Audio Technologies SUM100
Summing Amp Stereo w/o PwrSply


The SUM100 Summing Amplifier is an inexpensive, high performance amplifier that is designed as a line level stereo to mono summing amplifier. It is also useful as a gain block, and as an impedance converter and summing for IHF (RCA type) signals.

The inputs provide balanced 40Kohm bridging impedance for line levels up to +24dBm. The high input impedance allows the SUM100 inputs to also bridge - 10dBu (hi-fi, RCA plug) lines without loading.

Front panel, screwdriver adjust, full range gain controls provide 26dB gain at full clockwise rotation, unity gain at twelve o’clock and a smooth audio taper to full off. The output driver is a servo controlled, ground-sensing circuit, which will supply over +22dBm to 600 ohm balanced loads and +20dBu to high impedance, unbalanced loads. The SUM100 uses rugged XLR type input and output connectors.

Loop-through DC connectors allow several NANOAMPS to share a single external 24VDC power supply. Battery packs and DC-DC converters for portable use are also available.

Up to three amplifiers will mount side-by-side in only one rack unit using the available rack mounting kits. NANOAMPS may also be neatly stacked or mounted side by- side on your desk with the available angled desk mounting kits.


  • Gain: 28dB maximum, 0dB at 12 o’clock pot position
  • Nominal Levels: +4dBu in, +4dBm out to 600 ohm balanced load
  • Peak Levels: +24dBu in, +22 dBm out to 600 ohm balanced load
  • Noise 20kHz B.W.: -90dBm maximum output
  • Harmonic Dist.: .02% Max at Peak Level
  • 20Hz to 20 kHz .005% max at Nominal Level
  • Frequency Resp.: +.25dB, 20 to 20,000Hz
  • Crosstalk: 70dB minimum at 10kHz
  • Input Impedance: Balanced, 40kohm bridging
  • Output Impedance: Balanced, 40 ohms maximum Zs
  • Dimensions: 1.5"H by 5.5"W by 5.75"D; Weight: 1.5 Lb. Net
  • Connectors: XLR (balanced input/outputs)
  • Power: 24VDC @ .07A, connector sleeve is positive
  • Power Supplies: All units require 24VDC power supply, which is ordered separately.
  • Nanoamps can share a single supply-using loop thru DC cable (P/N 20602-1).
  • Do not exceed rated supply current
  • WA100-1: Wall mount power supply (UL), 24VDC @ .4 amp, 115 VAC/60 Hz
  • WA100-2: Tabletop power supply, 24VDC @ .4 amp, 230 VAC/50-60 Hz with IEC 320
  • male 3 pin AC input connector. User supplies matching AC line cord for local
  • power system
  • BBU100-1: Battery Pack unit houses four 9V alkaline batteries (batteries not included).
  • Four-to-six-hour life
  • DC100-1: DC to DC converter powers several units from 12VDC mobile and belt pack
  • batteries. Supplies 24VDC @ .2amp maximum
  • 20602-1: DC power cable assembly for looping the DC power between NanoAmps
  • DESK MOUNT KITS: 20617-501 Angled Desk Mount Base
  • 20617-502 Angled Desk Mount Base and One Stacker (2 units high)
  • 20617-503 Angled Desk Mount Base and Two Stackers (3 units high)
  • 20617-504 Stacker (2 units high)
  • 20617-505 Horizontal joiners for 2 units (side by side)
  • 21075-501: Rack mount system mounts three units in one rack

WARNING: Cancer and Reproductive Harm -

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