Left/Right Parametric EQ

A number of Element IV owners requested separate Left/Right PEQ for 2-channel room correction or to address asymmetric hearing loss. Processing separate curves per channel adds only slightly more overhead, since every sample is already being processed either way.

Nothing has changed by default. You’ll find a new “L+R” dropdown in the right corner of the EQ table:

A white curve appears when editing the Left EQ, and a red curve corresponds to the Right EQ. Because per-channel equalization is specific to a room or a pair of ears, preset sharing is only available in ‘Sync L&R’ mode.

Native Volume and Zero-Crossing Detection

Until now, Element IV relied on the volume control registers of its DAC. Full scale audio samples were sent to the ESS DAC, which handled attenuation. For safety, firmware all the way back to Element III had checked the ESS DAC every 5ms to ensure volume was always set at the intended level. But this approach felt backwards. It’s better to prevent an error than to correct errors that have already occurred.

In firmware v2.1.0+, volume is now managed by attenuating I2S samples before they reach the DAC, thereby eliminating the ESS chip as a point of error. We’ve also implemented our own zero-crossing algorithm to keep the experience audibly smooth. Performance is identical in terms of THD+N and linearity, so v2.1.0 defaults to the new “XMOS” Volume Processing mode.

Adding zero-crossing detection throughout the DSP pipeline makes changes smoother. Volume changes with Loudness enabled are especially more pleasant.

Note: All PCM and XMOS S/PDIF audio streams utilize native XMOS Volume Processing. DSD/DoP playback and ESS S/PDIF mode continue to adjust volume at the ESS DAC. You can opt for ESS based volume processing from Device Settings to compare, but there is no incentive to do so. 

Faster DSP Changes

We encountered a technical hurdle during development way back in 2024, long before Core was a reality: It was not possible to read/write to flash while sending I2S audio to the DAC. We devised a complicated workaround involving stopping the audio stream every time flash was accessed, and then restarting. That’s why you hear a mute upon making DSP changes. It turns out a simpler solution was available all along. A one-line code change resolved the resource conflict.

We’ve shortened the mute duration between DSP changes since flash access no longer disrupts audio. Fully eliminating the mute is possible but introduces audible discontinuities during large filter state changes, so for now a brief mute remains.

Other Changes

The rarely used “Mute S/PDIF” knob button option has been replaced with a more commonly requested UAC1/UAC2 mode toggle, and UAC1 mode is now shown on the main status screen since it was previously unclear when UAC1 was active. Please see release notes in Core for a full list of smaller improvements.

Proper Q Rendering in Core

Not a firmware change, but a notable improvement: Core now uses a pure-math implementation of the Audio EQ Cookbook formulas instead of relying on the Web Audio API. The Web API fixed shelf Q at 0.707, so even though firmware has always accepted custom Q values, the EQ curve displayed Q = 0.707 for all lowshelf and highshelf filters. Core now accurately renders the curve, matching firmware.

Because this release took longer than planned, firmware v1.7.4 contains extra improvements completed along the way:

USB Communication

We expected to release Core for iOS much sooner, given how easily Core for Android came together. The delay stemmed from my misinterpretation of Apple’s documentation, in which I believed it would be possible to write a custom USB serial driver for iPadOS 16+. It wasn’t. After weeks of stalled progress, I hired a developer with more experience, and he proved me wrong within a week (thanks, Vishnu!). Together, we pivoted to a known iOS workaround, using USB MIDI for communication. JDS Labs registered a SysEx ID with the MIDI Association and preliminary firmware support was completed within two short weeks.

Firmware continues to use a virtual serial port for web and desktop Core connections. Internally, Element IV speaks the same protocol whether connecting through USB MIDI or through a serial port. There’s nothing to configure at your end, aside from installing the latest firmware. It just works!

Core for iOS

Core for iOS supports all modern iPhones and iPads back to iOS 15. You can connect with any common USB C cable to recent iPhones/iPads. For older Lightning devices, you’ll need an Apple Lightning-to-USB adapter.

We also devoted extra time to making the Core interface more mobile-friendly. Those same changes have been backported to Android, and we liked the new EQ Canvas / DSP flip toggle so much that we brought it to the web and desktop builds of Core as well.

