DV Info Net - NEW: juicedLink DS214 for Run-n-Gun and Dual-System Audio

DESCRIPTION

The juicedLink DS214 is a low-noise preamplifier with a 3.5mm stereo minijack input. There are high/low gain settings, and each channel (left and right) have individual potentiometer control. The output is an amplified mic level suitable for driving the mic inputs on cameras and recorders. Each channel (right and left) has its own dedicated meter with the ability to calibrate them (as different cameras and settings will require different calibration set points). The right and left channels combine for a mono headphone amplifier. For the Canon 7D and T2i cameras which do not have manual audio control, the AGC Disable feature will force the camera to throttle back its noisy amplifiers, to be able to achieve better signal-to-noise performance from the camera.

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CANON T2I AND 7D - AGC DISABLE, ADDING HEADPHONE MONITORING AND METERS

For the Canon 7D and T2i cameras which do not have manual audio control, the DS214 AGC Disable feature will force the camera to throttle back its noisy amplifiers, and keep them there. Otherwise, the camera's AGC will increase the gain and noise during the quiet periods of the recording. This is accomplished by injecting a noise signal into the camera's right track, and the camera's AGC detects the presence of a high signal, and reacts by throttling back its noisy amplifiers. This technique sacrifices one of the camera recording tracks to yield a clean track for recording. Engaging the DS214 AGC Disable will pan all mics to the left track, as the right track is used for the AGC Disable signal (where it will be required to delete the right track in post). The DS214 can be used as a playback headphone monitor to play back your clip in the camera and review the audio in the field. For more detials, please see the DS214 Online User Manual.

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ADDING HEADPHONES AND METERING TO A RODE VIDEOMIC (OR SIMILAR)

There are many compact microphones intended for on-camera mounting, which can plug directly into the camera. Unfortunately, many of the DSLR cameras do not have headphone monitoring or metering capabilities. Use of the DS214 enables the addition of these features.

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ZOOM H4N DUAL-SYSTEM AUDIO WITH CAMERA

The H4n digital recorder has become very popular with DSLR users. Unfortunately, recording audio separate from the camera requires additional work in post to sync the audio with the video. Although there is software to help do this, the added effort sill increases exponentially with large numbers of short clips (and most of these DSLR cameras are only capable of short clips anyhow). Users have come up with the clever solution of plugging the headphone output of the H4n into the camera microphone input. But then, you have lost your ability for headphone monitoring. Using the DS214 as an interface between the H4n and camera allows you to regain the headphone monitoring capability, as well as level control and metering into the camera.

This first audio clip is of a Rode NTG2 being recorded directly by a Zoom H4n, and then this second audio clip is the headphone output from the H4n going through the DS214 and then recorded by a 60D. The second audio clip can be taken from the 60D directly without the need to sync in post, and there is a backup recording in the H4n for good measure. This technique depends on the quality of the recorder headphone amp (for example, the results are not very good using the H1 recorder).

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ADDING HEADPHONES, METERING, AND AGC DISABLE TO AN EXISTING CX211/CX231/CX431 LOW-NOISE PREAMP

There is a large installed base of loyal juicedLink CX211/CX231/CX431 low-noise preamp users who purchased their equipment before the DSLR revolution. The DS214 can be used to add the features to the CX preamp to make it a DSLR audio solution, with metering and headphone monitoring.

New DSLR customers should purchase the juicedLink DT454 integrated DSLR audio solution as an interface to XLR microphones, as opposed to one of the CX preamps.

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ADDING A LOW-NOISE PREAMP, METERING, AND HEADPHONES TO AN EXISTING BEACHTEK PASSIVE XLR ADAPTERS

There is also a large installed base of users who purchased passive XLR adapters (new customers in the XLR adapter market should not be purchasing passive XLR adapters, but should instead purchase the juicedLink CX211/CX231/CX431 low-noise preamps). Similar to the application above with the CX211/CX231/CX431, the DS214 can be used to add the features to the CX preamp to make it a DSLR audio solution, with metering and headphone monitoring. Additionally, the DS214 preamp feature may be able to buy you some additional signal-to-noise from the downstream camera. In the first clip, a Rode NTG2 is plugged into a Beachtek DXA-2s passive XLR adapter which is recorded by a Canon 60D. In the second clip, the output of the DXA2s is fed into a DS214 (providing headphones, meters) and its low-noise preamp allows you to throttle back the noisy camera amplifiers.

New DSLR customers should purchase the juicedLink DT454 integrated DSLR audio solution as an interface to XLR microphones, as opposed to some passive-type of XLR adapter.

