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Aphex 228 Unidirectional Level Interface

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Aphex 228 Unidirectional Level Interface

The Aphex 228 is a BIG problem-solver--I cannot operate my studio without it. It is an eight-channel -10dBv to +4dBu audio level converter--commonly known as a "bump box." It allows consumer electronics, that normally operate at unbalanced -10dBv levels, to be freely interfaced into the balanced, +4dB pro audio world of recording studios, video post-production editing suites, and high-end home theatres.

It replaced two Aphex 124A units I had borrowed and losing them crippled an important part of my studio workflow. In order to listen to my mixes as mp3 versions in iTunes, I had used the Aphex 124A units to jump the level coming out of my Mac up to the +4dBu level my Cranesong and KRK Ergo monitor controllers require. That way the level (and loudness and sound) coming from the Mac matches, as close as possible, the song's mix playing directly out of Pro Tools HD. I don't have to crank up the volume to try and match loudness and that is hard to do consistently! This ability also aids in comparing my mixes to what I hear or download from iTunes and other places on the Web.

The Aphex 228 retains the two-channel Aphex 124A's high definition servo-balanced circuits but has eight channels total of -10dBv to +4dBu conversion only (none of the 124A's +4dBu to -10dBv conversion that I didn't ever used anyway). With eight channels or four stereo pairs, I use two channels for the Mac, two for my HD TV audio so I can play it over my studio monitors (yowsa!), two more for a -10dBv level coming out of a vinyl turntable (remember those things?), and the last two are a duplicate of the Mac audio so I can route Skype audio from the computer back into a Pro Tools session for a remote record producer's talkback audio.

The 228's front panel has an extended range VU meter to read the exact +4dBu level, eight separate trim controls to calibrate each of them but know that a -10dBv input exactly produces a +4dBu output at a full CW setting. Then there is a meter select button to switch the meter to measure any of the eight channels, and eight, two-color signal presence/clip indicators let you know instantly if any sound is present on any channel or if an overload occurs. The same button toggles all front panel lights to dim for home theater installations.

Rear panel jacks on this single rack space unit include: eight unbalanced RCA input jacks, eight balanced, XLR line output males, plus an IEC power connector for the built-in AC power supply.

Other specs are: gain translation at 11.78 dB adjustable 6 dB, frequency response is rated at -3dB from 0.16 Hz to 80 kHz (wow!), THD at max output is less than .001%, IMD at max output less than .001%, noise is better than -90dBu, signal-to-noise ratio is 94 dB, dynamic range is 114 dB, and max output level is +24dBu.

The Aphex 228 solves big problems quietly and easily and is an integral part of my studio. It will work great in many applications such as interfacing consumer level CD and cassette players, routing home stereo gear you'd like to use in your mixing, and for connecting pro level powered speaker arrays to consumer 7.1 surround sound systems.

The Aphex 228 sells for $499 and for more information, check:

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