New OLED Layout

Volume now appears in a larger font and you can choose between Regular or Bold from the options menu. To improve mode visibility, we replaced the “VOL” label with the current output mode (“HP” or “RCA”), also in a larger font.

Moving output mode freed an entire line, so Element IV can now display the current state of DSP, Loudness, Crossfeed, and Soundstage settings rather than a generic “DSP Active” status.

DSP Profiles are alphabetically sorted in the OLED menu, and the screen wakes upon sample rate changes.

Let us know what you think!

Why Synapse Max?

When we designed Synapse, we optimized for size and compatibility with our own DACs, which do not consume USB power. Limiting Synapse to 100mA maximum output allowed a smaller transformer, which fit into a smaller enclosure.

It turns out that Synapse is incredibly useful for those running audio interfaces or DACs from other brands. Many of these devices are bus powered, drawing 500mA or more from the USB port, meaning they could not be used with Synapse.

Synapse MAX uses the same 480mbps isolation technology, but with 10x higher output power capacity than Synapse.

Hardware Overview

Synapse MAX maintains the same core architecture, now feeding a larger transformer rated for 5000 VRMS. Output of the larger transformer feeds a TPS737 linear regulator for up to 1A of current:

We plan to keep the original Synapse in production because it remains perfect for low-power USB devices. If you’re using JDS Labs DACs or a device which consumes less than 100mA, the original Synapse is all you need. Choose Synapse Max for use with bus powered interfaces and DACs.

Enclosure and Accessories

Like the original, Synapse MAX is available in a CNC’ed Al 6061 enclosure with a tinted glass top surface. For your convenience, Synapse Max ships with a braided, red USB C-to-C cable and adapters for converting to or from USB A.

Synapse MAX is in stock and ships today!

We’ve taken a slower, more diligent development path this summer to resolve minor quirks and implement suggestions received throughout the year. I’ll spare you the tedious details of edge-case bug fixes, but for those curious, each improvement is documented in the changelogs found in Core. Below, we’ll elaborate on the more exciting capabilities unlocked in v1.6.0:

Mixing Tab

Element IV provides a perfect stereo image as-is, while mastering engineers have asked for mid/side controls to aid workflow. Output Offset trims volume for mastering calibration, allowing headphones or monitors to be set to a known reference level.

Virtual Soundstage

Stereo Width can be thought of as a “Virtual Soundstage”, much like moving a set of speakers closer or further apart. A value of 0 produces mono output, 1.0 maintains the original stereo width, and 2.0 expands the soundstage via the following equations:

• Left Channel = Mid + (width * Side)
• Right Channel = Mid – (width * Side)

We considered placing Stereo Width in its own, dedicated tab. However, these features are interlinked. Moving the width slider away from stereo (1.0) forces selection of the “Stereo Width” mode. Likewise,  choosing any other mode forces stereo width back to 1.0.

Try it out and let us know what you think!

Volume Tab

Some have asked for the ability to adjust volume through Core. To do so safely, firmware now supports reading volume or applying volume changes. Volume adjustments are made using “volume deltas” at the firmware level to ensure that no one can accidentally set an unexpected volume.

Element IV’s knob is still preferred, but this capability makes it possible for you to make volume adjustments when the knob is out of reach.

Core Supports OPRA by Roon!

OPRA coincidentally appeared within weeks of Element IV’s release:

OPRA is an open, community-maintained directory of product information and EQ compensation curves that optimize a wide range of headphone models. Our mission is to simplify and reduce the effort required to unlock the full potential of your headphones regardless of your level of experience, which software you choose to use, or the price point of your gear.

Core has grown to over 3000 internal presets, while relatively few Element IV owners opt to share presets they have imported from elsewhere. Now, you can browse the OPRA preset database directly within Core, giving you effortless access to oratory1990‘s preset library and much of AutoEQ. No more manual entry. Just browse and enjoy!

As a reminder, presets are a starting point: find what you enjoy and then adjust to your preferences. We’ve also enhanced Preset entry so that you can easily add notes and author/attribution info when sharing in Core.

