Harman Kardon SR-900B (1966)

A hundred watts of germanium-transistor Stratophonic sound, sold through magazine pages and confirmed by almost nobody else.

Overview

The SR-900B survives in the record mostly as an advertisement. Harman-Kardon put the "B" Series into print across early 1966 - Audio (March 1966, p.33) and High Fidelity (January and June 1966) carried the Stratophonic line. The SR-900B sat at the top of it as an all-transistor FM stereo receiver, the upgraded "B" version of the earlier SR-900. What the Archive has is largely the manufacturer's own copy. Read it the way you'd read a period ad: specific, useful, and not independently corroborated.

The headline claim was 100 watts. Harman-Kardon advertised it alongside a power bandwidth of 5 to 60,000 cps at full rated output and distortion of 0.2%. The argument was that the receiver held its bandwidth and its composure at full power, not just at a watt or two where any amplifier looks good.

The one piece of independent confirmation comes from HiFI-Stereo's new-products column (May 1966, p.30). It reported that Harman-Kardon had upgraded the SR-900's output to 100 watts. It also noted the new B version's bandwidth at 50 watts per channel ran from 5 to 100,000 cps, with the tuner section unchanged from the original. That is a different measurement condition than the ad's full-rated-power figure, so keep the two apart. One describes the receiver at its ceiling, the other at 50 watts per channel. Both are period claims, and neither is a lab report.

Key Features

100 Watts, Advertised as Usable Power

The rated output was 100 watts, and the framing is the interesting part. Harman-Kardon claimed the receiver's flat frequency response at full 100-watt power exceeded what competing receivers managed at one watt. Most amplifiers are flattest when barely working, and the SR-900B was being sold on staying flat when pushed. Treat it as a manufacturer's claim, because no independent test bench figures have surfaced to confirm or refute it.

5–60,000 cps Power Bandwidth at Full Rated Output

The advertised power bandwidth was 5 to 60,000 cps at full rated power. That is a very wide window for 1966, and it ties to the germanium output devices Harman-Kardon was promoting. Whether the receiver held that bandwidth at 100 watts in a customer's living room is undocumented. The figure is the manufacturer's, so hedge it.

5–100,000 cps at 50 Watts per Channel

The independent figure on record is the one HiFI-Stereo (May 1966, p.30) reported: at 50 watts per channel, the SR-900B's bandwidth ran from 5 to 100,000 cps. That is a lower power point and a wider window than the ad's full-power claim, which is what you'd expect from an amplifier whose response narrows as output climbs. It is the more believable of the two numbers because the measurement condition is more modest.

0.2% Distortion

Harman-Kardon advertised 0.2% distortion for the SR-900B. No test report in the available record verifies that figure, so it remains a manufacturer's claim - respectable on paper for an all-transistor receiver of the period, unconfirmed in practice.

All-Transistor Stratophonic Design

The SR-900B was an all-transistor receiver, part of the Stratophonic "B" Series, and Harman-Kardon made the transistor story central to the pitch. The company's argument was that the design delivered the wide bandwidth and low distortion the ads promised while running cooler and more reliably than the alternatives. Solid-state receivers were being sold on the strength of their output devices.

Stereo in One or Two Rooms

One of the more practical claims in the advertising was that the SR-900B could deliver stereo to one or two rooms, separately or simultaneously. It reads as a period curiosity now. In 1966 it was a real selling point, since a household might want the same source in the living room and the den without a second receiver.

Tuner Section Carried Over from the SR-900

Per HiFI-Stereo (May 1966, p.30), the tuner specifications were unchanged from the original SR-900 — the "B" upgrade was about the amplifier, not the front end. The specific tuner figures are not enumerated in the surviving sources, so the practical takeaway is simply that buyers of the B got the same FM performance as the earlier model, with more power behind it.

Historical Context

The SR-900B was the upgraded "B" version of the earlier SR-900 and a member of Harman-Kardon's Stratophonic "B" Series. Its sibling in that line, the SR-600B, was rated at 80 watts IHF music power. It is a separate model, so keep it distinct from the 900B when sorting through listings or literature. The B Series was promoted across early-1966 audio publications, with advertising in Audio (March 1966, p.33) and High Fidelity (January and June 1966). The only independent notice the Archive has located is the HiFI-Stereo new-products item (May 1966, p.30).

Collectibility & Value

The market for the SR-900B is sparse and the data is thin. At the time of the Archive's research, no exact SR-900B listings were live on eBay. A "Harman Kardon SR900b Stereo Receiver -asis- Not Tested" example was recorded at $425 in November 2025, and a listing described as "perfect condition, for a collector" has appeared without a price attached. Treat those as anecdotes rather than a price guide. One untested unit and one collector-grade unit do not make a market.

Service literature is the more useful find for an owner. Schematic diagrams and service manuals for the SR-900B do exist, and an operation manual has been listed for sale. No common failure points, maintenance procedures, or parts availability information surfaced in the research, so anyone buying one should assume the usual risks of a sixty-year-old solid-state receiver without a known-issues list to work from. Beware listings that name a "900+" or similar designation. Those are different model numbers and should not be conflated with the SR-900B.

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