Harman Kardon TA600
Documentation on the Harman Kardon TA600 is thin. Nearly everything recorded about it comes from one highly opinionated source, the DIY audio site Lampizator, which published an extensive teardown and critique of one unit. What little is known describes a feature-packed vacuum tube integrated amplifier, designed to drive the acoustically-suspended speakers made by KLH and AR (Acoustic Research). Those speakers were ubiquitous in American homes in its era.
The TA600 used a pair of EL84 output tubes per channel in an ultra-linear configuration, with three 12AX7 preamp tubes and a GZ34 rectifier. Power output is where the record gets murky: the Lampizator source lists 20W RMS per channel, though one conflicting reference mentions "36 watt" — but that figure appears to come from a page about the related TA260 model, so it should not be attributed to the TA600. Frequency response is documented as 18Hz–40kHz ±1.5dB, with a tighter 20Hz–20kHz ±0.5dB at 1 watt. The amplifier offered a generous array of inputs — two magnetic phono inputs (2mV and 3mV sensitivity), a tape head input (1.5mV), tuner, and aux — plus outputs for speakers, tape recording, preamp, and a headphone jack. Speaker impedance is rated at 8 to 16 ohms, and total gain is listed as 1000 (60dB). Tone controls are based on a Baxendall circuit, with bass and treble, a presence switch, and hi/lo filters all present on the front panel.
The same source is sharply critical of the design. The writer calls it "a great classic example of 'tons of features' philosophy of hifi," and takes aim at the presence switch ("the most useless feature of every amplifier ever made"), the hi/lo filters ("useless"), and the placement of the bass and treble controls in the feedback loop. The phono stage's 2mV sensitivity is described as far too hot for modern MM cartridges that output 4-5mV, and the output transformers are called a "bottleneck." The writer does concede the amp is "quite an old and well built amp" and "not bad." The reviewed unit came complete with its original wood cabinet.
Beyond this single review, almost nothing else is recorded. No production years, no original price, no weight or dimensions, and no corroborating sources have surfaced. The specs above should be treated as observations of one particular unit rather than factory datasheet values. The Fisher 500 family of receivers, for example, was described as a generation of products that required only adding a record player and loudspeakers, as noted in Vacuum-Tube-Valley (????, p.3).
Known Specifications
- Output tubes: 4× EL84 (2 per channel), ultra-linear
- Preamp tubes: 3× 12AX7; rectifier: 1× GZ34
- Power output: 20W RMS per channel
- Frequency response: 18Hz–40kHz ±1.5dB; 20Hz–20kHz ±0.5dB at 1W
- Inputs: phono 1 (2mV), phono 2 (3mV), tape head (1.5mV), tuner, aux
- Outputs: speaker, tape out, preamp out, headphone
- Speaker impedance: 8–16 ohms
- Designed for KLH and AR acoustically-suspended speakers
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