Element IV Firmware v1.50

Some of this will come as no surprise to those following the blog:

• Replaced Auto Preamp gain approximation with transfer function
• Added configurable Loudness
• Added configurable Crossfeed
• Added Left/Right Balance adjustment
• Fixed random mutes and restarts upon DSP changes

Smarter Preamp Gain

Previously, Element IV performed a quick calculation to arrive at a usually adequate preamp gain. The math was simple: Set preamp gain 2 dB higher than the strongest DSP filter. This worked fine until using overlapping filters, in which case manual preamp gain adjustment was necessary to avoid digital clipping.

This simple calculation fell apart once we began testing the new Loudness and Crossfeed functions. Each placed shelf filters on top of any existing PEQ filters, requiring manual entry of preamp gain.

To improve the experience, Element IV now performs a proper transfer function to find the resulting frequency response of all 16 DSP filters (12 PEQ + 2 for Loudness + 2 for Crossfeed). The new algorithm finds the largest gain at 1000 logarithmically spaced points, as well as the center frequency of each DSP band, and then adds 1 dB headroom. Our firmware team and I spent weeks testing and iterating to make Auto Preamp Gain bulletproof—and it now provides 1 dB greater dynamic range than before.

In short, you will no longer need to use Manual Preamp gain under any scenario. We’ve retained the option in Core for backwards compatibly with older firmwares.

Loudness and Crossfeed

Loudness is fully configurable. You’ll need to experiment with the Reference Level based on the efficiency of your headphones/IEMs. The default Reference Level of  -20 dB is a decent starting point for most open-back headphones:

Crossfeed is similarly configurable. As with all features, we validated both by analyzer and by ear. It’s quite difficult to notice Crossfeed with modern mixes (it’s most useful with older recordings featuring hard panning).

Loudness and Crossfeed settings are never stored with Cloud presets, but will save to your EL4’s on-device profiles if you wish.

Balance

Valuable to those with specific hearing needs. Balance is saved as part of cloud Presets/Profiles:

What’s Next

As always, we appreciate your feedback! Firmware and iOS development is ongoing. By the way, you can find us at CanJam London on July 19th.

We’re pleased to announce:

Behind the Scenes

Porting Core to Android was relatively painless, thanks to Androids’s native USB Host driver. The app was mostly functional within a few days on an older phone. We spent far more time adapting the UI for phones and tablets, and another week navigating the Google Play publishing process.

What about iOS?

Yes, we’d also like to see a native app. Now that Core is available for all other platforms, we will explore iPad next.

Please keep in mind that Apple restricts USB serial access to iPads with DriverKit support (2022+), so iPhone support is unlikely unless Apple brings DriverKit to iPhone. Edit: iPhone and iPad support is possible–taking longer than planned.

v1.4.1

• Support for EQ Profiles stored directly on Element IV
• Added DSP Profiles to the OLED menu
• Display the active profile on the status screen
• Swapped bottom two lines on OLED for readability of active profile
• Factory Reset clears all DSP settings and Profiles
• Refactored JSON protocol to better support new features
• Increased size limit for future DFU upgrades from 256k to 512k

v1.3.1

• Optimized performance of each DSP filter stage
• Support for 12 DSP bands
• Support LS/PK/HS filter types for all 12 bands
• Resolved missing volume compensation step when Band 1
  was disabled while other filters were enabled
• Toggle gain relay at boot to ensure gain state is always valid

We originally planned to ship all of these improvements in one release, but the scope led us to split them into two. Offline profile support required major changes to flash storage, the menu system, and the Core API. One of our developers even paused progress to refactor the protocol, opting for a clean redesign rather than layering on top of the original command structure.

Core Updates

We’ve refined the Core UI and added full support for filter type selection and preset management. You can now save any of your Cloud presets directly to Element IV for use away from Core:

Filter Type Selection

Element IV now supports a full 12-band PEQ, meaning you can assign Lowshelf, Peaking, or Highself filter type to any band. This unlocks compatibility with advanced presets like those from oratory1990:

Offline Profile Storage

Up to 10 profiles can now be stored directly on Element IV—especially useful when listening from a console or offline source.

