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 Post subject: Musical Fidelity 550K
PostPosted: 03 Jul 2011, 17:22 
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Joined: 06 Jun 2008, 18:23
Posts: 4987
Location: Australia
Music Fidelity 550K: I was asked to convert a pair of Music Fidelity 550K tower monoblock amps from 115V to 240V. It should have been a simple job of removing the top and bottom plates to make the change. The power tranni primary is center tapped. But getting to the switch to change these two wires over was extremely difficult. Taking a look inside there was about 8 FETs down both sides of the heat sink. Some control and monitoring electronics on a back board and PS below all of that.

Though rated at 1000W into 2ohms the power tranni was way too small. The amp should deliver 500W without too much trouble. I had a quick listen by powering up the amps and connecting with my Oppo SE, single stage tube pre and connected to my very efficient Osbourn three way towers. Good bass as you would expect with good control. Clynical though and not fat and rounded. Mids were bright and the treble a little edgy. These amps had not been used for a while so some re-burnin may be needed. Yes they would play excessively loud and I wound them up a few times just to prove it.

Not an amp for me but for Kumar, for whom I did the work, who plays a lot of Rap and Rock these would be ideal. $10K amps to buy in Australia but Kumar got them for a song and a little whistling.

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Projects: "Grace" - Psvane 6SN7-SE Globe preamp | | "VoXUno" - Single driver MarkAudio 12P speaker | | "Lagoon Take 2" - Single stage tube preamp | Website: retro-thermionic


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PostPosted: 03 Jul 2011, 20:05 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Stereophile measurements - 500W into 8 ohms. Good guess. ;)

Cheers

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