Originally Posted by Auditor55
Regarding your point, I would steer away from the Rythmik F12. It was tested as having high levels of distortion. That sub is not really idiot proof, do the lack of a quality limiter.
If you are talking about Ilkka's test (http://www.hometheatershack.com/foru...ealed-56l.html
from about 5 years ago, you are missing a couple important facts and misinterpreting some of the measurements. First, that was a DIY sub, not a commercial version. Also, that DIY sub used the older 370PEQ amp. The newer PEQ2 and PEQ3 versions have a defeatable limiter. The PEQ3 is now standard on the F12. While maybe not idiot proof, even without a limiter, the rumble filter and extension settings can be used to control excursion and distortion with ULF content. If you are reaching the limits of the sub, those controls can be used almost like a limiter. In Ilkka's test, the sub was run in the lowest possible extension settings and with the rumble filter off.
Even with all of the above taken into consideration, let's compare the actual distortion measurements from the sweeps between the DIY Rythmik tested by Ilkka and the XRef-12 as tested by audioholics.
From the max output sweep, the Rythmik and XRef have similar output from 40hz and up. But below 40hz, the Rythmik has the advantage.
Now lets compare the distortion. Ilkka did not run CEA2010 tests so these are from the sweeps and THD graphs.
100db at 30hz: Rythmik - 10% XRef - more than 30%
95db at 25hz: Rythimik - 10% XRef - more than 30%
93db at 20hz: Rythimik - 23% XRef - Unknown, couldn't hit more than 84db (THD already more then 30% at 84db)
The Rythmik has the same or less distortion then the Emotiva at all frequencies if the SPL is the same. The Rythmik does have higher distortion below 30hz if compared at the same nominal sweep level, but with much higher output. However, you can use the extension, damping and rumble filter controls to change the low end roll off to lower the distortion at the expense of output.