At a time when nearly all competitors had gone over to 10.5 inch with NAB hubs. This entailed some modification of the original Series 7 design in order to accommodate the larger diameter reels.
New spool motors with higher starting torque were required, to safely handle the extra mass imposed by a 10.5 inch full reel of tape needing to be rewound. It also required the braking system to be beefed up. A lot more effort is required to safely stop a full 10 1/2" reel when at full speed.
The flap hiding the track switching controls on the Series 7 were replaced and a much better system of switching introduced. This new switching system was easier to use and understand.
A reel size selector switch was added to optimize the back tension between large and small hub spools. This helped reduce wow & flutter. The switch for Vertical or Horizontal operation was mainly for the benefit of the auto-stop mechanism.
The tape path arrangement was identical to the original Series 7, and unfortunately, the pressure pad system was retained once again, which was mistake number 2.
3 - erase, record, play
A-B Comparison
7502H 15 , 7 1/2 , 3 3/4
0.08% @ 71/2 ips
0.15% @ 3 3/4 ips
0.20% @ 1 7/8 ips
30Hz - 17kHz @ 7 1/2 +/- 2 dB
40Hz - 14kHz @ 3 3/4 +/- 3 dB
40Hz - 14kHz @ 1 7/8 +/- 3 dB
Replay Characteristic DIN
Mic 300 Microvolts - 15 mV @ 10kohm
Line 50 Microvolts - 10V @ 2 megohm
Line 2v into 600 ohm
Low level 300 mV into 10kohm
Low level variable up to 300 mV into 10kohm
1 x Synchronous
2 x Constant torque
Multi-play,
A/B comparison
Adjustable tape tension.
ALTERNATIVE MODELS