You can't get accurate and repeatable TSP measurements if the drivers are dangling loosely in the air. You must clamp the baskets in something solid like a vise, which simulates them being mounted firm in enclosures.
Phil,
Your results hardly changed from the first, but indicate changes in Re, which shouldn't have changed at all- the amount of wire in the coil is the same as it was before.
The driver's suspension still needs to be broken in, stretched at least to Xmax for the viscoelastic behavior and Fs to drop to near the factory specifications.
That said, as close as your driver measurements are to each other, I wouldn't worry about their differences any more than I'd worry about the moon's gravitational effects on a top-fuel dragster's ET from day to day 😉
Art
I noticed that Re changed too and I agree it shouldn't have. Scratched my head hard about that one.
I'm using the DATS V3 tool to do the measurements. I re-calibrate it before each use and let it "cook" for 10 minutes to minimize errors. Verified the calibration resistor [0.1%] and soldered the crimped connectors on both ends. May just be a flaky tool. Not sure why else the data would vary unless the alligator clips themselves are wonky [a possibility but unlikely].
Part 21 of the IEC 60268 standard says this about driver mounting for making T-S measurements:
Mounting
The performance of a loudspeaker drive unit (or driver) depends on the properties of the unit itself and its acoustic loading, which in turn, depends on its mounting arrangement. Drive units may be mounted in one of three configurations, with the selected configuration clearly described in the test results:
1. A standard baffle or in one of two specified standard measuring enclosures.
2. In free air without a baffle or enclosure.
3. In a half-space free field, flush with the reflecting plane
Loudspeaker systems are usually measured without any additional baffle. The manufacturer can specify that a baffle be used, in which case a description of the mounting arrangement should be included with the test results.
And of course Part 5 covers the measurement standard regarding microphone placement and environmental conditions also with five options yielding numerous permutations when combining the two.
Re: enclosures, each of the three options will of course will yield different results. That's what I love about standards: there are always so many from which to choose. 😉
I like the idea of building a box and measuring SPL and Z for all of them from that same box with say REW. I agree that overlaying the results will provide better matching.
Measuring TSPs at the same may also show better data for a more accurate Vb prediction, although I really do not trust this DATS V3 tool.
I'm using the DATS V3 tool to do the measurements. I re-calibrate it before each use and let it "cook" for 10 minutes to minimize errors. Verified the calibration resistor [0.1%] and soldered the crimped connectors on both ends. May just be a flaky tool. Not sure why else the data would vary unless the alligator clips themselves are wonky [a possibility but unlikely].
Part 21 of the IEC 60268 standard says this about driver mounting for making T-S measurements:
Mounting
The performance of a loudspeaker drive unit (or driver) depends on the properties of the unit itself and its acoustic loading, which in turn, depends on its mounting arrangement. Drive units may be mounted in one of three configurations, with the selected configuration clearly described in the test results:
1. A standard baffle or in one of two specified standard measuring enclosures.
2. In free air without a baffle or enclosure.
3. In a half-space free field, flush with the reflecting plane
Loudspeaker systems are usually measured without any additional baffle. The manufacturer can specify that a baffle be used, in which case a description of the mounting arrangement should be included with the test results.
And of course Part 5 covers the measurement standard regarding microphone placement and environmental conditions also with five options yielding numerous permutations when combining the two.
Re: enclosures, each of the three options will of course will yield different results. That's what I love about standards: there are always so many from which to choose. 😉
I like the idea of building a box and measuring SPL and Z for all of them from that same box with say REW. I agree that overlaying the results will provide better matching.
Measuring TSPs at the same may also show better data for a more accurate Vb prediction, although I really do not trust this DATS V3 tool.
Good plan if V3 isn't a ? improvement over V1, 2. These started as a cheap ripoff of a ~pro level Smith & Larson and apparently still only good enough for the casual DIYer.
Some folks are happy with this freeware.
Some folks are happy with this freeware.
Last edited:
Alligator clips are wonky, they have a variable resistance in the spring contact joint, and how well the jaw's teeth cut through oxidization on the surface they connect to.
While I was waiting for the glue to dry, I decided to do a quick study on matching four close-value resistors [here Re for my drivers 1-4]. I used Excel.
Interesting results shown here. There are six permutations for series matching and three for parallel matching of those six. While there are differences as expected, they are VERY small.
Interesting results shown here. There are six permutations for series matching and three for parallel matching of those six. While there are differences as expected, they are VERY small.