Introducing The Element by JDS Labs

JDS Labs has worked tirelessly to share this day with fellow headphone enthusiasts. We are proud to introduce The Element:the-element-top-down-wp

We designed The Element to enjoy our headphones without compromise. Its amplifier renders shocking power, driven by an ultra clean DAC, all housed in a precision machined chassis with a comfortable knob. The Element beautifully drives headphones of all technologies and sizes.


The Element is available for Preorder via JDS Labs. The first batch will ship by June 30th.

Mass production began six weeks ago and is now complete, pending final assembly (engraving, quality control, and packaging). Accessories are in transit with expected arrival later this week. We’ll share updates here, as well as on the item page.

  • June 22 Update – All accessories have arrived and engraving is 90% complete for batch #1. Knobs remain in anodizing. Preorders placed through will begin shipping June 30. We expect to conclude all shipments by mid-July at the latest.
  • June 29 Update – The first batch of knobs have arrived. Final assembly and Q/C is underway. We remain on schedule to begin shipping tomorrow, June 30th.
  • July 7 Update – All preorders placed through July 1 have shipped. A second batch of Elements are due for shipment in the next 3-10 business days.

Design Motivation

Each project we’ve embarked upon in the past eight years has been a step towards a better listening experience. The cMoyBB delivers better bass. NwAvGuy’s Objective2 and ODAC projects invigorated the headphone community in 2011, inviting disruptive leaps in headphone amp/DAC performance. While our manufacturing efforts have helped propel O2 to its #1 Desktop Amp community rating at, everyone recognizes the glaring problem with O2. It’s ugly. The mechanical design was an afterthought—a bare minimum solution to put the circuit in a box.

Years before JDS Labs, I often browsed impressive HiFi systems that I either could not afford, or lacked the resources to skillfully assemble. The average DIY amp in the early 2000’s demanded access to a machinist, and of course basic mechanical and electrical assembly knowledge. Whether commercial or DIY, a well designed enclosure is a work of art.


The Element places equal emphasis on external and internal design. We began with an ergonomic volume knob size and position (commonly found in pro gear), then designed an enclosure to accommodate the knob, and very last created the amplifier and DAC to fit the enclosure.

On Pushing Boundaries

Some of our competitors have scoffed in disbelief that a niche audio company can sustainably build a product like The Element. We’ve heard that it’s priced too low. We’ve heard that our volumes need to be in the millions. We’ve heard that we’ll ultimately fail and give up.

We thoroughly understand the pressures. The Element is an insane mechanical design–to most. One impressed applications engineer described our initial concept of The Element as, “This is the way it should be. Let the design test the limits of the machines and the machinists.”

The Element’s contoured chassis requires six sided machining, plus three machining processes for its volume knob, another operation for its custom buttons, as well as injection molding for its soft bottom surface. These requirements were beyond the capabilities of our single CNC in early 2014. Contract shops quoted labor costs that would have doubled The Element’s target price. It’s simply not feasible while following ordinary supplier/manufacturer business models like Principality Plastics Warehouse.

So, we made a judgement call last year. Rather than dismiss our vision, we chose to do what we’ve done best since 2007. Our head manufacturing engineer, Nick, retooled the company and developed a viable, in-house production process for The Element. Our machine shop now generates truckloads of locally recyclable aluminum chips. More on this another day.


Prototypes of The Element have been on my home and office desks for months, and I cannot stop smiling as it drives a set of Audeze LCD-XCs.

The enclosure was merely our starting point. As with the exterior design, we set strict performance standards of transparency and tremendous output power.

Linear regulators provide 30VDC to clean LME49600 buffer amplification stages, with peak output power in excess of 1.5W at 32 ohms. The Element drives all balanced armature, dynamic, and planar magnetic headphones with ease. A 3-inch volume knob and and dual gain levels make fine level adjustments possible.

Digital-to-Analog Conversion
The Element processes digital audio through an SA9023 controller and PCM5102A DAC. While the PCM5102A supports 32-bit, 384kHz audio, we’ve intentionally selected a UAC1 controller for maximum software and OS compatibility. DSD and 32-bit driver support remain unjustified. Quantization error of 24-bit audio yields a theoretical dynamic range of 144dB, several orders of magnitude beyond an audibly ideal dynamic range of >110dB. In other words, we value a clean implementation and real world performance over a superfluous feature-set.

Tactile Buttons and Logical Relays
We also designed The Element to interact as nicely as it looks and sounds. Custom, tactile buttons control power and dual gain functions. An onboard microcontroller operates failsafe relays which mute the output for 500ms during startup and shutdown, producing headphone silence (no DC offset, pops, or thumps).

Benchmark Performance

The Element was a mess in early prototyping! We started from scratch three times and produced over 125 development revisions of the PCB to achieve desired transparency, power, and functionality. That said, we’ll keep the technical discussion to a minimum. Know that the following specification tables are backed by the same test procedures as other JDS Labs products and Objective series designs.

All benchmarks are conducted on our Prism dScope Series III Audio Analyzer. Certain tests require additional data from a Tektronix 100MHz digital oscilloscope or Fluke 287.

