Today’s announcement of the Element Line and Objective Line makes most sense when viewed alongside our mission:
JDS Labs enables exceptional listening experiences, with underlying objectivity in our designs and transparency in our interactions.
JDS Labs is strongly associated with audio measurements these days–perhaps to an excessive degree. Still, the subjective experience certainly matters. Each amp and DAC we’ve offered over the past nine years has in some way made headphone listening more worthwhile. Enjoyable audio equipment just happens to measure well, so we take measurements seriously.
Expanding Connectivity for Desktop Audio
Expanded connectivity for Desktop Audio is the theme we’ve been working towards lately. I listen to powered speakers at my desk whenever I have the chance, and transition to headphones at other times. Many of our customers listen the same way, and agree that a single system should be able to interface with headphones and speakers. Sometimes a system doesn’t involve a USB connection. Thus, optical and coaxial S/PDIF inputs are long overdue. Element Line and Objective Line each provide means to switch between listening to headphones or to powered speakers. Introducing:
EL DAC– Self-powered USB UAC2, TOSLINK, and transformer isolated coaxial S/PDIF
EL Amp – 1.5W @ 32Ω Headphone Amp with RCA pass-through Line-Output
EL DAC and OL DAC both utilize an AK4490EQ digital-to-analog converter. Measurable performance is spectacular compared to the older PCM5102A, at similar cost. While it’s accepted that ODAC achieves baseline audible transparency, a look at THD+N shows why we’ve moved to AK4490. Note the order of magnitude improvement across the frequency band (log scale):
Support for 24/96kHz audio via USB Audio Class 1 (UAC1) is all you need for audible transparency. For simplicity and maximum value, OL DAC is a UAC1 device, which requires no third-party USB drivers.
EL DAC is the first JDS Labs DAC to support USB Audio Class 2 (UAC2). We’ve caved for two reasons. First, 24/192k and beyond is often requested by customers we hear from at audio meets. Second, Microsoft will soon provide native UAC2 drivers in Windows 10. We’ve promised UAC2 support as soon as the market fully embraces it, and that time is upon us. Until native Win10 drivers are available, EL DAC uses SaviAudio’s Bravo drivers with ASIO support.
Both EL and OL DAC use default filter parameters for AK4490. The alternative filters achieve less satisfactory measurements, especially in terms of high frequency response. If you wish to experiment, we left pads for DIP switches on the PCBs, Omron P/N A6SN-3104. Ask and we’ll be glad to pre-install.
Clean power is one of the keys to achieving high performance audio. As confident as I am in the USB powered regulation performance of past JDS Labs designs, we take feedback seriously, and feedback indicates limited trust in USB power. Also, operating system power management behavior continues to change, creating a continuing battle for support.
I’m glad to report that EL DAC and OL DAC are 100% self-powered. All of our future designs will be self-powered as well. [Nov 25th Edit: To clarify, “self-powered” means the DACs receive power from an AC outlet. Zero (0) power is consumed from the USB cable/hub/PC.]
The first prototypes ran rather hot with full linear regulation. Heatsinks were mandatory for stability in USB mode, and enclosures turned into space heaters. So, we moved to a higher efficiency, split, multi-stage approach. All analog audio circuitry is powered exclusively by linear regulation, while the power hungry digital USB controller receives power from the same primary, linear regulator, through a clean buck regulator, followed by multiple stages of linear regulation. This experiment paid off. Not only does the circuit run much cooler, THD+N improved by over 5dB across the entire audio band, and it passed FCC/CE compliance testing on the first try. Super clean.
JDS Labs has worked tirelessly to share this day with fellow headphone enthusiasts. We are proud to introduce The Element:
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.
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 jdslabs.com 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.
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 Head-Fi.org, 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.
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).
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.
