Higher quality image on my blog.

Let's get this out of the way: the Ola II has the trademarks of Tanchjim design. The DSP cable is good but sometimes a bit unwieldly, while the shells themselves have the usual distinct clean and even clinical look. The fit is a bit peculiar due to the very universal shape and tiny size, to the point of being a potential deal breaker for those that will not be able to form a seal. Personally, they are wonderful and have the same comfort as bullet-style IEMs that disappear in the ear.

As of late, they have deviated from their usual white/clear medical look they've adopted after the Hana 2021. The Soda, Fission, and now Ola are all lookers and keep that same aesthetic appeal while having distinct colors and quirks that make them stand out a bit more. The Ola II is on the more plain side of things, but the dark matte grey is definitely a looker!

As for sound, the Ola II is different from Tanchjim's lineup, opting for a more V-shape tuning while still retaining the mid bass and vocal emphasis character from all of the other 1DD. In a way, it reminds of the One without DSP, but with added air from the BA driver while having slightly less low treble glare. Overall, it sounds competent but it does seem to be more of the same from Tanchjim without much to make it stand out.

Full review will be coming out some time next week, with the usual detailed measurements.

All updates are tracked on my blog.

Context

I highly recommend the video "Does headphone EQ actually work?" (timestamp: 5:39) to fully understand why this article is needed.

To summarize, it is often taken for granted that PEQ is perfectly accurate and consistent from one implementation to another. However, as shown in the video, this is far from the case. Discrepancies arise, whether they are intentional or not, and so this article attempts to document some of them.

https://preview.redd.it/gcxndu5vgggh1.jpg?width=2400&format=pjpg&auto=webp&s=063fc81b052fd73ba90451c75781d5d3ab7bd5aa

This post will be updated frequently and is also separated into different EQ platform categories, mostly focusing on mobile PEQ apps and devices.

Methodology

All testing was done on a Samsung Galaxy S21 running Android 15. Note that for

Filters used are the same as in Super*Review's video, with the addition of two low frequency filters to push low frequency resolution to the limits (mostly for Android-based PEQ software).

Filter 1: ON PK Fc 100 Hz Gain 3 dB Q 0.5

Filter 2: ON PK Fc 200 Hz Gain -6 dB Q 0.5

Filter 3: ON PK Fc 1000 Hz Gain 3 dB Q 0.5

Filter 4: ON PK Fc 4000 Hz Gain -6 dB Q 0.5

Filter 5: ON PK Fc 8000 Hz Gain -6 dB Q 8

Filter 6: ON PK Fc 100 Hz Gain -6 dB Q 8

Filter 7: ON LSC Fc 50 Hz Gain -3 dB Q 2

https://preview.redd.it/80qkuh6wgggh1.jpg?width=2400&format=pjpg&auto=webp&s=cdd021dc9f7840157432d867512f8a952c7702dc

To measure the difference in output, I have opted out of loopback measurements due to technical issues on my side.

Instead, I measured the frequency response of an IEM and applied the PEQ for each implementations. First, the stock response was measured followed by a theoretical perfect EQ curve made in REW.

Then, the rest of the measurements were then compensated to the stock response to show the raw EQ filter curves. For some graphs below, the measurements were instead compensated to the Predicted REW response to showcase their behavior when deviating.

Please ignore fine grain deviations above 10 kHz.

Android

On Android, there are 2 categories to PEQ: in-app PEQ that comes with certain music players, and global PEQ that "should" work with most apps that output audio.

The former category is usually very accurate; many of the apps manage their own output and so they usually have a PEQ implementation that is close to perfect. Refer to this post made a while back. Global PEQ, however, is a different beast. Not only does the app need to find its place within the audio pipeline, it must also be able to be accurate while working within the confines of the Android audio stack.

This also means that devices running different OSes and Android versions will likely have different responses as well. Take all the following measurements and recommendations with a grain of salt.

Poweramp Player

https://preview.redd.it/0hr1uh6wgggh1.jpg?width=2400&format=pjpg&auto=webp&s=d5dcca4e9fa65ac5d12448af23fc7648db4fe859

For the sake of comparisons, I checked the PEQ output for the Poweramp Player app. As expected, it is essentially perfect. Since Neutron Player and UAPP, two of the most popular apps with PEQ, have been tested thoroughly in the past, I will skip them.

Symfonium

https://preview.redd.it/hpvkywxxgggh1.jpg?width=2400&format=pjpg&auto=webp&s=aed759a652e35e00eaa79a0843b7ef6dacadbeac

Symfonium is one that has not been covered much. There are two versions tested here; V13.7 is the initial PEQ Release while V15.0 uses an "audiophile-grade 64-bit DSP pipeline for local playback", "PEQ/GEQ [...] now run in Symfonium's own high-precision path". They are practically the same and have some significant deviations at low frequencies.

Poweramp EQ

https://preview.redd.it/rdybteuzgggh1.jpg?width=2400&format=pjpg&auto=webp&s=49871ee97be94177e2c830bd9ed6395c2203e634

This particular global PEQ is arguably the worst one with no accurate matching anywhere. These are with default settings except for changing the EQ to cascade mode.

PrecisEQ

https://preview.redd.it/f8qmm4c1hggh1.jpg?width=2400&format=pjpg&auto=webp&s=6faa580bf7fff1d066f727cae375d307dff5b7ff

Again, we see some significant deviations here. However, compared to other imperfect PEQ implementations, this one has issues at higher frequencies, with the lower range being quite accurate.

The Perfect Sound

https://preview.redd.it/bh03l3c1hggh1.jpg?width=2400&format=pjpg&auto=webp&s=00a4c2e82afb865ab539045785c4b6ccdd3dcdb4

Same story for this as the others, there are some very significant deviations at low frequencies. The offset from the predicted REW response is simply due to improper SPL alignment.

Wavelet

https://preview.redd.it/5g1ye4c1hggh1.jpg?width=2400&format=pjpg&auto=webp&s=6a28ded6f50f2746deb0b2d7aad0ae50a61f3080

The original global PEQ is still not quite at the accuracy level of other top implementations. Interesting to see the step-ladder effect created by the use of a large number of GEQ filters to recreate the desired response.

Rootless JamesDSP

https://preview.redd.it/m5otzv23hggh1.jpg?width=2400&format=pjpg&auto=webp&s=ecb2781ceb012981b49ab88a7e2292a6fcc7b2cf

This one is very accurate (again, ignore the small details above 10 kHz). It is currently my de facto recommendation for a global PEQ app.

Equalizer314

https://preview.redd.it/5sgdpw23hggh1.jpg?width=2400&format=pjpg&auto=webp&s=305623b51728c2eb4a4e75eda970d7c7f3596191

This measurement was done with the highest DP Latency Window in the app, resulting in higher accuracy at the cost of more latency.

Recommendations

Out of all the tested PEQ, which ones are the best?

For music player PEQs, most of them are very accurate and you cannot go wrong with any of the major apps. Symfonium has just implemented their PEQ and while it does suffer from deviations at low frequencies, it seems relatively simple to iron out.

For global PEQs, it is an entirely different story. I can safely recommend the Rootless JamesDSP PEQ fork as it is the most accurate by far. Tests done by others also show similar levels of accuracy. All other global PEQs lack something. The second runner-up is Equalizer314 (for these specific conditions).

u/InsertDeeper

Tanchjim Ola II First Impressions: It's good, but is that enough?

EQ Implementation Accuracy Test