PreAmp

Category: Product Published: Tuesday, 26 June 2018 Written by Richard Hoogeveen

The latest version of the HMR-audio preamp. This preamp is based on the PGA2310 digital volume control chip of Texas Instrument. A few of these preamps are already sold to audio enthusiasts.

This design is way different then the cheap sets on the Chinese market, so read on !

This latest models have been an integration of ideas of Jan Mulder and me. The inputs are buffered with Burr-Brown opamps to get rid of the possible DC offset. The outputs are also opamps of Burr-Brown to prevent load distortion of the PGA2310 outputs. Measurements on the pre-amp have proved that the complete distortion is very low. The discrete low noise power supply for the analog part is based on the LM337/LM317 and a separate power supply for the digital part. I use good quality parts like for example Wima MKT capacitors in the audio line.

The control is based upon an Arduino that takes care of setting the inputs, digital volume control signals PGA2310, remembering the volume levels, infrared remote, lcd,  rotary encoder knob/switch and startup shutdown sequence.

 

New HMR-Audio pre-amps will probably come with the distinctive thick 6082 aluminum frontplates. Other case and display designs on request.

 

Specification

220VAC /4 Watt

4 x RCA Stereo inputs

1 fixed RCA output

1 volume controlled RCA output

softstart switch, all start with -30dB or latest saved volume level

31.5dB to -95.5dB in steps of 0.5dB noisefree

low noise and distortion, around 120dB dynamic range, 0.0004% THD+N at 1 kHz

Interchannel crosstalk -126 dBFS

On/Off button takes care of clean shutdown and startup

2 x 16 LCD

Manual turn and push knob for volume control and input choice

RC-5 remote control capable, address 16, On/Off , Volume +/-, Mute, ch1, ch2, ch3, ch4 (optional HMR-audio remote)

+/- 3 kg

230x280x82mm

 

Optional HMR-audio RC-5 remote (handcrafted full aluminum 300gr)

 

 

 

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