This was a good exercise trying to estimate from a ported sub to its sealed counterpart. If I use the same methodology, I can get pretty close with a variety of subs. Here's the methodology I'm using for estimating (this was all derived by looking at data-bass measured results). Also, I'm estimating more optimistically in general (benefit of the doubt).
Again, this isn't perfect, but should get us pretty close.
Going from ported to sealed:
- Sealed is aprox. 10db down at the ported subs tune. If the measured result is not exactly at tune, I'll subtract 1-2 db to compensate for the difference: 18hz tune, I'll use 8db down instead of 10db, since there measurement on data-bass is 20hz.
- Example: The FV15HP outputs 108.1 at 20hz. The F15HP is it's sealed counterpart (using the same driver and amp), so I adjust it's 20hz output by 8db (FV15HP's tune is 18hz) to 100.1 at 20hz.
Estimating sealed max output from 20hz
- Looking at data-bass, most sealed subs are down 10-12db at 12.5hz compared to 20hz. Being optimistic, I use 10db down to get to the 12.5hz
- Example: Since I estimated the F15HP at 100.1 at 20hz, based on the above, it's 12.5hz output is 90.1db.
- In order to determine whether or not a sealed sub can dig cleanly to 10hz, I referenced data-bass again. Looking at 20hz, the lowest output where a sealed sub has clean CEA output at 10hz is when it had 99db or higher at 20hz (LMSR12-Sealed). Generally speaking, any sealed sub that produced 99db or higher, was able to get clean output at 10hz.
- To estimate 10hz output, looking at data-bass, most sealed subs are down 4-6db from 12.5hz. Being optimistic, I use 4db down from 12.5hz to get to 10hz.
- Example: Since the F15HP is estimated 100.1 at 20hz (>=99db), I will estimate it's 10hz output. Subtracting 4db from it's 12.5hz estimate puts it at 86.1db at 10hz
- For 16hz, I just took the midpoint between the 20hz output and the 12.5hz output.
- Example: The F15HP at 20hz is 100.1, and at 12.5hz is 90.1. The 16hz output is estimated at 95.1db.
Based on the above, I've filled in the blanks from 10-20hz for all sealed subs we've estimated so far. I've also completed some ported sub estimates based on mfg data being up or down certain db compared to their big brother ported subs on data-bass.
Note, I've re-estimated all Rythmik subs. The 20hz output looks more realistic to me compared to other estimates and data-bass data.
Look at the results, am I close here?
Edited by dominguez1 - 9/22/13 at 3:29pm