Custom IEM Model Overview 

64 Audio makes nine custom in-ear monitor (CIEM) models ranging from 2-18 drivers per side which cost between $499-$2,999. Our goal with the whole product range is to offer the best possible sounding monitor at each price point. Regardless of driver-count we aim to get the most out of components for balanced, accurate and musical IEMs. All of our models reflect that signature sound, and with the increase of drivers and cost you get increased fidelity/resolution.

For more IEM info take a look at our Educational Series.

64 Audio A4s custom in-ears on white table

A4s Story

Our A4s is a four-driver custom fit IEM, which replaced A4t in 2021. Similar to our N8 model A4s is a “hybrid” IEM utilizing two different driver types. The redesign of our four driver option centered around the dynamic low driver. We chose a dynamic driver (DD) for the lows for its enveloping and deep response. The new DD is paired with two balanced armature drivers (BA) and one tia high-driver. A4s is where you start to see our 4-way crossover implemented, similar to the rest of our higher driver count models. A single driver dedicated to each frequency band; highs, high-mids, low-mids, and lows. On top of our tia technology A4s is also built with our other patented technologies like LID, Apex and 3Dfit.

While this is targeted at musicians looking for a rich enveloping monitoring experience, the frequency response, detail, and soundstage capabilities of A4s exceed other audiophile products at almost any price point.

64 Audio A4s custom in-ears on poster

A4s Sound

It wouldn’t be surprising to see the A4s being used in a rigorous environment like a live musical performance, and then see that same product being worn by music enthusiasts, or a full blown audiophile, to listen to a recording of that same performance. This is a true audiophile grade IEM in every aspect, putting it in the same class as our higher priced IEMs like N8 and A18s. The frequency response follows proven targets for fidelity and preference. This is bass that can only be produced by a dynamic driver; it is powerful, enveloping and deep while avoiding being muddy. The mids are revealing and present, contributing greatly to its wide stereo imaging and separation. High frequency response toes the line between neutral and detailed; balanced enough to mix a record on while offering the extension needed to make a recording really come alive. 

Skyler Acord inserting his custom in-ears

I love how the A4s low end response is focused right where my bass sists. In a crowded mix with a loud auience and tons of stage noise, the booty never shrinks on me.

Skyler Acord (Bass: TwentyOne Pilots)
Andrew Marshall wearing his custom in-ears on blue background

The new A4s are a joy to listen to. They’re clear, balanced, and have rich gorgeous low-end. A perfect choice for drummers and bass players. Like all of 64 Audio’s IEMs, the fit is super comfortable and the apex vent makes it so you can wear them for hours without any ear fatigue, which really comes in handy for those long rehearsal days. There is no better option at this price point!

Andrew Marshall (Drums: Billie Eilish)

Custom-Fit, Custom-Look, & Custom-Made

Each 64 Audio CIEM is hand built in Vancouver Washington by highly specialized technicians.

Ear impressions are first trimmed and scanned into our 3D detailing software. Our patented 3Dfit technology is used to perfectly recreate the intricacies of your ear shape. We virtually accommodate for all of the internal components before 3D printing with hypoallergenic acrylic material.

Once the shell is printed our assemblers insert the pre-soldered driver packs associated with the model of the IEM.

hands assembling 64 Audio custom in-ears under microscope

The assembled CIEMs are later completed with a faceplate. Along with the 5 shell options, there are dozens of faceplate colors and materials which translates to hundreds of variations. On top of all of those options we’re also able to use custom artwork to make your IEMs truly one-of-a-kind.

earphones aligned on a white background to form a 64 Audio logo

A4s Specs

  • Transducer Type: Dynamic and BA
  • Transducer Configuration: 1 dynamic low, 1 BA low-mid, 1 BA high-mid, 1 tia high
  • Freq. Response: 10Hz – 20kHz
  • Sensitivity: 107 dB/mW @ 1kHz @ 1mW (94mV)
  • Impedance: 11Ω @ 1kHz
  • Crossover: Integrated 4-way passive crossover
  • Isolation: 20dB w/ m20 module, -15dB w/ m15 module
  • Ships with M20 Module standard

A4s Technology

Air Pressure Exchange (Apex) is a patented vent that releases air pressure in a sealed ear canal. In addition to relieving air pressure, it also maintains standard IEM levels of noise isolation. The attenuation of ambient noise and pressure relief enables musicians and music enthusiasts to listen more comfortably for longer. This venting alleviates listener fatigue and allows for a much more realistic soundstage. Apex comes in three module variations available for A4s: mX, m15 and m20.

Tubeless In-Ear Audio (tia) is a patented technology that reduces unwanted resonance and distortion for transparent and lifelike sound. Tia is comprised of three major elements: open balanced armature tia drivers, the tia single-bore design, and tia acoustic chambers. A4s features two major elements of the tia system: the tia driver and the tia single-bore design.

3D-Fit preserves the detail of your ear impressions using a new process of digital rendering and 3D-printing. The patented process of incorporating acoustical tuning features within the shell allows for designs that would traditionally be impossible. We incorporate these advanced and complex features into the shell in order to manipulate the audio produced by the IEM. This process also reduces distortion in the impression for the most precise and comfortable custom in-ear monitors available.

Linear Impedance Design (LID) is a patented circuit that corrects the non-linear electrical resistance balanced armature drivers. Varying source-amplifier output-impedance typically results in varying frequency response across devices, depending on the increase in resistance. Restoring proper interaction with the source and preserving the desired sound signature enables a consistent reliable sound.

A4s Testimonials