Originally Posted by drhack
From Ed's mail it seems like the JL is doing:
100 dB @ 20 Hz @ 2M GP @ <10% THD
110 dB @ 25 Hz @ 2M GP @ <10% THD
From the AVTalk website, the Pb12+2 is doing:
101db at 15% THD
106db at 5%THD
So at the tuning point of the Pb12+2 it is still outgunned by the JL.
What am i missing?
You're probably missing the fact that AVTalk doesn't conduct single sine wave 10% THD limited output tests. They conduct sine wave sweep compression tests and simply record the THD at the same time.
As I said earlier, after it was pointed out to me by Ilkka, the closest thing available is Ed's tests of the Ultra/2, which is said to be within .5 to 1dB of the Plus/2 at the frequencies we're talking about.
Here are some of Ed's THD (or amp) limited output numbers at various tune settings:
16 Hz Tune 10% THD Ground Plane 2M:
16 Hz: 92.2 dB
18 Hz: 95.6 dB
Average SPL: 106 dB (101.2 dB Nousaine Method)
20 Hz Tune 10% THD Ground Plane 2M:
16 Hz: 89.5 dB
18 Hz: 100.7 dB (8.4% THD amp limited)
20 Hz: 102.8 dB (9.4% THD amp limited)
22 Hz: 104.9 dB (7.7% THD amp limited)
25 Hz: 106 dB (6.2% THD amp limited)
30 Hz: 109.5 dB (7.9% THD amp limited)
40 Hz: 113.1 dB
50 Hz: 112.2 dB
Average SPL: 108.5 dB (104.8 dB Nousaine Method)
25 Hz Tune 10% THD Ground Plane 2M:
22 Hz: 105 dB (6.2% THD amp limited)
25 Hz: 109.3 dB (6.6% THD amp limited)
30 Hz: 110.4 dB (3.9% THD amp limited)
40 Hz: 117.1 dB
50 Hz: 114.9 dB (7.6% THD amp limited)
So, in 20Hz tune we have 102.8dB. Subtract 1dB and you still have higher output at lower THD.
Also, looking to my original point, if both subwoofers are in the same system and level matched, how would anyone be able to perceive that one of the subs 'plays louder and lower' than the other, when both subs are obviously very close from a GP THD limited output standpoint
Hey, Will...Ya got me there. I had a larger Xmax number for the said-to be-modded-for-HT 13" driver
I appreciate the heads up
With this displacement capability info in place, the JL should have a calculable slight edge above 35Hz. All we lack is the 1W/1M numbers for both drivers, but we can guess pretty closely.
As I've said, it would be hard to tell a clear 'plays lower and louder' winner. I believe the difference is in dynamic capability. The JL has more power available for transient peaks and is a better alignment overall when properly executed, which these subs certainly seem to be.