Overview

In portable audio, you have options to change how your audio sounds through IEM cables and IC cables. Based on my experience starting audio in 2005 and beginning cable DIY in 2011, I’ll share my personal opinions and biases on cable selection and considerations. Please read critically, keep in mind, and if you have the energy, try verifying these points yourself for your enjoyment.

Cable Construction

Cables are primarily composed of plugs and wires, with IEM cables using connectors compatible with IEMs to connect and disconnect equipment. Breaking down cables further, plugs and connectors consist of conductors and insulators, while wires include wire materials and insulators. Most wires and plugs/connectors are soldered together to create finished products. Wire processing methods and construction also create variations, but this would become extremely lengthy, so I’ll reference Audio-Technica’s article (“Twisted ‘Twisted Wire’ and ‘Insulator’ that covers the core wire also affect sound quality - The Deep World of Audio Cables”) as a substitute for some sections. This is from a trusted Japanese manufacturer, and it’s rare to find such comprehensive coverage. While the sections relevant to portable audio cable selection may be limited, those doing cable DIY will find useful references.

I’ve digressed slightly, but let’s examine individual impacts and considerations.

Prerequisites

While I’ll discuss sound changes from cables, the premise is that in portable audio, you should first properly equip yourself with solid IEMs or headphones, then upgrade your main equipment from downstream - DAPs, amplifiers, and for users, DACs - to improve overall sound quality more quickly and feel changes and quality improvements in sound. Due to these characteristics, experiencing changes and sound quality improvements from cables tends to be difficult or cost-ineffective. Therefore, I recommend first properly equipping yourself with earphones/headphones and amplifiers/DAPs before cables. Then, if you’re not satisfied, play with cables. Conversely, changing only cables first will likely yield almost no sound quality improvement from cables and leave you in a state of low satisfaction. However, with a solid environment, cable changes appear with synergistic effects, making the so-called recabling more enjoyable from a sound quality perspective. Given these characteristics, I’ll discuss cable changes but evaluate their impact relatively within the scope of cables.

Evaluation

Wire

Impact Level: High

The main component of IEM cables and IC cables is undoubtedly the wire. In wired environments, you can’t transmit signals without wire, making it the most impactful element. Wires have structural differences like solid core and stranded wire with different sound tendencies. These are covered in Audio-Technica’s article, so I’ll omit them. However, for understanding sound impacts of stranded wire and plated wire, the skin effect may be useful, so I’ll include it as a reference. More impactful than these are conductor materials and insulators. I’ll discuss each.

Conductor

Conductors are mainly copper and silver. There are also combinations like silver-plated copper wire, or alloys made by mixing gold and silver. Older wires might use tin-plated copper wire. For esoteric materials, there were cables using platinum and palladium circulating among audio enthusiasts in the past, but these are rarely seen in the 2020s.

While there are various materials, you’ll basically be choosing from mainstream copper or silver. Roughly summarizing general tendencies: copper tends toward thick bass, rich midrange, and smooth, natural treble; silver tends toward tight bass, cool and crisp midrange, and delicate or airy treble. However, wire thickness and purity also change the character, so these are general guidelines.

Purity is expressed by the number of “9”s. For example, 99.99% pure copper wire is called 4N. For copper wire, 4-6N is the standard; for silver wire, 3N-4N is typical. However, there are exceptional cases like NORDOST’s Spellbinder with 7N copper wire, or Tara Labs products with 8N - extremely high purity copper wire. For silver wire, 5N pure silver wire is rare, but there’s Jupiter’s 5N silver wire (cotton insulation) available as a stable new product.

Basically, 7N+ copper wire and 5N+ silver wire have limited supply and are rare. Despite this, suspicious, misleading, or questionable items like 6N silver wire or 6N silver-plated copper wire are circulating. While the idea that wire conductors affect sound quality is shared knowledge in the audio community that’s easy to understand, higher purity doesn’t necessarily mean better sound - high purity can have poor performance or not match preferences. So it’s advisable to use numbers and materials only as references and properly evaluate by sound.

