I visited Paul K. recently to listen to his fantastic speakers and while I was there picked up a pair of the new Tang Band 25-1744S 25cm ceramic dome tweeters to measure. I figured this would be a great chance to take some measurements with my new ECM8000 that I had calibrated by Kim Girardin. The tweeters were flush mounted on an 8" wide baffle that had a 1/2" roundover, something close to how they would be used in the real world. Four 22 uF capacitors (88 uf) were wired in series to protect the tweeters. The 1 meter frequency measurement were taken around 80 dB to protect the tweeters as I wanted to get an accurate low end. Distortion measurements still used the 88 uF of capacitors but started at 500 hz. for protection since they were receiving much more power.
The first measurements I took were nearfield frequency. After taking measurements for both tweeters and doing an overlay I was shocked. The second tweeter looks to be 3-4 dB less sensitive than the other. Not letting a single measurement be the proof I remeasured them both again and got the same result. Not good:
Up next is a 1 meter measurement at around 80 dB:
Here is the distortion measurement from 1 meter at around 90dB for the more sensitive tweeter. The F3 is higher down low, which could be due to the higher output at the same drive level:
And now the less sensitive tweeter's distortion measurement:
You can see how things get a little funky around 3 khz. with this tweeter. I remeasured both tweeters just to be certain the first measurements were accurate and both were very close. It looks for certain that something's not right with the second tweeter, which is a shame as I was hoping these would be a great performing, small flange tweeter.
Sorry, Paul. Probably not the news you were looking for but at least we know something needs fixed before you tried using these.
The first measurements I took were nearfield frequency. After taking measurements for both tweeters and doing an overlay I was shocked. The second tweeter looks to be 3-4 dB less sensitive than the other. Not letting a single measurement be the proof I remeasured them both again and got the same result. Not good:
Up next is a 1 meter measurement at around 80 dB:
Here is the distortion measurement from 1 meter at around 90dB for the more sensitive tweeter. The F3 is higher down low, which could be due to the higher output at the same drive level:
And now the less sensitive tweeter's distortion measurement:
You can see how things get a little funky around 3 khz. with this tweeter. I remeasured both tweeters just to be certain the first measurements were accurate and both were very close. It looks for certain that something's not right with the second tweeter, which is a shame as I was hoping these would be a great performing, small flange tweeter.
Sorry, Paul. Probably not the news you were looking for but at least we know something needs fixed before you tried using these.
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