Max Continuous Output Power is conservatively measured at 1kHz with THD+N below 0.005% for 45+ minutes of sine wave output. This endurance test places great stress on any amplifier. Many amps, including O2, overheat during extended 32 ohm sine tests (THD skyrockets and ICs may incur damage). The Element runs stable.

The Peak Output Power test demonstrates the highest power observed under the same conditions for less than 10 seconds. This approach gives a better view of the amplifier’s capability during real world usage.

The Element performs well in all areas: low noise, low output impedance, low harmonic and intermodulation distortion, and high output power.

Amplifier Performance

Frequency Response 20Hz-20kHz +/- 0.1 dB
THD+N @ 1kHz 150 Ω 0.0009%
IMD CCIF 19/20kHz 150 Ω 0.0004%
IMD SMPTE 150 Ω 0.0005%
Noise, A-Weighted -108 dBu
Crosstalk @ 150 Ω -67 dB
Output Impedance 0.1 Ω
Channel Balance +/- 0.56 dB
Max Continuous Output, 600Ω 140 mW
Max Continuous Output, 150Ω 505 mW
Max Continuous Output, 32Ω 1.1W
Peak Output Power, 32Ω > 1.5W

DAC Performance

Frequency Response 20Hz-20kHz +/- 0.15dB
THD+N 100 Hz -0.15 dBFS 0.0023%
THD+N 20 Hz -0.15 dBFS 0.0016%
THD+N 10 kHz -0.15 dBFS 0.0019%
IMD CCIF 19/20 kHz -6.03 dBFS 0.0011%
IMD SMPTE -6.03 dBFS 0.0012%
Noise A-Weighted dBu 24/96 -102 dBu
Dynamic Range (A-Weighted) > 112 dB
Linearity Error -90 dBFS 24/96 -0.02 dB
Crosstalk -10 dBFS 100K RCA -100 dB
USB Jitter Components 11025Hz -113dB
Maximum Output Line Out 100K 2.10 VRMS


We hope this article has given you a glimpse of our excitement towards The Element. Let the introduction of this bold new system empower you to hear what you’ve been missing.

Introducing C5D, Amp+DAC

Today we’re pleased to release our new C5D Headphone Amplifier + DAC:


On a related note, we pushed a major site update to last night. Please call, email, tweet, or reply below if you encounter any browsing issues.

C5D Production Status

  • Design: 100% Complete
  • Benchmarks: 100% Complete
  • Production: Ships by November 22

C5D is entirely complete and ships immediately! We temporarily paused production to make a final tweak. Shipments resume no later than November 22.

Design Priorities

C5D adds an outstanding PCM5102A DAC and extra bass boost level to our C5 headphone amplifier. Both C5 and C5D are built for portable users who demand exceptionally low noise, sufficient output power, and a super fine volume control to handle sensitive headphones and IEM’s.

Our goal for C5D is simple: Merge a reference grade DAC with C5, valuing performance and compatibility over superfluous features. C5D works natively with iPhone, iPad, and all devices and operating systems which support UAC1.

Going UAC1

USB Audio Class 1 (UAC1) is the widely compatible standard for transmitting digital audio over USBUAC2 is required to go beyond 24/96 audio, but UAC2 support remains limited and requires special drivers for Windows XP/7/8, etc. In other words, connecting a UAC2 DAC becomes more involved and potentially buggy.

It’s easy to understand why audiophiles develop specification wish lists such as 32/384kHz PCM via UAC2, or DSD, or asynchronous operation. The numbers and algorithms look really impressive. But ultimately, you can’t utilize 32/384 audio when your music collection is the bottleneck. It makes perfect sense from a marketing standpoint to enable the latest features on a new device. Fortunately, we’re engineers and not marketers.

C5D’s hardware actually supports DSD and 32-bit audio. We disabled both. UAC2 breaks compatibility with many portable devices, and C5D needs to work out of the box with phones and tablets. Plus, transparency is achievable through UAC1 and fully utilizing 24-bit depth can be unrealistic.

So instead of giving C5D compatibility limiting UAC2 features, it’s configured for awesome performance under UAC1. And we still managed some interesting characteristics–galvanic isolation, asynchronous operation, and a low latency jitter filter.

Reference D/A Conversion

C5D’s new DAC circuitry fits in previously unused space beneath the battery, so size remains identical to C5. The PCM5102A DAC and SA9027 controller pack incredible performance in this small space.

C5D Circuit Board
C5D Printed Circuit Board

Galvanic Isolation

The large chip next to the USB jack is an Analog Devices ADuM3160. This IC serves two functions:

  • Enhanced ESD protection at the USB jack
  • Galvanic Isolation

Also next to the USB jack is a new toggle switch. Flipping this switch right allows C5D to charge. Flipping the switch left makes use of the ADuM3160’s air core transformer technology to operate C5D in self-power mode*. That is, the DAC runs from its own battery when connected to a portable USB audio player. This is known as galvanic isolation, and it cleverly prevents the DAC from being subjected to noise on the USB +5V rail.

Self-power mode also gives C5D maximum flexibility with portable devices since most smartphones and tablets disable USB devices that consume too much power.

* Full isolation is utilized with low power USB devices. C5D enters a hybrid self-powered mode when connected to strong USB devices, only consuming extra power. DAC performance is identical in all power modes.

