Tin Hifi P1: a rough diamond

For more than a year now, a crazy hype has been created around these headphones in the various headphone forums. This is certainly due to their affordable price (~ € 150) and the type of driver they mount: a 10mm planar magnetic driver.
I state that planar magnetic headphones often divide listeners, they love them or hate them and practically all those headphones on the market (some more some less) have the same advantages and disadvantages in common. Thanks to the minimum weight of the diaphragm they are fast and very detailed. Another advantage is the very low distortion.
On the other hand if you are looking for a lot of punch and attack these are not the type of headphones suitable for you.
Furthermore, in general, I would not call them headphones with the most linear response on the market, but thanks to the very low distortion this can be fixed (as I will explain later).

Let’s go back to the P1, there are not many planar in-ear headphones, the only ones I tried, the Audeze iSine 10, did not surprise me particularly.
To solve the linearity problems, Audeze had to include an equalizer in the lightning connector, and with good reason since without it their sound is quite terrible.
Consequently my expectations when I received them were not high, quite the opposite.

Packaging and construction

The packaging is well cared, especially for this price range. The package includes both silicone and foam tips, a 3.5mm mmcx 4-core 5N copper cable and a nice leather-like case to store the headphones.
The cable is very soft and flexible, it is not microphonic and the intertwinement of the 4 cables is not particularly tight, you must be careful that it does not get caught while you use them.
The in-ears are made of aluminum, they are extremely comfortable and well finished.

Specifications:

Driver: 10 mm planar diaphragm
Impedance: 20 Ω ± 15%
Sensitivity: 96 ± 3 dB.
Frequency range: 10 Hz – 40 kHz
Nominal power: 5 mW
Maximum power: 10 mW
Maximum distortion: 1 dB.
Interface: Gold plated MMCX connector
Cable length: 1.2m (3.9in)

Reading the specifications before I even bought them, I knew that they would be quite capricious with the amplification, and that’s how it is. They are not headphones that can be plugged to a phone (unless it is an LG V series). You will need either a DAP or a portable amplifier.
Although they do not require an important voltage, they are particularly thirsty for current because of their low impedance and low sensitivity.

How do they sound?

Simple question with a difficult answer.
I start by saying that among the in-ear headphones that I have listened to and / or that I know these have a tuning and a frequency response that from 100hz to 6khz-8khz is nearly perfect. The whole range that goes from medium-lows to medium-highs is a delight.
Unfortunately, the trouble begins below 100hz and from 10khz upwards.
Below 100Hz the frequency response starts to drop, reaching about -7db at 20hz, making these headphones particularly anemic when it comes to sub-bass.
As for the highs after a narrow negative peak around 10khz, the frequency response begins to rise dramatically up to 20khz, this negatively affects for example the harmonics of the cymbals that sound totally unrealistic and thin.
If in acoustic music this defect is tolerable and indeed gives a fake sensation of detail in the highs, as soon as you listen to a piece of electronic music you immediately realize how much this defect is not insignificant.

The soundstage is that of a closed in-ear headphone: inside your head.

The instrumental separation and detail are excellent, you can focus on each individual instrument without difficulty.

The transients are extremely defined while the attack is that of the planar ones: not as decisive and incisive as a dynamic headphone.

In conclusion, if you are not going to equalize, forget the P1, they are an excellent attempt to bring this technology on closed in-ear headphones, but without a little tuning by the listener they will not be anywhere near good.
Otherwise, if you don’t mind correcting the imperfections go straight to the next section.

P.s. I made my listening test and the following EQ profile using foam tips

Let’s refine the diamond.

First of all, close the small hole on the inner side of the the P1, near the nozzle (next to the writing R or L).
There will be an increase of about + 3db in the sub-basses. I used a small square of electrical tape. This is a simple and reversible mod that will allow you to have greater linearity in the bass (although not perfect).

Now let’s start with the equalization: I used the measurements made by the user of the Head-Fi Crinacle forum as the basis. Measuring an iem is always difficult, and in specifically measuring the high frequencies is not always particularly reliable and therefore I prefer to always equalize them by ear.

After a couple of hours of continuous tests I decided to keep these parameters:
• 24 Hz +7 dB 0.30Q
• 303 Hz -3 dB 0.68Q
• 1870 Hz -2.50 dB 0.83Q
• 3110 Hz +3.20 dB 2.20Q
• 6434 Hz ​​+3 dB 2.18Q
• 10268 Hz +5.20 dB 2.89Q
• 20000Hz -7.50 dB 1Q
• Gain: -7 dB

Obtaining the following curve:

By applying this curve, the P1 re-gain the missing linearity while maintaining their character.
The very low distortion of the planar drivers is fundamental in these cases, allowing equalization without distortion or loss of sound quality.
In the future I could update the EQ, in which case I will also update the article.

Usually I create the curve on RePhase, then export it as a .wav and use it in a convolver (Or I enter the values ​​directly into a parametric EQ)

For those who are beginners I recommend:
On Windows: EqualizerAPO
On Android: JamesDSP (in case of root) or Usb Audio Player Pro
For Apple devices I have less experience but I know that eqMac2 is widely used, JRiver allows convolution and for iOS EQE (in case of jailbreak) or Equalizer (for a fee)
If you want to apply the EQ directly on the song files, I recommend SoX.

Conclusions

These P1s are a big step in the right direction, both for the company and for this technology.
Right now, given the need for good amplification and equalization, they will be appreciated only by a niche.
If you think you are part of that niche, jump in and buy them, they will not disappoint you.