Bi-amping not going well...help please!

BrentAric
BrentAric Posts: 9
edited July 2010 in Troubleshooting
I joined hoping I could find a little help. Please forgive my lengthy question.

The problem: I am trying to bi-amp my two-channel system and as soon as I power up, I hear a terrible sound and fuses blow in my amps.

More specifically:

I have a Rotel RC-1070 preamp which has dual amplifier outputs.

I have been running one Adcom GFA-535 into my Linn Keilidh speakers using Linn LK400 speaker wire.

I decided to add a second Adcom GFA-535 in order to bi-amp (known as passive bi-amping to be specific). This, I know, will only give me modest sound gains at best, but I needed to fill a spot on my setup and thought it would be fun to try.

So, I bought a second GFA 535 which arrived today.

For the last six hours I've had nothing but failure.

Each amp works fine on its own.

I connected the positive treble wire to the treble input on the Linns to one amp, and the positive bass wire to the bass input on the Linns, the treble and the bass each of course connected to a different amp.

In other words, one amp was to power the tweeters the other the drivers.

My power comes through a Rotel line conditioner.

As soon as the Adcoms received power when bi-amped...I'd hear "ZIP!" the fuses all blow in the bass amp and none or some in the treble amp.

After trying this three times I gave up...I don't have any more fuses!

There are passive diagrams for bi-amping online and it would seem I'm doing things right. I am at a loss and really frustrated.

I'm at my wit's end and desperate for some input. Any thoughts?

Thanks in advance-

Brent
Post edited by BrentAric on
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Comments

  • F1nut
    F1nut Posts: 50,552
    edited July 2010
    Did you remove the jumpers on the binding posts?
    Political Correctness'.........defined

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  • decal
    decal Posts: 3,205
    edited July 2010
    I connected the positive treble wire to the treble input on the Linns to one amp, and the positive bass wire to the bass input on the Linns, the treble and the bass each of course connected to a different amp.

    What did you do with the negative wires?
    If you can't hear a difference, don't waste your money.
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  • F1nut
    F1nut Posts: 50,552
    edited July 2010
    That comment struck me as odd as well.
    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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  • hearingimpared
    hearingimpared Posts: 21,137
    edited July 2010
    Besides the question of the negative wires, which I don't think you are that goofy not to hook up properly, I question the use of the Rotel RC-1070 preamp dual amplifier outputs. I've found that in the higher end preamps that have two outputs, one is for DC coupled amps, the other for AC coupled amps.

    This is an excerpt from my Spectral DMC 10G preamplier user manual;
    MAIN OUTPUT – DC COUPLED. These outputs are controlled by the volume and balance controls. They are coupled for flat gain to DC. it is important that these outputs only be used with AC coupled amplifiers.

    MAIN OUTPUT – AC. These outputs are the same as those above except the signal is coupled through 10uF film capacitors. These outputs may be used with direct-coupled amplifiers.

    CAUTION; ONLY ONE OUTPUT SHOULD BE USED AT ANY GIVEN TIME. USING THE TWO OUTPUTS TOGETHER CAN CAUSE DAMAGE TO THE PREAMP OR AMPLIFIERS.

    I spoke with the engineer at Spectral and he advised that the DC coupled outputs ONLY be used with a Spectral amplifier. He said that even if the amplifier I am using IS DC coupled do not use the DC coupled output as it may be a mismatch with the Spectral DC coupled stage of the preamp.

    This link describes how I biamped my 1.2 TLs;

    http://www.polkaudio.com/forums/showthread.php?t=50391&highlight=biamped+1.2tls

    I hope this helps you with your problem. To summarize use a 'Y' connector on just one of your preamps outputs.
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  • tonyb
    tonyb Posts: 32,962
    edited July 2010
    Good call Joe, but we may never know for sure untill the OP gets a tad more specific on his connections.
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  • quadzilla
    quadzilla Posts: 1,543
    edited July 2010
    Just a suggestion for bi-amping. Instead of trying to run the tweeters on one amp and the woofers on another, just switch each amp to mono (not bridged) and use one amp to drive the left channel and one to drive the right. I run mine that way without problems, and I got more than a modest gain in sound quality. It also lets you avoid having to use splitters.
    Turntable: Empire 208
    Arm: Rega 300
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    Phono Pre: Aural Thrills
    Digital: Pioneer DV-79ai
    Pre: Conrad Johnson ET3 SE
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    Cables: Cardas Neutral Reference
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  • BrentAric
    BrentAric Posts: 9
    edited July 2010
    Sorry about the lack of clarity on my original post. The negative "black" wires are of course matched to their appropriate inputs on the amp. I typed the original while stressed out and wasn't thinking clearly.

    The Rotel manual says:

    "There are two sets of variable gain outputs on
    the RC-1070. The second set of outputs may
    be used in custom system configurations to drive
    a second power amplifier or to supply a sig-
    nal to a signal processor."

    There are three sets of inputs on the back of my Linn speakers. The top is treble, the middle bass, the bottom bass. The middle and bottom are connected with jumpers. According to the Linn dealer the jumpers should only be removed if I am tri-amping with a Linn Aktiv system. When going Aktive, the dealer (or me) would disable the internal crossovers. Does that sound logical?

    Quadzilla, I don't think my Adcom GFA 535's can be made mono, can they? That is a nice option, but I don't think I can make them mono.