Asynchronous Mode

Just weeks before we approved C5D for production, I received word that a code update could convert C5D from adaptive to asynchronous operation. Features are always second to performance at JDS Labs, so we repeated all benchmarks.

C5D jitter already measured extremely well in adaptive mode. We want to see a sharp signal in this test, with minimal sidebands (especially near the signal). Keeping the sum of matched components below -100dBFS prevents an audible impact. C5D in adaptive mode far surpasses this reference goal at -111dBFS:

Jitter in Adaptive Mode, -3dBFS, LLF High
Jitter in Adaptive Mode, -3dBFS, LLF High

Running asynchronously, jitter improves little more than the measurement’s margin of error:

Jitter in Asynchronous Mode, -3dBFS, LLF High
Jitter in Asynchronous Mode, -3dBFS, LLF High

Jitter measures slightly better at -112dB in async mode, and is the only standard test that revealed any difference from adaptive mode on C5D. All other benchmarks returned identical results. Thus, C5D ships in asynchronous mode.

Technical Specifications

Asynchronous mode and galvanic isolation together make C5D a rare UAC1 DAC. These features make it highly self-reliant, generating its own clock and power.

DAC Specifications

Frequency Response +/- 0.14 dB
THD+N 100Hz 0.0014%
THD+N 20Hz 0.0015%
THD+N 10kHz 0.0025%
IMD 19/20kHz, -7dBFS 0.0015%
Noise, A-Weighted -103 dBu
Dynamic Range > 109 dB A-Weighted
Linearity Error, -90dBFS 24/96 0.2 dB
Crosstalk -10dBFS -80 dB
USB Jitter, Marked Sum -112 dB
Maximum Output 2.0 VRMS

DAC measurements were obtained by hardwiring a line-output jack to C5D’s PCM5102A output for connection to our dScope Series III audio analyzer.

Frequency response is excellent, with negligible rolloff of 0.1dB in the final octave of human hearing.

C5D Frequency Response
Frequency Response of C5D’s PCM5102A (direct DAC output signal; amplifier bypassed)

THD+N measures well below our reference goal of 0.005% at all frequencies:

THD+N @ 20Hz
THD+N @ 20Hz
THD+N @ 100Hz
THD+N @ 100Hz

A-Weighted noise exceeds expectations with components at -110dBu, and overall noise better than -100dBu:

Noise, A-Weighted
Noise, A-Weighted – C5D DAC line output

Dynamic range measures quite well at 109dB:

Dynamic Range
Dynamic Range – C5D DAC line output

The DAC’s line output crosstalk measures at -86.1dB, outperforming our reference requirement of -80dBFS. Note that crosstalk is limited by 3.5mm cables in actual use (still excellent).

Crosstalk (C5D DAC line output)

The IMD CCIF test checks DAC performance during simultaneously playback of 19kHz and 20kHz tones. C5D returns excellent results here, with minimal blurring between the high frequency signals (noise below -120dB). Total distortion measures well at a very low 0.0013%:

IMD CCIF: 19kHz + 20kHz, -7dBFS.
IMD CCIF: 19kHz + 20kHz, -7dBFS.

Low Latency Filter

The PCM5102A DAC used in C5D features a configurable low latency filter. In testing, we’ve observed no significantly audible difference. C5D ships with its Low Latency Filter set High.

C5D’s firmware is released freely under the Creative Commons BY-SA 3.0 license. Refer to line 55 if you wish to experiment with the PCM5102A’s LLF feature. Note that a programmer and pogo pins are required for DIY tinkering.

Amplifier Performance

C5D’s amplifier and supporting power circuitry is identical to that of C5, with the exception of an additional bass boost level and smaller output resistors. Output impedance of C5D has improved to 0.62Ω. This specification change minimally impacts overall performance, and ensures neutral operation with low-impedance balanced armature IEMs.

Amplifier Specifications

Frequency Response +/- 0.1 dB
THD+N (20-20kHz, 150 Ω) 0.0015%
THD+N (20-20kHz, 32 Ω) 0.0045%
Noise -105 dBu
Crosstalk @ 150 Ω -67 dB
Inter-channel Phase @ 1kHz +/- 0.01 degrees
Channel Balance +/- 0.55 dB
Max Output @ 600Ω 4.146 VRMS
Max Output @ 150Ω 3.580 VRMS
Max Output @ 32 Ω 1.182 VRMS
Power Supply 14.0 Vpp
Output Impedance 0.62 Ω
Battery Run Time 7-12 Hours
Charge Time 2-4 Hours
Operating Temp 0°C to 60°C
Operating Humidity 0 to 85% Relative
Dimensions 99.5 x 61.5 x 14.0 mm
Weight 4.2 ounces

Triple Bass Boost

C5D’s bass boost has three positions: Off / Medium / High. The High position is identical to C5’s bass boost, with the Medium level residing audibly halfway between off and high. Below are C5D’s bass boost curves in low gain:

C5D Bass boost reponse at Low Gain
C5D Bass boost response at Low Gain (2.3x)

These curves relax at high gain, in effect producing four unique bass boost curves:

C5D Bass Boost Response at High gain
C5D Bass Boost Response at High gain (6.5x)

DAC Compatibility

Compatible Requirements
iPhone Yes Camera Connection Kit and iOS7
iPad Yes Camera Connection Kit
Windows XP/Vista/7/8 Yes
Linux Yes
Android Some ROM and OS must support UAC1
Mac OS X Yes


We considered developing C5D for fully native operation with Android, and discovered the goal is presently futile. Even a DAC designed for native functionality via Android’s Open Accessory Protocol remains limited to 16-bit, 44.1kHz operation. And even then, support is not 100% guaranteed across all Android devices! Only an app like USB Audio Recorder Pro unlocks full 24-bit digital audio, by utilizing alternative drivers.

