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Hand-Assembled · 3-Year Warranty
Every Diadem Tone unit is hand-assembled one at a time using carefully selected components, and is individually quality checked before it leaves the factory. That's why Diadem Tone backs every product with a 3-year warranty.
Diadem Tone DT-2A Optical Tube Compressor
Some compressors grab. The DT-2A glides. It is a single-channel optical valve leveling amplifier built on the classic 2A architecture, delivering the smooth, natural gain reduction and valve warmth that have made this style of compressor a studio staple for decades.
At its heart is Diadem Tone's own enhanced DT-T4 optical cell, designed for extended high-frequency response and exceptionally smooth compression. Four valves carry the signal: two 12AX7s for gain and harmonic texture, a 12BH7 for robust, low-distortion drive, and a 6AQ5 that adds thickness and warmth at the output. Careful circuit design and component selection give it a noise floor of -90 dB, so it stays clean even at high gain.
What the DT-2A Recreates
The LA-2A leveling amplifier appeared in the early 1960s and is one of the most recognisable compressors ever made. Rather than a transistor, it uses an optical cell: a light source and a light-sensitive resistor inside a sealed module. As the signal gets louder, the light glows brighter and the resistor turns the level down. That optical process reacts in a naturally smooth, program-dependent way. It has a fixed 10 ms attack and a two-stage release, recovering the first half of its gain reduction in about 60 ms and the rest over 0.5 to 5 seconds, depending on what you feed it.
Why Engineers Still Reach for It
The 2A is loved because it is both musical and simple. There are really only two knobs: Peak Reduction sets how much it compresses, and Gain sets the output. Yet the results sound polished almost instantly. The optical cell never clamps down harshly. It gently levels a performance so it sits consistently in the mix, while the valve stages add a warmth and density that make sources sound finished.
What to Use It On
- Vocals – its signature application. Smooth, transparent leveling that keeps a vocal present without sounding squashed. For the classic combination, follow a DT-76: the FET catches the fast peaks, and the DT-2A evens out the overall level.
- Bass – holds bass guitar and synth bass steady and full, with valve weight in the low end.
- Acoustic instruments – acoustic guitar, piano and strings get gentle control that preserves their natural dynamics.
- Buses and stems – light gain reduction on a vocal or instrument group glues parts together without obvious pumping.
- Tracking – its forgiving response makes it a safe, great-sounding choice to record through.
A fast FET compressor and a smooth optical compressor are two of the most useful tools any studio can own, and each does what the other can't. The DT-2A brings genuine optical compression and a four-valve signal path to your rack, with the hands-on simplicity that lets you set it by ear and get back to the music.
Front Panel
- Gain – sets the output level
- Peak Reduction – sets the amount of compression
- Compress / Limit switch – selects compression or limiting mode
- R37 – trim adjustment
- Meter – VU meter switchable between Gain Reduction, Output +10 and Output +4
- Power switch
Specifications
| Type | Single-channel optical valve compressor |
| Optical Cell | Diadem Tone enhanced DT-T4 |
| Valves | 2 × 12AX7, 1 × 12BH7, 1 × 6AQ5 |
| Attack Time | 10 ms |
| Release Time | 0.06 s for 50% release; 0.5 to 5 s for complete release |
| Gain | 40 dB |
| Frequency Response | 15 Hz to 20 kHz |
| Total Harmonic Distortion | < 0.5% |
| Noise Floor | -90 dB ±5 |
| Input Level | +16 dB |
| Output Level | +10 dB nominal, +16 dB maximum |
| Input Impedance | 600 Ω (balanced) |
| Output Load Impedance | 600 Ω (balanced) |
| Connections | XLR |
| Power | 115 / 230 VAC, 50–60 Hz |
| Size | 19″ rackmount, 3U |
| Weight | 5.5 kg |
| Warranty | 3 years |
LA-2A is a trademark of its respective owner and is referenced for descriptive purposes only.
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