The headphone amplifiers are based on Texas Instrument TPA6120A2 chips, optimised for use with low-impedance headphones. The A-D converters comprise a pair of four-channel AKM AK5388s, while four Cirrus Logic CS4398s provide the D-A conversion. ![]() Texas Instrument PGA2500 digitally controlled microphone amplifiers are used for the first four inputs, with NE5532 op-amps handling more or less everything else. The Apollo’s internal electronics are constructed to a very high standard, with surface-mount components on three main circuit boards and a couple of daughterboards on the front and rear panels. I measured the Effective Input Noise (EIN) figure for the mic preamp to be -128.4dB, which is pretty good, if not class-leading, and the input impedance measured 2.7k. The frequency response for all inputs is ruler-flat, with the low-frequency 3dB roll-off at about 3Hz, rising to 75Hz with the HP filter switched in. The strongest mains-related harmonic is at 100Hz and measured about -105dBFS, with the bulk of the noise floor sitting around -125dBFS. The input noise floor spectrum is very smooth, with a distinct reduction in level above 3kHz. The inputs have a slight tendency towards odd-harmonic distortion when the levels are pushed towards 0dBFS, but at around -20dBFS the balance is very even and all distortion components are below 110dB. Harmonic distortion on the outputs is very low indeed (below 110dB), with evenly distributed even and odd components. The line inputs have maximum and minimum levels of +20dBu and -36dBu, while the corresponding instrument sensitivities are +10dBu and -38dBu. The first four preamps provide a 55dB gain range, giving maximum and minimum microphone input levels (for 0dBFS) of +6dBu (+16dBu with the pad) and -50dBu. The monitor output performance was a little below that of the line outputs, but only by two or three decibels on the dynamic range, S/N ratio and THD+N figures - a difference I attribute to the analogue gain-control circuitry employed. ![]() The THD+N figure is 107dB and the line outputs (from a digital input) performed similarly with a signal-noise ratio of 118dB (A-wtd) and THD+N figure of 106dB, which is well below 0.001 percent. ![]() For example, the AES17 dynamic range and signal-noise ratio figures for the line inputs (to a digital output) are 117dB with A-weighting (107dB without). My own bench tests matched the published figures very closely. Universal Audio claim that the Apollo performs as well as or better than interfaces costing far more, so naturally I ran a full series of bench tests using an Audio Precision system. Tape Op - the Creative Music Recording Magazine > Reviews > Gear > Apollo audio interface with real-time UAD processingĪnd this SOS review with mre real world specs on the components used Which is the case?Please read this Tape Op review which goes under the hood and describes the components used in the converters and preamps. Can anyone concur that they are the same quality as other "me too" preamps in modest interfaces? Like Steinberg MR816, Mackie Onyx, etc? Or, would you go so far to say that they are real outboard quality preamps that happen to be inside an Apollo? Like a Metric Halo unit. I can't seem to find much information about the true quality of the Apollo preamps.
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