Micca PB42x Powered Bookshelf Speakers

This is a combo review of sorts, as the PB42x is made up of the updated MB42x with an amp added in, so it's a look at both of them. The MB42x was a great speaker for the price when I reviewed it back in March of 2013. I liked it so much that a few people on the internet thought I might of been drunk at the time of review. Jokes on them, I was drunk and the speaker was still good in the morning.

At any rate I got the Micca PB42x powered bookshelf speakers in the mail about 2 months ago. I'm just getting around to finding out what makes them tick. Let's do this thing.


Well, the tweeter looks familiar.

Sneaky shot from the port shows that this a new revision on the tweeter. Borrowing from one of Lincoln's naming schemes this is Mark II.

Woofer looks a little nicer, maybe it's just a little shinier.

This is a revised part as well. Mark III here. Not sure what happened to Mark II, I never saw it. Take note of the poly blanket and foam wrapped wires, Micca is really upping their game here.

The grills are the same, magenetic and cool like that.

Another upgrade, gone is the cardboard tube, instead we have a shiny new plastic port.

This is why we are here, for $20 more than the passive version these have the potential to be quality computer/portable speakers for the masses that's don't want to deal with different components. There was an internet rumor that the amps have the left and right wrong on the back of the speaker, mine are marked correctly. The amp sits on the back of the left channel speaker, and has two inputs. I'm told the amp is based on a newer Texas Instruments Class D amp chip that puts out 50 watts per channel if given enough power.

Speaking of power, the power supply is a 18 volt 2 amp unit that looks like something to charge a laptop. This power supply is not enough to get 50 watts per channel from the board. Micca says 15 watts per channel of clean power, and for once this is a spec I can believe. If you want to unleash the full potential of the onboard amp you will need a 24 volt 5 amp power supply.

Pulling the back plate off we can get a good look at the packaging. The crossover is mounted behind the amp, and good helpings of black goop keep everything from rattling or leaking.

The board is not very impressive. I have a feeling this is very similar to what Texas Instruments sends out as sample boards. There is not much to it, and I'm a little surprised to see a heat sink as many cheap class D amps run without one at all. The amp seems to be lacking any voltage regulators and looks like there is only a single cap on it to buffer the power. This places a lot of hope in the external power supply doing what it's supposed to do.

The crossover is Mark II of the MB42x, so upgrades a plenty on these speakers. It's nice to see that they tweaked the crossover to work with the updated drivers, something that shows a concern for quality. Should be interested to see if the changes made improvements or ruined a budget king.

The Setup:

Just like everything, Pick these up off of the desk to where your ears are either on the tweeter axis or slightly below. I've got my home made desktop stands, but canned food or books will work just as well. I ran from my receiver's headphone out to the RCA inputs on the amp on the back of the speaker, but you could hook it up to onboard computer sound, or an external DAC.

Listening impressions

These sound different than the original MB42x, but it's not a massive difference. These have a forward sound like the music is in your head, a little tighter bass, but also like it's adding reverb to everything.

15 watts per channel is enough to get the speakers to about 100dB near field. At that level it's not a good loud, it's a painful loud. For elevated listening I kept the speakers around 85dB which is pretty damn loud and never heard any distortion.

Run through of some old favorites with my asshole reviewer cap on:

Bad to the Bone - George Thorogood - Guitar sucks, Upper midrange is bright, sounds cheap and hollow. Cymbals don't sound bad. There is supposed to be a piano playing, I can't hear it. Sax is rough, too high pitch, like the music is being played too fast.

True Affection - The Blow - Near field bass is great, listening distance beats the room modes out at lower volumes. Voice sounds thin and strained, possible treble problems. Too much emphasis on some upper bass notes.

Sweet Potato Shuffle - The Polish Ambassador - Highs do not translate properly, something is missing or over done. Very hard to nail down problems with highs because ears really suck above 9k.

Soulwax remix of Justice's Phantom Pt II - Bass authority, warm overall balance. Sounds covering other sounds like a tonal aberrations remix. Very slow drivers make a mess even at low volumes

Come with us - The Chemical Brothers - Not running a compression/headroom test here, just a seeing if at low listening levels if it can make it work. Sounds are too grounded, they do not take flight. The sound is in head instead of taking over the space. I feel like I'm sitting too close for these speakers to be their best. At low levels the PB42x does a pretty good job.

We are the night - The Chemical Brothers - Highs can't keep up with the asshole of an intro. Cones move a hair, but 17Hz is not here, not that I expected it to be.

Sara - Fleetwood Mac - At low volume levels close to a wall these sounds very good. A very little bit of toe in helps to bring things into focus. I think they are still the best bargain in sound today.


Very similar to the old version. Damn near +-3dB, and has bass extension out to the upper 40Hz range. Similar peak in the upper midrange, 1000hz area which causes the forward sound, and dip in the 5k range which hides information. But it sounds different enough to warrant a new DSP correction.

DSP Correction

Worked on this one for a while. Looks like the new woofers cone breakup is in the 5300Hz range, down from 7k in the original design. This is a problem because it's too low to be eaten by the crossover and leads to the woofer singing painfully if the speaker is brought flat on the tweeter axis. I had to do a number of off axis measurements and tweaking of the correction to get the speakers as neutral as possible while still hiding the ringing.

This is what I ended up with, the bass gets a little boost, and the 1000Hz bubble is mostly smashed.

Corrected Listening Impressions

Sounds good, maybe not quite as good as the original design with DSP correction, but applying the DSP is definately an improvement worth the hassle.

With the correction I can get to about 95dB on the desktop before distorting.

Corrected vs Corrected the old ones sound better. The cone breakup moving down into the 5k range is pretty nasty if it's brought up to level, so compromise is needed. The old ones are not available, so no use fretting over it. There is maybe a 5% difference between the speakers, some good and some bad.

Final Thoughts:

The Micca MB42x is still the best sounding speaker in the ultra budget price range that I've heard and is available. The PB42x makes that bargain even better replacing crappy T-amp's in most budget builds with a pretty good amp that can drive the speakers on the desktop.

Click here to buy Micca PB42x speakers.

Click here to get the DSP correction file for these speakers.

Check out the system finder to see what I recommend.

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