First, some background explanation of my band and the environment of our test is probably in order. My band is a heavily progressive influenced rock trio (guitar, bass, drums), with lots of guitar solos, bass solos, significant dynamics - ranging from very quiet, to heavy distortion with extremely intense double-kick (sounding) drum beats. During these louder parts, there are often very intricate bass lines that need to be articulated well, so a loud-yet-accurate amp is part of my requirement.
The venue is a basement bar affair with half stone/ledge wall on 3 sides, and half wood. Because of the significant presence of stone walls, it takes a lot of acoustic energy to sound "loud" in that room. The PA consisted of two QSC 15" 3-way speakers, and a 600 watt Yorkville sub.
Load InLoading in was awesome. I walked in with my bass in a soft case gig bag, over my shoulder, pedal bag in one hand, and my amp in the other. Now if only I didn't also have to bring in an entire PA system for the rest of the band... But anyway.
So I'll get straight to the point. The MB212 impressed me. Once I had everything dialed in, it had no problem cutting through even during very loud passages, and I never got lost once (I'm primarily an ear player, so if I can't hear myself I find it very difficult to blindly finger a riff). By the end of the first set, the band had gotten a lot louder (as they do), and I turned up my amp to compensate. I was very pleased as it easily rose to the challenge.
Finer DetailsA few finer details about this amp. First off, it naturally seems quite "boomy". This is generally an undesirable aspect to the sound of an amp - muddiness in the 120-200Hz region. I found that it was very easily dialed out by significantly lowering the "low mid" knob. It is just short of being all the way down. I also learned that this issue seems to diminish as the volume gets higher. I've heard that the MB210, the 2x10 version of this amp, doesn't have as much of an issue with this. It has a slightly reduced top end volume.
I also have learned through experience that, with this band, I must leave the contour knob "off". This function basically scoops out much of the mid range, and is probably better suited for playing in bands with more instrumentation. At least in my case, it caused me not to be able to hear a portion of the notes in my solos (only the bottom and really top end notes came out strong).
After having played a Mesa Venture combo for the last 7 years, I have to (unfairly) say that the tone of the MB212 is not "sweet". It is NOT bad. It is strong, complete, and articulate at high volume. The tone shaping controls are sufficient to make whatever adjustments are necessary. I would probably not prefer this amp in situations that are guaranteed to be fairly low volume - I'd probably use my 10" Fender B-Dec 30. However, the MB212 is light and convenient enough that it might still end up going along.
The build quality of the MB212 is excellent. It feels very sturdy, and the newer, all-black look is subdued yet polished. I do get the sense that the finish is easily damaged. I got an excellent padded cover from Sweetwater.com for a cool $50.
So in retrospect, I'm happy I got it. At times I am haunted by the thought that I should have considered the TC Helicon BG250 . I played it in the music store and it had a much cleaner (albeit somewhat sterile) sound. I didn't get a chance to turn it up, so I don't know if it would meet the volume requirements, but the reviews are good.