Let's get the most important thing on the table right now: this thing is $300. I've spotted some negativity over various bits of this mixer/recorder around the net, and just about all that negativity is either unfounded and/or completely oblivious of the value that this thing is for its feature set.
Show me another 4 track, 4 pot(control knobs) phantom powered recorder on the market for anywhere near this price? Sure you can pick up some higher end mixer/recorders used, but the 70d was targeted at a specific crowd: DSLR/single shooters. So let's dive in.
Let's start with a little highlight breakdown:
-$300 is damn cheap for a 4 track recorder
-Nice size, not too tall, and just wide enough to fit proper controls and screen
-4 XLR/TRS inputs, line/camera out, camera in
-Phantom power for all XLRs
-Sufficient gain settings for inputs and outputs
-Limiters and lowcut
-SD card in the rear(can't see where else they could have fit it anyways)
-Battery/SD door can be annoying, i might just take it out.
-Wish all the 1/8" ports were 1/4", but again, size limitation, so can't really nitpick
-Battery life is OK, but Zoom's are amazing.
-A compressor would have been nice
-MP3 option would have been nice
-It would have been great if it could make bacon pancakes
Overall there's not much you can complain about for 300 bucks
Layout & Design
It's like a 60d, but shorter and wider, which is a nice change. It's about as small as i think is possible for a 4 XLR unit. It'll fit quite nicely under a full size DSLR, but looks pretty big under anything smaller such as a mirrorless camera. None of that really bothers me though, because it just comes off as a wider base on your tripod, i haven't had it get in the way at all.
3 of the XLRs are on one side, the 4th being on the opposite side. This may sound odd, but having that 1 XLR on the opposite side can come in very handy depending on your setup and wiring. The rest of the connections are on that side as well, nothing sticks out of the front or back. Speaking of the rear, that's where the two onboard mics are, as well as the 4 AA battery bay and SD card port. If your doing camera mounted work, this is totally OK, if you plan on bag work, it could be annoying, but then again: where else could they have stuffed the batteries? I do think they could have squeezed the SD card port somewhere else, but once again, i'm not going to nitpick at this price.
Speaking of bag work (what the audio pros do with having all their gear in their audio bag doing production audio) The 70d does have the form factor to work well in a bag despite its relatively tiny footprint. Although it seems targeted at the sole shooter/rungun/under camera type crowd, i do see this as an affordable first mixer/recorder for someone wanting to get into production sound work. It has the essentials, but do some digging and make sure it has everything that you need, as higher end recorders of course come with additional features and tools.
The front end of the unit has a small but decent screen, a big enough knob to control it, a record button, slate button, some lights, and those ever useful 4 control knobs. Many recorders sacrifice having a knob-per-input because you typically would make such adjustments with a separate mixer. In this case, the target market being those who likely wouldn't want yet another box to haul/mount/plug, they gave it all 4 knobs. From what i'm told, these are digital knobs, not analog, meaning when you turn the knob it's making a digital adjustment and i found when making fast/big changes it can feel a bit disconnected. Meaning, the change in gain/volume comes a bit after your actually turn the knob. I've only really noticed it in extreme testing of ramping the knobs quickly.
Subjective for sure, but it's as you can expect from a lower end Tascam, which is to say pretty darn good! It goes up to 24bit, 96khz. There is zero point in doing side by side comparisons with higher end units, because A: this is certainly not higher end, and B: your end viewer isn't getting a side by side to know that the audio could have been better. The rated noise floor is respectable, but not quite as good as higher end models. That said, my subjective ear liked what i heard. One thing that concerned me was an odd amount of noise i had for one of my mics, but it seemed to go away with my general troubleshooting of unplugging/replugging/powercycling. It only occurred with 1 mic, so i cannot blame the 70d outright without further testing.
So what i boil that down to is that for this price, you're getting as good a quality as you can expect, it's higher end sound than your camera's built in recorder, and if you think you need better than that, you should be hiring a dedicated audio professional.
Clicks? Many folks are wondering if this has one of the 60d faults: since it's digital knobs, the 60d suffered from faint but noticeable clicks when adjusting the levels. Thankfully, that appears to be worked out on the 70d, the level adjustments sound smooth. The only instance i heard a click was with the build in mic, the knob turned all the way down aka OFF, and heard a click just as i started upping the level. This did not occur when i tried the same test on a shotgun mic.
It feels like a mix of metal and plastic, overall feels very good. Both the top and bottom have rubber to ensure good connections, and the camera's bolt goes on/off in a matter of seconds with the large screw head. Knob wise, it feels all plastic, but doesn't feel too cheap. Connection wise, the XLRs all snap in nicely and feel secure.
As for the other connections... well, they're all 1/8"(cam/line/headphones/EXT) and micro usb, not great, but for the money it's serviceable. They definitely could have squeezed at least 1 or 2 of those 1/4", but no use in wishing. I did notice my unit's SD card port on the inside is slightly askew, which doesn't really affect anything, just makes the SD card have a slight resistance going in.
Menu & features
The menu is pretty simple and straightforward, the only shortcuts to get through are the 1,2,3,4 buttons which can jump you through the input settings, otherwise you just use the main dial to pass through each sequentially. You can turn on/off phantom to any of the XLRs, and the 4 inputs are paired in 2s (1/2, 3/4) And you can have it record stereo files accordingly, or mono files. You can also adjust the left/right pan of each pair: channel 1 & 2 can each be totally left/right, or can be mixed together, or dialed to be somewhat left/right. Effects wise, you get a few useful basics: Low cut, & Limiter. Format wise, you only get standard WAV, and BWF, which is a wav with metadata.
Thus far, it's been mostly smooth, i did have it lock up once, a reboot got it back to normal. During recording i haven't had any hiccups. The battery life indicator hasn't been the most consistent, jumping down pretty quick then hovering around low for quite awhile. I'll need to have a few more tries with different sets of rechargeable.
Sum it up
It's $300. Seriously, go try and find something comparable for that price. It's by no means perfect, but it has the essentials in there to give DSLR/rungun/single shooters a relatively painless bump in audio inputs and quality. And if you're someone who wants to get into production sound and don't have a big budget, i'd definitely take this over a higher end unit and spend the remaining budget on quality shotgun/wireless mics. But that's just this one guy's opinion, you should of course check out a few more ;)