Vintage Roberts/AKAI 990 Left and Right Tube Amplifier – 6BQ5. The amplifiers were tested in the reel-to-reel recorder, and both powered on. We tested both the left and right amplifiers using a microphone. The left amplifier and VU meter functioned properly with good output. However, we were unable to get the right amplifier working and were unsure whether it was connected incorrectly or if there were other issues. The tubes were tested using a Hickok TV-7/U tube tester-see below for test results. Cosmetically, the unit is in good condition with some light wear and dust. Please review all photos for details. The tubes tested as follows. Left Amp : 6BQ5 – 50 min. Value 50; 6AR5 – 78 min. Value 40; 12AD7 – Triode 1: 38, Triode 2: 42 min. Value 32; 6267 – 27 min. Right Amp : 6BQ5 – has shorts, tested 42 min. Value 50; 12AD7 – Triode 1: 46, Triode 2: 46 min. Value 32; 6267 – 22 min. The 6X4 tubes were not tested. The amplifiers each measure 12.5 x 5.5 x 5. Combined weight is 18 lbs 10 oz.