IE 900 Audiophile in-Ear Monitors with X3R Technology and DIY Kit

(1 customer review)



  • Technology                 : Unique X3R technology
  • Transducer principle   : Single Dynamic Driver with Pressure Chamber
  • Impedance                  : 16 Ω
  • Frequency Response : 5Hz-48kHz (-10dB)
  • SPL                             : 123 dB (1 kHz, 1 Vrms)
  • THD-N                        : <0.05% (94 dB, 1 kHz)
  • Housing Material        : One-piece precision-milled aluminum
  • Cable Length              : 125cm
  • Weight                        : 4gram


This is a custom product built by Earphone DIY Labs with original IE900 shell with X3R Technology and True-Response Transducers (Drivers). We proudly provide the upgrade option to our Micro-Tesla Drivers which got 100% positive feedback from thousands of users, and work seamlessly with X3R.  Scroll down for a step by step DIY tutorial to build this IEM from scratch.

Inner structure of IE900
Inner structure of IE900

Key values for you: 

  • Innovative X3R technology unique to IE 900. As displayed above, the X3R is a unique triple-chamber absorber system and acoustic vortex removes masking resonances for a refined and extended treble. 
  • Larger-than-life sound from 7mm TrueResponse Transducer, crafted specifically for in-ear listening using the entire frequency spectrum for critical hearing of all elements of the source
  • The upgrade option with 8mm Mirco-Tesla drivers, choose of thousands EDL IE800 users
  • Equipped with para-aramid reinforced cables with gold plated MMCX connectors which possesses a special recessed and robust design to ensure reliability even after over 500 attachment cycles
  • Selection of silicone and memory foam ear adaptors in 3 sizes (S/M/L) and adjustable ear hooks to ensure an optimal fit and high noise isolation
  • Upgrade cable with Teflon coat, Silver and 6N OFC hybrid 128 cores100% Left/Right channel separation at the 3.5mm jack

Also note IE900 follows Sennheiser proprietary MMCX specification, which is not compatible with most MMCX cables (Shure/SONY spec).

Know more about IE900

We recommend this video for a very objective review of IE900.

And in case you need a subjective review, here is a good one at IE 900 Review – Flagship Dynamic Driver IEM (

About X3R technology

Developed with an audience of high-fidelity sound enthusiasts in mind, the IE 900 makes even the subtlest nuances of sound audible. The X3R technology is the three Helmholtz resonator chambers which are precision-drilled into the elegant aluminum chassis of the IE 900 and placed between the diaphragm and the nozzle. To further smoothen the treble, we integrated an acoustic vortex. This is a complex shape that maximizes acoustic friction so that excessive energy is scattered. The effect is measurable and audible and serves to make the treble as smooth and pleasing as possible.

What options can I choose from?

You can choose from 2 driver options.

True Response drivers and sound characters

The True-Response transducer is one of the world’s smallest within its category. It consists of a single high-performance dynamic driver, with a diaphragm of only 7 mm in diameter to cover the entire frequency spectrum. A custom-made magnet system with triple-channel ventilation significantly reduces the distortion factor. Even at high sound pressure levels, the sound remains clean and free of distortion.

  • Impedance
    18 Ω
  • Sound pressure level (SPL)
    123 dB (1 kHz, 1 Vrms)
  • THD, total harmonic distortion
    <0.05% (94 dB, 1 kHz)
Original 7mm Drivers
Original True Response Transducers with 7mm diaphragm
Original True Response Transducers with 7mm diaphragm
Original True Response Transducers with 7mm diaphragm

FR measurement for reference only, to be updated

FR measurement for reference only, to be updated

Why shall I upgrade to Micro-Tesla Drivers

This is a 8mm driver powered by Micro-Tesla drive technology with ultra-wide-band(5~46Khz) performance. It’s our flagship product, which outperform all the high-end micros drivers we have ever tested(including the original IE800). If you are looking for the extreme experience, we are proud highly recommend it.

  • The Micro-Tesla drive technology is characterized by maximum magnetic field strength greater than 1Telsa, focusing on the air gap inside the dynamic driver unit in a micro drive unit, which is 2 or 3 times the conventional IEM drivers.
  • Ultra Wide Band means the driver performs excellently from 5Hz to 45KHz, which greatly exceeds the ordinary IEM 20~20Khz range.
  • The main benefits to users are
    • Ultra-high density of the bass. With precise volume, the bass is well controlled and deeply extend to subwoofer area. It’s the most powerful and balanced bass we’ve ever tested among dozens of high-end drivers!
    • Ultra-low distortion in the middle. The human voice is precisely pinpointed and sounds like it should.
    • Unmatchable treble. If you haven’t tried a top level IEMs like IE800, T8iE, you may feel it is too bright in 1 second but then you will know it’s only because the high resolution can make details crystal clear – your ears are a little bit overloaded.

