To correctly splice the reel and cassette magnetic tapes, proceed as follows
obtain the appropriate adhesive tape (1/8 ", 1/4", 1/2 ", 1", 2 ") that must always be glued on the part of the back of the tape (the one that does not touch the head), have clean and dry hands to avoid oily or sweat releases on the tape;
reel tapes: splice of the leader with vertical cut; to join intermediate points of the tape it is preferable to use the cut at 45°, because it has a greater hold being the length of the joined part greater; if you do not want to lose the continuity of a precise point of the recorded, it is necessary to use the vertical cut at 90°; to obtain a perfect alignment of the parts to be joined, it is recommended, at the time of cutting, to overlap the tapes / tapes or tapes / leaders to obtain a perfect match of the parts.
tapes in cassette: same system as tapes on reels.
Another important precaution is to use scissors or razor blade (in the case of the cutting block) that are demagnetized to avoid those annoying "tac" that would then be heard while listening to the passage of the joints on the head; to get these tools temporarily free from the problem just use a demagnetizer.