2A3, 300B as well as SV811 and SV572 are directly heated triode (DHT) tubes.
RCA introduced 2A3 in 1932 as a low-frequency amplifier tube. Today 2A3 is often found in the output stage of single-ended audio amplifiers. Despite its relatively low output power of 3.5W, 2A3 delivers that magical sonic signature unique to a directly heated triode tube.
Western Electric introduced 300B for phone audio amplification in the telephone system in 1938. 300B outputs 10W in a single-ended configuration. 300B delivers smooth and natural sound, especially when coupled with high-efficiency speakers.
SV811, SV572 Super Triodes
Svetlana SV811 and SV572 tubes are high output triodes. With Thoriated Tungsten filament and no getter, these tubes have a unique look. These tubes are the ultimate final evolution of audio triodes, and very deserving for special DIY audio amp projects with high aspirations.
- Shuguang 811A Matched Pair$49.50
- Sovtek 2A3 Matched Pair$113.30
- Sovtek 6A3 Matched PairOut of stock
- Electro-Harmonix 2A3 Gold Matched PairOut of stock
- Electro-Harmonix 300B Matched Pair$164.28
- Svetlana SV811-10 Matched PairOut of stock
- Svetlana SV811-3 Matched Pair$176.00
- Electro-Harmonix 300B Gold Matched Pair$221.12
- Svetlana SV572-3 Matched Pair$240.00
- JJ/Tesla 2A3-40 Matched PairOut of stock
- JJ/Tesla 300B Matched PairOut of stock
- Genalex PX300B Gold Lion Matched Pair$305.20