FOXPRO, Inc. - High Performance Game Calls.

MA-21, Meet the Krakatoa

We decided to compare the new FOXPRO Krakatoa to the Wildlife Technologies MA-21. Both are larger size remote controlled wildlife callers, and both operate on rechargeable NiMH batteries. The MA-21 weighs in at 5.95 lbs with batteries, and the Krakatoa at 5.40 lbs with batteries.

We started by disassembling the MA-21. We were surprised to see that the small single printed circuit board containing the electronics appeared identical to the board used on the previous KAS-2030 model. The MA-15 uses the same board (in fact, the only difference from a hardware standpoint between the MA-15 and MA-21 is that the MA-21 operates from 14 batteries while the MA-15 uses only 10). We could find nothing different with the board since our 2009 exposé. Then we checked the digital sample and bit rates. Again, the results were the same as with the KAS-2030 we examined back in early 2009. All sounds were 16 bit resolution and sampled at 32 kHz. While we don't believe that all sounds used to attract animals need to have 24 bit resolution, we will insist that if someone implies that their product offers 24 bit performance, then it must be able to play a 24 bit file. We have yet to see any Wildlife Technologies caller that stored and played a 24 bit sound.

Additionally, the advertising copy for the MA-15 and MA-21 still claims that "The audio signal chain is completely digital from the digital audio files to the digital amplifier at the end of the processing chain." This statement was patently false when we exposed the KAS-2030, and is just as false with reference to the MA-15 and MA-21. The DAC output is an analog signal which is sent to the pulse-width modulated audio power amplifier, which makes this "completely digital" claim false.

Next, we examined the MA-21 speaker. The Selenium speaker driver is a fairly heavy device that sports a pretty good frequency response for animal sounds. Selenium publishes specifications for this D250X driver when mounted to their six inch by 10.5 inch HL14-25 exponential horn. However, the MA-21 uses a much shorter folded horn that appears to decrease the speaker sensitivity, particularly at midrange and lower frequencies. This becomes an issue for sounds with frequency content below 500 Hertz. An exhaustive A-B comparison test between the Krakatoa TOA SC-630 and the MA-21 speaker has proven the TOA to sound much more realistic with more presence when reproducing sounds with even minimal frequency spectrum content below 500 Hertz. On sounds with moderate lower frequency content the difference was dramatic! Particularly, owl hoots and canine growls, snarls, and barks are reproduced with astounding improvement with the TOA when compared to the MA-21 speaker. Likewise, mountain lion growls were much more pronounced and realistic. Even when we placed the recommended exponential horn onto the Selenium driver, the TOA SC-630 had better response to lower frequency sounds. However, higher frequency sounds such as bird chirps or cottontail distress cries didn't show much difference between the speakers aside from the difference in sensitivity between the two speakers. The Selenium driver manufacturer specifies a sensitivity of 107 dB with an input power of 1 watt, measured at 1 meter in an anechoic chamber. As previously mentioned, the specified HL14-25 large horn is not used in the MA-21. For sure, the smaller MA-21 folded horn will not increase the driver sensitivity, and may well decrease it to some degree.

By comparison, The TOA SC-630 speaker used in the Krakatoa has a manufacturer rated sensitivity of 113 dB with 1 watt input, measured at a 1 meter distance, again in an anechoic chamber. Compared to the 107 dB sensitivity rating of the Selenium driver used in the MA-15 and MA-21 speakers, the Krakatoa achieves a 6 dB loudness advantage just from the TOA sensitivity alone. Even if both the Krakatoa and MA-21 used identical amplifiers, this would be a substantial advantage.

Finally, an examination of the MA-21 power amplifier revealed a class D mono power amplifier with a 15 watt rating. Class D amplifiers are preferred because they waste less battery power. The Krakatoa class D amplifier has two channels each rated at 25 watts. The chart below shows how much power is generated with each product. The MA-15 and MA-21 show power generated from two power sources. This is because the specifications for these products indicate unrealistically high voltage levels. Power output levels are therefore shown with a laboratory power supply, and again with a more realistic NiMH battery pack which would be utilized by nearly all users. The Krakatoa power measurements were made using the included dual NiMH welded battery packs. With respect to the Krakatoa, it should be noted that we have measured over 30 watts of power from each channel while operating from the included battery packs. That's more than 60 watts of total power. To date, we have never measured this much power from any other wildlife caller.

Table 1 shows how much power can be generated with typical power sources. Also shown is the maximum SPL that can be generated according to the sometimes inconvenient laws of science and physics.

UNIT	MAXIMUM UNCLIPPED POWER OUTPUT	dB GAIN REFERENCED TO 1 WATT	SPEAKER SPL 1W / 1M IN dB	MAXIMUM SPL dB AT 1 METER
Krakatoa with Standard supplied battery packs	30 Watts	14.77	113	127.77*
Krakatoa with additional external SC-630 Speaker	60 Watts	17.77	113	130.77**
MA-21 with 21 Volt Labratory Power Supply	21 Watts	13.22	107	120.22
MA-21 with 14 NiMH Batteries	15.2 Watts	11.82	107	118.82*
MA-15 with 15 Volt Labratory Power Supply	12.5 Watts	10.96	107	117.96
MA-15 with 10 NiMH Batteries	8.5 Watts	9.29	107	116.29

* As you can see, the total SPL (loudness) advantage of 8.95 dB goes to the Krakatoa. The Krakatoa wins the SPL battle - hands down!

** With an external SC-630 speaker connected to the Krakatoa, the user can project sound at an SPL of 127.77 dB from the main speaker, and 127.77 dB in a different direction from the external speaker. The sound coverage area advantage of this option is tremendous! This is not possible with the MA-21 as it has only one channel and no external speaker jack.

It seems clear from the above data that the MA-21 claimed SPL level of 130 dB cannot be achieved...Not even close! Likewise, the MA-15 SPL is overstated.

Always be suspicious of an SPL number presented without the measurement distance and power input specified. The common industry standard is 1 watt input to the speaker with the measurement instrument placed 1 meter away. Measurements must be taken in an anechoic chamber because echoes and reflections from walls, floors, ceilings, and other room objects will make measurements highly inaccurate. This is why we like to start with the speaker manufacturers SPL specification. Most all of the reputable speaker manufacturers are honest with their specifications. If they state that the SPL is 107 dB with 1 watt at 1 meter, it can be believed reliably. Not so much when someone simply specifies an SPL of 130 dB with no mention of qualifiers. Once the raw speaker SPL is accurately known, it becomes simple science and math to calculate the maximum SPL of an audio product. There is no room for smoke and mirrors, and therefore there can be no arguments.

Krakatoa features that are not available or are limited for the MA-21:

• 10 presets including volume

° MA-21 has 4 presets that do NOT include volume levels

• Large Red Backlit LCD for easy sound selection

° MA-21 users are forced to remember numbers or carry a paper listing

• Users sounds can be programmed using a computer interface. Formats include .mp3, .wav, .FXP, .24b.

° MA-21 does not allow the user to add their own sounds. File format is hidden from the user and inaccessible.

• Max sound quality is 24 bit 48 KHz stereo

° MA-21 has never been able to demonstrate 24 bit. It has been measured numerous times as only having 16 bit 32 KHz stereo sound quality in spite of the advertised specs. The "UP TO 24 BIT" has never been demonstrated.

• Aux Jack for controlling decoys or cameras