SOL Republic Tracks Page 2

Sound Quality
No doubt, this is a bass heavy headphone made for the kids that like the thumping bass, and they're gonna get it. These cans put out plenty of lows. While I found the impact of the bass good, and the extension into the lowest octaves good as well, they did have a somewhat murky bloated sound in the upper-bass. That said, the power handling of these cans is quite good and those looking for slamming lows might find them attractive.

While the treble was significantly lower in level than the bass, it's clean and quite natural. I'm quite averse to artificial sounding highs, and I thought the Tracks did a pretty darn good job in this area.

While the highs and low are pretty good with the Tracks, the mid-range has some serious trouble. While listening to pink noise, I readily detected a significant portion of the mids have gone missing. On some songs the vocals seem very recessed, in fact, at one point I had to check and see if the headphone plug was fully inserted as sometimes when not fully inserted you get a difference signal that tends to remove the center information leaving the vocals sounding low in level and hollow.

On some contemporary music tracks (trace, electronica, dubstep) this unevenness of the mids wasn't quite as noticeable as very often these genres are so artificial there it's hard to tell what's normal. But with acoustic jazz, chamber music, and vocals a significant unfaithfulness of the mids was readily apparent.


Click on graphs image to download .pdf for closer inspection.

Well ... there you have it. Right smack dab in the middle of the mid-range a fairly deep and well defined notch is readily apparent in the frequency response. If the notch wasn't there, I'd say this was a pretty respectable showing for a bass heavy can with a warm and fairly linear frequency response, but it is there, it is deep, and it was easily heard during listening tests.

Notice also how the THD+noise plots show a rise in distortion which coincides with the mid-range notch, I suspect this is indicative of the bloaty sound I heard, though I heard it as lower in frequency. Otherwise the THD is fairly low, and the 100dB plot being significantly lower in level than the 90dB plot indicate good power handling capability. I did think they played pretty clean at loud levels. Low THD below 100Hz and 30Hz square wave top remaining above zero indicate punchy, tight bass. The measured performance here seems slightly better than what I heard.

Even though the 300Hz square wave is severely misshapen due to the mid-range notch, the leading edge and first overshoot is nicely controlled, as is the impulse response, which backs up the listening test experience of a substantially responsive and clean treble response.

Impedance response shows a roughly 60 Ohm impedance which varys little over frequency; these cans should keep their character regardless of source output impedance. With 42mVrms needed to achieve 90dB, these headphones will be driven to fairly loud levels on portable devices. The isolation is modest at -11dB broadband; the Track will provide enough isolation for home and office and the moderate noise levels outdoors, but will not provide enough isolation for airplane and rail commuting.

I think SOL Republic has made a valiant first attempt with the Tracks. There is a lot in these headphones to admire at this price point. It ticks all the boxes nicely with excellent styling, build quality, and ergonomics.

While I think think they've also done a good job sonically in the bass and treble, the mid-range notch and recessed vocals just doesn't cut it, and this fatal flaw looses my recommendation. However, I think there will be a lot of folks who will get these cans and enjoy them for their big bass and clear highs. My recommendations for a low-cost, bass-heavy headphone would be the Sony MDR-XB500 and the Skullcandy Hesh 2 (not the Hesh, which don't sound nearly as good).

It really bums me out, these show a great deal of promise. So close, so close, and yet so far away. Oh well.

SOL headphones are not the standard fair at Head-Fi, but there are a few threads here, here, and here.
SOL Republic website and Tracks product page.

SOL Republic
9375 Commerce Circle, Suite 9
Wilsonville Oregon, 97070

kongmw's picture

Even various models from Beats by Dr. Dre measured better than these....

Serious_Listener's picture

Tyll, several times in your reviews you've made comments like the following: "Even though the 300Hz square wave is severely misshapen due to the mid-range notch..." But the notch is in the frequency response--that is, amplitude relative to frequency. Square waves don't aren't a measure of amplitude; they indicate waveform--the characteristics of wave we're hearing. One is a measure of quantity, and the other is a measure of quality or specific features, without regard to quantity. They simply aren't related. So I don't really understand why you think the shape of a square wave indicates something about how much bass or midrange there is, or how it can indicate where a notch might be.

But thanks again for the great website, and the measurements as well, which are still highly informative and the easiest to understand of any graphs I've seen.

ultrabike's picture

Hi Serious_Listener,

Think of the headphone as an acoustic filter whose frequency response is shown in Tyll's plot. It has a severe notch that covers roughly 200 to 700 Hz. This means that sound around those frequencies will be attenuated relative to the frequencies between 20 to 200 Hz and 700 Hz to 1kHz. Things are a bit attenuated above 1kHz (relative to the lower frequencies - hence a bass heavy can)

The square wave is used to excite the headphone. A 300 Hz square wave will have a fundamental at 300 Hz, and odd harmonics decreasing in magnitude by 1/n where n is the nth harmonic. This means that the 600 Hz harmonic will be severely attenuated by the headphone.

How would this look? Run this in MATLAB or Octave:

% parameters
fs = 44.1e3; % sampling frequency in Hz
f = 300; % square wave frequency
N = 1024; % FFT bins
t = (0:N-1)/fs; % time

% square wave
s = (sin(2*pi*f*t)>0)-0.5;
figure; plot(t,s); grid on; axis tight;
xlabel('s'); ylabel('au');title('square wave');

% "headphone" (filter with notch 300-700 Hz)
[B, A] = butter(1,[200, 700]/(fs/2),'stop');
[H, W] = freqz(B,A); H = H(2:end);W = W(2:end);
figure;semilogx((W/pi/2)*fs/2,20*log10(abs(H)));grid on; axis tight;
xlabel('Hz');ylabel('au');title('HP - FR mag - no phase!');

% pass signal through "headphone"
y = filter(B,A,s);
xlabel('s'); grid on; axis tight;
xlabel('s'); ylabel('au');title('severely misshapen');

I don't know how to attach plots... but the results are similar to what Tyll has...

