Tag Archives: JDS Labs

Announcing EL DAC, EL Amp, OL DAC, and OL Switcher by JDS Labs

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

EL Amp + EL DAC
EL Amp + EL DAC

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
  • OL DAC – Self-powered USB UAC1 and TOSLINK
  • OL Switcher – 2 Input : 2 Output Passive Preamp
Custom Objective2 + OL DAC + OL Switcher
Custom Objective2 + OL DAC + OL Switcher

Performance Characteristics

EL DAC OL DAC
Frequency Response 20Hz-20kHz +/- 0.15 dB +/- 0.15 dB
THD+N 20Hz-20kHz < 0.0011% < 0.0025%
IMD CCIF 19/20 kHz -6.03 dBFS 0.00017% 0.00033%
IMD SMPTE -6.03 dBFS 0.00061% 0.00031%
Noise (A-Weighted) -109 dBu -109 dBu
Dynamic Range (A-Weighted) 117 dB 114 dB
Linearity Error -90 dBFS -0.01 dB -0.01 dB
Crosstalk -10 dBFS 100K RCA -108 dB -108 dB
USB Jitter Components 11025Hz -116 dB -116 dB
Maximum DAC Line-Output, 100K 2.00 VRMS 2.00 VRMS

AKM AK4490

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):

THD+N of AK4490EQ vs PCM5102A (EL DAC vs ODAC RevB)
THD+N of AK4490EQ vs PCM5102A (EL DAC vs ODAC RevB)

UAC2

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.

Interpolation Filters

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.

OL DAC - Printed Circuit Board
OL DAC – Printed Circuit Board

100% Self-Powered

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.

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)

New Products for May

We have three great additions to the store this month.

AD8620ARZ with BrownDog Adapter

After our recent opamp swapping article, we received several requests for pre-soldered opamps. Therefore, Analog Devices AD8620 opamps are now available for purchase.

NiMH Adapter for cMoyBB

Also new is a 9V NiMH charging accessory. This small board fits into the cMoyBB’s enclosure (or other cMoys) to provide battery recharging functionality. The charger uses the same DC jack as the cMoyBB v2.03, allowing it to utilize any cMoyBB-compatible power adapter. Installation is easily accomplished with a hole-punch and double-sided adhesive (included). No soldering is required.

Tenergy 9V NiMH and Charger in cMoyBB

One obviously needs 9V NiMH batteries to go along with a NiMH charger, so we now carry Tenergy 9V, 200mAh NiMH low self-discharge batteries. These rechargeable 9V’s are available in single- or two-packs. Typical rechargeable NiMH batteries lose charge in a matter of days, but low-self discharge technology enables these batteries to maintain 80% charge after 12 months of storage.

Order the NiMH Adapter and a Tenergy 9V with a new cMoyBB and we’ll install the set for free!

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

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