My understanding is that the only difference between the mk1 and mk2 is the ability to switch between ported and sealed modes. Please correct me if I'm wrong. I certainly wouldn't mind learning that my MBMs are more capable than I thought they were. That said, I looked at the old MBM web page, and it looks like it has the same amp, so they probably do perform about the same.
I'm running my MBMs in ported mode after having measured and compared the two. (Note: These were done in-room where the variation in location between woofer and port plays a bigger role so these numbers are rough estimates.) The ported mode boosts output up to 2-3 dB between about 30 and 200 Hz and shows no evidence of ringing or other substantial change in transient response. The port-contributed phase delay stays under 90 degrees above 30 Hz. I believe the built-in high-pass filters probably contributes a lot more phase delay (at least 180 degrees at 50 Hz, right?) in both modes. As such, I think the sealed mode is most useful for those without EQ capability who may achieve a better sub/MBM crossover with it.
Anyway, going by the Ilkkas measurements (don't forget to add 6 dB for the change in reference distance), it appears the MBM may perform slightly worse (~2 dB) than the VTF-15H. Hsu Research indicated otherwise in a phone conversation, saying the MBM should hold its own or exceed the performance of the 15H. I don't know if this statement assumes improvement gained in actual application by bi-amping the bass or by virtue of increased placement flexibility. Even if the MBM is more powerful than the 15H, I doubt it can beat either of the new products. I still think there's a niche for the MBM though. It costs a little more than 1/2 as much and takes up 1/3 of the space of a VTF-15H.
Last edited by SME : November 17th, 2014 at 11:48 PM.
Reason: correct typos