Headphone Reviews

Isolation
The noise canceling circuit on these cans works only moderately well, delivering isolation that might be more typical of a good passive sealed headphone. I would not recommend these as an air or train travel headphone, as they really won't cut down on external noise well enough for that purpose. It does have the nice feature of being able to operate without turning on the noise canceling, which is great if you run out of battery, but the sound of the cans suffer when operating without power.

Sound Quality
With the noise canceling on, these headphones are moderately colored sounding overall with a mild bass boost and lively, but not harsh, treble. Mids are somewhat withdrawn and overall the SL300 has a "U" shaped "fun" sound. I listen to a lot of headphones, and I would characterize these as okay sounding. The headphone market has many really bad sounding headphones, and I think Ludacris has done a pretty good job of producing a listenable headphone early in its game. That said, it does have its failings.

When listening to pink noise, I heard a very audible honkiness right in the middle of the midrange. This particular localized coloration is fairly strong, and does give a marked "cupped hands" hollow sound with some tracks. This coloration sounds like it has something to do with earcup resonances interacting with the noise canceling mike. With the noise canceling circuit off, this coloration pretty much disappeared.

Unfortunately, when the noise canceling circuit is turned of, so is any active equalization, and the sound of the cans becomes quite poor. In this passive mode, the SL300 exhibits a substantially rolled-off bass, and somewhat strident treble. Obviously, these cans are mostly tweaked to sound good by active EQ in the noise canceling circuit.

I thought Ludacris did a good job of dialing in a tasteful amount of bass boost. The lows aren't particularly tight, but they do a decent job of delivering "oomph" when called for. The bass does have fairly good extension, missing only the lowest octave. The treble is fairly good, having just a bit more sparkle than neutral, but I didn't have any problem with excessive harshness. The imaging and dynamics of these cans is just okay.

Measurements

Raw frequency response measurements show the SL300 is relatively immune to positional changes to the sound. Compensated frequency response show a moderately uneven response, but it does generally track in a straight line with a slightly warm (bass high, treble low) tilt. Bass response is flat to about 50Hz, which is pretty good, and then falls very rapidly indicating some strong filtering in the active circuits. There is a fairly strong suck-out (lowering of response) centered at 8kHz. This may be the "cupped hands" coloration I heard in listening tests, but it seemed to me lower in frequency as I heard it. Nonetheless, this feature is troubling. The treble is fairly clean and even relative to many cans I've measured.

30Hz square wave response shows significant shifting in phase of the low frequencies resulting in large swings below zero of the waveform top, and I think this often results in a lack of impact and tightness of bass. The bass I heard in listening seemed to be a bit better than these results would indicate.

300Hz square wave is a bit ragged, with a moderately strong first overshoot of the leading edges. Again, I'm a bit surprised since the frequency response of the treble seems fairly good, and in listening I heard little in the way of biting or harsh highs. However, the noisiness of the remaining waveform after the initial spike, which is also seen as noise in the impulse response long after the impulse, may have contributed to the only modest imaging heard in listening. Impulse response also shows the acoustic signal is out of polarity with the electrical signal.

The THD+noise data shows a headphone with fairly good power handling, and fairly clean bass response. You'll note the moderate spike at 8kHz coincides with the notch in the frequency response. Not sure what to make of it.

The impedance and phase chart indicate a capacitively coupled input to the active circuitry with low notes seeing 20k Ohm rapidly dropping to 4230 Ohm at 1kHz. This seems a bit high to me. Monster puts a 220 Ohm resistor in parallel with the input on the Studios to ensure the amp driving the cans sees a relatively constant headphone impedance.

The isolation plot shows only modest noise canceling, and broad band attenuation of outside noise is only 15dB.

With 47mVrms needed to drive these cans to 90dBSPL, they will work fine with portable players and will deliver satisfying volume.

Summary
I think Ludacris fans will find these cans a welcome relief from the stock earbuds that come with a portable player. They look terrific, have some sexy features (like the light-up ear pieces), and will comfortably dangle around your neck as you flash the bling to the boys in the hood. Most consumers likely will not have heard sound this good previously.

But audio enthusiasts will be disappointed with the colorations and high price for mediocre performance. I found the Beats by Dre Studios very similar in sound, but somewhat cleaner and less colored, for overall modestly better sonic performance. The Studios, however, were a bit less comfortable around the neck, won't work when the battery runs out, don't light up, and I don't think are quite as good looking.

In the end, I'll give them a guarded recommendation, I don't think they're terrible, and I do understand how fans need to express their fanaticism. If you love Ludacris, go ahead, but I want to tell you one little thing: while they don't have the cool light-up ear pieces, the less costly Soul by Ludacris SL150 sounds every bit as good to me and maybe better (the bass is tighter, for sure), and you'd save a Benjamin in the deal. Jus' sayin'.

Big thanks to Headphones.com for the loan of the cans!

Resources after the video.

Resources
Product page at Soul website, and at headphones.com.
Just a couple of threads at Head-Fi here and here.