HXM-1 Hx Series Microphone Preamplifier User’s Guide
The Hx Series from Demeter Amplification is a revolutionary approach in tube design utilizing innova
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tive tube circuitry for the amplification functions and the latest in solid state for the driver functions.
All Hx Series equipment use the finest quality components featuring metal film resistors, high quality
film capacitors, and custom toroidal power transformers housed an attractive aluminum and steel single
space rack mount case. All units feature fully regulated power supplies supplying 200V to the tubes and
+ and - 18V for the solid state components, giving all Hx series components tremendous head room up
to +28 dB output into 600 ohms.
The HXM-1 is a two channel microphone preamplifier utilizing Jensen transformers and the revolution
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ary Hx Series tube amplification circuitry. Each channel has variable gain (30 to 60 dB) instrument input,
low cut, phase, pad, overload indicator, volume, 48V phantom and 10 section VU with selectable sensi
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tivity.
INPUTS, CONTROLS AND FEATURES
CH Input: instrument level input used to amplify guitars, keyboards etc. to line level. This input turns
the microphone preamplifier into a tube direct box.
Low Cut: this switch inserts a 6 dB per octave low cut filter starting around 200 Hz and is down -12 dB
at 40 Hz. The slow slope reduces phase shift.
Microphone Pad: this switch inserts a 20 dB pad in front of the Jensen microphone transformer; it is
used to prevent overload distortion (red LED above) when the gain control cannot. it also prevents the
transformer from saturating. Overload is indicated by the red LED above the switch.
Phantom: this switch turns on the 48V phantom power to microphones requiring it. This switch should
not be turned on for dynamic microphones or other microphones that do not require it. It should not be
turned on for any microphones plugged into the 1/4” TRS inputs in the back of the unit or damage to
microphone may result. Phantom on is indicated by the yellow led above.
Phase: this switch reverses the phase of the microphone input. It can be used to match phase of differ
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ing inputs or as an effect to enhance a mixing of sources by canceling out some bass frequencies.
Gain: this control changes the gain (30 to 60 dB) of the tube preamplifier by controlling the amount of
feedback going to the tube. The gain should be set at the lowest setting that will still produce a usable
signal level. It should not be set too high or the unit will overload (red LED) and distort. If turning down
the gain does not stop overloading, use the microphone pad switch. It is OK for the overload LED to
flicker occasionally.
6990 Kingsbury Road | Templeton, CA 93465 | 805-461-4100 | http://www.demeteramps.com/
