Independent Reviews of Bat Detectors

Batbox BATON - reviewed August 2009

The Batbox BATON is a single channel frequency division bat detector. A factor of ten division is used so that for example, Noctule calls at 25kHz result in a sound at 2.5kHz, while Lesser Horseshoe bat calls at 100kHz produce a 10kHz sound. The detector needs no tuning because all bat calls will result in audible sounds from the speaker, and in fact the only control is the on/off button. When first switched on in a quiet room quite a lot of white noise "hiss" was noticed, but this was much less apparent outdoors and in no way interfered with the effectiveness or enjoyment of the detector.
Historically FD detectors have been characterised by low sensitivity, threshold effects and (if fitted with a speaker) a tendency to feedback. They have produced an unpleasant scratchy sound, and attempts to restore the amplitude of the bat call have met with limited success. The BATON is different.

In use the BATON amazed me both by its sensitivity and the pleasant sound it produced, with a completely different quality to other makes of FD bat detectors, and much more like that from a good heterodyne detector. Even when the bat was at a good distance the call was still clearly distinguishable above the background noise.
The BATON proved its worth in enabling me to pick up Noctules at the same time as both 45 and 55 Pips; and also showed that it was possible to distinguish between calls from Pips and Daubentons bats.

Examples of sound

This is the "sensor" end of the baton: an ultrasonic microphone fitted into the end of the casing which is moulded to form an acoustic horn. This improves both sensitivity and directionality.

You've guessed - everyone I've shown it to has liked this detector very much. One very minor criticism - when juggling the detector, torch and recorder in the dark a wrist strap would have been nice.
And finally - its only Ł60 - great value for money!

Our friend Al from the USA says "this is the most comfortable detector I've held." He also liked the unobtrusive on/off switch and blue "power on" led.

Batbox Duet - reviewed Feb 2010 Jonathan Pounder

The Duet is a dual mode detector, providing both heterodyne and frequency division techniques.
The dial system is difficult to use at first, and takes a little practise to get used to. The large screen is very easy to use and allows you to see easily the frequency you are listening to – although switching between frequencies quickly can take a while to master.

The Duet has an excellent range – 30 to 40 metres, and is exceptionally good at differentiating between 45 and 55 pips in the field. Its is lightweight, robust and waterproof, including a hand strap and earphone jack. It has a good battery life especially if you use the earphones.

The main advantage of the Duet is the ability to connect to a recorder and have that running in conjunction with your detector while listening.

Everything you need for consultancy and analysis
Currently Ł212

Batbox III - reviewed Feb 2010 Jonathan Pounder

A good all round heterodyne type bat detector.
This is a robust field consultancy tool. It has good discrimination allowing you to differentiate between 45 and 55 pips. The wide frequency range on the knobs and the backlight allow you to accurately search through the frequency range to identify different species. The backlight also allows you to gauge the remaining battery life of the detector; the major flaw is if the bulb breaks then the detector is a lot harder to use.
It has a fair range in the field of 20 to 30 metres and has a large speaker and hand strap to secure during surveys.
Frequency range 19kHz – 125kHz
Earphone jack present
PP3 battery gives good battery life
Compact and lightweight (slightly heavier than a Magenta)

Excellent for consultancy work but lacks the frequency division capability. Compared to other detectors the BATBOX detectors can be quite loud - ideal for group work.

Newer version (Batbox 3D) includes a digital display and dial system price about Ł130

Image is of 3D model

Magenta 2 - reviewed Feb 2010 Jonathan Pounder

An excellent introductory heterodyne type bat detector, it is fairly large, at 80X140 mm, but relatively light in weight.
It has a very easy to use knob system which is perfect for starting out and getting to know how to use and listen to bat detectors; but less suitable for more detailed investigations to determine call frequencies and identify exact bat species.

The frequency marks around the knob are fairly close together and the frequency band has a habit of creeping over time and use, so its not great for discriminating between types of pip.

It has a limited range in the field of 15 to 20 metres and its small speaker can easily be covered with a stray cold finger, and it does not have any hand straps. (Later versions have larger speakers). Earphones can be used , and you can record from the earphone output jack.

A single PP3 battery gives good battery life.
Available as a kit for Ł38

Newer (and more expensive) versions the Magenta 4 includes a larger speaker and frequency control, further improving the bat detector for use. The Magenta 5 Includes a digital display and dial system.

Bat Scanner - Review Sept 09 by Al Milano (New York, USA)

A new and unique bat detector kit is now available, from Tony Messina in the US. The result of a joint effort by Tony Messina & Frank Pliquett (in Germany), this heterodyne-based Bat Detector is unique because it has the ability to actively scan ultrasonic frequencies for bats.
The Bat scanner is currently available as an almost completed kit, where all of the delicate soldering and assembly has already been done for you. The kit is supplied with everything you need to complete the construction. All that is required are basic soldering skills and the proper tools to create the needed holes and openings in the plastic case provided. Video and photos of the prototype can be seen here: http://www.zwergfledermaus.de/neues/neues_e.htm Step-by-step assembly instructions, with colour pictures are provided with the kit. I found the assembly straight-forward and fun! The very first, original units had a buzz/hum caused by the multiplexing of the 2 digit LED display. This issue has been addressed, and the current version of this kit no longer produces this low hum/buzz. Several other modifications and enhancements have been made, to further improve the detector's performance.	Dimensions: 13 * 8 * 4.5 cm not including knob.
I like this bat detector very much! During operation, it scans very quickly through it's frequency range (10 to 80kHz, in 2kHz increments) and will stop and display the frequency of whichever bat happens to fly within range! The buttons also allow the unit to be used as a conventional Heterodyne bat detector where the desired frequency can be selected and monitored. When used in this manner, the unit goes into a Power Saving mode, where the LED display powers off, while it waits and "listens" for any signals. At which point, it will blink in sync with the signals received (while also being heard through the speaker). I have used this detector very extensively since completing the assembly. I've found its sensitivity to be equal to many of the other bat detectors I own, including commercial units costing twice as much. The compact speaker provides plenty of nice sounding audio and the unit is a lot of fun to use. And of course, this detector is very useful in the field when encountering flights of more than one species of bat at a time. You can ID the bats right in the field, just by glancing at the display - without having to do any tuning. If you enjoy enjoy building bat detector kits I would recommend this kit very highly. It is also a great platform for experimenting. From Frank (see below) at 66 euro inc. Frank also has a simple heterodyne detector available at 32 euro Bat Scanner main page (USA) http://home.earthlink.net/~bat-detector/Scanner/ Frank Pliquett (Germany) - http://www.zwergfledermaus.de/index_e.html
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Ciel Electronique - reviewed June 2009