C5D works with every Android device we’ve tested under USB Audio Recorder Pro. We met a few Android users at the 2013 CanJam who successfully used C5D natively (i.e., with any app). Some Android phones and tablets output UAC1 natively. Others require special ROMs or apps.

Guaranteeing DAC operation with all Android devices is currently not realistic. Since Android is opensource, it’s definitely possible to enable 24-bit digital audio output on any Android device. Hopefully Google will make UAC1 output standard in future Android updates to simplify the user experience.

The good news: C5D is self-powered, so its power consumption is not a limitation. You’ll only need to enable digital audio output on your device if it’s not already available.

iPad and iPhone

C5D works out of the box with iPad and iPhone! Apple has finally enabled UAC1 output as of iOS7. You simply need a Camera Connection Kit cable. C5D is self-powered, so power consumption is of no concern.

iPhone connected to C5D at CanJam
iPhone connected to C5D at CanJam





C5 Headphone Amplifier

Today we’re excited to announce our new C5 Headphone Amplifier:

C5 Headphone Amplifiers in Red, Slate and Silver
C5 Headphone Amplifiers in Red, Slate and Silver

C5 Production Status

  • Design: 100% complete
  • Engineering Samples: Approved
  • Benchmarks: 100% Complete
  • PCB Assembly: 100% Complete, on a UPS truck
  • Enclosures: In stock, awaiting anodizing February 19-22

Barring unforeseen catastrophic failures, C5 preorders will ship no later than February 28. Review samples and distributor orders will ship on February 22.

Wed., March 13 Update: The C5 preorder sold out this morning. Mass production began two weeks ago, so C5 will be in stock in just 2-4 weeks.

[expand title=”View All Status Updates”]

Tues., March 12 Update: 99% of preorders have shipped! New Slate C5’s ship immediately. New Red C5’s will ship next Tuesday, March 19.

Mon., March 11 Update: Slate anodizing remains on schedule for completion tomorrow morning. Our anodizer says this batch is turning out as desired.

Fri., March 8 Update: Over 75% of preorders have shipped (all Red and Silver). All Slate preorders are scheduled to ship by Tuesday evening.

Thurs., March 7 Update: We inspected and approved a new batch of enclosures today, and now expect to complete preorder shipments within 3 business days.

Tues., March 5 Update: We have encountered an “unforeseen catastrophic failure” as I wrote on February 16th. The enclosure delay mentioned last week was caused by our local metal finishing shop. Their job is to apply the smooth, blasted finish to C5 (bead blasting). As of last Tuesday, they realized they’d blasted our C5 cases with the wrong parameters. Already one week late, they called on 2/26 and promised to start over and deliver perfect pieces by Thursday, 2/28. All seemed fine, until we anodized those pieces. Our anodizer called this morning apologetically. His shop follows this blog and is well aware of the significance and beauty of C5. Every single piece from the “fixed” batch was not fixed. Anodizing had revealed severe cosmetic defects–all pieces from 2/28 were junk.

I drove to the blasting facility this afternoon and handed them two C5 enclosures: one from the first batch, and one from the 2/28 batch. The production manager was as shocked as we are, and will begin another batch in the morning with strict supervision.

It’s an absolute shame that one shop foiled our ambitions to ship early. As soon as we realized the possibility of failure, we began identical blasting production at a second metal finishing shop, for redundancy.

The Good News:

  • We have a strong supply of raw enclosures; without delays, metal finishing normally takes just 2-5 business days.
  • Over 61.5% of C5 preorders have already shipped

For those affected by the delay (mainly Silver and Slate preorders), we promise to upgrade all USPS First Class shipments to USPS Priority. Please do not hesitate to contact us if we can be more helpful!

Mon., March 4 Update: All Red C5’s have shipped. All outstanding preorders will ship by Wednesday.

Thurs., Feb 28 Update: Enclosure anodizing is in progress, and we still expect to ship on Monday afternoon.

Wed., Feb 27 Update: A large batch of C5 enclosures will enter anodizing by 1PM Thursday (a 1-2 day process). Preorders will resume shipping on Monday afternoon.

Tues., Feb 26 Update: Over 25% of C5 preorders have shipped. All PCBs have been tested and are awaiting final enclosure assembly. Our enclosure finishing contractors called this morning to report a 2-3 day delay, so remaining C5 orders will ship Feb 28 thru March 6.[/expand]

Design Priorities

C5 is not a response to the Objective2, nor to competitors’ products. C5 began as a fun project in 2012 to build a smarter headphone amplifier to solve the single greatest hindrance we see in DIY audio: the analog volume potentiometer.

