I've built myself an ancient analogue 'Comb Filter' to these specs, followed all the instructions, fired loads of noise at it and I just can't get it to work...

Can anybody tell me what I'm doing wrong???

Spoiler: AI Says

Conclusion

It is not feasible for a granite vase, like those found at the Step Pyramid, to input broadband noise and output a specific frequency (or a comb of frequencies) without the output being mixed with the input signal. The reasons are:

• A comb filter, by definition, produces an output that includes the input signal modified by interference, not a clean, isolated frequency. The vase’s geometry might produce resonant modes or a comb-like response, but it would still contain remnants of the broadband input due to incomplete suppression of non-resonant frequencies.
• The vase’s irregular internal surfaces and simple cavity design are better suited to Helmholtz resonance (amplifying a single frequency) than comb filtering, but even this would not fully isolate the output from the input.
• Achieving a clean, specific frequency output requires a highly selective filter or a system to separate input and output paths, which is beyond the capabilities of a passive stone vessel.
• The lack of archaeological evidence for acoustic engineering in these vases further suggests that any filtering effect would be incidental, not intentional.

[Humor Section]