Scott 99D (1964)
The Scott 99D is a vacuum tube preamplifier introduced in 1959 by H.H. Scott, Inc. Scott was known for high-fidelity engineering. The 99D is less widely known than some of its contemporaries from Marantz or McIntosh, but it has a devoted following among audiophiles and vintage audio collectors for its sound quality, its design, and its engineering.
Historical Context and Design Philosophy
Hermon Hosmer Scott founded H.H. Scott in the late 1940s. The company was among the first to apply rigorous measurement techniques to audio equipment design, aiming for low distortion, wide frequency response, and high stability. The 99D, released in 1959, represents the end point of Scott's tube-era philosophy: transparency, linearity, and reliability.
Scott positioned the 99D as a high-end preamplifier in its lineup. It was designed to pair with power amplifiers such as the 299 or 210 series, and it was part of a broader group of Scott components built around modular compatibility. The 99D replaced earlier models like the 98D, with changes to circuit layout, power supply filtering, and user interface.
Technical Specifications and Circuit Design
The Scott 99D is a dual-mono, all-tube preamplifier with a fully balanced differential input stage followed by an unbalanced output stage. It uses five vacuum tubes: three 12AX7 dual-triodes for voltage amplification and two 6X4 rectifiers for the power supply. The differential input stage gave excellent common-mode noise rejection, which was a rarity in consumer preamplifiers of the era.
Key specifications include:
- Frequency Response: 10 Hz – 100 kHz (±0.5 dB)
- Total Harmonic Distortion: Less than 0.1% at rated output
- Input Sensitivity: 150 mV for rated output
- Output Voltage: 2 V RMS maximum
- Input Impedance: 1 MΩ (adjustable on some versions)
- Output Impedance: 600 Ω
- Channel Separation: Better than 60 dB at 1 kHz
- Signal-to-Noise Ratio: Greater than 80 dB (A-weighted)
- Power Supply: Tube-rectified, multi-stage RC filtering for low ripple
The 99D has multiple line-level inputs, including Tuner and Auxiliary, each with an individual level control. The exact number and labeling varied by source. The phono stage is designed for moving magnet cartridges and has switchable equalization for both 78 RPM and 33⅓/45 RPM records, so it handles a wide range of vintage vinyl. The RIAA equalization network is passive and precision-tuned, which contributes to a warm yet detailed sound.
A unique feature of the 99D is its stepped attenuator volume control, which uses a precision rotary switch and resistor ladder network rather than a potentiometer. This design ensures precise channel balance and long-term reliability, as it avoids the wear and channel imbalance common in potentiometers over time.
The front panel has a large VU meter that switches between input and output levels. That is rare in a preamplifier, and it suits users who want technical feedback.
Build Quality and Aesthetic
The Scott 99D has a heavy-gauge steel chassis, a brushed aluminum front panel, black enamel side cheeks, and a clear plexiglass top cover that shows the tubes and internal components. That cover was a hallmark of Scott's premium models. The layout is clean and functional, with large, clearly labeled knobs and switches.
The internal construction is point-to-point wired with paper-in-oil capacitors, carbon composition resistors, and custom-wound transformers. The power transformer and output transformer are potted to reduce microphonics and hum, which helps keep the noise floor low.
Dimensions: 8.5" W × 3.625" H × 20" D
Weight: Approximately 22 lbs (10 kg)
Sound Characteristics
The Scott 99D is known for a full-bodied midrange, extended highs, and tight bass control. These qualities suit jazz, classical, and vocal recordings. The tube design adds a slight harmonic richness without sacrificing clarity, a balance between warmth and accuracy that many modern solid-state preamplifiers struggle to match.
Users often describe the 99D's sound as “effortless” and “organic,” with a spacious soundstage and excellent instrument separation. The phono stage is praised for pulling detail from vinyl without harshness, and it is a favorite among analog enthusiasts.
Legacy and Collectibility
By the late 1960s the market was shifting toward solid-state electronics, and Scott eventually phased out its tube models. The 99D was discontinued around 1967 and succeeded by solid-state designs like the 399. Collectors now seek it out, especially in working condition with original tubes and minimal wear.
Original Scott 99D units in good condition can command prices from $800 to $1,500, depending on provenance, cosmetics, and functionality. Restorations are common. Many technicians replace aging capacitors and upgrade power supplies while keeping the original circuit topology.
The 99D's influence can be seen in modern high-end preamplifiers that emphasize balanced design, precision attenuation, and low distortion. Few contemporary manufacturers use tube rectifiers or differential input stages in consumer gear, and the 99D remains a benchmark for what analog preamplification can achieve.
Conclusion
The Scott 99D is more than just a vintage preamplifier—it is a testament to a time when audio engineering was both a science and an art. Its meticulous design, superb build quality, and enduring sonic excellence have secured its place in the pantheon of classic American hi-fi. For collectors, restorers, and audiophiles alike, the 99D offers not only exceptional sound but also a tangible connection to the legacy of H.H. Scott and the golden age of vacuum tube audio.
Market Value
┌──────────────────────────────────────────────────────────────────────────┐ │ SCOTT 99D Nov 2026 │ ├──────────────────────────────────────────────────────────────────────────┤ │ High $460 Latest $295 │ │ Median $263 Trend — │ │ Low $10 Volume ~1/mo │ ├──────────────────────────────────────────────────────────────────────────┤ │ $500 ┤ │ │ │. │ │ │ │ │ $286 ┤ . .│ │ │ . │ │ │ │ │ │ . │ │ $0 ┤ . . │ │ ├─────────────────────────────────────────────────────────────────│ │ vol │▄▄ ▄ ▄ █ ▄│ │ └─────────────────────────────────────────────────────────────────│ │ 2026-02 2026-05 2026-08│ └──────────────────────────────────────────────────────────────────────────┘
eBay completed sales. Excludes accessories, parts, and non-working units. Hover points for details.
eBay Listings
Recently sold on eBay: $41–$295 (median $263, based on 7 completed sales, past 12 months)
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.
Related Models
- Scott 310E (1969)
- Scott 330D (1965)
- Scott 370 (1973)
- Scott 399 (1969)
- Scott S-15 (1957)
- Eico 3150 (1967)
- Fisher CUSTOM-ELECTRA-I (K-14/K-15) (1957)
- Fisher CUSTOM-ELECTRA IV (E33/E44) (1960)
- Akai AM-2400 (1978)
- Akai AM-2600 (1977)