C5 is built for portable users who need a small amp with USB recharging, exceptionally low noise, sufficient output power, long battery life, and most importantly, a super fine volume control to handle sensitive headphones and IEM’s.

Analog Potentiometers’ True Performance

I interviewed an electrical engineer in January. He’d applied here after discovering the Objective2, and during our discussion, he asked, “What’s there left to design? The O2 is audibly perfect. How can you build anything better than that?”

Easy, there’s no such thing as a perfect product. Every design has its unique goals and constraints. For product help, you can call vodafone customer care and speak with an agent 24/7/365.

Our Chinese competitor says the Alps RK097 analog pots are “still the best” solution, presumably based on low cost and decent benchmark performance. NwAvGuy dismissed digital potentiometers as too expensive to implement with good performance, while acknowledging the major shortfall of the Alps pot he settled on for the Objective2:

 THE CHANNEL BALANCE PROBLEM: Devices with conventional volume controls may have audible channel imbalance at very low volumes [i.e., one side is much louder than the other –JDS]. It’s extremely difficult to manufacture volume control potentiometers that maintain tight channel balance below about -40 dB (referenced to full volume). — NwAvGuy

In this article he briefly describes how imbalance can be resolved with proper excess gain. The excess gain problem is primarily why we’ve custom built cMoyBBs for over five years. That is, setting a suitable gain usually avoids channel imbalance. Usually–until you’re sitting in a quiet room and want to listen at low volumes, or until you try a set of high efficiency headphones. Even at 1.0x gain, you’ll encounter major channel imbalance from your so-called high performance analog headphone amplifier in such situations.

Let’s take a look at channel balance of c421, measured by the dScope as I slowly turn the knob from maximum to minimum position:

c421: Severe channel imbalance
c421 Channel Balance (Alps RK10J, 3B Taper)

The yellow line represents the left channel; pink represents the right channel. Lines resting exactly on top of each other indicate audibly perfect balance (no deviation in L and R volume).

c421’s Alps RK10J imbalance grows after just -12dB. The problem becomes severe by -22dB, and it’s quite useless by -30dB. If you called or emailed in the past year, you know we didn’t recommended c421 for IEM’s. If you tried c421 without seeking our advice, you either listen above the imbalanced region, or you returned the product.

Here’s an Alps RK097 implemented in the cMoyBB (Objective2 uses the same series potentiometer):

cMoyBB / O2 Channel Imbalance (Alps RK097, 3B Taper)
cMoyBB / O2 Channel Balance (Alps RK097, 3B Taper)

Channel balance of the RK097 fairs much better, due to its larger mechanical size. You can see 1-2dB deviations at -25dB, with otherwise decent balance down to -40 to -50dB. And that’s where things get nasty. I only managed to turn the knob at a single point when the dScope cycled to measure the imbalanced region, which is exactly the problem IEM users face. You can either turn the knob to mute, or to a point of imbalance, or to a level louder than you’d prefer.

Even with the RK097, we still receive a few emails and phone calls each month about channel imbalance. So what good is a HiFi amplifier when it actually hurts your listening experience?

Going Digital

For years, audiophiles feared digital volume controls. Software based digital volume control is the worst, causing you to “lose bits”–the audio signal itself is digitally divided and becomes less precise. Bad!

Early digital potentiometers solved the basic mechanical problems of analog potentiometers. A digital potentiometer is electrically equivalent to an analog potentiometer. Both feature High, Low, and Wiper terminals. The potentiometer is mechanically or digitally set to determine the ratio of High:Low resistance. However, bad digital pots added a large amount of capacitance to the Wiper, and thus, audiophiles frowned at the resulting THD+N (often 0.1% or worse).

It’s 2013, and it’s finally time to say goodbye to the analog potentiometer. C5 features 64 steps of audibly perfect digital attenuation:

C5 Channel Balance: Atmega168A + DS1882
C5 Channel Balance (DS1882 + Atmega168A)

C5 presents only +/-0.1dB of deviation all the way down to -50dB, and only +/-0.55dB at -60dB! [Yes, you can only see 28 steps here, as I’m manually racing the dScope test duration by making larger volume transitions.]

In other words, C5’s digital attenuation achieves perfect audible balance at volumes -20dB lower than the analog Alps RK097. Remember that audio sounds twice as loud every 10dB, so this is no small improvement.

Reference Level Performance

C5 began as an experiment, and even I was skeptical that we could outmatch c421’s THD+N with a digital potentiometer. Thus, we bought a dScope III and set no project deadline and no budget. We’d either continue shipping c421’s, or continue experimenting.

C5 Printed Circuit Board

By January 2013, it was clear that C5 was electrically complete. We quietly put C5 PCB’s into production instead of another batch of c421’s. C5 had not only hit our THD+N goal, it had matched the O2!

