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Thread: bi-amping c*ck-up

  1. #1
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    Default bi-amping c*ck-up

    I've been wanting to convert the hifi system to a bi-amping mode, using the two Cambridge Audio amplifiers I have, and connect them to my floor standing Usher 604's.

    I have also been 'rationalizing' my interconnects and LS cables, with all Cambridge Audio stuff, to, at least, give a stable datum for upgrading, if ever...

    So I bought some CA Symphony LS cable, which was wrongly advertised on ebay as 4 x 3 m lengths, turned out to be 4 x 3m lengths of double stranded. So I thought I could wire up one channel so that the existing silver plated copper conductors I have been using could be used for the tweeter alone, and I could run two pairs of CA Symphony to the bass/midrange units, and connect each pair to the A channel output or B channel switched output. I could then have one or two cables for the bass/midrange at the switch of a button, and the spare B channel can be for the augmented ribbon tweeter I'm going to add.

    Well, it was just c*ck-up after c*ck-up on my part. The CA Symphony cable is very poorly marked with + and -, but also a * every so often. So connecting up all the cable tripped the amplifier, time after time. Eventually, I gave up, and came back to it, today. With better light (and a fresh mind) I found I had connected A channel L to right channel B, and the + and - reversed on one of them. Today, all is well, sorted.

    Only one channel (one amplifier) connected, but sounding rather special already, a little hum from somewhere, but Stravinski's Pulcinella Suite (L. Bernstein, NY Phil, on CBS) sounding clear with more controlled bottom end. Still early days, but I'm expecting better soundds when the other channel is working.

    ps still in c*ck-up mode, left channel bass, right channel treble, such is life...
    Last edited by cat's squirrel; 15th September 2014 at 14:50. Reason: finger problems
    cheers.....Bryan

    http://qualia.webs.com/

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    What are you hoping to gain by this?

    Is it just more power?

    Ta
    20 years ago we had Johnny Cash, Bob Hope and Steve Jobs. Now we have no Cash, no Hope and no Jobs. Please God, don't take Kevin Bacon

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    probably not more power, but clearer sound, as each channel has only the respective part of the sonic spectrum to reproduce. I'll not be going the whole way with electronic crossovers, though!

    Already, I can hear a clearer sound, or, at least, I think I can... even only listening to one channel (bass and treble from same channel with Y-connector).
    Last edited by cat's squirrel; 15th September 2014 at 15:42.
    cheers.....Bryan

    http://qualia.webs.com/

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    Thumbs up

    things have settle a little more, and this morning I played some 'pop' records. Free (Tons of sobs), Carole King (Tapestry) and John Martyn (Grace and Danger). All sounded OK, but no cigar, with a little 3rd harmonic creeping in. Decided to go bach to basics, and put on the Brandenburg Concerti, (George Malcolm and the Northern Sinfonia on ASD).
    As I manipulated the tone arm, I thought that the overhanged seemed a little short. The set-up I have comprises a Lenco 75 turned sideways and on a separate arm pod, I have mounted, a Rega 250 arm. The arm pod is free to move, at the moment, so I have placed a pencil mark where the proper alignment should be. I find that I have two pencil marks, and I had aligned the pod against the wrong pencil mark! All is now as it should be, and the sound is getting better all the time. Now to get the other channel/s working, for stereo!

    ps still listening to the concerti, its that good!
    Last edited by cat's squirrel; 16th September 2014 at 12:28.
    cheers.....Bryan

    http://qualia.webs.com/

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    with a mile of cable under the rack from a previous den, when i worked for JA, I once wired the left channel of a Mac MC275 power amp, to the right channel, no sound from speakers, but strangely there was sound coming from somewhere, and it was volume dependant, it turned out that the valves (or their glass envelopes) where the source, it was weird, sounded like the music coming from a telephone earpiece, easy done if done in a hurry.

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    ps you're lucky your amp cut out, one of my colleagues did something similar to a Bryston $bsst power amp, result…loss of magic smoke from one channel

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    owchhhh!

    I know my Cambridge Audio amps are not the last word, but they do have some advantages for people like me (and others, it seems). I once connected up a tweeter (with crossover) to the output, and wound up the power. The amp didn't like the load, but I was astonished to see the amp wind its own volume knob back to safe levels, I kid you not!

    I have placed big red arrows on the volume knobs to see the position of the things, especially as I have used the amps for PA duty on am dram nights!
    Last edited by cat's squirrel; 16th September 2014 at 12:33.
    cheers.....Bryan

    http://qualia.webs.com/

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    If I could figure out how you've wired things up I'd comment on it. Having two mono power amps here confuses the hell out of me and I once managed to get those the wrong way round. Nothing much wrong with CA gear, it does what it says on the tin but it will never be spectacular.

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    I have two CA stereo amplifiers. I have only set up one, ATM.

    For each channel, I have three stereo (pairs) cables. One set, which are silver plated, go from one channel (call it left) to the tweeter terminals on the 'speaker.

    For each channel I have two lengths of stereo copper conductors, which are wound together at the 'speaker end, and connected to its mid/bass terminals. At the amplifier end, one set goes to the right channel.

    Now the tricky bit. One of my CA640v2 amplifiers, each channel of each amplifier has two sets of terminals, one set (A) is always in circuit, but the second set of terminals can be switched in or out from the front panel. So I have connected one of the bass pairs to the A terminals, and one to the B terminals, which can be switched in if wanted.

    A further complexity arises as I want to add a super tweeter, and this will be connected to the switched B terminals feeding the extant tweeter.

    All this will be repeated (without the c*ck-ups, I hope) for the other 'speaker/amplifier.

    So far, and with only one channel connected, I have convinced myself there is definite improvement, but time will tell.

    HTH
    cheers.....Bryan

    http://qualia.webs.com/

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    today I have managed to wire up the other channel, with no problems this time, worked first time!!

    I am listening to Beethoven's late string quartet (Opus 131) and it's sounding better than ever before. Everything sounds so natural and unforced. Sound depth has increased, and I have a string quartet just behind the fire place (each side of which sits a 'speaker.

    And this is with my cAT92e cheap (14) cartridge. What would I get with my DL110 or 10x5 I wonder?

    Forgot to mention, I mislaid my tiny scales I use for measuring tracking weight. So I guessed at the setting, I wanted 1.50g. I found the scales and checked, 1.58g, so not bad.
    Last edited by cat's squirrel; 14th October 2014 at 16:57. Reason: extra bit
    cheers.....Bryan

    http://qualia.webs.com/

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    Makes you think, doesn't it. Great reproduction doesn't need to be expensive (said the bishop to the actress).

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    always impresses me how some inexprensive components can sound so good. But also, how some expensive stuff doesn't live up to it's billing. However, for a lot of the time, we get what we pay for.

    Heard a system comprising a master tape (copy 1st generation) on a pro Studer R2R, feeding a couple of the 音楽 (ongaku) amplifiers (at 21k a pop) into Quad 57 electrostatics. The result was pants!!
    Last edited by cat's squirrel; 15th October 2014 at 00:09.
    cheers.....Bryan

    http://qualia.webs.com/

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    system still sounding very good, and it's so handy to be able to adjust things that are not possible with just one stereo amplifier, like remotely controlled balance (separate volume of each stereo channel) and treble/mid band-bass levels.

    My feelings are that with the new set-up, bass is better and articulation improved, but some records have been found not to be as good as was once thought, though others sound better than before.
    cheers.....Bryan

    http://qualia.webs.com/

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