This Arrived some time ago and I hadn't had the chance to run it through its paces.
I have some excellent Columbia recordings of Leonard Bernstein originals. If your testing these old reel to reels I find piano and Symphony ensembles are an excellent, discriminating source for any fluctuation or unwanted noise.
This 4000DB is an attractively designed compact tape deck offering multiple connections and controls and quality features among which are Akai's one micron gap heads for high density recording and the well known the incorporation of Dolby Noise Reduction System.
As you can see the Akai's one-micron gap head is responsible for an amazingly important difference in tape recording. It's the difference between ordinary performance and high density quality recording and playback. Ordinary head gaps are from 2 to 4 microns, but the gap of this outstanding head is only one micron. This high density recording system provides excellent frequency response and clear, high pitched sound is generated as a frequency tone and recorded smoothly without distortion.
With the Dolby Noise Reduction System, hissing noise heretofore thought impossible to eliminate, is reduced to a completely inaudible level. Basically, this circuit boosts the low level signals prior to recording and lowers them by precisely that same amount at playback time. During this revolutionary process, the extraneous noise is eliminated, thus also eliminating tape hiss.
Internally illuminated and quite cool are the VU Meters
In keeping with Akai's top quality parts utilization policy, the 4000DB also features robust construction and sturdy mechanism. Further, a highly efficient induction type motor assures stable tape travel and ideal starting torque. The characteristics of this motor coupled with a boldly designed flywheel reduces wow and flutter significantly.
Specs on this little babyTrack system: 4 track 2-channel stereo / monaural system
Reel capacity: up to 7" reel
Tape speed: 7-1/2 and 3-3/4ips (±2%)
Wow & flutter: less than 0.15% at 7-1/2ips, Less than 0.2% at 3-3/4ips
Frequency Response: 30Hz to 23,000Hz (±3dB)
7-1/2ips, 30Hz to 16,000Hz (±3dB) at 3-3/4ips
Distortion: less than 1.0%
Signal to noise ratio: better than 55dB (with Dolby process 60dB at 5kHz)