The new DSP Profiles menu on the OLED lets you choose from your saved EQ settings, filtered by the current output mode (Headphone or RCA):

In audio terms, “Presets” usually refer to predefined EQ settings. We use “Profiles” because each setting also stores its output mode and future DSP options, making them fully aware of your DSP selections.

Community Presets

You’ll find a new “Browse Community Presets” button in the sidebar, allowing you to filter EQ presets by headphone model and listen on-the-fly.

Around 3% of registered Core users have shared their presets thus far. If you’re among the 97% enjoying Core and Element IV, consider helping others by tagging your headphones and sharing your favorite profiles!

What’s Next

Core Desktop & Android

Core Desktop is now available for macOS and Linux. The Windows build is ready and will be posted as soon as we complete code signing. Core for Android is also up and running internally—more on that soon!

Firmware

Development continues, with Loudness and Crossfeed currently underway. Expect more top-requested features later this summer!

Core

• Added LED Mode: OFF
• Reimplemented the OLED DSP Menu, including Gain/Freq/Q for all 10 bands
• Added XMOS based decoding of S/PDIF (optical) input, with full 10-band EQ support
• Added ability to toggle between S/PDIF input modes from the OLED menu or Core Device Settings:
  • ESS: 44.1-192 kHz, no DSP
  • XMOS: 44.1- 96 kHz, full DSP support

What’s not clear from these brief notes is the incredible amount of thought and development that went into S/PIDF-to-I2S decoding. Implementation began years ago. If you had asked me in 2022, I would have told you we’d wasted months on software development—we abandoned the project after AKM’s factory fire. There was no reason to build an S/PDIF converter when ESS gives one away for “free” with every chip.

As Element IV took shape, the archived S/PDIF-to-I2S project suddenly made perfect sense. We could decode S/PDIF on Element IV, unlocking the ability to run its 10-band EQ in both USB and Optical modes.

In this post, we’ll walk through the high level architecture and performance considerations when using Element IV’s new S/PDIF modes.

Element IV’s Optical Modes

Element IV’s incoming optical signal is fed directly to its ESS DAC, as well as to a GPIO pin of its XMOS processor. As of firmware v1.2.0, you can now choose between the following modes from Core’s Device Settings or the OLED menu:

• XMOS S/PDIF Mode [default]: Optical decoding at up to 96 kHz with full DSP support
• ESS S/PDIF Mode: Optical decoding at up to 192 kHz (no DSP)

If you have no need for equalization, choose ESS mode. ESS’s patented algorithm decodes S/PDIF remarkably well—arguably the best in the industry.

Element IV’s XMOS S/PDIF mode is tuned in firmware to balance performance and computational resources. Keep in mind that Core firmware running on Element IV currently consumes 60-80% of available resources to run its 10-band EQ and general functionality.

Three of 16 XMOS cores are now dedicated to S/PDIF decoding. Under the current computational budget, jitter sidebands are slightly higher and THD is elevated by 1 dB when decoding optical in XMOS mode vs. ESS mode. These minor differences are imperceptible, and obviously more than compensated for by the ability to run the 10-band EQ in optical mode!

System Architecture: S/PDIF Reception to I2S Output

The S/PDIF-to-I2S engine uses a custom Asynchronous Sample Rate Converter (ASRC) implementation and a lock-protected ring buffer to hold I2S audio stream data at a nominal 50% fill level, protecting against underruns or overruns.

Precision & Buffer Management

Please keep in mind that v1.2.0 is our initial release of XMOS S/PDIF mode! While it’s been tediously tuned and auditions well, S/PDIF signals from some consumer devices can be unpredictable. Let us know if you encounter anything unexpected.

What’s Next

With DSP-over-optical complete, our devs are now hard at work on your feature requests! I’m pushing for on-device profile storage next (yes, it’s possible). One of our lead developers is optimizing the DSP stage this week, so stay tuned for spring Core firmware updates.

Core—

Many of you asked for more EQ bands and advanced DSP capabilities, and we immediately realized that managing parametric EQ bands on a device display would be a user interface disaster. So, we envisioned a next-generation app to support our DACs. Enter Core, our new web app, designed to provide you with intuitive, driverless control over Element’s 10-band PEQ and more. Together, Element IV and Core mark the future of desktop audio.

