Bias Testing Devices

Eurotubes™ Bias Probe
For 8-pin power tubes such as 6L6, 5881, 6550, 6V6, EL34, etc.   Requires separate digital volt-ohmmeter capable of reading current.   This device reads cathode current, but not plate voltage. 

Not a kit - this device is fully assembled and ready to use!

Complete with detailed instructions.   Used with a basic multimeter (Get Yours Here).  Note: this adapter, as designed, will NOT test 7591 tubes.  
Part #EBP-1

$34.99



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Revisit™ Bias Checker Kit by Hoffman Amps The Revisit Bias Checker Kit by Hoffman Amps is the best of both worlds when it comes to ease of assembly and cost effectiveness. This kit is easy to build, and comes with assembly instructions in the link below. 

Kit builds one bias probe to be used with a multimeter.

Materials list for each Bias Current Checker:
  • 1 - 8 pin tube base with hole and sticker
  • 1 - 8 pin PC board tube socket
  • 1 - Dual banana plug
  • 1 - Bias checker PCB
  • 1 - Bias checker Ring
  • 1 foot of 18 gauge zip cord
  • 2 feet of buss wire

Download assembly manual here.   Requires assembly.  Soldering capability and tools required.

KIT ASSEMBLY DIFFICULTY:

For 8-pin power tubes such as 6L6, 5881, 6550, 6V6, EL34, etc.   Requires separate digital volt-ohmmeter capable of reading current.   This device reads cathode current, but not plate voltage.   Used with a basic multimeter (Get Yours Here).  Note: this adapter, as designed, will NOT test 7591 tubes.  

Part #HABK-100

$24.95



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KIT, TUBEDEPOT BIAS SCOUT
The average bias job costs $40 - $60. Build your own bias adapter with our TubeDepot Bias Scout
kit and you'll save money every time you set the bias on your amp. This kit includes all the parts to build a single octal socket TubeDepot Bias Scout. Used with a basic multimeter (Get Yours Here), the finished adapter will allow you to measure both cathode current and plate voltage of a single tube position. We recommend purchasing two of these kits so you can easily monitor both halves of a push-pull circuit.  For 8-pin power tubes such as 6L6, 5881, 6550, 6V6, EL34, etc.  Note: this adapter, as designed, will NOT test 7591 tubes.  

KIT ASSEMBLY DIFFICULTY:

Requires assembly.  Soldering capability and tools required.   Download assembly manual here 

Part #BIAS-SCOUT

$29.95


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COMPACT DIGITAL MULTIMETER.  Compact meter features a wide range of measurement capabilities, and is ergonomically designed to easily fit in the palm of your hand. 3-1/2 digit, 1999 count display measures AC/DC voltage, DC current, ohms and diode check.   Works well with our bias probes, and for general trouble-shooting.  Backlit LCD display, easy-to-read 1/2" high digits, square wave output, continuity buzzer, protective holster, meets 600V CATI standards.
Includes test leads, standard 9V battery and owners manual.  5-3/8"(H) x 3" (W) x 1-3/8" (D).
Part #CDM-72-7770
$20.95


  
TUBE BIAS CALCULATOR (for push pull class AB1/AB2)

Tube Type

Plate Voltage

Power W

Plate Current mA
+/-10%
Cathode Current mA
+/- 10%
- - -