BBD chips tend to have a LOT of high end rolled off, to filter out the HF clocking noise of the BBDs, it’s inherent in the design. If you’re feeding it something with mainly high frequency content (like a hi hat), it’s not surprising you won’t hear much effect. Shorter delay times tend to have more high frequwncies with BBDs, so you may get away with that. If not I’d suggest a basic full frequency delay like the Digital Delay, no high end roll off!