    Is it possible that both amps coming on at the same time (the Rotel line conditioner turns them on at the same time) is the problem?

    THANKS for all the input. I appreciate all of it.

    Brent
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  • hearingimpared
    hearingimpared Posts: 21,137
    edited July 2010
    BrentAric wrote: »
    The Rotel manual says:

    "There are two sets of variable gain outputs on
    the RC-1070. The second set of outputs may
    be used in custom system configurations to drive
    a second power amplifier or to supply a sig-
    nal to a signal processor."
    Brent

    The only thing I would add to that is, does the manual state that you can use both outputs simultaneously? Also, is there a switch that you may have missed on the back that allows the amps run simulataneously?

    Other than that I would check with the speaker manufacturer and make absolutely sure the jumpers are in the right place.

    If all else fails, try the 'Y' connector configuration.
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  • BrentAric
    BrentAric Posts: 9
    edited July 2010
    Disaster again.

    I just tried plugging everything into the line conditioner but turning things on myself. Turned on my sources. No problem.

    Turned on the treble amp. No problem.

    Turned on the bass amp...it blew.
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  • hearingimpared
    hearingimpared Posts: 21,137
    edited July 2010
    BrentAric wrote: »
    Disaster again.

    I just tried plugging everything into the line conditioner but turning things on myself. Turned on my sources. No problem.

    Turned on the treble amp. No problem.

    Turned on the bass amp...it blew.

    Have you tried plugging the amp directly to the wall outlets.

    Also, have you switch amps from bass to treble and visa versa and turned them on one at a time? If so did the same amp cause the blowout? If so you've got a problem with your one amp.

    I just thought of this although it's off the wall but do the Linns require common ground amplifiers?
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  • decal
    decal Posts: 3,205
    edited July 2010
    Quadzilla, I don't think my Adcom GFA 535's can be made mono, can they? That is a nice option, but I don't think I can make them mono.

    They can't.
    If you can't hear a difference, don't waste your money.
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  • george daniel
    george daniel Posts: 12,096
    edited July 2010
    Dunno if this helps, but this is my experience with bi-amping with 535's,,,pre out--used a "y" splitter-- one pair of red/black to each amp.L&R speaker connections to bass from one amp----one pair of speaker cables to tweeters,, be sure that you have the "jumper cables" removed from the speakers.In the end I settled for a pair of small tube monoblocks--but,,good luck and keep us posted.
    JC approves....he told me so. (F-1 nut)
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  • george daniel
    george daniel Posts: 12,096
    edited July 2010
    decal wrote: »
    They can't.

    you are correct sir,, the Adcom 535's are a dual mono amp,sweet little puppies too.
    JC approves....he told me so. (F-1 nut)
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  • quadzilla
    quadzilla Posts: 1,543
    edited July 2010
    Ah well.
    Turntable: Empire 208
    Arm: Rega 300
    Cart: Shelter 501 III
    Phono Pre: Aural Thrills
    Digital: Pioneer DV-79ai
    Pre: Conrad Johnson ET3 SE
    Amp: Conrad Johnson Evolution 2000
    Cables: Cardas Neutral Reference
    Speakers: SDA 2.3TL, heavily modified
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  • BrentAric
    BrentAric Posts: 9
    edited July 2010
    All:

    I'm ashamed to admit all it required, as advised, was removing the second set of jumpers from my Linn speakers.

    As we speak my kids are listening to Lady Gaga in the living room (no comment required) with both amps doing their jobs beautifully.

    I wish I knew how to post a photo, the end results looks great.

    In terms of sound, bass is more "gentle" and easier sounding and it images away from other sounds better. I broke out my MFSL Ultradisk of Rush's Signals album and the difference was very apparent.

    Thanks again everyone, very nice forum and people.

    Brent
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  • F1nut
    F1nut Posts: 50,552
    edited July 2010
    I knew it. Glad you're enjoying the improvement.
    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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  • Toolfan66
    Toolfan66 Posts: 17,240
    edited July 2010
    For the record I like Lady GaGa.. I find her CD to be very well recorded..

    Glad your up and running...
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  • george daniel
    george daniel Posts: 12,096
    edited July 2010
    Who is Lady gaga? Good to hear that you got it worked out.
    JC approves....he told me so. (F-1 nut)
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  • BrentAric
    BrentAric Posts: 9
    edited July 2010
    Okay, I'll admit it...I like her too. Quite a bit.

    Good call on the jumpers.
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  • frodaddy
    frodaddy Posts: 124
    edited July 2010
    You shouldn't allow Lady Gaga to break in the new amp, or it will sound awful for the rest of it's existence like Lady Gaga does.





    Obviously this is a joke :) I'm sorry for all of you that admitted you like her :P Jumper plates were my guess too.
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  • BrentAric
    BrentAric Posts: 9
    edited July 2010
    Oh that's okay. I listened to Spoon's newest album Transference on vinyl, the above mentioned MFSL copy of Rush's Signals, then my all time favorite album, Amused to Death by Roger Waters, which I'm lucky enough to also have an original master recording of.

    However, the new amp has also helped play a lot more Lady Gaga, Ke$ha and other stuff like that in the last 24 hours. I'm just happy my daughter wants to use our main stereo and not the little one in her room!

    Brent
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