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Camcorder using juicedLink’s low-noise preamps performs 8.3 dB better in signal-to-noise ratio, versus when it is used with a Beachtek DXA-6 (passive-type Camcorder XLR Audio Adapter)!
It is all about the signal-to-noise ratio of the entire SYSTEM.
The system is not just the XLR Camcorder Audio Adapter, but includes the camcorder amplifier circuitry.
Yes, it is true that a passive-type XLR Camcorder Audio Adapter does not add noise. But, it requires the camcorder amplifier circuitry to do all of the work, since the passive XLR Camcorder Audio adapter does not have any gain.
The juicedLink approach is to use low-noise preamps … amplifiers that are often quieter than the camcorder amplifier circuitry. So, when you have the low-noise preamps do the front end work for the amplification so the camcorder amplifiers can be throttled back, the result is a better overall signal-to-noise ratio for the entire system.
You can actually hear the difference. Check out the comparison video with a Beachtek DXA-6 passive Camcorder XLR Audio Adapter.
The ability to have low-noise performance while recording low-level signals is important for the videographer. It is at the times when you are trying to pick up fine detail, when you want your best low-noise performance. Otherwise, the noise will mask the fine detail that you are attempting to pick up. In addition to picking up fine detail, you may encounter low level signals for a number of reasons: 1) use of dynamic mics, 2) not all condensers produce high output voltage/Pascal (lavs, older shotguns, some wireless receivers, etc), 3) sometimes, you can't get the optimal mic placement and need to crank up the gain.
There is more discussion on preamps in the TechTalk section.
Additionally, we use the low-noise preamps as part of our input balance technique, which is an integral part in the exceptional juicedLink frequency response.
For those of you interested in the test setup, here are the details.
Calibration: 1) The equipment used for the evaluation was a Canon GL-2 (set on manual), a Hewlett-Packard 8903A Audio Analyzer, a Beachtek DXA-6 Camcorder XLR Audio Adapter, and a juicedLink CX471 Camcorder XLR Audio Adapter/Mixer/Preamp. 2) The 8903 used the PSOPH and 30kHz filters. 3) We took the audio output from the camcorder’s headphone jack. To calibrate, we applied a signal at the input, adjusted the GL-2 gain until the GL-2 VU meter was reading –12dBFS (per Canon recommendation). 4) Then, we measured the voltage level coming out of the camcorder headphone jack. This was 0.13V
Test of Canon GL-2 with Beachtek DXA-6 (passive-type Camcorder XLR Audio Adapter): 1) The 8903 was set for an output voltage of 0.6mV. 2) The 0.6mV was applied to the input of the Beachtek DXA-6 Camcorder XLR Audio Adapter. Both potentiometers were turned all of the way up. 3) The camcorder gain was adjusted until the output signal measured 0.13V. 4) The measured SNR was 51dB.
Test of Canon GL-2 with juicedLink CX471 Camcorder XLR Audio Adapter/Mixer/Preamp using low-noise preamplifiers: 1) The 8903 was set for an output voltage of 0.6mV. 2) The 0.6mV was applied to the input of the juicedLink CX471 Camcorder XLR Audio Adapter/Mixer/Preamp. The potentiometer was turned all of the way up. 3) The camcorder gain was adjusted until the output signal measured 0.13V. 4) The measured SNR was 59.3dB.
A note on the input level used for the tests. Say you were using a dynamic microphone with a sensitivity of 2.8mV/Pa. A sound pressure level of 0.2Pa would result in an open circuit voltage from the microphone of 0.6mV (as used in the tests). This is a reasonable signal level and voltage level, as it is less than the SPL for long term hearing damage (0.6Pa), and greater than normal talking at 1m (0.02Pa). It is roughly the SPL measured 10m from a major road. (source for SPL references from Wikipedia). Obviously, increasing signal level will increase the signal-to-noise ratio.
Note: All AC voltages are Vrms.
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