QUAD 306 Power Amplifier
The QUAD 306 was a power amplifier manufactured by the QUAD Electroacoustics Corporation of United Kingdom. Its power output rating is 50-watts per channel with an 8 Ω load, or 70-watts per channel with a 4 Ω load. It was typically used in conjunction with a QUAD 44 or QUAD 34 preamplifier control unit, QUAD FM4 tuner, and ESL63 loudspeakers. In comparison with the 100-watts per channel (at 8 Ω) Quad 405-2, the 306 was slightly less powerful, however still desirable.
Review
The 306 was a high-quality power amplifier utilising the famous Quad-patented current dumping technology, which they also incorporated into the 405, 510, and 520 amplifiers. This technology eliminates crossover distortion, and the need for quiescent current adjustment, thermal tracking, and transistor matching. At 50 W output and 1 kHz the distortion figure is 0.01 %, and at 20 kHz it is 0.03 %.
Capacitor Upgrade Service
Many firms provide a capacitor upgrade service, which definitely improves the sound quality and reduces noise. Capacitors usually do not last forever as the electrolyte within them dries out and even leaks. Over time, their performance degrades and they are not able to perform as when the amplifier was new from the factory. A typical capacitor upgrade service usually consists of fitting additional PPS capacitors to filter noise in critical areas. Upgrading capacitors within the signal path with high specification Mundorf Mcap Evo Oil, can improve the sound quality dramatically.
When the capacitors within the power supply have degraded, there is usually an increase of mains hum because they not able to smooth the current to the required amount. Usually replacing these capacitors with larger high-specification Elna Cerafine capacitors can make a dramatic difference to the sound quality and bring life back into a fading amplifier.
Specifications
| Model | QUAD 306 |
| Power Output | 50-watts (8 Ω load), or 70-watts (4 Ω load) |
| Distortion at 50 W | <0.01 % (at 20 Hz), <0.01 % (at 1 kHz), <0.03 % (at 20 kHz) |
| Dimensions | 321 mm × 64 mm × 207 mm |
| Mass | 4.62 kg |
Cost/eBay
The QUAD 306 is a superb British amplifier with wonderful sound and it is often for sale on eBay in the pre-used section. The price can vary because many owners upgrade their amplifiers with better high-specification capacitors, which are expensive. A highly upgraded amplifier with new expensive capacitors can cost as much as three to four hundred pounds, due to their desirability.