to Crown's website http://www.crownaudio.com/amp_htm/xls.htm
    If you run them bridged then you will need the cable.
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  • michaeljhsda2
    michaeljhsda2 Posts: 2,185
    edited October 2007
    Thanks GV#27, my quest for the cable now begins......
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
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  • F1nut
    F1nut Posts: 50,734
    edited October 2007
    Another idea would be to buy an amp worthy of the 1.2TL's.
    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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  • avguytx
    avguytx Posts: 1,628
    edited October 2007
    Maybe a Carver TFM-75. :D
    Richard? Who's your favorite Little Rascal? Alfalfa? Or is it........................Spanky?.................................Sinner.
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  • michaeljhsda2
    michaeljhsda2 Posts: 2,185
    edited October 2007
    And which amp would that be?
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
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  • F1nut
    F1nut Posts: 50,734
    edited October 2007
    There's a whole host of amps made for quality sound reproduction in the home, take your pick. Massive wpc ratings mean very little in relation to sound quality and fans are a no-no.
    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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  • michaeljhsda2
    michaeljhsda2 Posts: 2,185
    edited October 2007
    and why are fans a no no?
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
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  • treitz3
    treitz3 Posts: 19,195
    edited October 2007
    Shhhh...because you can hear them during quite passages...and they draw power from where you want it to go.

    Why would you want to bridge anyway? Yeah, you have higher voltage....but where's the beef?
    ~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~
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  • rocket
    rocket Posts: 71
    edited October 2007
    anyone else have monster power? i have the monster backbone, i have owned many amps(carver, adcom, pioneer elite, etc.) and the power of these amps are truly amazing! i've seen over 1200 watts registered-600 a side into my 2.3's, and they just keep going. if you can find a deal, these babies really sing! all reviews are excellent. LC
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  • michaeljhsda2
    michaeljhsda2 Posts: 2,185
    edited October 2007
    All I wanted to know is if I need the AI-1 cable when using bridged mono amplifiers with the SDA SRS 1.2 TL's and I got my answer from GV#27. Thanks again GV#27
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
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  • michaeljhsda2
    michaeljhsda2 Posts: 2,185
    edited October 2007
    To Treitz3...I listen to rock and roll so there are no quiet passages. Where's the beef? It's 380 watts of clean power. My system sounds excellent with the Crown XLS 602 amplifier. I am sitting 15 feet away from the amp and you can't hear the fans between songs. Have you ever listened to any Crown amps before? Crown amps are used in all venues, both big and small. If you've ever been to a concert, chances are you were listening to the music powered by Crown amplifiers. If the amps were just throwing out high voltage garbage instead of clean undistorted power, you probably would have left the event, demanding your money back.
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
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  • Systems
    Systems Posts: 14,873
    edited October 2007
    michaeljhsda2 wrote: »
    Thanks again GV#27
    Your welcome.
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  • ka7niq
    ka7niq Posts: 577
    edited October 2007
    michaeljhsda2 wrote: »
    To Treitz3...I listen to rock and roll so there are no quiet passages. Where's the beef? It's 380 watts of clean power. My system sounds excellent with the Crown XLS 602 amplifier. I am sitting 15 feet away from the amp and you can't hear the fans between songs. Have you ever listened to any Crown amps before? Crown amps are used in all venues, both big and small. If you've ever been to a concert, chances are you were listening to the music powered by Crown amplifiers. If the amps were just throwing out high voltage garbage instead of clean undistorted power, you probably would have left the event, demanding your money back.
    I have two pairs of amps with fans.
    One pair are Ashly FET 500's
    One pair are DVAudio amps.
    Both are well over 250 WPC into 8 ohms, and have fans.
    The Ashly's are quiet, and you really have to listen to hear fans.
    The DVAudio's sound like a helipcopter if you lean into the amps.
    I can see why F1NUT would suggest an amp w/o fans.

    All things equal, heat sinks are better.
    But I paid very little for the 4 amps, so I just live with it.

    My room is pretty good sized, and mostly I use the amps for subwoofer duty.

    My experience with bridged amps tells me they do not sound as good generally for a given power level as a big, high current conventional amp.

    My limiteed experience with the SRS 2's tells me they like a ton of current.

    This is because there are 6 "motors" per side to drive.
    The more 'motors" there are, the more current is ate up.

    It will be even worse with the larger SRS speakers.

    Just for kicks, I put a receiver I own on the SRS 2's.

    That lasted for about 4 songs, and it immediately came back out.

    It was a big receiver too, a JVC RX DP 9.
    I also have a big Onkyo 919 THX I bought cheap from a local Pawnshop.

    Haven't tried it yet because no remote :eek:
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  • michaeljhsda2
    michaeljhsda2 Posts: 2,185
    edited October 2007
    The fans on the Crown are very quiet like your Ashly. Maybe we should start our own "fan" club for owners of amps with fans. cheers
    SDA SRS 2.3TL's
    Silk Audio MS-90-BT integrated tube amp
    Yaqin MS-20L integrated tube amp
    SDA 2B TL's
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  • F1nut
    F1nut Posts: 50,734
    edited October 2007
    If you think they produce clean power, that mega watt ratings are king and that the fans do not induce both external and internal noise, you have a lot to learn.
    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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