There's so much potential in this product--it can do so much more than any other portable recorder at this price point--but it has a critical flaw that makes it absolutely useless to anyone recording audio for video (or anyone wanting to record accurate audio).
By way of explanation, here's an email I wrote to Zoom's support department:
"Hello,
I have a problem with my Zoom R24, and I'm hoping you can help me out. I bought the R24 to record audio during video location shoots (recording at 48khz on all devices, of course). But when I import the audio tracks to the video after the recording, I the audio and video go "out of synch" very quickly--after only a few minutes.
So I ran a test:
I recorded a digital metronome from my computer's DAW for about 20 minutes and sent the signal to the R24, and also to my new Zoom H2N, an M-audio Microtrack II, and to an external audio interface (a Pro Tools M-box) recording straight to my computer. Then I imported each recording and compared the waveforms in my DAW (Logic). I've attached some screenshots to demonstrate this. As you can see in the pictures, the R24 goes out of synch in just a few minutes. (You also can HEAR it going out of phase as clearly as you can SEE it.) Based on my measurements, it drifts at about 4.16 ms per minute. (The Zoom H2N also drifts a little, but NOT nearly as bad--after 20 minutes it was still in synch with my audio interface.) So in other words, the synch/timing drift problem on the R24 is very bad--much worse than any other device I tested.
However, when I use the R24 in audio interface mode (orange track in my pictures), I DO get accurate recordings.
I called Samson, and they told me to try a different SD card. I tried a Transcend 16GB card (TS16G-SDHC6), which is approved for use on the R24 and had the same problem. I also had this problem with the 1GB card included with the R24. Samson said my R24 might just be defective, so I returned it to the store and exchanged it for a new one. The new R24 has the exact same problem, so I think this might be an issue with all of them...
I bought the R24 to record audio for video shoots (as advertized uses on Zoom's website), but with this problem I can't rely on the R24. The most important thing is that I get accurate recordings--at least as good as the Zoom H2N can do. Does the R16 have this problem? If not, I might exchange it for an R16.
How can I we fix this problem? Could you fix this with a firmware update? (I'm currently running version 1.10.)
Thank you for your help and looking forward to your advice."
Here's Zoom's response:
"Thank you for your inquiry.
I'm sorry for the delay. We consulted to our engineer, and received reply from them. As a conclusion, it is a spec for the R24. It is concern with accuracy of crystal oscillator. Usually, acceptable range of the crystal oscillator is +/- 50ppm. Maybe we think that it is acceptable range, but we think that it is bad result. As the reason, the R24 is using chip of clock generator. And, the accuracy of the clock generator has brought this result. We adopted it for supporting standalone recorder and USB audio interface. In short, it is concern with hardware. Therefore, it can't fix with firmware updates. Then, the R16 is using same chip.
Thank you for your patience and cooperation."
I realize, of course, that I might be loosing something in translation, but it certainly sounds like there's a known hardware problem with the accuracy of clock generator on both the R24 and the R16. It's not clear what, if anything, they can or will do to fix it...
