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Today I finally measured one of my 1st generation JBL LSR305s, using the quasi-anechoic method, and used it to create a spinorama-style report. It is far from the precision of an NFS, but I hope it might still provide some qualitative insight on these pretty common loudspeakers.
Some information on measurement procedure first:
I tried comparing it with a spin made by the vendor (JBL), by digitizing the very low res image available online:
It appears there some qualitative overlap, especially in the DIs - most of the differences seem to be in the 1-2k range, and these could be due to unit-to-unit variation, imprecise digitization of data, low resolution of the original image, or of course - due to errors in my measurement rig or process.
Horizontal directivity:
Vertical directivity:
We can see above I was slightly below the tweeter axis - as mentioned in the introduction.
I was also interested how the 1st gen compares with the newer 305p MKII, here's a listening window comparison from spins by @amirm and @hardisj:
There is some similarity, though it looks like the newer model might be brighter (but it also has a less pronounced 12k dip and slightly better DI).
Lastly I compared just the on-axis measurement of the two units I own to see unit-to-unit variation. The differences mainly show above ~1kHz:
There is a slightly bigger difference around the crossover, but above 2,5k both units seem within ~1,5dB of each other.
NOTE: Originally one of the units I own had a ~2dB tweeter level difference vs the other, and I had to replace the tweeter on one of them to get the slightly closer match that you see above.
In case @MZKM and/or @pierre (or others) might be interested to do their magic, CTA-2034-A export from VCAD is attached.
EDIT [2021-07-01]: Added distortion and individual driver nearfield measurements and a few misc. tests in post #15.
Some information on measurement procedure first:
- Made with the quasi-anechoic method, in principle equivalent to the one from the amazing guide by @napilopez
- Measurements were done in an apartment using a makeshift turntable and stand
- EDIT 2021-06-28: Measurements were done with Cross-Spectrum labs calibrated Dayton Audio EMM-6 microphone, pointed horizontally (towards the loudspeaker) and 0° calibration file was applied
- Nearest reflective surface was the ceiling, ~1,2m away from center of the woofer
- Measured at 0,5m distance so I could use ~5,2ms gate for the HF part of the measurement (IMHO this should satisfy far-field criteria as at it is ~4,4 times the radiating diameter of the woofer)
- SPL in REW was calibrated by a cheap SPL meter - measurement level was ~83-85dB SPL at 0,5m
- For the horizontals measurement axis was the tweeter
- For the verticals I had to move the measurement axis to the LED below the tweeter, as that was the only way to safely balance the loudspeaker on the stand - however the 0°/on-axis measurement for both the tweeter and LED axis seems very close, so I hope the total error is not very large
- Used 10° increments for the measurements, and covered one half-plane with the horizontals (0-180°, should be OK as the loudspeaker is symmetrical), and the full 360° for the verticals
- The nearfield LF measurements were spliced with the gated HF measurements at ~250Hz. Note that due to splicing there is some uncertainty in how the low frequencies are depicted (should be close, though - see comparisons with other measurements below)
I tried comparing it with a spin made by the vendor (JBL), by digitizing the very low res image available online:
It appears there some qualitative overlap, especially in the DIs - most of the differences seem to be in the 1-2k range, and these could be due to unit-to-unit variation, imprecise digitization of data, low resolution of the original image, or of course - due to errors in my measurement rig or process.
Horizontal directivity:
Vertical directivity:
We can see above I was slightly below the tweeter axis - as mentioned in the introduction.
I was also interested how the 1st gen compares with the newer 305p MKII, here's a listening window comparison from spins by @amirm and @hardisj:
There is some similarity, though it looks like the newer model might be brighter (but it also has a less pronounced 12k dip and slightly better DI).
Lastly I compared just the on-axis measurement of the two units I own to see unit-to-unit variation. The differences mainly show above ~1kHz:
There is a slightly bigger difference around the crossover, but above 2,5k both units seem within ~1,5dB of each other.
NOTE: Originally one of the units I own had a ~2dB tweeter level difference vs the other, and I had to replace the tweeter on one of them to get the slightly closer match that you see above.
In case @MZKM and/or @pierre (or others) might be interested to do their magic, CTA-2034-A export from VCAD is attached.
EDIT [2021-07-01]: Added distortion and individual driver nearfield measurements and a few misc. tests in post #15.
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