If the OP means "loud" in reference to how various makes of Low D compare to each other, the Dixon and Optima were two of the three
quietest whistles of several I recently reviewed
viewtopic.php?f=1&t=95717&hilit=optima&start=45
In relation to other instruments one encounters at typical Irish sessions, even the loudest Low Ds tend to get lost in the low register, in a medium-sized or larger session.
Following the OP's specifications (cheap, loud, good) is difficult, because in general one gets what one pays for.
In that review the volume was (loudest > quietest)
Maplehead Reyburn > MK > Burke/Susato > Optima/Polyhead Reyburn > Dixon
Setting "good" aside for a moment, if we go "loud and cheap" it would have to be Susato, one of the cheapest Low Ds available yet middle-of-the-pack in terms of volume.
Susato aside, generally you pay more to get more volume (MK, Burke, Goldie are among the loudest whistles).
The "good" part is complicated, potentially encompassing tuning, timbre, evenness of volume/voicing across the gamut, strength of Bottom D, quickness of response, nimbleness of octaves, ease/sweetness of high notes, air usage, and ergonomics.
Just one of these, ergonomics, is complicated, encompassing fingerhole spacing and size, tube diameter, and weight to name just three.
No Low D, perhaps, is the best at all of these various things. Low Ds which are the best at most of them are not cheap.
). Since I had a Susato low D and didn't like it much, I don't know if I'll like the low F. If it was as good as the high whistles then it would be a favorite.