Frequency Response 20Hz-20kHz
+/- 0.1 dB
THD+N @ 1kHz 150 Ω
IMD CCIF 19/20kHz 150 Ω
IMD SMPTE 150 Ω
Crosstalk @ 150 Ω
+/- 0.56 dB
Max Continuous Output, 600Ω
Max Continuous Output, 150Ω
Max Continuous Output, 32Ω
Peak Output Power, 32Ω
Frequency Response 20Hz-20kHz
THD+N 100 Hz -0.15 dBFS
THD+N 20 Hz -0.15 dBFS
THD+N 10 kHz -0.15 dBFS
IMD CCIF 19/20 kHz -6.03 dBFS
IMD SMPTE -6.03 dBFS
Noise A-Weighted dBu 24/96
Dynamic Range (A-Weighted)
> 112 dB
Linearity Error -90 dBFS 24/96
Crosstalk -10 dBFS 100K RCA
USB Jitter Components 11025Hz
Maximum Output Line Out 100K
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.
Today we’re announcing a chipset update to ODAC. Revision B improves general reliability, while meeting or exceeding the original performance criteria set forth by NwAvGuy.
This announcement will come as a surprise to many, considering ODAC was declared as the be-all and end-all of DAC transparency by a now absent engineer. This article explains who owns the ODAC design, why an update is prudent, and how ODAC Revision B’s objectivity has been exhaustively verified.
Scroll towards the end for benchmarks, or read on for the full story.
ODAC was released on May 9, 2012, shortly before NwAvGuy vanished from the community. While his name is closely tied to ODAC, it’s critical to understand that ODAC was jointly developed by NwAvGuy and Yoyodyne Consulting.
Yoyodyne generated ODAC’s schematic and PCB, and NwAvGuy provided prototyping feedback and performance analysis. Yoyodyne also generated the project title, “ODAC” in 2011 and has remained responsible for all production engineering and distribution of the project to end retailers like JDS Labs and our counterparts.
In other words, ODAC was benchmarked and certified Objective by NwAvGuy; Yoyodyne generated the design and controls its manufacturing to this day.
NwAvGuy’s name has been intentionally omitted from ODAC RevB, so as not to imply an ongoing collaboration.
Why Update ODAC?!
Our job is to deliver perfect audio performance to every user. We’ve hit this goal for 99.5% of ODAC users out of the box, and have found a way push ODAC’s reliability and objectivity to an even higher standard.
To better convey ODAC’s position, Yoyodyne has shared worldwide distribution data. ODAC’s popularity continues to grow. Over twice as many ODACs shipped in 2014 compared to 2012, with a total of 12,000 units in circulation:
Increasing demand over time is amazingly rare for electronic production, and is a testament to ODAC’s positive reception.
Although ODAC has proven itself in the audio community, JDS Labs and fellow retailers have observed lower than expected yield (<1% DOA units), higher than expected long-term failure rates (< 2%), and an ongoing USB hub issue that NwAvGuy did not have an opportunity to address before his 2012 departure.
One of the first bits of ODAC feedback we received in 2012 revealed odd behavior: severe distortion, completely resolved by a USB hub. This peculiarity would ultimately affect less than 0.5% of all users, and the simple USB hub solution became well known within the audio community (later published to ODAC’s operating instructions). We invested in a dScope Series III audio analyzer in 2012 and verified ODAC’s performance.
The behavior was later identified as a power supply regulation design choice made by NwAvGuy. ODAC performs consistently with all devices, unless the host USB bus has remarkably low ESR ceramic capacitors placed too closely to the USB 5V output pin (rare). When ODAC is connected to such a host computer, ODAC’s 3.6V linear regulator performance plummets from 100% stable operation to extreme oscillation, which turns the perfect audio signal into garbage (lots of very audible distortion). There is no in-between. The regulator is either 100% stable, or 0% stable. Consequently, we’ve offered support for this rare behavior since 2012.
So, ODAC performs as described for about 99.5% of users. As demand grows, that USB bug becomes increasingly pronounced. Add in 1-2% DOA and long-term ES9023 failures, and ODAC retailers have growing collections of bad ICs. DOA boards are easy to catch via quality control, but long-term failures require frustrating warranty service.
Meanwhile, JDS Labs and Yoyodyne have engineered solutions to each reliability concern, meaning we can make ODAC reliable and objective for virtually 100% of users.
