I’m not sure what ‘Dynamizer Technology’ really is or does, and Behringer’s manual doesn’t do much to really explain it. But it appears to be a sort of a pre-set ‘compander’ type thing, keeping the levels under control. However, this function has no external user control.

The ‘Shape’ function frankly doesn’t do much for me. It seems to be a resonant (voicing) filter with a control to set the peak/cut frequency, but no control for the ‘amount’ or ‘intensity’ of this function. This would be a very useful function if it had that intensity control. But as it is, it seems a bit too ‘much’. In other words, the filter ‘peak’ or ‘cut’ is a bit too much for my taste.

The “Ultrabass’ function is also not one I’ll ever use much, although it sounds kinda neat on a solo-type passage. It seems to track very well on single notes, and can be set so that the added low octave equals the original signal’s level…which is way more intense than I’d ever want it to be. I’d only use it at very spare levels.

The EQ section is where this amp really shines, in my book. I can dial in just about any timbre I could want or need, and easily adjust for room acoustics if needed. The ‘bright’ and ‘deep’ switches are very effective, and in my view, only really need to be used as a sort of ‘loudness contour’ control at very low volumes.

I’m not real sure what good a VU meter is on a bass amp, as I depend on my ears to let me know what’s happening back there. Maybe it’s good for something besides just looking kinda cool. The Preamp Gain lets me drive a little hard, into a very mild clipping that actually sounds ‘tubey’ (should I ever want my bass tone to be clipped and crunchy). I usually run this control about halfway up.

Though this amp has a tweeter in it, along with the 10” speakers, I keep the tweeter unplugged, as I get more top-end bite than I need from those aluminum-coned Bugera drivers. I can see where it might be desired if the amp had paper-cone drivers in it, though. One thing about piezo tweeters is that their frequency response rolls off really abruptly, and that is actually audible. You can play one high note and hear it in the tweeter, then go down a fourth from that and it’s not coming out the tweet anymore. The rolloff seems to happen within a ½-octave or less, which results in a rather abrupt overall timbre change around the rolloff point.

Fit and Finish:

This is a unique-looking amp, in my view. Kinda squat and chunky, and with the cabinetry being wider than the head unit, the control panel presents the illusion of looking cramped (though it’s really not, at all). Louvered filler panels on either side of the head unit fill out the cabinet space. The control panel is very plainly labeled and readable. The combo is covered in black ‘speaker carpet’, with very stout flush-mounted handles and a very open-pattern perforated metal grille over the speakers.

There are two little wheels built into one end of the bottom of the cabinet to help in moving the amp around, but they’re frankly almost useless since they’re only about 1-1/2” in diameter and almost set flush to the cabinet. And they’re too close together, not giving much lateral stability while trying to roll the unit around. But overall, when you look at this amp, it looks like it means business.

Behringer BX4201A Amp Tone:

The twin aluminum 10” drivers, in a slot-ported enclosure, give a surprising amount of low-frequency output. I’m of an age where I remember that ALL bass amps used to have 15” or 18” speakers, the prevalent thinking being that to make low-frequency sounds, you had to have a large cone area in your driver(s). But hearing this and other multiple-10” bass speaker systems has changed my mindset completely.

The big cones have the drawback of not responding quickly enough for a crisp, punchy attack (which I like, being a fretless guy). These drivers in this amp are tight, punchy, and still have a great low-end. And their upper frequency response is such that, as I mentioned before, I don’t even use the tweeter in the unit. I get plenty of ‘spank’ out the 10’s alone.

Now, I’ve read reports about the Bugera aluminum-cone drivers being easy to blow out (and the same about the Hartke drivers), but also have read that if these drivers are given time to mechanically break in at lower output levels, this isn’t really a problem. The 5-band EQ in the amp gives me plenty of tonal flexibility.

I’m not crazy about the ‘shape’ thing, nor the ‘Ultrabass’ sub-octave generator, but for me, they’re simply window-dressing; not needed, not used. At really low levels, where amplifiers generally aren’t producing the full spectrum as at higher levels, the ‘bright’ and ‘deep’ can act as ‘loudness contour’ controls to boost both ends of the frequency response back up.

In short, I get the kinds of tones I want out of this amp without a lot of fuss involved in doing so. I like tight, punchy, very present bass. This little guy delivers on that.

Power:

This Behringer BX4201A delivers 300W as-is, and if you add another 8 Ohm cab in parallel for a total 4 Ohm load, it delivers 450W. This may not be enough power for a stadium gig alongside two 100W Marshall guitar stacks, but it will definitely fill up any club, church, or dance-hall that I ever saw. And the integral DI and Line-level outputs give the ability to supplement that power thru the house sound system if needed. I can get a well-rounded tone at low levels, or I can blow the walls down.

Behringer BX4201A Bass Amp Review Summary:

I get what I want and need out of this amp, and I didn’t have to spend a ton to get it. That’s my bottom line. Truth be told, I’ve never run it up over halfway, and I’ve never plugged an extension cabinet into it for the 450W configuration. But I’ve had every window in my house about to come out of their sills, and the neighbors stepping outside to see where that rumbling sound was coming from...at half-volume…enough loud for me!

The Behringer BX4201A Combo amp has all the features I need (and a couple that I don’t…), excellent tonal flexibility, and plenty of power for my purposes. The only thing I can think of that I’d really like to try with it is to plug a 15” cabinet into it and see how much more bottom-end comes out. As it is, though, I seem to have plenty of that, with only the two 10” drivers on board.

Great amp for the money, fully twice what I expected to get for the money I had to spend on it. I quite frankly don’t know how Behringer does it with their Behringer BX4201A.