Also, don’t worry too much about whether silver is superior to copper. Silver’s selling points include low resistance and clear sound. Since it clearly changes sound from copper, it’s easy to appeal based on sound changes. However, since sound changes, rather than resistance values, consider which matches your preferences and moves you emotionally when listening.

For wire thickness, thicker is better than too thin, but once you have adequate thickness, the impact is lower than conductor material or insulation, so I’ll omit this.

Insulation

In portable audio, insulation materials aren’t often discussed. Cable sound changes aren’t easily understandable to begin with. Within cables, conductor materials or plug/IEM connector plating materials (silver plating probably gives good impressions) are easier to imagine changing sound clearly. However, I consider insulation materials as important as or more important than conductors.

The image shows listening comparisons using identical wire, plugs, solder, and processing methods, changing only the insulation. I tested PVC (polyvinyl chloride) commonly used in portable audio, plus PTFE and other fluorine-based materials, and polyimide. Changing only insulation shows changes in resolution and sound characteristics. PVC has an overall natural, straightforward sound but lacks information density and sound range; PTFE has high information density but sounds tight with wide range both up and down; polyimide combines PTFE’s high information density with smooth midrange for good sound balance. The cotton insulation mentioned for the 5N pure silver above contains air, allowing you to aim for soft sound or high-information sound while maintaining proper insulation. It’s said that incomplete insulation, electrical accumulation or discharge affects sound, and friction noise or vibration from insulation hardness has effects.

However, since these aren’t immediately obvious, remember these three points: (1) Insulation changes sound as much as or more than conductors and is important, (2) In portable audio, PVC (polyvinyl chloride) is mainstream but has low performance, (3) If possible, try cables with non-PVC insulation that’s acceptably stiff to increase chances of finding high-performance cables. If you can audition at physical stores, you can directly confirm sound while feeling materials by hand, making it easier to understand through experience.

However, stiff IEM cables can cause touch noise, so this requires attention. Sometimes flexible tubes are placed over insulation, which provides handling benefits while suppressing sound quality impacts, so stiff cables aren’t necessarily bad. This is a balance between hardness and acceptance.

Plugs and IEM Connectors

Impact Level: Medium

However, this becomes the bottleneck. Plug construction consists of conductor, insulator, and plating. However, there are basically almost no choices - brass conductor with unknown insulator material and gold plating is the usual option. For DIY, besides gold plating, there are clean and brilliant nickel plating, rhodium plating, no plating, silver plating, copper plating, etc. In the past, Oyaide had gold-palladium and platinum-palladium. This is similar to the copper vs. silver debate for wire - choose by preference.

What becomes the bottleneck is the plug conductor. Plugs are usually made from brass, a material mixing copper and zinc. Comparing brass to pure copper, brass has lower mid-bass center of gravity and less sound information than pure copper. Before preference, information decreases, creating performance issues. So targeting α-OCC conductor from companies like Furutech or tellurium copper (and beryllium copper) here resolves the plug bottleneck.

However, choices for such special conductor plugs are extremely limited, and you rarely encounter them in commercial finished IEM cables. Also, tellurium copper and α-OCC have some sound quirks, especially tellurium copper plugs/connectors have mid-treble peaks and can be fatiguing with poor balance when used as-is. Simply changing isn’t necessarily good - you often need to properly listen to finished product sound and adopt other copper-based plugs or adjust with wire and solder. So while it’s a bottleneck, it’s not as simple as just avoiding brass. You’ll either adopt copper-based plugs after proper adjustment, or accept brass conductor’s abundant choices. Personally, I’m copper-oriented since I want to avoid the bottleneck, and I recommend gold-plated plugs from aeco and Furutech. For IEM cables, for 2Pin and MMCX, I recommend Bispa’s CIEM 2Pin and MMCX. I’ll continue buying these, but if supply stops, I’ll be in trouble, so please try them!