Yoyodyne produced a series of ODAC RevB variants in 2014 with reliability fixes. JDS Labs benchmarked each prototype to ensure equal or better performance compared to the original ODAC. Although the update was ready in late 2014, ODAC production runs occur about once annually. This long production cycle is best for the project, as it minimizes supply constraints and keeps distribution flowing smoothly to several O2/ODAC manufacturers.
I think the community hoped NwAvGuy would return and publish necessary updates to O2/ODAC/ODA himself. At this point, a reliability update is the best judgment we can make for ODAC’s long-term success. Keep in mind that O2 is protected from derivatives by its license; ODAC is coordinated by Yoyodyne and nondisclosure agreements with its IC suppliers. Even so, we do not want to modify ODAC. Subjective bias is not trivial in the audio business.
All of that being said, we’re confident ODAC RevB is a perfect reliability update. The newer DAC IC has proven reliable in other projects. In addition to thorough benchmarks, we’ve shipped ODAC RevB to a few users seeking support for their original ODACs. Feedback is perfect. We also shared ODAC RevB at the 2015 AXPONA tradeshow and allowed some random visitors to perform A/B tests. No one could differentiate.
ODAC RevB resolves all reliability inadequacies of the original ODAC, while meeting or exceeding original transparency requirements.
ODAC RevB utilizes the same PCB footprint and is a physical drop-in replacement to all existing ODAC and O2+ODAC assemblies. Revision B’s stronger output voltage of 2.10VRMS must also be accompanied by a slight DAC volume or gain adjustment when used in O2+ODAC; optimal gain is now 1.0/3.33x.
Analog filters and power supply passive components remain identical to the original board. The new chipset consists of an SA9023+PCM5102A, and the LDO has been updated to a ceramic stable Analog Devices ADP151 equivalent part. Fixes include:
Added 16x vias to USB support pads to improve mechanical strength of mini-USB jack
New chipset and locked EEPROM to prevent IC failures
Fixed USB supply stability, affecting < 0.5% of systems
Minor performance improvements (audibly equivalent)
ObjectiveDAC was designed for measurable and audible perfection. Reduced performance from ODAC RevB would be absolutely unacceptable, so we took great care in checking our work.
Engineering test methods impact test results. While THD+N, frequency response, and crosstalk are straightforward, even these basic tests are impacted by audio analyzer setup parameters and real world hardware setup. Certain ferrites on the mini-USB cable improve dynamic range by up to 10dB versus an ordinary USB cable. More complex tests like Jitter and IMD produce surprisingly different results based on signal strength, averaging, etc.. As Yoyodyne and I analyzed performance of the original ODAC through a TDK ZCAT2035-0930 ferrite equipped USB cable via dScope audio analyzers, it was clear that NwAvGuy had utilized averaging and custom dScope routines. We would never be able to definitively duplicate his work due to unknown averaging, scripting variables, and exact ferrite type.
To ensure a fair comparison, we measured a randomly selected ODAC production unit to establish baseline requirements. Measurements were repeated with two additional, randomly selected units to confirm consistency. The exact same cable and test scripts were then repeated with ODAC revB. All tests are performed under a standard 100k load.
In particular, please note that many of our measurements are taken at different signal strengths and sampling rates than used by NwAvGuy. Our table results are also taken without averaging; instead, we observe worst case performance over the course of 5 seconds of data collection.
So do not be surprised that our baseline ODAC measurements reflect lower performance than NwAvGuy’s nicely averaged 2012 results!
Frequency Response, 20-20kHz
THD+N 100 Hz, -0.15dBFS
THD+N 20 Hz -0.15dBFS
THD+N 10 kHz -0.15dBFS
– 103 dBu
Dynamic Range (A-Weighted)
> 111 dB
> 112 dB
Dynamic Range (Un-Weighted)
> 107 dB
> 109 dB
Crosstalk @ 1kHz, -10dBFS (3.5mm)
Sum of Jitter Components @ 11025 Hz, -1dBFS
IMD CCIF, -6.03 dBFS, 19/20kHz, 24/96k
IMD SMPTE -2 dBFS, 24/96k
Linearity @ -90dBFS
Frequency Response: NwAvGuy’s DAC Transparency Guideline calls for response of +/- 0.1 dB from 20 Hz – 19 kHz. RevB is slightly flatter than the original ODAC, exceeding the proposed transparency requirement for the complete audible range, 20 Hz – 20 kHz.
