Comments: As can be seen from the power output numbers the 2800E is actually an unregulated design. However the amplifier does make respectable power output; it is either higher or lower than claimed depending upon how you look at it. The results for damping factor and THD are indicative of a high feedback design; DF is high and THD is very low. The bass boost circuit appears to offer +15 dB of boost at 55 Hz, slightly different from the claimed numbers; but it's nothing much to worry about - if you need more than 15 dB of boost at 55Hz then something else is wrong! As for the crossovers on the 2800E - neither the frequency ranges nor filter alignments are accurate. In fact the Q of the filters appears to change significantly as the frequency control is rotated, changing from under damped to over damped response. This is can certainly detract from the overall sonic quality in some instances. The actual response curves can be seen in figures (3) & (4). Overall bench performance was fine with the exception of the crossover filters.
ConclusionThe 2800E from an overall standpoint is an interesting design cosmetically as well as from an engineering standpoint. It is relatively well built and has decent electrical performance, aside from the performance of the crossovers. From a sound quality standpoint the unit faired quite well. There are no real weaknesses. The bass sounds have a tight and dry feel to them, and are not quite so effortless and deep sounding as some other models. Midrange and treble sounds are detailed and quite articulate, sometimes bordering on a cold and non-involving nature. It is fair to say that the nature of sound is one intrinsic of a high feedback design. Not a bad package.
| Performance Testing |
| Output Power: |
| | 10.5V | 12.0V | 14.4V |
| 4 ohms | 126.6 | 162.6 | 237.2 |
| 2 ohms | 174.8 | 231.2 | 332.8 |
| All above measurements taken just below visible clipping. |
| Damping Factor: | |
| 231 | measured at 1 kHz with a 4 ohm load. |
| Gain Range: | |
| Max | 36.5 dB |
| Min | 6.3 dB |
Protection: Protection circuitry latches requiring power cycle to reboot. Bass boost: +15 dB at 55Hz, see figure (1)High pass filter: -3 dB at approximately 100 Hz and 500 Hz, slope appears to be 12dB/oct.Low pass filter: -3 dB at approximately 65 Hz and 140Hz.THD+N: 0.035%, see figure (2)