Ciel Electronique make a range of bat detectors from a simple heterodyne detector for children to dual mode and stereo types. All use a 9V battery and have a plastic case that seems quite robust. The smaller versions are just 5.5 inches long and fit nicely in the hand, while the larger versions are about 6.5 inches. Ciel also sell both passive and active external speakers. Due to the change in exchange rates British detectors offer better value for money at present. Further information on individual models follows.


BATZ: A single mode heterodyne detector that is cheap (70E) and easy to use. Attractive for kids and not too big for small hands. A button on the side activates a bright LED light for use as a torch. Has a built-in loudspeaker.	CDB305 R2: inexpensive (100E) dual mode (FD/Heterodyne) detector with a push switch to select FD or HD modes. I'd have preferred a rocker switch as the push button spoils the smooth line of the case and could cause it to catch in a pocket. Has a built-in loudspeaker.
Both were very effective and my children enjoyed using them. Although the knobs are spaced to the right of the case within easy reach they are too small and stiff when new to allow one handed operation. Audio output of half a watt is comparable with other detectors eg Magenta; however the sound from the very small speaker was not really loud enough and overpowered in windy conditions or by the sound of moving water. Better with 'phones.
The units below are more advanced and all provide outputs for headphones and line out for recording.

CDB101 Stereophonic heterodyne detector uses a backlit two line LCD display reading to 0.1kHz. No speaker.	CDB103 Stereophonic (two microphone) heterodyne detector uses a three digit LED display. Has a built-in loudspeaker.
Not much to choose between these units so as its a bit cheaper and has a speaker I'd prefer the 103. Its also easier to read and set the frequency. The two microphones give a good stereo effect. Sensitivity seems quite good and at full volume on speaker can cause feedback; however plugging in the phones cuts off the speaker and stops this. Both have good sensitivity and produced a clear sound when monitoring Daubentons bats, even on the opposite side of the river, about 15m away. Generally nice to use with headphones. Calibration was spot-on and picked up TV at 16, 31, 47, 62 and 94kHz.

CDB301 advanced dual mode (FD / HD) detector: one button on the far side allows mode selection while the other provides for a commentary, using a separate microphone. The most expensive at 230E - about Ł190 I found when I turned the volume up to listen to the HD signal the FD was way too loud and unpleasant to use. Perhaps the FD sensitivity could be better, or the FD output attenuated a bit. HD was fine.	CDP102 R3 a dual heterodyne detector designed for long term surveys this detector uses external microphones and a mains power supply. I found the unit drew 40mA from a 9V battery, and only 20mA with the display turned off - so it could run for a full day from a duracell battery. Two separate channels allows tuning for two different frequency ranges. It can also be used as a stereo detector.
No problems with the units in use, the heterodyne circuit seems well developed in this latest revision. The frequency control is smooth and linear, and with care I was able to tune to 50.0 kHz. Once set the frequency is very stable. The FD circuit does not have amplitude restoration, which would have been better for use with headphones.
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CSE - Reviewed 2007

Armin Lenk's CSE bat detector is available in both mono and stereo versions. It has a frequency range of 20 - 110 kHz allowing detection of noctules (20kHz), pipistrelles and both lesser (80kHz) and greater (100kHz) horseshoe bats. Its a heterodyne detector and unlike others doesn't have a built-in speaker, just a headphone / line out socket. (you can buy a splitter if you want to use both at the same time) Armin sent me his stereo version to try, and I was very impressed. (correct prices Jun 2009 STILL ONLY 52 euro, 78 euro)
The detector measures about 4" * 2" * 1" and pops easily into a pocket. It's built to take knocks of field use.	The CSE bat detector is light and fits comfortably in your hand, thumb resting on the tuning control. No volume control or on-off switch are needed as plugging in the phones turns on the detector. The tuning dial has a spread scale at the lower frequencies where most common bat calls occur. The scale is accurate enough to help distinguish between common (pipistrellus pipistrellus, 45kHz), and soprano pipistrelles (pipistrellus pygmaeus, 55kHz).
Uses two microphones for stereo detection. The casing is shaped to give an acoustic horn effect improving channel separation.
As supplied the dial calibration is reasonably accurate across the range. I found the stereo output really helpful in locating bats and has a clear light airy sound. All told a nice detector and excellent value for money. Use a dab of blue tack to prevent the battery from moving inside the case. Because there is no loudspeaker or power amplifier the battery drain is tiny - only 10 mA! so an alkaline battery will give up to 50 hours CONTINUOUS use. Here is a recording made using my minidisc recorder. See if you can tell what the bats are!
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