BTW, a 300 Hz square wave does not tell the story < 300Hz because unless there is a DC offset, it doesn't have those frequencies:

S = fft(s);
F = (0:length(s)-1)*fs/(length(s)-1);
figure;semilogx(F(2:end/2),abs(S(2:end/2)));grid on;axis tight;
title('square wave FR');

This is as objective as one can be IMHO...

Tyll Hertsens's picture
His comments may be a little tough to follow for the uninitiated, but he's absolutely correct. The square wave responses and impulse response contains essentially the same information as the frequency response, but just let's you visualize the information in a different way.

That's not exactly correct as the square waves also include time delay information that isn't contained in the frequency response.

@Ultrabike - if you email me the image you mention I'l post it. And isn't there a thread where folks have taken EQ info and recreated square waves that look very similar to the measured data?

ultrabike's picture

As always, very nice and thorough article.

"if you email me the image you mention I'l post it."

Message sent. The 1st order Butterworth stop-band filter is not exactly like the Sol HP (an understatement there), but it emulates a similar notch, and the square wave result looks relatively close to what you have! (or closer than I thought they would look given I don't have the real FR of the HP) My purpose was to illustrate how the FR relates to the square wave response.

It also shows that the statement "the 300Hz square wave is severely misshapen due to the mid-range notch" is remarkably accurate.

"And isn't there a thread where folks have taken EQ info and recreated square waves that look very similar to the measured data?"

I'll look for it. Thanks for the heads up.

Tyll Hertsens's picture
... but I found the thread I was thinking of, and it's graph is so awesome I need to post it instead. Head-Fi member Soaa- created a parametric eq setting that closely matched the measured fr of the DT48. Then he simulated putting a squarewave through the eq filter he build, and the results match spectacularly.

A lot is clearly explained in his thread here. He's got many more headphones and graphs shown. Awesome stuff.

mikes62's picture

Besides owning these and the sony xb500's I would clearly recommend the new sony mdr-v55's and the xb600 over the XB500's and the SOL's which are in this price point range put out heavy bass but are surprisingly well balanced in sound.

tds101's picture

Great review, as always. I would like to know if you plan on reviewing the Tracks HD. They say what the Tracks HP's lack the HD model more than makes up for. I hope to see these reviewed, as I'd buy them ASAP!!!

IgorC's picture


First of all, your site and videos are very useful for me.
I don't want to sound harsh but I think the reviews like these deserve a higher video/audio quality. Especially true for headphones when users want to see all details.

Now the best quality of the channel is 360p and the audio is muffled. Quite low for today displays. Those almost all are capable of 720p. I don't talk about super Blu Ray quality but some 480p or 720p with a better audio will be great. Some information about Youtube quality options can be find on wikipedia It will take more extra time to upload higher quality video but I think Innefidelity worth it.

Serious_Listener's picture

I appreciate the replies about frequency response vs. square waves. I get the idea, and when I have time I'll try to gain a more in-depth understanding based on what's been posted. Sometimes a one or two sentence summary along the lines of "Square waves are related to frequency response because ....." would also be nice for those of us who can understand the concepts but don't necessarily have a full math or physics background.

Tyll, all of us appreciate the thoroughness of your reviews and your experience. But it can also be frustrating because, in the case of this review, the Tracks come in two flavors, regular and HD. But we are left in the dark about the HD, the one that many of your readers who are interested in sound quality would be the most curious about. It's kind of like reading Sterophile and finding out about one speaker in a line with five models, but not hearing a single word about any of the others. Any chance you could just do some listening impressions on something like the HD and compare it to the Tracks, but without spending the time for a full work-up? Thanks.

Tyll Hertsens's picture
I'll try to get in touch with SOL after I get back from the NY meet. Not sure they'll really appreciate the current review, so we'll see if they send me a set of HDs.
ScaryFatKidGT's picture

I'd skip the HD's and try the Ultra's the HD's are right inbetween but I still think you will find them way to bassy

ednaz's picture

And that's about all it took.  I was looking for a set of 'phones with some bass boost - my electronica, alt rock, and bluegrass (washtub bass, baby) tastes are often a little disappointed when I listen through my custom in-ear monitors or my home listening headphones.  Looking for fun headphones, I called it.  An airline cancelled my flight giving me time to kill in the airport, so I went over to the big headphone store and listened to some candidates with my ipod, and then with my zune.  Was really interested in the Tracks HD because fun headphones should look fun... and they do.

It took two tracks to decide they weren't for me. I used to be a professional musician, so I actually do care about what notes are being played, and I found the Tracks HD to turn bass into bass drum, a problem I have with a lot of the fun headphones out there. And then I tried a track with some male voice singing, and was left wondering if something had happened to the track on my ipod.  Sounded like he was way, way over there somewhere, far away, behind a wall of rolling bass drums. I was pretty surprised. Reading the review above, the "hole" in the sound spectrum - well, I think I know what that sounds like now.

BTW, the same phenomenon happens with lighting in photography. Daylight florescent bulbs have huge dropouts here and there, and some colors can completely disappear, others become muted. There's light from A to Z on the spectrum, so they get called daylight bulbs, but a few letters are missing here and there. To normal eyes, no big deal. if you're photographing someone's product and it becomes mucky colored, big deal.

ScaryFatKidGT's picture

The Tracks HD's are a LITTLE better but the Ultra's are more like an actual headphone you should check those out and the Master tracks both much better than the first try basic Tracks fart cannons

kellyie's picture
kellyie's picture

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