THD+N: The original ODAC measures 0.0056% at 10kHz -0.15dBFS using our worst case scenario measurements (see above table). RevB manages just 0.0024% under the same condition.
Shown below are THD+N -1dBFS, 8x averaged sweeps of each channel, directly comparing ODAC to ODAC RevB . The original ODAC’s right channel closely resembles NwAvGuy’s 2012 THD+N sweep, with a peak of 0.005% at 9kHz, and 0.004% at 10kHz. Note that the Left channel of the original ODAC differs from its Right channel in our sweeps. This observation is consistent across each unit tested from 2013 and 2014 production batches, despite no channel differences visible in 2012 benchmarks. RevB’s THD+N is consistent between Left and Right channels.
Revision B also cuts THD+N in half at 10kHz, and remains below 0.0030% across the entire audible spectrum for each channel. Both versions are well below NwAvGuy’s suggested transparency limits (green line).
Full-Scale Performance:Rumor suggests that PCM5102 clips at full scale. We first investigated this concern in 2013 with the then newly released PCM5102A. Empirical results show clean sine output at all frequencies. ODAC’s ES9023 reaches 1.99VRMS, and RevB’s PCM5102A generates 2.07VRMS at 0dBFS.
RevB’s full-scale performance is remarkably similar to the original ODAC. Notice that both DACs produce THD > 0.005% at 0dBFS due to FFT summing phenomenon at full-scale:
Elevated THD at 0dBFS is consistent for all DACs we’ve measured, and is the reason engineers (including NwAvGuy) typically conduct DAC benchmarks at -1dBFS or -3dBFS. Simply put, digital to analog conversion is less ideal at 0dBFS. Any reasonable recording should be free of such peaks. At any rate, it’s ideal to slightly reduce DAC volume when listening to recordings containing frequent 0dB peaks.
Noise: The newer PCM5102A DAC automatically enters a soft mute condition in the absence of an audio signal, pushing the measurable noise floor to an impressive -115dBu (near the dScope’s measurable limit). Therefore, noise was also measured with an applied -180dBFS, 20kHz signal, revealing the active state noise floor. RevB manages -103 dBu, slightly superior to the original ODAC’s -102 dBu. All noise components of RevB are well below the transparency requirement of -110dB for both mute conditions.
Dynamic Range: RevB improves A-weighted dynamic range by about 2dB, and achieves a cleaner noise floor.
Crosstalk: The PCM5102A’s soft mute function causes a standard crosstalk measurement to produce abnormally impressive results, as one channel is digitally muted. Thus, crosstalk looks substantially superior at all frequencies for RevB. Crosstalk measurements are similar between ODAC and ODAC RevB with a sufficiently small signal applied to the “muted” channel. Also note that the 20kHz “Ch A” test point is invalid for all four curves, as the dScope script conducts the test too quickly during relay initialization. “Ch B” curves at 20kHz are accurate.
Jitter: Testing is conducted using an 11025Hz, -1dBFS signal with 8x averaging.
Reliability fixes only necessitated a new power supply LDO and DAC IC. We swapped the USB controller for two reasons. First, the SA9023 provides 16/88.2kHz support. Second, its jitter performance is noticeably superior to the older TE7022L. We actually tested a TE7022L+PCM5102A prototype in effort to stay closer to the original ODAC. The SA9023 was ultimately a finer choice. Keep in mind that even the TE7022L produced audibly insignificant jitter (components below -110 dB). Hopefully 16/88.2kHz functionality adds value to some.
IMD SMPTE: The 60Hz/7kHz IMD test returns similar measurements for both DACs: 0.0008% using a -2dBFS signal referenced to 2VRMS.
ODAC produces audibly negligible sidebands (below -120dB) within a few thousand Hz of 7kHz, whereas RevB’s distortion shows less jitter but higher amplitude components around the same tone. Note that all of these components are more than an order of magnitude below the audible transparency limit of -90dBFS (green line).