And we didn’t stop there! Element IV features USB Type-C connectivity, failsafe DC protection, and outputs an incredible 3.2W per channel—3x the power of the original Element III—while running cooler than a Boosted MK2. We also upgraded the discrete optical encoder for faster interaction and refined the auto-vanishing display with tinted Gorilla Glass. All in the same desktop form factor with a wobble-free knob. Pure bliss.

What is Core

It took our top developers over a year to build the firmware and Core platform for Element IV. Now, as I listen through Element IV, I’m certain that Core is the future of desktop DACs.

Core brings a new level of control to modern DACs, offering easy access to every setting exposed in firmware, along with a sleek yet powerful equalizer canvas. Core parses EQ profiles from Autoeq.app and Squiglink so that you can apply headphone profiles effortlessly.

Element IV connects to Core under Windows, macOS, and Linux without custom drivers or additional software. We’ve also eliminated third-party firmware tools and tedious command line procedures. Core detects when hardware updates are available and easily installs new firmware through your browser.

And this is just the beginning. Development is ongoing, and Core will continue to evolve.

Element IV’s DSP Implementation

Element IV currently supports up to 10 real-time, parametric EQ bands managed through Core:

• 1 Lowshelf Filter
• 1 Highshelf Filter
• 8 Peaking Filters
• Gain Range: +/-30.0 dB
• Frequency Precision: 0.1 dB
• Q Range (peaking): 0.1 to 50.0
• Q Range (low/highshelf): 0.1 to 3.0
• Preamp Gain: Auto or Manual

Firmware automatically sets preamp gain, volume compensation, and amplifier gain, so you can experiment without worrying about clipping or unintentionally distorting your music.

DSP is currently supported through USB input. Support for DSP over optical input is underway, along with several additional functions.

Lossless DSP?

The term “lossless DSP” has begun to appear in certain corners of the market. It’s tempting to label DSP performance as “lossless” if distortion and noise levels remain unchanged whether filters are enabled or disabled. But consider this: applying equalization intentionally changes the output. That change represents a loss of original frequency response. Rather than “lossless”, an appropriate label is “no added distortion or noise.” Admittedly too wordy for marketing teams.

With this in mind, we will not be so bold as to claim that any EQ is lossless. Instead, Element IV’s DSP is engineered to avoid distortion. On the left is SINAD with all 10 DSP filters enabled with volume at -3 dBFS; on the right is the same Element IV with DSP disabled. The DSP altered profile has favorable performance because of its slightly higher internal signal strength. No loss of quality!

Initial Release

Core has been running smoothly for a couple months. We shared the app at CanJam SoCal 2024 with trusted faces, along with reviewers. While Core is fully functional, we’re keeping the “Beta” status label until we’ve gathered more of your feedback.

Why a Web App? What happens in 10+ years?

Timmy is our full stack developer. He built jdslabs.com from scratch and has solved major challenges we’ve encountered throughout the past decade. When I pitched Core to Timmy, he immediately suggested a web app over native. Thus, Core is a web app.

Core is built in React, meaning it can potentially be ported to a native Electron app. For now, the server costs far less than our daily coffee, so it’s financially sustainable.  Core as a web app is always up-to-date, and it’s OS agnostic. Use it with Windows, macOS, or Linux.

As for the far distant future, I’ll be glad to release the codebase under an open-source license if the time ever comes to decommission the app server. It’s also possible to run Core locally on any machine with access to the codebase. In short, Core will always be available for your Element IV—barring, of course, world domination by emerging AI.

Requirements

Core connects to Element IV through a virtual serial port. You may use any Chromium based browser:

• Chrome
• Edge
• Opera
• Brave
• Firefox with WebSerial for Firefox

We’re curious to hear how many of you would like to use Element IV with an iOS or Android app. Let us know in the comments!

Core is free to use, and accounts are entirely optional. Unlimited EQ profiles or “presets” are possible through accounts, and you are welcome to export all of your EQ settings as you see fit.

Software Development Journey

Building Element IV and Core has been the most exciting project our team has undertaken. Core departs from decades of simple DAC interfaces, addressing the UI challenges required to introduce powerful features many of us have wanted for years.

