This is actually something I wrote up a couple of years ago when I upgraded my digital portable recorder from a Zoom H4n to a Tascam DR-680. It just touches on my experiences with both these bits of gear, mainly regarding noise performance, and also about interfacing them with an external field mixer…
The Zoom H4n is a very handy little recorder, which has become a favourite for indie filmmakers and musicians. It is packed with a great number of features and is quite good for the price, however, it’s weak point in my experience is the quality of it’s microphone preamps. I have come across many a short film with fairly noisy production recordings which were recorded onto a Zoom H4n with a medium output shotgun microphone such as a Rode NTG-2.
Looking in the Zoom H4n’s manual, noise specifications are not defined. It is a common issue for gear specifications to be unclear or questionable. Avisoft Bioacoustics have done some testing on digital recorders in order to provide “more homogeneous specifications across the different recorder models”. (http://www.avisoft.com/recordertests.htm). Their testing shows an unweighted Equivalent Input Noise (EIN) of -104dBu which is fairly poor. By comparison, the best performing model is the Sound Devices 722 with an equivalent EIN spec of -128dBu. The Tascam DR-680 has an equivalent EIN spec of -125dBu.
With the poor performance of the Zoom H4n’s preamps in mind, I looked into teaming up the recorder with a Sound Devices 442 field mixer. Other people have used and documented the use of other preamps as a “front end” for their Zoom Recorder. An example is Dan McComb who has teamed up a Sound Devices MixPre with his Zoom H4n. (http://www.danmccomb.com/posts/880/zoom-h4n-with-sound-devices-mixpre-how-to-properly-connect-the-two-for-pristine-audio/).
If you try to send a line level signal into the Zoom H4n it will clip and distort on the inputs no matter how low you set your recording level. Setting a recording level on the Zoom H4n of less than 1 seems to attenuate the signal after the input which is a little pointless, as you would have clipped the signal on the input already before turning it down. The point here is, it is no use turning your Zoom H4n recording level to less than 1.
With this in mind there are a couple of options for ways of connecting up the Sound Devices 442 to the Zoom H4n. The Sound Devices 442 has the option of setting your Mix outputs at Line, -10 or Mic level. Both the Line and -10 options result in too high an output for the inputs of the Zoom H4n. You could use an inline attenuator to bring down the level by a fixed amount however. The other option is to send out a Mic level signal to the Zoom H4n’s input. After testing the various options, this is what I decided was best in my case. A recording level of 32 on the Zoom H4n got me the level I required, setting it so that the 442’s output limiter would kick in before we clip on the Zoom H4n’s inputs.
The Mono Mix function in the Zoom H4n blends the left and right inputs and records the same mono mix to both the left and right channel of a stereo file. While it might be a temptation for indie filmmakers that are using just one shotgun mic for a shoot to use the mono mix function, I would recommend this as we are adding the additional noise from preamp 2 to the mix and reducing the overall level by 6dB, which ultimately results in a noisier recording.
Noise Performance Comparison
I connected up from the Zoom H4n plugging into XLR input from Sound Devices 442 Mix output at Mic Level. Noise was measured at -69.0 dB at the settings used. Trying different combinations of attenuators, levels and inputs got me similar results, but none better than -69.0 dB.
What about the Tascam DR-680?
As stated earlier, the Tascam DR-680 has an equivalent EIN spec of -125dBu according to the Avisoft Bioacoustics testing (http://www.avisoft.com/recordertests.htm). This is really quite decent for a digital recorder, and within a few dB of the Sound Devices recorders. Nevertheless, I thought I’d try a similar test by pairing up the Sound Devices 442 with the Tascam DR-680.
Then I connected up the Sound Devices 442 Line output to the Tascam DR-680 plugging into the XLR input and selecting line level. I used the same signal to set the gain through the 442 and into the DR-680 just before clipping. Noise was measured at -69.5 dB. This is a little better than the 442 teamed up with the Zoom H4n, although not by much. It is a little better than using the Tascam DR-680’s built-in preamps, although whether the benefit is worthwhile will really depend on the recording situation and how much gain is required.
Other noise from the Tascam DR-680
I undertook some other testing with the DR-680. I have to say it performs quite well generally, although I found a couple of things that worried me…
The headphone amp is noisy generally, although many users have already commented on this.
With headphone volume turned up high, there seems to be some cross-talk into the recording on channels 5 and 6. I guess the channel 5 and 6 wiring runs very close to the amplified signal from the headphone amplifier, and cabling isn’t shielded very well. This means if you want a clean recording on inputs 5 and 6 you can’t monitor it properly through the headphones. Potentially there is also the danger of causing feedback within the device due to this crosstalk.
Editor’s Note 04/12/19: If you are after more general info for the Zoom H4n in a video review format then you might check out: https://www.youtube.com/watch?v=hgcFVbzQvCQ