Gated Sweep PL27TG35
the PL27 mounted onto the box, a 300 Points Precision Gated
Sweep was taken at 1 Meter, on axis with the tweeter.
20 is the result of the sweep.
unbelievable. Ran the sweep a few times, just to be sure.
No change. Replaced the PL27 with another unit. Same result.
Replaced with a 3rd unit - no difference. Finally, connected
my 4th and last tweeter, again no difference. Four units of
PL27, all displaying the same curve.
reason for this huge discrepancy lies in the measuring method
used in the industry.
standardize measurements, tweeters are mounted onto an infinite
baffle. Because of this requirement, manufacturers naturally
design tweeters based on infinite baffle response.
in real use, tweeters are mounted onto a box. As can be seen
from our measurements, the differences are tremendous, enough
to render the manufacturer's frequency response useless.
put it succinctly, a ruler flat response of a tweeter on an
infinite baffle is not an accurate indication of the tweeter's
response when mounted onto a box.
Now that we know what we are up against, we shall proceed
with the crossover