What is the CM1?

The CM1 is a high performance, hand made contact microphone based on the preamp design presented elsewhere on this site along with a robust, shielded balanced piezo microphone element connected up with very flexible Kevlar re-enforced minature balanced microphone cable.

The preamp is phantom powered, has balanced inputs and outputs to eliminate hum, uses a pair of hand matched low noise FETs to ensure very good hum rejection, is entirely surface mount and fitted inside a professional quality XLR connector. It is DC coupled and can drive loads down to 600 ohms albeit with reduced gain.

The piezo element itself is the best design selected from over 10 that I've tried. It's fully shielded and has a balanced floating output to allow the pre-amplifier to remove any remaining hum. It is robust and waterproof and can be used as a hydrophone.

Together they combine to make a highly sensitive contact microphone that's equally suited to discerning studio recording of acoustic instruments. It produces an exceptionally natural sound on accoustic instruments with none of the loss of bass or honky sound common to many passive piezo microphones. It sounds rather similar to a decent condesner microphone with the key advantage that it is totally immune to problems caused by room acoustics.

Sound Samples

Acoustic Guitar: A short passage played on a Simon and Patrick acoustic 6 string guitar. Contact mic placed next to the bridge and temporarily attached with BlueTak. No dynamics, reverbs or other effects applied.

More sounds to follow...

Specifications

Download Datasheet

Options

High Pass Filter : The standard mic has a response down to below 5Hz, but I can add a pair of capacitors to provide a 1st order high pass filter if you know that you don't want response that low. This avoids the possibility of the pre-amp clipping due to large amounts of ELF.

Pictures

Overall view

Closeup of mic element

Closeup of preamp