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The MaxiPreamp II - the new standard of tube measurement. The MaxiPreamp II Digital Tube Tester is a compact, precision measurement station for the test bench or sales counter. It's designed to test dual triodes and other signal tubes for the electrical characteristics of gain (A), transconductance (Gm) and noise (dBm). Any of the standard dual triodes common in today's audio amplifiers such as 12AX7, 12AU7 and 7025 can be tested. With optional adapters the MaxiPreamp will also measure 6DJ8, 6N1P, 6H30 and octal type dual triodes such as 6SL7 and 6SN7.

The MaxiPreamp II is, like its predecessor, a new approach to signal tube measurement - the most comprehensive test station yet in its capabilities. The Pre II utilizes two proprietary high-performance current sources, an independent circuit for each section of a tube under test, to create the most accurate results possible for todays demanding listeners. Measurements are captured by a precision scanning A/D converter reducing crosstalk to a minimum.

The instrument has separate controls for Measurement Function, Gain Type, Socket Select, Audio Output Level and Section Listen. The Function control selects the type of test, while the Gain type calibrates the MaxiPre for high, medium and low Mu types. The Output Level controls the listening volume at the dual RCA jacks, and the Section Listen switch allows you to audition each amp in a dual triode individually. The Noise Test is calibrated in absolute dBm and is a full-spectrum True RMS measurement.

The MaxiPreamp II mounts up to four tubes at once, and measures one tube while simultaneously heating and stabilizing three more. Leapfrogging from the classic MaxiPreamp, the new design incorporates a number of upgrades including increased filament power, transconductance range, improved noise testing and a snazzy new carry-case with a clean new look.

he MaxiPreamp II is used by the electronics tech, audiophile or music store salesperson to quickly test a tube for character and function. Each of the four test sockets has two bi-color LEDs displaying operational status for the tubes currently under test - you get eight individual testers in one package! All tests are continuously sampled, averaged and then updated every 250 milliseconds for the most accurate measurement. Test results for both halves of a dual triode are displayed simultaneously on the backlit LCD.


  • Measure preamp tubes for Gain, Transconductance and Noise
  • Test any common dual or single preamp triode
  • Listen to your tubes with dual-RCA Direct Audio Output
  • Scanning Digital Sampling Converter for highest accuracy
  • Continuously updated every 250 milliseconds
  • Displays two results on LCD simultaneously
  • Eight bi-color operational LEDs - one for each tube section
  • Proprietary dual matched current-source drive circuits
  • New elegant carry-case increases portability
  • A sophisticated new approach to signal tube testing

Only $989.00 Update 15 Jan 2017: The MaxiPreamp II is in stock.

AC Mains Voltage Selection

MaxiPreamp specifications
Directly testable tube types 12AX7, 12AU7, 12AT7, 12AY7, 12DW7, 12BH7, ECC81, ECC82, ECC83, 7025, 5751, 5814,
and all other tubes with 9A base
Optional types:
9AJ adaptor 6DJ8, 6922, 6N1P, ECC88, 6AQ8, 6BQ7
6BZ7, 6GM8, 6CG7, 6FQ7, ECC85, ECC86
9LS adaptor
9DD adaptor
9H adaptor
6CW7, ECC84
Transconductance (Gm, mA/Volt)
   Range 0 - 9900 µmhos (Siemens)
Gain (Mu, µ)
   Gain Range 0 - 120
Noise (0 dBm = 775mVrms)
   Noise meas. -92 dBm < -48 dBm
Gain Types
(dual triodes)
High Mu 1 mA Icathode
Medium Mu 2 mA Icathode
Low Mu 4 mA Icathode
Gain specification chart
High Mu 1 mA -1 VDC 200 VDC 1k Ω 100k Ω 1k Ω
Med Mu 2 mA -3 VDC 200 VDC 1.5k Ω 100k Ω 1.5k Ω
Low Mu 4 mA -4 VDC 200 VDC 1k Ω 100k Ω 1k Ω
Filament voltage 6.3 VDC regulated
Filament current 1.5 A DC Maximum
Plate Voltage 200 VDC regulated
AC input mains 120 (240 Euro) VAC / 50 Watts
Dimensions 12.5" (317 mm) x 8.5" (215 mm)
Shipping Weight 9.3 lbs. (4.2kg)
Read the manual PDF
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• Stabilize tubes before matching for more accurate results
• Improve reliability by eliminating
early failures
• Visual indicator on each tube to sort out failed tubes
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• Instantly identify weak or damaged
power tubes
• Accurately measure a tubes
amplification quality
• Precision-match tubes for plate current and transconductance
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• Measure preamp tubes for Gain, Transconductance and Noise
• Test any common dual or single
preamp triode
• Audition tubes with dual-RCA Direct Audio Output
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• Adapt non-standard pinouts to
the testers
• Adaptors available for power tubes and for preamp tubes
• SocketSavers for preserving your investment
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