Living with Dolby B (continued)
So I just had to gnash my teeth, visit the dentist, and wait for the Hitachi to re-materialise. It eventually did, and I plonked it next to the PD2B — which was already in intimate DIN to DIN contact with my amplifier — hooked up the remaining DIN lead, and switched on. Now to calibrate the thing. First, replay calibration. Put the calibration cassette tape into the Hitachi, play it with the output level controls at 2/3rds, switch the PD2B to Dolby "on" and replay, then adjust the two replay presets on the PD2B so that its two meters read 0 dB. Fine, what could be simpler? Now, what's next?
Record calibration. Put a blank tape in the Hitachi. Change the PD2B from replay to record. Switch on its built-in oscillator. Adjust its record level controls so that it feeds the Hitachi this tone at 0 dB. Set the Hitachi's input level controls to 50%. Adjust the two record presets on the PD2B to give half-scale deflection on the Hitachi's meters. Start recording.
Done all that? (Without straining your eyes watching four meters; changing the wrong pair of presets; forgetting to switch Dolby processing "on"; knocking over the cat.) Good! Now play back the signal you've just recorded. Set the PD2B to replay from record. Switch off its oscillator (just in case). Do you now get 0 dB on the PD2B's meters? Do you heck! In fact, to shorten a painfully long story, I found the only way to get that magical 0 dB on playback was to record the signal in the first place at about +1 dB rather than the -3 dB that "half-scale deflection" implies.
Oh well, as McWatt says, what the hell? Let's try it out on some music, shall we?
That's when the real problems started.
If you remember, I was using Sony DIN to Dolby DIN; Dolby DIN to Hitachi DIN. (Sounds pretty noisy already, doesn't it?) Well, I've no choice but to use Dolby DIN, it's all there is. Anyway, optimistic fool that I am, I'd assumed all would be well and that I'd now sit back, relax, and strain my ears listening for the missing hiss. Hah! Ever heard of interconnection problems?
