2 plus 2, Driving with two ML-3's

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Robertsabelis2007-07-13 00:41

Is it possible with two bridged Levinson ML-3\'s (dual mono concept with big toroids and capacitance) two drive the Acoustat 2 + 2. I\'m still contemplating what would be the most efficient way to exploit a second amp into my system. Bridging the amps is technically possible but maybe even the load that a Acoustat presents at the high frequencies is to much for a bridged ML-3. Mono parallel configuration would be ideally but I do not now if that\'s wise/possible with this amp. Biamping could be the savest solution it leaves the amps as the are but there will be some hardware work on the interfaces and another speakerwire pair would be needed. Second, as for biampliifing, I measured and thought the most of the energy goes to the mid/high trafo while the impedence of the Acoustat goes down when the frequenz=cies risis. When I play Norah Jones with lots a bass and her voice I measure definitely the most current when she raises her voice. Should the fuse then not be situated at that region, I mean at the mid/high transformer connections? Thanks in advance


Andy Szabo2007-07-27 23:49

I\'m not a big fan of bridged-mono amplifiers, especially when driving a difficult load like an ESL. The problem is that each half of the bridged amp \'sees\' only half the load impedance. So, with the Acoustat, you may be loading each half of the bridged amp with as low as 1-ohm at certain frequencies. That said, the ML amps are probably better than most at tolerating low impedance loads. I\'d check with ML to see what they have to say. The circuit location of the audio fuse in the stock interface is sufficient to protect both audio transformers, as well as the amplifier. If you were to bi-amp, I would suggest a fuse be used in both high and low frequency circuits. When you say \"mono parallel configuration\", if you mean connecting two amplfier outputs in parallel across a single loudspeaker load, this is a very bad idea. This will present an effective short circuit on each amplifier, with resulting smoke and sparks (or at least fuse blowing). Don\'t even try this with somebody else\'s amplfier :).

Robert Sabelis2007-08-20 00:10

What I ment with mono-parallel configuration ia that the ML-3 stereo-amp will be setup as a no 20. or Threshold SA/1 or the older Stasis 1. So not inverting but paralleling the 40 outputtransistors together to get not more Voltage gain but increasing the currentcapability. The multichannel Jeff Rowland MC-6 can be converted by that way from a 6 to a stereo- or even monochannel amp. The safest option anyway would be the semi-biamplifing solution you mentioned before. I bought the speakers new in 1990 so I do have the original schematics supplied wit the Owner\'s manual which should help me out with the proposed option of biamplifying. Maybe there\'s a more detailed description possible from you i time to get it working. Thanks for your answer

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