IMD CCIF: Twin tone amplitude is closely matched in the IMD CCIF 19/20kHz test. The test returns numerically superior measurements for RevB due to smaller 1kHz components.
Sidebands are slightly more pronounced from RevB. While sidebands are higher, NwAvGuy prescribed a maximum sideband limit of -90dBr with 2VRMS reference for frequencies below 19kHz, and -80dBr above 20kHz to achieve transparency. RevB meets expectations.
The dScope is internally limited to -6.03dBFS for the Twin-tone script. Yoyodyne points out that NwAvGuy displayed a sum of powers and utilized custom scripts when conducting IMD measurements (-6dB + -6dB = -3dB).
Linearity: Both versions demonstrate excellent linearity from -1dBFS, down to their respective noise floors.
Price and Availability
ODAC RevB begins shipping in all JDS Labs ODAC products ordered after 9:00AM CST on Monday, May 11 with unchanged pricing:
We’re running half staff today and tomorrow while JDS Labs presents at CanJam. If you’re anywhere near Denver this weekend, CanJam at Rocky Mountain Audio Fest is the place to be. Check out our booth for freebies and a first look at our upcoming amp + DAC.
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.
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.
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.
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:
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):
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?
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 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.
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!
+/- 0.02 dB
THD+N (20-20kHz, 150 Ω)
THD+N (20-20kHz, 32 Ω)
Crosstalk @ 150 Ω
Inter-channel Phase @ 1kHz
+/- 0.55 dB, all volume positions
Max Output @ 600Ω
Max Output @ 150Ω
Max Output @ 32Ω
Battery Run Time
2 Hrs to 80%, < 4 Hrs to 100%
–40°C to 85°C
0 to 85% Rel. Humidity
Dimensions (excluding switches)
99.5 x 61.5 x 14.0 mm (LxWxH)
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
How to Use
Hold volume lever left to decrease volume, or right to increase volume.
Push volume control to toggle high/low
Toggle up for normal audio, toggle down for bass boost
A single LED conveys all of C5’s behaviors:
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!
First of all, we published a huge site update last night. JDS Labs no longer relies on the PayPal shopping cart!
We’ve been testing and revising the new site for 2 months. If you see anything out of place, do not hesitate to send us a note.
Short Story: ODACs began shipping at 11am yesterday.
Long Story: The second batch of ODAC boards were scheduled to arrive about 2 weeks ago. They did arrive on time, but every single board was defective due to a production error. This wasn’t our mistake, but a PCB production issue which affected 100% of ODACs supplied to every single distributor worldwide. Ouch.
Amazingly, the ODAC assembler managed to fix 1500 boards in just 1 week. A+ to them!
We finally received a partial shipment of ODACs at 11am yesterday, July 31 (more arriving Friday). This gave us only five hours to assemble, test, and ship 5+ weeks backorders…
We managed to ship 2 weeks worth of backorders by the end of the day. If our site listed an arrival date of “July 31” when you ordered, we’re doing everything possible to ship today.
While we’re busy shipping backorders, here are a couple ODACpictures taken last Friday:
** Scheduled Maintenance: We’re moving our server tomorrow night at 1:00AM CST, Saturday, July 14th. Anticipated downtime is 1-4 hours. JDSLabs.com may be difficult to access in some parts of the world for the next 24-48 hours while our new IP address propagates. **
Nick has spent the past three weeks making noise, breaking drill bits, and splashing super fun blue coolant all over the office. Most people don’t pick up mechanical engineering and machining as new “skills” in just three weeks, but we do what we have to here.
With the basics of CNC’ing out of the way, our attention has turned back to the reason we bought the CNC in the the first place. We want brilliant quality, and we want our parts now.
We’ve specified brushed aluminum on our endplates since they were first designed. It turns out that most aluminum suppliers do not offer brushing. The process is a time consuming and challenging task even for most machine shops. That was a disappointing discovery!
