do you need to tweak a tape deck???

If you want to tweek it further, get a meter and fine tune the bias for each type and brand of tape you use.

Great you consider the bias. I mentioned bias, because I used to have a tape deck that a tech friend measured and marked the bias adjustment for various brands of tape. While they are all simiar, there are small differences. Most folks just leave the bias adjustment (if there is one) at the center.

He also adjusted the bias adjustment so it really was center. He claimed many tape decks out of the box are not calibrated very well.