As with any ambitious project, the vision came easily. The reality of building Element IV involved our top developers across four countries. Concept hardware was completed in 2023, and I underestimated the complexity of migrating to a new processor, leading to several months of groundwork before we had USB audio running on an early Element IV. Only then could we lay the foundation for Core, which involved designing a custom protocol to handle settings transfers to and from the app.

A test app was built early on, permitting firmware and Core development teams to work concurrently and independently. Building Core’s parametric EQ canvas was no small feat either, requiring some outside expertise. Special thanks to Rick, Oskar, Julian, Timmy, and Thiago for making Core a reality!

Element IV Hardware Overview

Amplifier Stage

The gain stage of Element IV has been upgraded with an OPA1656 for ultra low THD, while the output buffer has been overhauled with 14 paralleled OPA1692s. This topology reduces common-mode noise and allows Element IV to deliver over 3.2W per channel at 32 ohms while running cooler than a Boosted Element III MK2.

Gain has also been increased, reaching maximum output in excess of 10 VRMS = 28.7 Vpp!

Failsafe DC Protection

Adding DC protection to Atom Amp 2 was a hedged bet. Worst case, each amplifier would cost us more to produce. In hindsight, it was a solid decision, protecting a handful of customers’ headphones from dangerous ESD events throughout the first year alone.

Thus, DC detection and failsafe relay muting is standard in Element IV. The same analog detection method is used, rather than resorting to a digital detection technique. Going digital would have reduced cost, and maybe yielded similar safety. But do we need more “maybes” in a design? Nope.

By the way, DC protection can trigger when listening to clipped audio. This is not a design defect. It’s DC protection at work. We plan to add Soft Clipping to Element IV in a future firmware update, for those of you listening to speedcore (warning, clipped!).

Power Supply

Element IV uses a new 17VAC transformer delivering 40% more current than before, in the exact same physical form factor as the previous generation 16V supply.

The USB Type C port is used exclusively for data, consuming no power. We evaluated USB C PD to eliminate the transformer. Given the extra circuitry required and the need for a 20V USB C charger, cost would have increased with debatable convenience.

D/A Stage

Implementation is everything. We explored ES9038Q2M and revisited AKM DACs early in the project and found that our tightly tuned 9018K2M performs every bit as well at lower cost.

Element IV’s transimpedance stage has been further refined, using triple OPA1612s and 0.1% thin-film resistors, with an LT3045 analog supply to reduce noise by several dB.

Oscillators received additional scrutiny. Master clocks now use ultra low phase noise crystal oscillators. There was no obvious measurement disadvantage by installing cheap oscillators rated at 80000 fs jitter. With that in mind, Element IV uses 43 fs clocks for its 45/49MHz clock pair, which look better on paper for a relatively small change in cost. Without delving into a longer discussion, the I2S engine and ESS’s algorithm influence jitter more.

Processor & Storage

The leap to a 16-core XMOS XU316 processor unlocks new possibilities. With 4 cores and 70% of memory remaining free even when running 10 EQ filters, there’s plenty of headroom for future feature expansions.

Element IV stores all settings, as well as your active Headphone and Preamp DSP settings, onboard. This means your EQ settings follow your Element IV wherever you use it (i.e., multiple PCs, tablets, phones, or consoles). When you open Core on another system, it reads settings from the Element IV connected to your machine.

You may save unlimited EQ “presets” in your optional Core account, allowing you to toggle between headphone profiles with a single click.

Knob

Element III MK2’s discrete encoder proved durable and wobble-free, so we improved it even further for Element IV by increasing the fin count from 8 to 12 fins. This gives the knob a more responsive feel, with the same smooth rotation.

Knobs are available in aluminum by default, or in polished “Clear Resin.” To streamline manufacturing, the Clear knobs for Element IV are now crafted in two parts: the clear knob itself and the encoder fins.

Clear knobs and PCBs arrived after our photo shoot, so stay tuned for updated images. For now, here’s a render:

Ring Colors: Element IV features a copper-colored accent ring by default. While black and red accent rings are still available upon request, over 80% of customers choose copper. Managing a single color simplifies inventory for our team.