Our endplates will still be brushed, but this sourcing realization led us to experiment with the aluminum. The test pieces shown above were machined at our shop on Friday afternoon, then plated on Monday morning in downtown St. Louis. Clear alodine and black anodizing finishes both look fantastic. And it was all done in under 2 business days. 🙂
O2+ODAC Rear Panel with 3.5mm Output
Although we don’t recommend that you install a 3.5mm output jack on your O2+ODAC, some customers have requested to do so anyway. This is for you: Machined O2+ODAC Endplate w/3.5mm output. These are made from stock endplates included with the Box B2-080 cases, thus, the price is lower than other endplates.
We’ve avoided RCA outputs on the Standalone ODAC for several reasons. RCA jacks take longer to assemble and cost more than a 3.5mm jack, but this has been irrelevant to our decision.
We haven’t offered RCA jacks on the ODAC due to virtually identical performance: Why complicate a product with multiple variations and increased build cost at no benefit? The 3.5mm jack on the ODAC circuit board is wired to the same line output header as used by RCA jacks. Some customers have asked, “Aren’t 3.5mm cables more lossy than RCA?”. As NwAvGuy has stated, characteristic impedance is a non-issue in unbalanced audio systems. There are no impedance mismatches to be concerned with, and there are no significant losses resulting from the use of a 3.5mm cable. Crosstalk might change negligibly (1-3dB), but overall, it’s a myth that RCA cables are less lossy than 3.5mm cords. Case in point, why would NwAvGuy (an audio benchmark and measurement fanatic) have designed the ODAC with a 3.5mm jack if it were “lossy”? He wouldn’t have! I’m sure NwAvGuy can provide benchmarks if badgered.
Moreover, you can use a common 3.5mm to RCA cable for direct connection of a 3.5mm device to an RCA device.
With all of that said, it’s easier to build products customers want, than to convince everyone that what we’re building is the best solution.
So last week we set out to fit RCA jacks into our Standalone ODAC enclosure. I had briefly collaborated with Stefan of Head ‘n’ HiFi earlier this year on the Standalone ODAC case. We’d been asked by NwAvGuy’s contractor to lead the design and distribution of a standardized ODAC case for the DIY community. I wanted ultimate enclosure quality, and was willing to wait until late July for a custom case fabricated in the USA.
However, Stefan wanted cases immediately, and didn’t think he could fit RCA jacks into our thin case, with only 10mm to work with (a typical RCA jack is 9.5mm). Stefan’s a nice guy, but we had to agree to disagree on our design goals. Product excellence is more important than expedited delivery and cost, especially when a product will stick around for years to come.
Despite the tiny clearance, we’ve managed to design ODAC endplates that will accept 2x RCA jacks and still fit into our thin ODAC enclosure, without losing ground isolation. This is only possible due to a beautiful, black anodized finish. More pictures are coming soon. For now, imagine the gold RCA jack pictured above on our Standalone ODAC.
ODACs are scheduled to arrive July 19-25. All Standalone ODACs will ship by the end of July.
This week I was asked if we could provide support in raising donations for a charitable cause in Africa, Challenge Tanzania 2012. Filling ODAC orders and moving into our new office made this past week by far the busiest of the year, so I flagged the email when it came in on Tuesday morning. Flagged emails at JDS Labs either get read in weeks, or never at all.
At the end of the day, I found 2 minutes to read through that email, which most people would consider spam. The author was a past customer and it was immediately apparent that he follows our blog, and understood that we might not reply. But more compelling was the cause. He’s helping children who lack food, water, and access to education.
Matt volunteers for Challenge Worldwide (registered UK charity #1130522). Donations will be used to provide necessities at St Lazarus School in the Kibera Slums, Kenya, as well as to the Makat Village Community (Maasai) in Lake Natron, Longido District, Tanzania. Volunteers personally finance their expeditions in full; donations are applied directly to the causes.
To bolster interest, Matt has personally setup a “JDS Labs Charity Raffle” page. Support Challenge Tanzania 2012 and you will have a chance to win one of our great amplifiers! Again, prizes are graciously financed by Matt and all donations will benefit the causes of Challenge Tanzania 2012.
Complete descriptions and goals of the Challenge Tanzania causes can be found on the donation page.