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INDIVIDUAL CONTROL AND METERING OF TWO SOURCES

The right and left channels of the DS214 can be individually controlled via dedicated potentiometers. The input uses a single stereo minijack connector, so it can directly interface to dual signals from sources such as the H4n headphone amplifier. However, if you wish to use 2 separate microphones, then you can use a minijack Y cable (such as the Hosa YMM-232, about $6) to individually access the right and left inputs for the 2 mics.

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LOW-NOISE PREAMP TO IMPROVE SIGNAL-TO-NOISE WHILE BOOMING DECENT SNR MICS

XLR microphones typically have better noise specs than minijack mics. Additionally, they are less susceptible to picking up noise and interference on the cable because of the balanced signaling that they employ. This is important, because you need to get the microphone very close to the subject for picking up quality dialogue. Although the DS214 does not have XLR inputs, you can use an inexpensive balanced line termination (such as the Hosa MIT-156) to feed the input of the DS214. Now, using a mic with decent noise specs and getting it close to the subject, the DS214 can be used as a low-noise preamp to achieve better signal-to-noise performance from the camera.

Here are some example clips. The first clip uses a NTG2 going into a MIT-156 directly into the 60D. The second clip uses a NTG2 into a MIT-156 feeding the DS214 into the 60D. You can hear the improvement in signal-to-noise performance, because the DS214 low-noise preamp allowed you to throttle back the noisy amps in the camera.

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SIGNAL-TO-NOISE EXPECTATIONS WITH VARIOUS MICS AND CAMERAS

You can not remove noise from electronic equipment. The name of the game is to optimize the signal-to-noise performance. This becomes more important when recording things like dialogue in quiet rooms. There are many elements in the signal chain which impact this (noise in the camera, noise in the microphone, how close the microphone is placed to the source). Low-noise preamps can improve the signal-to-noise performance of noisy downstream elements such as a camera. This is accomplished by throttling back the noisy camera amps, and replacing the noisy gain with clean gain from a juicedLink low-noise preamp. The amount of improvement will depend on how noisy the camera amps were in the first place. However, a preamp can not fix poor signal-to-noise upstream that gets plugged into its input. So, low-noise preamps can not fix microphones with poor signal-to-noise, or the effects of poor microphone placement.

In practice, what does this all mean?

Run-n-gun microphones with unbalanced outputs (stereo minijack) will typically not have as good of noise performance as reasonable quality balanced XLR microphones. Plus, they are used on-camera (such as the Rode VideoMic) which is further from the speaker (resulting in much less signal getting into the mic ... important in signal-to-noise), compared to booming the mic and getting it really close to the speaker. Since the signal level going into an on-camera mic such as the VideoMic will be lower, so will its signal-to-noise ratio that will be presented to the equipment downstream (even though the VideoMic has decent noise specs). This will set the signal-to-noise of the system, masking any improvement in signal-to-noise that the preamp can get from the camera. So, the value of the DS214, in this case, is to be able to dial in the signal level for the camera (not too high, or too low) as the microphones have limited controls, and also providing metering and headphone monitoring. There are unbalanced minijack microphones of such poor quality (we won't call out names here), where the low-noise preamp can not provide any improvement in signal-to-noise of the camera at all (because the noise from the mic masks the improvement), even at close distances.

So, the DS214 is not being marketed as a low-noise preamp that can improve the SNR from your camera for run-n-gun, because of the typical type of minijack microphones used and where they will typically be placed (on camera).

So, there is a little tradeoff between the convenience of run-n-gun, and optimal signal-to-noise performance.

The DS214 is being marketed as a low-noise preamp if you are using a decent SNR mic (>76dB SNR) and booming it to get it close to the source (< 1.5ft from source). These will typically be XLR mics, so you will need to use some type of XLR adapter to feed the DS214 (Hosa MIT-156, Beachtek passive, juicedLink CX211/CX231/CX431low-noise preamp (much preferred for better frequency response)).

New DSLR customers should consider the juicedLink DT454 integrated DSLR audio solution for added flexibility, convenience to minimize multiple connectors, XLR balanced preamps tend to be quieter, and the frequency response going directly into the juicedLink DT454 XLR inputs will be better.

You can learn more about the principles quality audio from our Tutorial Videos on Audio.

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MOUNTING OPTIONS

There are various Accessory Mounting Brackets which can be used to attach the DS214 to the camera, via its 1/4-20 female threads.
- DIY107B Accessory Bracket for VideoMic
- DIY102B Left-Side Bracket
- DIY101B Rectangular Bracket

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