Objective Reviews & Commentary - An Engineer's Perspective

February 1, 2012

Feb 1 Update

BLOGGER PROBLEMS: Just a quick update. I've been away from the blog for a couple of days only to find Google Blogger is having problems displaying more than 200 comments per article. Sometimes when you click “Load More” at the bottom of the comments it just gets stuck on “Loading…” and never refreshes the page with the latest comments. I’m not sure yet what the problem is, but if you can’t see comments posted in the last few days to articles with over 200 comments, that’s probably why. If I can’t find another fix, or Google doesn’t fix it, I need to find the time to go back and “clean up” the comments to keep the total number under 200 per article.

ODA/ODAC UPDATE: Many want to know when I’ll have the next ODA/ODAC article done. I’m working on it as time allows but that hasn’t been very often lately. I’ve been severely overloaded with other obligations, many of them unexpected, so progress has been much slower than I would like. Hopefully everyone can understand this not-for-profit blog, and related projects like the ODA/ODAC, are not my highest priority in life. I do plan on completing both the ODA and especially the ODAC. It’s likely the ODAC will be available first.

odac plus o2ODAC + O2 = USB DESKTOP AUDIO JOY: The current ODAC revision is designed to fit inside the O2 if you remove the batteries. This works even with the slim B2-080 standard enclosure. It’s not a plug-and-play modification, but anyone with a soldering iron and some DIY skills shouldn’t have any problem. The O2 will need to be powered from the AC wall adapter and the ODAC is self powered from USB. It will require a rear panel modification for the mini USB jack. Hopefully someone can design (perhaps with some key dimensions from me) a Front Panel Express CAD file for the rear panel. The ultra-high quality photo at right--the best image I could get with a flagship Nikon D4 DSLR ;)--clearly shows the ODAC PCB laying on top of the O2 PCB where the batteries usually hang out. Many are using their O2 for desktop duty so hopefully this might be a worthwhile option for some of them.

NEW SCOPE: Adding to my arsenal of test equipment is a new heavily optioned Agilent oscilloscope with one option that’s very applicable to this blog and the development of the ODAC—it has I2S audio decoding and triggering. So with the new scope I’ll be able to very precisely measure things like DAC chip latency and explore bit accuracy and other parameters in more detail. I’m not aware of anyone beyond a few of the chip makers publishing such data. The new scope can correlate digital audio bitstream data against the analog DAC output with nanosecond accuracy. Stay tuned for more.

questionmarkA NOTE ON COMMENTS & QUESTIONS: Increasingly I’m receiving a lot of public and private comments that boil down to something like: “Would the UltraDAC XL or the UberDac 4000 be a better match for my TurboAmp and Mk II WonderPhones?” While I’ve tried to answer most such questions, the volume is becoming overwhelming. Often the questions have little to do with the topic of the article they’re posted under or even anything I’ve reviewed on the entire blog. Paid advice columnists typically only reply to a few such comments per week or per month but I’m getting several per day. Regrettably, I just don’t have the time to answer them all. I will still try to answer questions directly related to a specific article and those with broad appeal. So please don’t take offense if you don’t receive a reply to a question. I wish I could answer everyone but it’s turning into nearly a full time job and I have to pay the bills somehow.