This is a great article from B&H about Audio Adaptors.
Guide to Beachtek Audio Adapters: Which one is Right for Your HDSLR and Camcorder?
Nothing ruins a video faster than a bad audio track. Thankfully, Beachtek offers specialized audio adapters designed for the connection of professional audio recording equipment and microphones to HDSLR and camcorder cameras. Without the need for a separate recorder, the adapters provide exceptional audio quality directly to your camera, in perfect sync with the video. Beachtek employs high-quality components throughout, resulting in low-noise, high-gain, and high-fidelity sound. Each adapter offers unique features designed to aid professionals and consumers in capturing audio, while providing a variety of secure mounts for peripherals, such as wireless receivers, self-powered microphones, and condenser microphones requiring phantom power.
The DXA-SLR ULTRA is a two-channel, active XLR audio adapter featuring high-quality, low-noise preamplifiers for connecting external microphones and other audio gear to any DSLR camera with built-in mic input jacks. Connections are made via the Neutrik combo XLR/1/4″ jacks, which are compatible with a variety of gear, including wireless microphone systems, mixing boards, and professional condenser microphones.
The unit utilizes active electronics to boost the gain of mic or line signals without the added noise generated from the camera’s onboard preamplifiers. Additionally, the inputs are electronically transformer-balanced for isolation and enhanced circuit protection. The built-in VU meters allow you to set and verify levels properly when using the onboard level controls. The fast-acting limiters prevent distortion from high-level transients and overly hot signals, thus providing worry-free operation. A headphone jack allows for audio monitoring from the adapter during recording or camera during playback. A unique feature of the DXA-SLR is the rod support system, designed to attach a matte box, follow focus, and other peripherals. The rod support attaches neatly to the bottom of the adapter and includes additional threads for mounting on any standard tripod. The two 3″ rods are threaded at both ends and can be extended to any length with additional rods.
The DXA-SLR PURE is also a two-channel audio adapter, but employs passive circuitry for connecting wireless microphone systems, mixing boards, or any other amplified sound signal not requiring a microphone preamp. The adapter utilizes low-noise, wide-bandwidth, balancing transformers and provides full-frequency audio. The Neutrik combo XLR/1/4″ connectors are designed to work with any balanced or unbalanced audio signal. The mixer section is set at unity gain, which allows you to attenuate signals, but not boost. This adapter is not intended for direct connection to microphones, but because of the passive topology, offers a pure signal, free from coloration when compared to active circuits. The unit mounts on the bottom of the camera and can also be mounted on any standard tripod.
The DXA-POCKET is an active, two-channel compact audio adapter designed to work with DSLR cameras or camcorders. The unit features two unbalanced 1/8″ mini jack inputs and one stereo 1/8″ mini jack. The adapter is designed to work with wireless microphone systems and self-powered microphones. It does not offer phantom power, but the active circuitry does provide +30 dB of gain, which allows you to lower the camera mic pres and noticeably reduce any audible hiss. The dual trim controls allow for setting levels independently, while the bright, easy-to-read VU meter makes setting levels precise for optimal results. There is an A/B switch for meter calibration, where A should be used for a Black Magic Pocket Cinema camera, while B is designed for any other DSLR.
The adapter is designed to mount on the top or bottom of a camera and provides a rubber grip for comfortably and securely holding smaller cameras. Additionally, the rubber grip may be removed to reveal an additional shoe mount for connecting peripherals, such as wireless receivers or microphones.
The DXA-Pocket connected to a Blackmagic Design Pocket Cinema Camera equipped with on-camera shotgun microphone.
The MCC-2 is a passive, two-channel audio adapter/bracket combo. With a passive topology, the unit does not boost, but attenuates signals and is designed to work with wireless microphone systems and self-powered camera-mounted microphones. The adapter requires no batteries and does not color the sound or add noise to the signal. There are two onboard level controls, two 1/8″ inputs for two mono signals, and one stereo 1/8″ input for stereo signals. The MCC-2 attaches to your camera via a shoe mount and offers an additional three shoe mounts for connecting wireless receivers or microphones.
The DXA-CONNECT combines a two-channel, active XLR audio adapter with an accessory bracket for mounting a multitude of peripherals and devices on the camera. The adapter features two high-quality, low-noise microphone preamps with plenty of gain for any microphone or wireless microphone system. There are three level gain switches for each preamp, as well as onboard level controls. Phantom power is provided to power condenser microphones.
The DXA-Connect on a Nikon DSLR, supporting an Atomos Ninja 2 on-camera field monitor.
The brass mounting foot allows for sturdy connection to any camera and provides an additional four shoe mounts, ideal for attaching mics, monitors, receivers, lights, or field recorders. Additionally, a top handle can be added to provide a convenient grip for your camera.
The DXA-2T is a passive, compact camcorder audio adapter designed to connect balanced microphones, external audio mixers, preamplifiers, and wireless microphone systems to your camcorder without adding noise or coloration of the signal. The there are two transformer-balanced XLR inputs and a single unbalanced 1/8″ auxiliary input for connecting wireless receivers. The stereo 1/8″ output connects the included cable to the microphone input of your camcorder. The adapter allows for the attenuation of audio signals via two level controls, as well as switches for mic/line, mono/stereo, and gain. The passive circuit design does not require a battery and provides a wide dynamic range, flat frequency response, and no distortion, noise, or clipping.
The Beachtek line of audio adapters provides exceptional value, while offering high-quality results. Whether you are using an HDSLR camera or a professional-consumer camcorder, Beachtek has an adapter for your needs, and within your budget.