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HEAD UNITS
The CDC-X707M is a single-DIN head unit with CD player, AM/FM tuner, and CD changer control. Features include a detachable faceplate with multi-color display, a steering wheel-mounted IR remote, and variable Hbass (High Bass) and DSSA (Drivers Sound Stage Adjustment). The CDC-X707M provides four preamp outputs, a 3.5 mm auxiliary input jack, and internal amps rated at 45 watts x 4. A Source Level Adjustment feature allows users to match output levels for different sources by +/– 4 dB. The unit also boasts the ability to play both CD-R and CD-RW discs.
Performance
The CDC-X707M’s preamp outputs are capable of about 2 volts without significant distortion and about 2.2 volts at clipping. Useable dynamic range measured -87.3 dB, and frequency response fits easily within a 2 dB window from 20 Hz to 20 kHz. Output impedance measured a very high 2.7 kohms. Lower operating voltage coupled with a high output impedance couldn’t exactly be called optimum from a noise rejection standpoint, but in most installs the CDC-X707M’s pre-out section should prove to be more than adequate.
With all channels driven into 4 ohms, the CDC-X707M’s internal amps produced about 11 watts x 4 @ 0.8 % THD+N. The next click up on the volume control produced about 14 watts x 4 @ 1.2 % THD+N. A tough call, but we always spec 1% or less on decks with a stepped volume control. Of course, anything under a few percent THD+N is still completely usable, just like gain overlap with an external amplifier. Max output from the internal amps measured 29 watts x 4 @ 35% THD+N. That’s definitely among the highest power levels that we’ve seen from a head unit — although at a distortion level of 35%, it’s not exactly usable power.
The DSSA circuit optimizes the soundstage&Mac226; for either the left or right seating position. It essentially involves a balance offset of about 4 dB and a high frequency rise of about 6 dB. This will certainly change your soundstage, but there’s a bit more to proper imaging and staging than balance and EQ. The Hbass circuit provides either 2.5 dB or 4.5 dB of boost centered at 80 Hz. Tone controls are quite wide in bandwidth and provide + or – 12.5 dB, centered at 35 Hz and 18.5 kHz.
User Evaluation
The CDC-X707M’s user interface includes eight buttons, four rocker switches, and a single digi-pot. While I’m not a huge fan of digi-pots, they are far better than rocker switches for volume, tone, and balance controls. If you’re going to use one, it only makes sense to utilize the one advantage that they have — multi-function. This unit’s volume, balance/fader, DSSA, Hbass, and tone adjustments are controlled by the digi-pot and a large select button. The select, power/mute, and function buttons, along with the tuner/track skip rocker, surround the control knob. Almost every frequently-used function is at your fingertips every time you reach for the gas.
In most cases, I intentionally ignore the operating instructions when beginning a head unit evaluation; a good user interface should be self-explanatory. For some reason, I decided to actually sit down and read the manual all the way through beforehand, only to discover that it was completely unnecessary. The user interface for the CDC-X707M is actually very intuitive and offered a very shallow learning curve.
Aiwa CDC-X707M Specs
Price & Contact: $250, 201-512-3600; www.aiwa.com
Max output level: 2.2 volts @ 1.3% THD+N
Max undistorted output: 2 volts @ 0.8% THD+N
Relative loudness: -11.6 dBu
Usable dynamic range: -87.3 dB
THD+N @ full output: 1.30%
Output impedance: 2.7 kohms
L-R channel error: 0.13 dB
Frequency response: +0.6 dB, -1 dB
Internal Amps
Max Output: 29 watts x 4 @ 35% THD+N
Max Undistorted Output: 11 watts x 4 @ 0.8% THD+N
Signal to Noise: -85.5 dB
Channel Error: 0.17 dB
Frequency Response: +0.6 dB, -1.8 dB
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