For the measurements using IEC711 coupler, ARTA and customized sound card,  see below.

Frequency response
Cumulative Spectrum Decay (i.e., the waterfall diagram)
Energy decay
Burst Decay


Impulse Response

The Upgrade MMCX cable

We provide 1 pcs of unbalanced Para-aramid Reinforced cable with 3.5mm connector. It’s a major upgrade to original one from any perspective:

  • Silver and 6N OFC hybrid with 128 cores, providing 50% less impedance than original cable
  • 100% Left/Right channel separation at the 3.5mm jack
  • Teflon coat and stainless steel jack and spliter, super durable

DIY Tutorials

With basic soldering and gluing skills, anyone can make the audiophile class IEM in just a few hours following the 3 step instructions. Before we start. let’s take a look at the kit:

The 2 shells are manufactured by high precision CNC, and are preinstalled with the MMCX connectors.

IE900 shells and front covers
IE900 shells and front covers

The driver is also preinstalled and fine-tuned in the front cover.  Note the polarity marked in the pic.

Step 1: solder the cable to the driver

Make sure the polarity is correctly matched. The red wire is positive and the green is ground.

Step 2: Glue the front cover to the shell

Note the notch on the shell which is designed to hold the pins on the driver. Make sure when you press the cover into the shell, the pin is correctly positioned.

You may use any instant dry glue compatible with aluminum.

Step 3: Put on cables and earpads

Note again IE900 cannot work with most MMCX cables on the market, the cable has to be compatible with Sennheiser spec on IE300/500/900. The good news is the nozzle being compatible with most 3.5~4mm earpads, so you can choose freely from the market.

The pic shows the IE900 kit works with the upgrade cable and SONY Columbia earpads.

How if I have special requirements?

Please leave your requirements in the ordering note and we’ll handle them accordingly, or contact our service account for any issue. 

Additional information

Weight 0.1 kg
Dimensions 15 × 10 × 3 cm
Driver options

7mm TrueResponse Transducer (Drivers), 8mm Micro-Tesla Drivers

Cable options

Original cable with 3.5mm jack, Upgrade cable with Teflon coat and 128core silver/OFC

DIY Options

Assemble it for me, I want a DIY kit

1 review for IE 900 Audiophile in-Ear Monitors with X3R Technology and DIY Kit

  1. Daniel Kwon (verified owner)

    I’d give these a 4.5 rounded up to a 5.

    – Amazing bass/sub-bass resolution
    – Great treble extension and clarity
    – Great value

    – Mids/vocals are a bit dark, at times overwhelmed by the bass
    – Very tip dependent
    – Non-existent customer service

    I ordered these with the 8mm micro-tesla drivers and the upgraded cable. I’ve been using these non-stop for about a week now. I’ve used them for everything – music (via Tidal), Zoom meetings, movies, YouTube videos, you name it.

    Shipping was fast – took about a week and included a neat magnetic pouch and a generous amount of ear tips.

    Customer service is non-existent so don’t expect to get in touch. I’ve reached out and followed-up via email and their Facebook page with zero replies.

    I struggled a bit with the ear tips at first. I had trouble getting a good seal before eventually finding a good fit. A lot of ear tips of every size were included – kudos to the seller for that. Getting a good seal improved the sound quality.

    I ran these through a Chord Mojo DAC and through a Apple dongle and streamed Master/Hi-Fi quality music through Tidal.

    The bass and treble extension/resolution are the real stars here. The soundstage and imaging are very good but not amazing. I have foam tips coming in soon that I hope improve this.

    My main grievance is that vocals/mids are a bit dark and get overwhelmed at times on bass-heavy tracks but I got used to it after a while where it didn’t feel like a problem anymore.

    The issue with voices being a little low is apparent when watching movies or on Zoom calls. The voices of actors and people on Zoom calls are less audible compared to other IEMs and headphones I use.

    For these use cases these IEMs are still usable – this is just something to note.

    Passive noise-cancelling is great on these IEMs so these are great for travel/working at cafes.

    Overall, these are good all-rounders and are a fantastic value for the technical aspects they provide. I would recommend them to almost anyone but especially to people that want to experience a kilo-buck type IEM for less than a third of the price.

    Thank you Earphone DIY Labs for a fantastic product!

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