ODAC

ODAC ( Objective DAC ) What is it:

The trademarks ObjectiveDAC and ODAC are owned byYoyodyne Consulting Inc.  Usage of "ObjectiveDAC" or "ODAC" for commercioal purposes without written permission is strictly forbidden.

The ODAC, a UAC1 DAC, is a co-design between Yoyodyne Consulting and audio blogger NwAvGuy. The ODAC adheres to the principle of measurable performance (objective) versus subjective performance (marketing and personal bias). All claims made about the ODAC are supported by repeatable testing procedures.

The ODAC is a daughter card that will mount in the ODA with a 4-pin header and mounting hardware. The ODAC may also be retrofitted internally to an O2 headphone amplifier when the rechargable batteries are removed. A 4-40 3/8" screw and 2 nuts will physicially secure the ODAC to the O2 board. 3 wires must be soldered between the ODAC and the O2 to connect the LINE-OUT of the ODAC to the input of the O2 input.

Alternately, the ODAC can be mounted in a small custom enclosure and used as a standalone DAC with the O2 or any amplifier that has a 2vrms LINE-IN port. You may mount a 3.5mm connector (footprint on the board) or take the LINE-OUT to a pair of panel mounted RCA connectors.

The card is built around the Tenor TE7022L UAC1 engine and the ESS Technology ES9023 24 bit DAC. The ODAC is powered from the USB bus with a low noise, filtered power supply.

ODAC-revB:

The trademarks ODAC-revB is owned byYoyodyne Consulting Inc.  Usage of "ODAC-revB" for commercial purposes without written permission is strictly forbidden.. The ODAC and ODAC-revB layouts ares copyrighted as works of art and are the intellectual property, IP, of Yoyodyne Consulting Inc;

The ODAC-revB was not created to replace the original ODAC created by Yoyodyne Consulting and NwAvGuy with a superior design but to extend the life of the Ojective DAC concept promoted by NwAvGuy. The ODAC-revB was created to deal with unforeseen component issues. The resulting board has the same footprint as the original and is a drop-in replacement.

At this time it was decided to move to a new UAC1 interface chip. The SA9023 has been around for a few years and I have had no problems with designs using this chip. The SA9023 supports 16/24 bit depths with all sample rates from 44.1-96k including 16b / 88.2K.

With a change in the major components there is an accompanying change in layout. Multiple reversions made sure the maximum performance was squeezed from the chip set. It should be noted the Micrel LDO regulators have been replaced with higher performance ADP151 devices.

The performance comparison chart below shows one of the last ODAC boards built compared to one of the first ODAC-revB boards.  From the side by side comparison you can see the combination of SA9023 and PCM5012A has improved numbers for all measured parameters with jitter showing the largest improvement.

An an added bonus the ODAC-revB supports direct connection to an Apple iPad using the Apple Camera Connection Kit.

Performance:  ( verified using a Prism Sound dScopeIII )

Yoyodyne Consulting does have an extensive testing lab including the dScopeIII but it was decided to utilize the services of JDS Labs to remove the appearance of bias.  John Seaber of JDS Labs has created a detailed blog entry documenting some of the discussions surrounding the changes to the ODAC as well as screen snapsots of the dScopeIII tests.

The results presented show the ODAC-revB matches the original ODAC.


ODAC ODAC -revB
Frequency response 20-20kHz +/-0.14dB +/-0.04dB
THD+N 100Hz -0.15dBFS 0.0022% 0.0013%
THD+N 20 Hz -0.15dBFS 0.0017% 0.0015%
THD+N 10Khz -0.15dBFS 0.0056% 0.0024%
IMD CCIF 19/20 Khz -6.03 dBFS 24/96k 0.0027% 0.0005%
IMD SMPTE -6.03 dBFS 24/96k 0.0008% 0.0008%
Noise A-weighted -102dB -103dB
Dynamic Range A-weighted >111dB >112dB
Dynamic Range (un-weighted) >107 dB >109dB
Linearity -90 dBFS -0.09dB -0.08dB
Crosstalk 1kHz, - 10dBFS (3.5mm jack) -80.4dB -86.4dB
USB Jitter 11025 hz 100K -105.8dB -112.3dB
Output voltage 100K 2.0Vrms 2.1Vrms
USB controller TE7022L SA9023
DAC ES9023A PCM5102A


Prices and Ordering:

The ODAC was "Designed and Assembled in the USA" and is available now. ODAC-revB boards and enclosures can be purchased from

Please contact me directly if you wish a large OEM quantity purchase for your local market. George.Boudreau@YoyodyneConsulting.ca





ODAC-revB  printed circuit board

ODAC-revB with the optional 3.5mm connector installed