Article from Home & Studio Recording, March 1984
Physically the Realistic PZM appears to resemble quite closely the original 'Crown' product with a very similar 5½" x 4¾" metal 'boundary plate' finished in a practical matt black. The electret capsule housing however, which extends from the rear edge to the centre of the plate, is plastic and has a fixed cable exit point. Five metres of rather thin cable connects the mic to its power supply from which emerges another half metre of cable terminated by the moulded ¼" mono jack output connector. Power is provided by one AA size 1.5 volt battery with a nominal battery life of 2000 hours. The power supply box also houses a sensibly recessed on-off-stand-by switch - the standby mode disconnecting the audio line whilst maintaining the power connection, thus eliminating the possibility of a 'turn-on thump'.
The user is also offered the interesting option of using two significantly higher powered 6 volt batteries which fit neatly into the existing battery compartment. The resulting 12 volt supply gives improved dynamic range and increases the maximum SPL (sound pressure level) to 135dB. No battery life figure is given for these batteries but the Owners Manual advises that they should be removed when the mic is not in use.
The output is low impedance, unbalanced and the sensitivity not particularly high at -74dB (0db = 1 V/ubar @ 1kHz). The stated frequency response of an unqualified 20Hz to 18kHz is fairly meaningless for a mic of this type - subjectively the sound is bright but smooth while the bottom end, although tight, is rather lightweight unless the mic is mounted on a suitably large flat surface to extend the effective boundary plate size - a wall or hard floor works very well.
A hemispherical pick-up pattern in any uncontrolled acoustic environment might suggest that room colourations would be a problem. In practice this tends not to be the case, in fact, by varying the distance between mic and source you can control the ambience pick-up very usefully. The direct sound quality will not vary with working distance but the relative ambience content will change.
Whatever instrument you are recording, simply placing a PZM anywhere nearby will usually suffice to produce a natural recorded sound. Lack of directionality is, of course, not a problem when only one instrument is to be recorded at a time such as when overdubbing or working alone.
If this all seems too good to be true for a microphone that sells for less than the price of a couple of reels of tape then perhaps it is a time to examine the weak points. The output is unbalanced and the screening is not particularly good. The plastic battery housing is not very robust and could easily be damaged, also the fact that the mic and power supply are permanently linked by a long length of thin cable, very prone to tangling and knotting, makes storage and setting up rather tedious.
I used a pair of these mics mounted back to back in a 'dummy head' configuration to make a binaural recording in a small theatre. The results recorded on Sony PCM F1 Digital equipment showed the characteristically excellent ability of all PZMs to convey accurately the precise nature of the acoustic in which they are used. However it was also apparent that the unbalanced outputs were unable to reject interference from the theatre lighting system and the recording was accompanied by the low level but persistent 'buzz' caused by dimmer racks. The only cure for this problem is a balanced output and improved screening but fortunately this should not be too difficult for anyone with a little DIY ability.
In conclusion the Realistic 'PZM' cannot be dismissed as a 'cheap imitation', subjectively its performance rivals that of any of the other 'boundary principle' microphones on the market. Its remarkably low price has been achieved without compromising the audio performance to any significant degree and its limitations in the area of immunity to interference are easily remedied if necessary. This mic would not be out of place in a professional environment and yet must be said to bring the attributes of the 'PZM' within reach of anybody interested in recording at any level.
The Realistic 'PZM' is priced at £19.95. Available from any Tandy store.
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Review by Dave Lockwood
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