Testing tweeters means putting them in the exact same position, playing tones and turning your head. Side by side is no good. They will always sound different, side by side.
A steady frequencies tone will shift as you turn your head. It's your ears shape. My right ear, positioned 'just so' can vanish a 7khz test tone. Enough heard in and out of phase for cancellation. At first I was horrified, but really it's to be expected. My dad didn't stretch the other enough when I was a kid.
If you decide to juice up, then the viscosity of oil you use is a big deal. I was temped by black-strap molasses as a substitute, but I believe the Denton, as a commercial speaker, should probably get the right stuff. Not make a meal out of it.
A steady frequencies tone will shift as you turn your head. It's your ears shape. My right ear, positioned 'just so' can vanish a 7khz test tone. Enough heard in and out of phase for cancellation. At first I was horrified, but really it's to be expected. My dad didn't stretch the other enough when I was a kid.
If you decide to juice up, then the viscosity of oil you use is a big deal. I was temped by black-strap molasses as a substitute, but I believe the Denton, as a commercial speaker, should probably get the right stuff. Not make a meal out of it.
Test the DC resistance of each tweeter with a multimeter. A difference of more than about 0.5 Ohms would suggest a problem with manufacturing consistency and would likely explain the differences in sensitivity. Differences in ferrofluid thickness or amount shouldn't affect their DC resistance.
If the DC resistance of each is similar, try swapping the left and right tweeters to eliminate other variables. If those tests don't reveal anything, then it might be the ferrofluid.
If the DC resistance of each is similar, try swapping the left and right tweeters to eliminate other variables. If those tests don't reveal anything, then it might be the ferrofluid.