Testing two Inkax models: EP33 (aka HiFI) vsR9

 

This is a text piece about my interest in audio engineering and my passion for testing audio equipment. I own a large collection of headphones and earphones including many from the Inkax series. I often purchase these from the local distributor, which offers a wide variety of smartphone products at very affordable prices.

The first I found / bought were so trebly which irritated my ears putting the 5+ kHz range with more than 20 db comparing to the remain audio spectrum. This was a reason I stopped for long time spending in earbuds and finding from competitors. 3 years ago their HIFI model was quite better in it response curve with trebly sound but not so high as their predecessors. A newer addition was replacing their sponge buds with comply type which added more bass than the relatively dull sound of the silicon. That translates into a model with near to real HiFi performance as for example the JBL T500 cabled model , one model I use for about 3 years.

The packing of

The latest model I found is the R9. I bet that it is a very recent fron its series of products with a new slimmer design . Marked as stales steel as the color used for the design of this plastic model separates well from is predecessor HiFi with the half on the rear part with the audio transformer and using a quite good insulated cable that seems to be closer to a higher level to the HIFi or even the Muse (design similar to the R9)

As with most of the Inkax models this includes also a microphone and a splitter/switch which can stop /play the music from the smartphone and still be cheaper than its predecessor

Operation and impressions.

I tested for a very short time with its own buds and immediately replaced them with Comply compatible buds. These buds can offer much better isolation then the typical bud and can keep the earphones better and stiffer inside the ear canal .

The first step was to listen to both using some Malaysian music of the 90s with a middle class DAP called Amoi C10 a brick like mp3 player . Malay recordings are usually more bright than the western counterparts with treble curve shaped as in Dolby cassette recording ,while Dolby is not used while tape is playing . An audio splitter is connected between the DAP and the two earphone sets. At first the R9 was not pushed enough into the air canal making the sound rather poor with low bass. A further press and keeping the tips , finger pressed added much of bass and closer to the HiFI model with identical sound response. Note that the HIfi model uses the 400 model tat is a bit wider than the T300 used on R9

Tested them in parallel and seen that the sound level is the same in both stakes: R/R and R/L modes There was no difference in sound level that can shift the audio point towards the left or right ear(eg R)

All together to listen to the music

Next step is testing their frequency rage. The set is very simple: A audio file is previously prepared with test tones , evenly spaced across the audio band with more emphasis on the higher spectrum total 25 tones WAV format! A lavalier microphone is touched in earbuds foam tip ad the sound is finally driven to the smartphone where a program records and saves the audio. The final stage is made in the computer with audio software for making he spectrogram.

The picture is quite clear. This picture joints with two spectrans showing the resulted curves form the above process for HIFi (2014) and R9 (2017)

HiFi shows a linear response on the voice part while the R9 has a steep response. The remain part is nearly similar to both. All recording settings are the sane for both As it clear e R9 is has a lower audio level than HiFi

The final part of the test : Checking microphones

Putting the microphones in front of the DAPs’s speaker and isolating them from outside noises with a ….dry sponge. I adjusted once the audio level because otherwise the result will be garbled. The two files were scanned with the software for spectrum analysis and grouped into one image.

My reflections : There is a hum of 55 Hz from R9 (at right) . R9 produces 12 db lower audio (or 4 times lower volume) than the HiFI with a peak on the upper level of voice and losing some lower notes . I have not tested in practice to the moment

Nothing more to notice .Both earphones have a good and reliable sound. The primary issue with HiFi is its splitter design, which causes the cable to tear after only 8 months and heavy use , rendering it unusable. The connections are lost in the one bud’s cable , in the splitter part , Will the R9, with a similar splitter design, be able to resist this problem? Only time will tell!