“Hey, I was just wondering what the major differences were between the ODAC and the OL DAC.”
This fine question continues to pop up in emails, on the phone, on reddit, on Head-Fi, etc.
I was excited to push OL DAC into the wild last November for a number of reasons. I’ve always placed great trust in JDS Labs customers, finding them to be knowledgeable value hunters, and OL DAC set a new bar. Alas, we omitted too many details at release, like why we created another transparent DAC in the first place. Rumors took off. My favorite assumptions include:
- ODAC and OL DAC are the same circuit in different boxes (False)
- OL DAC costs less, so performance must be lower (False)
In short, the DACs share few similarities, aside from comparable transparency.
| ODAC | OL DAC | |
| DAC IC | PCM5102A | AK4490EQ |
| Powered By | USB | AC Adapter |
| USB Input | YES | YES |
| TOSLINK Input | NO | YES |
| Configurable Filters | NO | YES |
OL DAC clearly has the upper hand in terms of performance.:
| SPECIFICATIONS | ODAC RevB | OL DAC |
| Frequency Response | +/- 0.04 dB | +/- 0.15 dB |
| THD+N, 20-20kHz | < 0.0029 % | < 0.0010 % |
| Noise, A-Weighted | -103 dBu | -109 dBu |
| Dynamic Range (A-Weighted) | > 112 dB | > 114 dB |
| Crosstalk @ 1kHz, -10dBFS (RCA) | -86.4 dB | -108 dB |
| Sum of Jitter Components @ 11025 Hz | -112.3 dB | -116 dB |
| IMD CCIF, -6.03 dBFS, 19/20kHz, 24/96k | 0.0015% | 0.00033% |
| IMD SMPTE -2VRMS, 24/96k | 0.0015% | 0.00031% |
| Linearity @ -90dBFS | -0.08 dB | +/- 0.01 dB |
THD+N Sweep (24/96kHz, 20-20kHz)
Noise, A-Weighted
Frequency Response (24/96kHz, 20-20kHz)
IMD CCIF
IMD SMPTE
Linearity
USB Jitter @ 11025Hz
Crosstalk
Why Another Transparent DAC?
ODAC was interesting five years ago for its claim of transparency at only $149. DAC performance and features improve every year; OL DAC is the logical successor. While there’s no need for “greater transparency”, few can argue with getting more for less.
There remains one potential advantage to choose a Standalone ODAC–running from USB power can be useful in certain scenarios. Thus, we decided to maintain ODAC and OL DAC concurrently. Confusing? Yes, sorry about that.
Hello,
Thanks for a great post! Does OL (or EL) DAC offer headroom for intersample peaks (https://benchmarkmedia.com/blogs/application_notes/intersample-overs-in-cd-recordings)? Have you performed any corresponding measurements?
Thanks for the link! I’ve observed this behavior before, and like Benchmark writes, it happens with every D/A chip.
With such high dynamic range performance of today’s DACs, a simple solution is to reduce PC volume slightly to increase interpolation headroom. I commend Benchmark’s implementation of an external interpolator. That’s certainly a nice feature. To answer your question, no, I think Benchmark is the only manufacturer with such technology. Also note that of all six example tracks, the worst case peaks were +1.49dBFS; most were about +0.5dBFS. It would be interesting to study a wide range of music to determine just how often peaks in excess of 0dBFS occur (quite rarely?).
Again, I’ve advocated setting OS volume below 100% for years now!
Thanks for the reply! But I guess for DACs that are USB Audio compliant and declare volume control support, adjusting the volume on the OS side is actually applied on the DAC board itself in the analog domain after the signal leaves the DAC chip. You probably need to reduce the volume in the audio player instead to make sure it happens in the digital domain before the bits of the signal go into the DAC chip.
Is that correct? I always wanted to confirm this with anyone who actually makes DACs 🙂
Yes, I believe you’re correct. The idea is to ensure volume is adjusted in the digital domain, before reaching the D/A converter. Adjusting at the app level is a good approach.
This will depend on how the digital volume control is implemented. 32-bit ESS chips attenuate before filtering (before both oversampling and ASRC). 24-bit Wolfson chips that have attenuation control also apply it before filtering. If the hardware designer doesn’t use the DAC’s on-chip filtering and does some other DSP beforehand, then the problem arises again of course.