Specification C5 Measurement
Frequency Response  +/- 0.02 dB
THD+N (20-20kHz, 150 Ω) 0.0009%
THD+N (20-20kHz, 32 Ω) 0.0045%
Noise -105 dBu
Crosstalk @ 150 Ω -67 dB
Inter-channel Phase @ 1kHz +/- 0.01°
Channel Balance +/- 0.55 dB, all volume positions
Max Output @ 600Ω 4.146 VRMS
Max Output @ 150Ω 3.337 VRMS
Max Output @ 32Ω 1.010 VRMS
Power Supply 14.0 Vpp
Output Impedance 2.2 Ω
Battery Run Time 11-14 Hours
Charge Time 2 Hrs to 80%, < 4 Hrs to 100%
Operating Temp –40°C to 85°C
Operating Humidity 0 to 85% Rel. Humidity
Dimensions (excluding switches) 99.5 x 61.5 x 14.0 mm (LxWxH)
Weight 4.2 ounces
C5 THD+N Measurement @ 150 ohm load
C5 THD+N Measurement @ 150 ohm load: 0.0009%
C5 Idle Noise
C5 Idle Noise
C5 Frequency Response (Flat)
C5 Frequency Response (Flat): +/- 0.02 dB
C5 Frequency Response (Bass boost)
C5 Frequency Response (Bass boost): +6.5dB @ 80Hz

Achieving high output power was not a primary goal of C5. Referring to its design objectives, portable users do not need inordinate amounts of power (note: P = V^2/R); you need run-time and just enough power. C5 has equal output power to that of c421, and we know from measurements and subjective results that c421 and C5 are well suited to driving 90+ dB/mW headphones. IEMs and common 32-250 ohm dynamic sets are okay for C5. It’s not meant for your planar orthodynamics. Therefore, instead of setting unnecessary supply voltage and output power, we set adequate supply voltage for moderately demanding headphones and achieved run-time of 14 hours.

Dual LDO Supply Regulation

C5 builds upon c421’s proven power stage by adding cutting edge TPS7A4700 and TPS7A3301 regulators to the supply rails. Hats off to HiFiDuino’s blog post for catching my attention back in September.

We wanted to place LDO’s in c421, but there was no way to control them, and without control, unsynchronized LDO’s produce unsafe turn-on transients. C5 is smarter than c421, so its firmware simultaneously enables the positive and negative LDO’s after the rest of the amp has initialized. You hear only a safe turn-on transient with C5, and reap the benefits of ultra-low supply noise.


  • Digital Stepped Attenuation (63 steps + mute)
  • Dual Gain: 2.3x or 6.5x, MOSFET controlled
  • Bass Boost: +6.5dB @ 80Hz
  • 20-Minute Low Battery Indication
  • 0.1% Thin Film Resistors
  • 1200mAh, 3.7V Li-Ion Battery
  • Smart USB Charging
  • Ultra Low Noise +/-7V rails
  • 3.5mm Input and Output Jacks
  • Gold Immersion, 4-Layer Printed Circuit Board
  • Atmega168A MCU w/Opensource Arduino Firmware
Feature How to Use
Volume Hold volume lever left to decrease volume, or right to increase volume.
Gain Push volume control to toggle high/low
Bass Boost Toggle up for normal audio, toggle down for bass boost

A single LED conveys all of C5’s behaviors:

Amplifier State LED Status
Off Off
On Solid Green
Low Battery Flashing Green
Charging Blue


Opensource Firmware

C5 Proof of Concept
C5 Proof of Concept

The C5 proof of concept began as an Arduino Pro with messy wires coupled to a c421: DIY style.

Writing firmware for a digital potentiometer is surely a hurdle for many in the DIY audio community. In pursuit of retiring analog potentiometers in DIY HiFi, we’re releasing C5’s firmware under the CC BY-SA 3.0 license. Note that a 6-pin header and ISP programmer are required to write to C5. Enjoy!

On the ODAC, and Recent Reviews

Okay, this post is in reply to our full email inbox this morning. Regarding NwAvGuy’s upcoming ODAC:

  • JDS Labs is an official distributor of the ODAC
  • An ODAC preorder page is live
  • ODAC production began late last week in the USA, and will take about 4 weeks (release = May 2012)
  • NwAvGuy has not released specific information yet; we have little more information than what’s already revealed in his blog [Edit 4/18/2012: Now Released]
  • ODAC absolutely requires a headphone amplifier for proper operation

I know many of you are looking forward to installing ODAC in your O2’s, or having it retrofitted at our factory. (For those new to this project, three wires from ODAC must be soldered to input jack terminals P1 on the Objective2, a couple traces must be cut, and the 2x9V batteries must be removed.) A retrofit is a nightmare of a design choice for us. Sorry, NwAvGUy! Soldering one DAC is no big deal for a do-it-yourself’er, but we’re faced with soldering hundreds. And that means hundreds of our past O2 customers might want to send their amps in for the upgrade. Cost for the O2+ODAC retrofit will be announced after ODAC is released. But we’ve devised a far more elegant solution.

Option 1: Standalone ODAC in Enclosure

NwAvGuy equipped ODAC with an optional 3.5mm line-output jack, for use with other headphone amps. It just so happens that ODAC fits into the same custom aluminum enclosure we built for c421. Nick sketched new end-plates, and voila:

This is only a preview! We’ve printed prototypes and tested fit. Design files are now under review by our machine shop, so things could change based on manufacturability.

