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Zoom H4 SD card recorder

Zoom H4 general view
Zoom H4 overview

The Zoom H4, retailing at around £240, is an all-in-one mic/field recorder, recording onto standard SD cards. It is the bigger brother to the Zoom H2, and has a number of features the H2 does not have which are of interest to wildlife sound recordists.

As well as the built in microphones on top of the unit, the H4 can accept balanced microphone inputs, and proved P48 phantom power for capacitor mics where required.

The recorder uses two standard AA size batteries, either alkaline or NiMH rechargeable. There is an external mic and line input, which disabled the internal mics if used. Three stages of mic gain are available. Although the format is a handheld recorder, you cannot really use the internal mics handheld as like any cardioid mic the H4 is quite sensitive to handling noise. A foam windshield is supplied as shown in the photo.

You can select a number of recording modes  and sampling rates -  44.1kHz, 48kHz, 96kHz and bit depths of 16 or 24 bits, plus a range of mp3 recording modes.

Like many CF recorders, this product is clearly aimed at musicians rather than widlife sound recordists, with a large number of music-related effects and equalisers. However, the compact form factor makes it attractive to the widlife sound recordist on a budget, with the built in mics there for soundscapes and the external input available for more specialist mics.  

In the field the small size and ever-ready nature are attractive. However, using the unit outdoors showed two significant , though not insuperable operational issues. The first issue is that you need to go into the menu structure to adjust recording level. Level adjustment is such a fundamental part of recording that it really should have its own dedicated buttons. The second is that the combined ¼ inch jack/XLR sockets on the base do not provide a very positive contact for XLRs, and are thus subject to getting noisy when moved, and there is no positive plug latching as you would expect on a normal XLR plug/socket (even if the plug normally latches). 

The CF card/battery door is slightly fiddly, and changing the CF card requires sharp fingernails and slim fingers, which are perhaps less common among typical wildlife sound recordists!

The maximum gain available is significantly lower than, say a RH-1 minidisc recorder. It slightly hampered the ability to monitor some softer sounds in the field. Although the basic noise performance of the input stages is a lot better than the Zoom H2, a significant amount of interference from the CF card write mechanism seemed to be observed on both channels. 


The performance using the built-in mics is rather better than this measurement would indicate - here is a recording of a robin about 10m away from the H4. (note this recording has been filtered for urban traffic noise, but not HF hiss. There was a light drizzle starting up, the ticks are rain falling on leaves and not an artifact of the H4)


Robin.

Either the internal mic capsules are unusually sensitive, or the signal path for these capsules is different to the external mic input. For voice recordings  it is worth watching the bass enhancement which makes the voice unnaturally deep at a distance of less than 30cm, but the performance is otherwise good for general field recording.

Technical Measurements

Settings - Microphone input, gain H unless stated otherwise,  level 127 sampling rate 44.1kHz Source impedance 150Ω Software level 1.30 S/N 078144

Minimum input for 0dBFS = -41dBu (H)  -32dBu (Med gain) -19dBu (Low gain) 

Noise. Note that the noise floor of the H4 is anomalous during recording, see [1]

Ein = -95dBu (unweighted, 22kHz BW)

Ein (A) = -114dBu (A weighted, 20kHz BW)

A plot of the noise floor at maximum gain is shown below, when the noise is boosted by about 40dB a tone can be heard, presumably the 688Hz component. The low-frequency thumping noise is correlated to the SD card write LED (it is not present in record-pause) .

noise spectrum
noise spectrum (IF BW 2.7Hz) 


noise floor, boosted by 40dB if recorded at full gain, terminated in 150 ohms

Users should be warned that the polarity of the 9V DC power socket is opposite to the most common usage, with the inner being -ve and the outer being +ve. This is not a problem using the supplied adapter, but users should take extra care to avoid swapping the supply with that of another device.

Conclusion

As a low cost standalone field recorder/microphone combination the H4 is one of the cheapest recorders that can be used with phantom-powered balanced mics, such as the ATR55 and Sennheiser ME66. It can not be used with unbalanced electret types such as the MKE300 unless an adapter cable is used. As such, for a wildlife sound recordist looking to concentrate their budget on quality microphones first (in the £200 upwards bracket), it is a good first choice.

The Wildlife Sound Recording Society would like to thank Solid State Sound for the loan of the Zoom H4 reviewed here. You can purchase this recorder at their website http://www.solidstatesound.co.uk/

Review date: October 2007

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  1. It should be noted that the noise components are very unusual in nature. When writing to the SD card during recording, the card light flashes about every second. This corresponds with a large LF disturbance in the H4 noise. A weighting reduces the importance of low frequencies, but was never designed for rhythmic noises like this.

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