I’ve never used one of these machines personally. Anyone?
The 250AV, btw, is the same as the 250, except that it runs at 1.875ips (the same as a regular consumer tape deck); the intent was to simplify multi-track bouncing in audio-visual post-production situations. Read the product sheet and you will see what i mean. It also boasts a 5db lower crosstalk spec than the 250; FOSTEX claims that this allows a pulse (sync) tone can be placed on one the tracks to drive other machines without the pulse -sound getting into your other 3 tracks.