DACS MicAmp is a 2 channel discrete-component-based microphone amplifier. The triple ultra low noise matched-pair transistor input stage is a high current circuit. This gives a transparency, warmth and depth, particularly at low levels, similar in character to the very best of valve circuits, but without the unavoidable noise generated by such circuits.
The first question people ask is "Does it sound good?". The answer in tests has been an unequivocal "YES!". One engineer tried it out while recording a jazz album. He plugged it in and ended up recording the vocals for the whole album. He loved the sound of it, particularly when it was working hard. Another MicAmp, in the hands of a seasoned classical engineer, rapidly notched up two Hyperion releases. In direct comparison with other microphone amplifiers he owns, and he owns many of the best and most prestigious, he found only one, (no longer manufactured), whose performance he considered to be on a par with the DACS MicAmp.
The MicAmp is very straightforward to set up and use. The main gain setting is via a self cleaning rotary switch in seven 6dB steps from +20dB to +62dB. There is also a 0dB to +10dB trim with 19 scale marks to allow accurate repetition of settings. For bass roll-off there is a very smooth two stage high pass filter which gives no coloration.
Two microphone inputs are provided for each amplifier, one with 48V phantom power and one without. The non-powered inputs by-pass the high value polyester (far better performance, matching (5% not 20%) and longer life than electrolytic) input capacitors necessary to block the 48VDC. This minimises the signal path for non phantom powered microphones, and gives a bass response flat down to DC. Low frequency response for the phantom powered input is absolutely flat to below 20Hz, with sub-sonic roll-off at 6dB per octave. The high frequency response reaches its -3dB point around 48kHz. The input stage has very fast protection that prevents expensive damage to the amplifier by over-voltage or phantom power short circuit.
The DACS MicAmp's metering consists of a unique tri-segment LED which one field tester said gave him the clearest sense of the signal level he'd seen on such a piece of equipment. It also includes an ultra bright overload LED which remains on for a few seconds, ensuring that if an overload has occurred you don't miss it.
It has ultra low noise performance. Some other well loved amplifiers add coloration ("glitter" as it was described by one field tester in a comparison) that sounds 'good', but for sheer accuracy the DACS MicAmp is hard to beat. This accuracy is not 'clinical' but 'real' - one user said it was when the sound didn't change as he moved between the recording space and the control room that he realised how good the unit was. Others have found that the usual equalisation they used to liven up the sound was no longer required.
The common mode rejection ratio (CMRR) of an amplifier like this is a measure of its ability to reject induced signals in the microphone cable; the higher it is the better. Values for the DACS MicAmp vary with gain, giving higher rejection ratios at higher gains. The CMRR of each DACS MicAmp is individually trimmed using low-noise multi-turn cermet trimmers and high quality polyester trimmer capacitors, resulting in unparalleled and stable performance.
The feedback loop of the main amplifier stage and the electronically balanced output use silver mica capacitors; they are of a very close tolerance (1%) and ensure high frequency stability and balance. The balanced output is trimmed to very close match using another low noise cermet multi-turn trimmer set up through a test rig using .1% resistors to ensure very accurate output. These trimmers, also used to trim the mid-range CMRR, have a resistive element and wipers far wider than standard multi-turn trimmers, giving more stable, and less noisy performance over a very long lifespan.
The operational amplifiers (op-amps) used throughout are extremely high specification ICs. They are designed and optimised specifically for audio use with dual rail power supply, and have very high slew rates and are capable of driving with full voltage swing into 600R lines at all audio frequencies.