No, its not an issue with the operating level of the tape; the thing you are dealing with is calibrating the electronics. According to Tascam Analog support the difference in BIAS requirement is significantly different between 457 and LPR35. Usually you adjust the bias by turning up the level of the bias tone being put out by the bias amps and watching its effect on a high-frequency tone being recorded to tape, usually 10kHz or so. As the level of the bias goes up the HF tone being tracked to tape will decrease and most manuals state a certain amount of "over-bias" as the right bias level to be produced by the bias amp. Well, the 388 manual just says to measure the level of the current being produced by the bias amps and 150mV is it. But Tascam Analog Support tells me that was based on 457, and that LPR35 has a different requirement, and advised me to monitor the HF tone with a scope and set the bias level at whatever the minimum distortion level was. I haven't done that yet but I intend to and to then measure where the bias amps are at and then maybe 388 owners using LPR35 can use that figure...maybe its 175mV...maybe 250mV...I don't know. For now just follow the procedure in the manual...calibrate just like you would according to the manual and I'd say just use 150mV for now.