Performance

Element IV is cleaner than ever, reaching up to 118 dB SINAD at high gain. During a month-long hiatus when our APx555 analyzer was down, none of us were able to audibly differentiate between untuned Element IVs at 110 dB SINAD and tuned boards at 118 dB. As mentioned in recent years, advancing SINAD is not a major priority. But yes, Element IV measures well.

Test Setup: ApX555 analyzer bandwidth = 22.4k, LPF = ADC passband, HPF = AC coupling, 300 ohm load, and Element IV USB input @ 48kHz fed from Synapse unless otherwise noted.

Just-in-Time Production

Element IV has been on our roadmap for over a year, and we’ve been refining prototypes for months. The final build passed all FCC/CE compliance tests on the first try. Just in case, we added a two-week buffer to the release schedule. Thankfully, we did.

First, enclosures arrived late. Then, first-article production boards were completely unresponsive—no screen, no USB, no audio. I confirmed the cause after hours of probing test points: the processor ground pad was missing on the production silkscreen. Working closely with our assembly partners, a corrected stencil was overnighted, and we approved proper assemblies after a long drive to Chicago.

Hurry, Price Goes Up!

Element IV’s base price of $499 USD is valid through the end of 2024 and will increase by 10% thereafter. I know many of you are eager to upgrade, so now is the best time! The circuit board is packed with more silicon than ever before and software development will be ongoing as we add capabilities.

Availability

Element IV is in stock, exclusively at jdslabs.com. A limited number are ready to ship today, and we know they will move fast! All U.S. orders will ship first, while 220-240V power supplies for international orders are scheduled to arrive on Monday.

Tone Controls?

HiFi is evolving into an ever more digital era, and we recognize that anyone serious about equalization has limited use for a 3-band equalizer like the now retired Subjective3. When using a DAC, high-performance equalization is accomplished with a parametric, multi-band EQ app. 

In a 3-band EQ, a fixed “mids” knob is unlikely to correspond to any useful frequency that you may wish to alter. The same holds true for the inner bands of 4- or even 5-band analog EQs: Bass and treble knobs get used, while non-parametric mids are often left alone. Douglas Self agrees:

“It must be said at once that middle controls, while useful in mixers, are of very little value in a preamplifier. If the middle frequency is fixed, then the chances that this frequency and its associated Q correspond with room shortcomings or loudspeaker [driver] problems are remote in the extreme.“  

A 2-band EQ is simply a “tone control”, giving you a convenient way to adjust bass and treble. Thus, Atom Phono replaces Subjective3 for those seeking dedicated bass and treble adjustment for their Atom 2 stack.

Hardware

Atom Phono’s RIAA preamp leverages paralleled passives to minimize tolerance errors. Output from its subsonic filter passes to a gain stage to optionally double the turntable signal from 30 dB to 40 dB.

The tone control is a low-noise adaptation of a Baxandall circuit, customized for deeper bass and sparkly treble.

A network of quad relays allow you to enable or bypass the phono and EQ stages: Use one or the other, or both, or neither.

Performance

Atom Phono is clean! But I’d be lying if I said it was an easy design. Atom Phono took months of prototypes to remove DC offset and achieve stability with low noise. Without further ado:

The noise and distortion components of the EQ circuit are low enough that there is no measurable impact when enabling the EQ stage alongside the Phono stage. Here’s the EQ by itself with knobs centered:

Paired with a moving magnet cartridge at 15mV, Atom Phono delivers over 1.5VRMS output at high gain. For comparison, integrated phono preamps found on turntables typically have a maximum gain of 25 or 30 dB, limiting output to around 0.3VRMS. As a reminder, signal level matters!

The RIAA phono response tapers a bit at the low end. This is not a mistake! Keep in mind that bass response varies by turntable cartridge and vinyl, and larger capacitors are neither ideal in a circuit or from a cost perspective. Atom Phono’s tone controls allow you to adjust bass as needed, while maintaining the same THD+N!

Availability

Atom Phono is in stock today at jdslabs.com.

Edited 19-Nov 2024: Added EQ response curves. Updated Performance section to more accurately reflect measurement fluctuations (SNR cannot exceed SINAD)! Added more Dynamic Range test points.