Placing ODAC in a standalone enclosure means:

  • Objective2 owners can add an ODAC without modifying their perfectly good amp
  • All features of the O2 are retained (no need to remove 9V batteries)
  • Standalone ODACs can be paired with any headphone amp!
  • Same performance as coupled to the O2

This standalone ODAC edition will be added to the preorder page as soon production begins–any day now. Available approximately upon release of ODAC.

Option 2: O2+ODAC Combo

As NwAvGuy plans, we’ll offer ODAC preinstalled in new O2’s, which will look something like this:

These will also appear on our preorder page after production begins. Available approximately upon release of ODAC.

Option 3: O2+ODAC Retrofit/Upgrade

Identical to option 2, but for those who already own an Objective2. Available in late May.

Option 4: Assembled ODAC PCB

Consists only of an assembled ODAC circuit board–no amplifier or enclosure. This is the only offering on our preorder page for now. Ships mid May.


As you can see from the above images, the ODAC product lineup is well underway. All prices and preorder options will be available by the end of May.

A Note on Reviews

The first time I browsed to, I couldn’t imagine seeing our products on Mike’s awesome review site. It was all high-end gear, way beyond anything we’d built at the time. So I was surprised when Mike e-mailed me for a cMoyBB sample in early 2011. The review went well.

Note: We are not a Headfonia sponsor. In fact, we don’t sponsor or endorse any audio publications. I’d rather see our great products spread through the audio community by word of mouth, and use cash-flow instead to increase product development and distribution.

Headfonia Review - Flyin’ High: JDSLabs C421

Anyway, Mike posted a well received review of our c421 last month, with the OPA2227. But he was quite opposed to the AD8620, totally contradicting my opinion.

Then came the controversial Objective2 review, which led to a follow-up article from NwAvGuy.

I’m not taking sides. I fully endorse NwAvGuy’s work and his rebuttal, and I’ve always been a fan of Headfonia.

I personally prefer to listen to c421 with bass boost on, with DT-880’s. I have nothing bad to say about the Objective2. It’s a technically brilliant amp. But I’m a bass boost guy. Hence, cMoyBB.

The fact is, audio is subjective. NwAvGuy can post measurements and discuss psychological theory all day long, but we’re humans. Our brains operate subjectively (“expectation bias”, as NwAvGuy wrote).

Case in point, Nick says O2 and c421 sound the same. But Nick isn’t an audiophile and doesn’t spend his free time reading audio forums and reviews. He just knows that JDS Labs sells nice headphone amps.

I don’t intend to discredit Mike or Headfonia. There’s a lot of truth to what NwAvGuy writes, especially in regards to expectation bias. Mike e-mailed us after the O2 review went live; I replied explaining that I wasn’t disappointed. He expresses his honest opinion in his reviews. NwAvGuy blogs about objective audio engineering. JDS Labs has to tie everything together. We build amps that we believe in, both in terms of design, and in terms of taste/expectation bias. We receive dozens of emails each week asking for comparison of one amp to another. While I could steer a customer one way or another, I sincerely avoid replying in depth to any of these messages.

Read reviews and blogs. Read specifications. Look at pictures. Borrow a friend’s amp, or go to an audio meet. In the end, pick an amp that meets your needs and expectations.

Cyber Monday – O2 Front Panels!

It’s doubtful I can convey anything more worthwhile than the pictures, so here’s this week’s big news:

Looks amazing, doesn’t it? Nick had a difficult time stepping away from the 3D model:

Our JDS Labs branded O2 front panels and fully assembled O2’s are available now for preorder.

c421: Quality Inspection 3

Continuing from our last update, the third batch of c421 cases arrived last week. To our great dismay, the manufacturer damaged our $1500 custom die (a tool to make the cases), so batch #3 turned out far worse than the first two batches. Instead of scratches, batch #3 pieces weren’t even the correct shape.

We’re moving case production to a high precision aluminum manufacturer. These guys understand the perfection we’re seeking and will ship nothing less than excellent. Since they’re starting from scratch, it will be February before final c421 cases are ready.

All c421 preorders will be shipped this week in batch #2 cases. You will be able to request a final case for free in February. Batch #2 cases aren’t terrible; they’re simply not up to our standards. Keep watching for more updates…

Side note: We had no trouble with c421 front panels. O2 panel production really will be done by January! We’ll post a “lessons learned” story when this mess is finished.

Rechargeable cMoyBB, First c421 Image

Rechargeable cMoyBB v2.03R

When we released the NiMH Module earlier this year, the idea was to bring recharging to the cMoyBB in a versatile fashion. Owners of existing cMoyBBs could add the feature to their older amps, and there was no need to revise the cMoyBB circuit board.

cMoyBB v2.03R Printed Circuit Board

But, the charging module placed too many limitations on the amp: no 18V support, batteries were difficult to remove, and the dual DC jacks confused new users.

As of this week, the NiMH Module is discontinued. In its place is a brand new cMoyBB v2.03R circuit board, which adds simple NiMH recharging support to the cMoyBB.  The cMoyBB finally accepts single- or dual-9V NiMH batteries!

Slip-on on 5.5 to 3.5mm Barrel Adapter

Ordering a rechargeable cMoyBB has been streamlined as well. Simply select standard or rechargeable.

To make matters even easier, we now stock a rare 5.5mm to 3.5mm barrel adapter. This allows you to power the cMoyBB from common AC/DC adapters, including most laptop power adapters.

