Monitor 3, Identification needed

Read more on the Acoustat Monitor 3 in our home audio section

Mike Savuto2004-02-23 22:21

The version of Monitor 3 you are describing was, as Andy said (below), an early 80\'s model. I believe in late 1980 or early 1981 Acoustat changed the design of the 3 panel speaker from the original wood cabinet ”X” to the style of Monitor 3 you have. They also changed the Monitor 4 speaker to the same configuration, eliminating the plastic base and the complicated stand. (To the best of my knowledge there was not a Monitor 3 version with the a plastic base like the original Monitor 4.)

One interesting point is that Acoustat made a novel subwoofer base stand for the original Monitor 4 that allowed owners to mount the panel array directly on top of the sub. This stand was marketed for and most often used with the RH Labs subwoofers. This made an attractive combination although I never heard them used together. It was also at that time that the Monitor ”3” and Monitor ”4” designations became official.

Your version was the only 3 panel Acoustat speaker available with either the original Servo-Charge amplifier or the first version of the MK-121. The same was true for the companion Monitor 4. 1980 to 1981 was the transition period for Acoustat with the introduction of the Magnetic Kinetic Interface and the phasing out of the Servo-Charge amplifier. By the end of 1981 the last of the Servo-Charge amplifiers had been built by Acoustat. Term ”Monitor” became associated with the Servo-Charge amplifier driven models and ”Model” became the designation for those driven through the later MK-121 interface.


Chuck Knapp2004-02-23 22:21

Andy, thank you for all the wonderful information on Acoustat. My question is: What is it I bought ten years ago? Mine apear to be some variation on the Monitor 3. There are three 4\' high electrostatic panels, the narrower one in the middle. They are in a frame 7 1/2” deep (across the wood cap) and arranged with the outer panels at about a 10 degree angle to the middle one. The overall dimensions are 60” x 29” wide, including the bottom wood cap which is the same as the top. The grill cloth goes all the way to the bottom (no wood panel in front). They have the original (very wide) MK-121 interface. Are they a variation of the Monitor 3? Could you guess at the production dates?

I\'ve driven them with old Amber Series 70 amps, from a small now defunct \'high end\' mfg. here in Virginia, with the amps in bridged mono mode. These amps have very high current output transistors, a huge poewer transfomer, and no protective security except for speaker and power supply rail fuses. Not really high end sound quality, but robust and not afraid of the low impedience. I\'m now using a Soundwave Fidelity Symphony 2 MOSFET amp, which also seems happy with the load and sounds better. Speaker placement is very difficult, and they\'re beamy, but the sound quality, at least for classical music, is very satisfying. Chuck Knapp

Andy Szabo2004-02-23 22:21

Your Acoustat speaker was discontinued long before I joined the company, so I am at a disadvantage in answering your question.

My best guess is that you have a Monitor Three. It appears that the Monitor Series had at least two major variants. One version has a molded plastic pedestal, as shown under ”Brochures, Monitor 4”. (I am assuming that the Monitor Three was also available in this configuration.) The transformer interface (or servocharge amplifier) mounts inside that pedestal. The other version, which I believe you have, uses a similar frame structure, but without the pedestal. This is the version shown under ”Manuals, Monitor 3 & 4”, where the interface (or servocharge amplifier) sits on a metal platform at the rear of the speaker.

I do not know which version came first. It is also possible that the pedestal was an option. In any case, your speaker was likely manufactured in the early 1980\'s.

Can someone else provide a more complete answer?

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