Just noticed this...and looking for something to comment on, so here goes...
As far as cackles go, I think your call is more than sufficient to fool a gobbler. It is wayyyy better than most guys I have heard trying to pull off a cackle.
Quite honestly, before I was aware that you were using a trumpet, I would have guessed that tonal quality was coming from a scratch box (so much for my old-age hearing, I suppose).
I think the cadence is great and the crispness of the individual notes is good, but I agree with a couple of other commenters that the tonal quality is off slightly in that my perception is that the notes of a cackle are somewhat hollow sounding...and to me kind of a hybrid sound between fast clucking and speedy yelping. It is a difficult sound/call to pull off...and especially at the speed at which it is done from a live turkey.
On the other hand, where I mostly hunt, the Merriam's turkeys that frequent this region rarely, if ever, cackle when they leave the tree (or otherwise)...so the number of times I have heard REAL turkeys cackle leaves my opinion to be suspect...and more likely, unworthy of serious consideration.
...But I threw it out there anyway...just for the heck of it...