What do you consider normal variation in response?
I have here two HIVI iso tweeters. These measurements were taken back to back in the same enclosure with not changed except I swapped out the tweeter in the cabinet.
Is this considered normal? Is this too far off from one another?
I have here two HIVI iso tweeters. These measurements were taken back to back in the same enclosure with not changed except I swapped out the tweeter in the cabinet.
Is this considered normal? Is this too far off from one another?
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How repeatable are your measurements?
Tom
Tom
Your SPL still seems a little high (but not as high as before, so you did move in the right direction from a microphone limit standpoint). What was the microphone to speaker distance, and is your dB scale correct? A typical high level test is 96 dB at 1 meter. Back your microphone up to 1 meter and check the level to see if you are pushing the drivers hard (or check it with a handheld SPL meter to confirm).
@OllBoll's test of 17 planar drivers
https://www.diyaudio.com/community/threads/new-planar-drivers-at-parts-express.360339/post-6523979
@OllBoll's test of 17 planar drivers
https://www.diyaudio.com/community/threads/new-planar-drivers-at-parts-express.360339/post-6523979
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When I toured the LA Altec Plant in '68 I had just been 'selected' to be one of the brand new, first ever, Quality Assurance' (QA) overseers at work, so with only some historical evidence dating back to the 1890s that was subject to much personal interpretation, figured these pioneers of all things audio reproduction would have it 'nailed down' to a 'fare thee well', so FWIW/YMMV, etc: +/-2.5% of its mid-band efficiency, from which all I got was blank stares when asked at which frequency or range thereof. 
Fast forward a decade and I would learn it was the driver design's Fhm spec @ 10% rated power where presumably thermal power distortion would begin to modify its specs.
Fast forward a decade and I would learn it was the driver design's Fhm spec @ 10% rated power where presumably thermal power distortion would begin to modify its specs.
IF your measurements are good, then that is pretty poor QC. I've never seen that much variation before. The last screenshot with the 5db spacing is the most telling to me.
Mic is at 1 meter. He is me taking the same measurement of the same driver twice in a row.
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With these tweeters. Not very repeatable. This is a measurement of the same tweeter, same everything, taken back to back
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I’m inclined to say the damping of the foil of the one with the highest output above 10k isn’t sufficient. That is the (one) issue with these constructions as Philips and Technics could have witnessed (and they mastered it reasonably well decades ago…).
Nope. They are from two different tweeters. I was asking for measurements using the same tweeter to see how reproducible the measurements are.
I'd expect pretty much +/- 0.2dB accuracy between identical measurement sweeps. Even closer.
First we need to remove the noise from your sweeps. Are you measuring in a quiet location? (any background HVAC or other racket?)
Your gate markers are hard to see. What is your environment? In a typical 8' room - putting the DUT midway between floor / ceiling - you're looking at a gate of around 4msec (i.e. 1000/4 = no lower than 250Hz resolution).
Can we see your impulse window in % Y scale - with horizontal range of -0.5 to 8 msec?
First we need to remove the noise from your sweeps. Are you measuring in a quiet location? (any background HVAC or other racket?)
Your gate markers are hard to see. What is your environment? In a typical 8' room - putting the DUT midway between floor / ceiling - you're looking at a gate of around 4msec (i.e. 1000/4 = no lower than 250Hz resolution).
Can we see your impulse window in % Y scale - with horizontal range of -0.5 to 8 msec?
Again you have 2 seconds of delay (2000 ft!)...
There is something wrong with your measurement.