NiMH vs. Alkaline vs. Li-Ion

Adding recharging support to the cMoyBB has never been a high priority, despite popular request. We’ve avoided it for a few reasons:

  • NiMH batteries are typically 1V weaker than alkalines = Less voltage swing.
  • NiMH recharging circuits lose 0.7V-1.2V on top of the battery voltage! More lost output power.
  • NiMH run-time is about half that of alkaline batteries
  • Separate AC/DC adapter required
  • Long charge time (10-12 hours)
c421 - High Performance Li-Ion Headphone Amplifier

If you’re using moderately low impedance headphones (under 64 ohms), a single 8.4V NiMH is usually adequate for high volume amplification. Even if you have higher impedance headphones, voltage is no longer an issue since the cMoyBB v2.03R supports 18V (2x9V)!

For top performance, a fixed voltage Li-Ion amp like c421 is the way to go. You’ll always have maximum output power, long run-time, and short charge time. For those who have already pre-ordered c421, we’re 1 week ahead of schedule!

c421 Pre-order Goes Live

Someone reminded us that we haven’t posted a c421 update in “forever”. Today’s your day:

  • The c421 preorder page is now up! Note that the release date is tentative, so the page cannot yet be found through our store, and the formal announcement e-mail has not been sent out. We’ll send the official message when the date is 100% certain.
  • Features, specifications, and a description of c421 can be found on the preorder page.
  • Fewer than 95 amps are available for pre-order.
  • Price: $169

Quality Inspection 1…

The first batch of enclosures arrived Monday, but we rejected the shipment due to a total lack of packaging. Every single case was scratched. I don’t know about you, but if I’m paying $169 for a device, it better look decent! The manufacturer is redoing the job immediately. This sets us back 1-3 weeks, but high quality is more important than speed.


Assembled c421 circuit boards are scheduled for arrival by October 24th [Edit: Arrived OCt-21]. If you preorder now and get impatient, we can send the amp in a temporary rejected enclosure. You can order another enclosure later for the cost of shipping. Just send us a note.

October 31 is the earliest expected shipment date. Realistically, we anticipate all preorders to ship by November 14.

Rocky Mountain Audio Fest

It’s 1PM Wednesday and I’m scrambling to fly out to Denver for the 2011 RMAF. We’re not exhibiting, however, I will be wandering around the show. Tweet (@jdslabs), e-mail, text, or call if you’d like to hear c421!

Preview of c421 Enclosure

While we eagerly await the release of c421, here are a few rough, rendered previews. The enclosure will be composed of black anodized aluminum with black or natural brushed aluminum end panels, unless we’re persuaded differently!

Screws, light pipes, and the battery are not shown…

Rear view of c421, showing countersink screw holes. Color of end panels not final!


Obligatory size comparison to a popular portable source
Size comparison at another angle

We expected to have real samples in hand by now. So what happened?

A reputable aluminum extrusion shop promised us 6-8 week lead time and a a competitive price, so we faxed over the deal on July 1. Three weeks passed and I recieved a phone call from their company president, Bob. He said, “Hi, John. I have some bad news . . . We dropped the ball on this one.”

Bob’s company  had severely underestimated their bid and refused to fabricate C421’s enclosures unless we forked over another $10,000. Wasn’t gonna happen, Bob! $10k would have ruined our project goals.

Although this delayed c421 by three weeks, everything has worked out for the best. We’ve used the extra time for additional circuit tweaking. And, we signed a better enclosure deal with an amazing extrusion shop whose manufacturing plant is only four hours south of our office! Their staff has kindly invited JDS Labs to witness on-site sample inspection.

Samples are due approximately 4 weeks from today. I will personally inspect the enclosures and post pictures if possible. Final device specifications and pricing will follow soon afterwards.

One final note: We’ve received countless offers from past customers and new faces seeking to review c421. Thank you! The first production batch will be a small run of only 100 units. Just two amps will go out for initial review (more later). A pre-order page will be posted around the time reviews go live, no more than 4 weeks before we can ship.

Like the design? Hate it? Let us know!

Headphone jack at front of C421 (rendering with transparency)

Announcing Codename “c421”

We’re past due on several announcements, but not due to a lack of content. In fact, we’ve been exceptionally busy this spring.

After returning from Silicon Valley last week, I was thrilled to see a package from Advanced Assembly at my office. Inside were two recently completed “c421” prototype headphone amplifiers:

A first look at codename c421, Prototype II (v0.84) - May 2011

Read More

Opamp Rolling and New Kits

New to our store this month are Brown Dog SOIC-8 to DIP-8 adapter sockets. A great number of fantastic opamps are only available in surface mount form. These adapters allow you to enjoy noteworthy chips such as the AD8620, AD8599, etc.

Below are two cMoyBBs with freshly seated SOIC adapters. Powered from a mandatory 10V+ DC adapter, the AD8620 sounds stunning!

BrownDog adapters installed in the cMoyBB

It’s a good idea to measure DC offset when rolling opamps. An unusually loud pop when turning the amplifier on is a definite sign of error. Weak or cold soldering joints are usually the cause.

Another long awaited addition to the store is Read More