Fostex E-16 high end cuts out ATR tape

[xraymind7781]

I have a Fostex E16 1/2" tape machine. I recently switched to new ATR tape. On playback im getting drops only on my drum overhead tracks. The signal doesn't drop completely, just a noticeable loss of high end in the mix. Drops range anywhere from a couple seconds up to 10. Sometimes on the left overhead, sometimes on the right. On playback it doesn't always drop at the same time but there are instances where it does. My heads show no visible signs of wear and i've tried tracking overheads on different tracks but have the same results. Ive also tried different mixers, same results.

Could this be a bias problem from switching from 456 to the new ATR? I've never biased a machine before and was considering taking it in. Thought id see if I could find some pointers here before I opened up my wallet.

Thanks in advance.
Rob

[kslight]

How hot are you hitting the tape? Could be an artifact of the noise reduction. I would back off your level (peaking below 0db) and see what happens.