Solder

Impact Level: Low

Impact isn’t large, but it’s a flexible adjustment point with choices. However, since consumers usually can’t be very conscious of this area, you can skip this section!

Solder sound changes with metal material ratios, flux types, and flux amounts. Leaded solder tends toward higher information density centered on midrange; lead-free tends toward natural sound without biased information density. For flux, the impact is small within the solder world, so I’ll omit it, but you can understand by using flux-free solder and preparing paste or flux yourself for soldering. However, even with low impact, there’s compatibility between solder, plug, and wire combinations. If there’s miso soup, probably 99.9% of people don’t have the hobby of drinking miso soup with okonomiyaki sauce and yogurt. It’s intuitively clear that omurice goes with ketchup or demi-glace sauce, and okonomiyaki goes with sauce and mayonnaise. Adjusting mid-treble like making sound luster more masculine or feminine, bringing out treble delicacy and resonance, or creating edge is very easy, so please select solder while considering sound resonance. Vintage solder occasionally has quirks in bass too, so targeting old solder might be fun.

Shielding

Impact Level: Low

Shielding includes conductive metal mesh or film, and decorative outer tubes for cables. Metal types conduct and act like wire while absorbing external noise for clear sound transmission. Outer tubes have no noise blocking effects and avoid conduction impacts, but treble can attenuate and sound thin. So we sometimes choose one when treble is harsh or noise is bothersome. Especially with metal film or mesh, besides calming treble, midrange information increases and sounds clearer, and it can reduce external noise that easily occurs with tube amplifier use, so choose shielding presence/absence and materials based on which direction you want to go.

Processing Methods

Impact Level: Low

In portable audio, there are methods like braiding wire, twisting to bundle, applying shielding, or for short IC cables, deliberately connecting wire without processing. No method is superior, and shielding has the same effects as the shielding above. However, one important point is not applying strong stress to cables. For example, braiding or twisting with very strong force to bundle cables creates tight sound but reduces information and makes treble and bass range feel narrow. So if possible, connecting wire without stress or applying shielding over that is recommended. Braiding looks beautiful and can create beautiful cable construction, but loose braiding loses organization, so some force is needed. However, it’s not very advantageous for sound quality. A balanced, realistic solution is twisting. For IEM cables, not bundling anything is difficult, so twisting is recommended, and for single-ended, IEM cables bundled with shielding can be one option.

What Should You Choose?

First, if you can go to stores, listen at stores! That’s the fastest and most intuitive way to understand. For commercial products, conductors are mostly disclosed. So first consider whether copper or silver is better (or proceed to third options). However, be careful of products that overly emphasize purity, obviously too high purity conductors, or expressions that could be misleading. After that, check whether insulation is PVC or not, and confirming non-PVC gives you a certain probability of getting good cables.

For DIY products, in addition to the above, consider plug materials and wire/plug/solder combination thinking, and check how cables are processed (whether they’re braided too tightly). If you have abundant money and want reasonably high quality, there may be pros/cons and preferences, but WAGNUS.’s quality and sound creation stability is very powerful. Even if not, if you have a trusted cable builder nearby whom you’ve auditioned, you can purchase with confidence, which is also good.

Summary

I’ve summarized sound changes by breaking down cables into elements, which have smaller change amounts compared to earphones and DAPs. Honestly, around the insulator area, it’s quite difficult to intuitively understand why sound changes, and reading this far must have been challenging. Thank you for reading to the end. This isn’t content you can digest in one reading, but I hope this somewhat questionable article serves as a reference for cable selection (or choosing not to recable) when you’re lost in cable selection!

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Addendum: I’ve corrected “insulation film” to “insulation” throughout the text. I had been habitually using “film” but that was incorrect. Thank you for pointing this out!