If you're a musician, you'll appreciate the sound of a properly biased tube amp. Your wallet will appreciate the longer life you can get from your output tubes.
Our bias tools are easy to use, and provides a fast and accurate way to get the best sound from of your amp. Matched output tubes and proper bias are the ingredients to quality sound and longer tube life.
A bias probe is inserted between an output tube and the amplifier. It monitors the total current flowing through the tube. Current is read on a digital voltmeter (DVM) and may then be easily adjusted to the required settings.
TUBE
BIAS CALCULATOR (for push pull class AB1/AB2)
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
Click on photo for
larger view
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.
(Get Yours Here).
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
Click on photo for
larger view
COMPACT DIGITAL MULTIMETER. Compact, reliable, inexpensive.
Dimensions: 5-3/4" L x 2-7/8" W x 1-1/2" H
LCD backlit for low light
situations
Rubber outer case makes it shock resistant
Flip out stand for workbench testing
Continuity tone for blind testing
Right angle banana jack test leads save space
DC Voltage: 200mV/2V/20V/200V/600V
AC Voltage: 200mV/2V/20V/200V/600V
DC Current: 200uA/2mA/20mA/200mA/2A/10A
Resistance: 200/2K/20K/200K/2M/20M Ohm
3-1/2 digit, 1999 count display measures AC/DC
voltage, DC current, ohms and diode/transistor check.
Works well with our bias probes, and for general trouble-shooting. Backlit
LCD display, easy-to-read 1/2" high digits,
Includes test leads, standard 9V battery and owners manual. Part #A830L
$22.95
Compatibility
The Eurotubes™ Bias Probe™
and
the Revisit/Hoffman Bias Checker may be used with any amplifier that provides for adjustable bias and uses 8-pin
power tubes with the cathode connection on pin 8, including:
EL-34
KT-66
KT-77
KT-88
6CA7
6L6
6V6
5881
6550
Note: Some amplifiers offer adjustable bias, and some do not.
Bias adapters will properly measure the cathode current on most all amplifiers, even if they do not offer a bias settings (certain Music Man amps are an exception). You may wish to have certain fixed bias amps (such as Mesa Boogie™) modified by a technician to provide for bias adjustment. Vintage blackface Fender™ amps from
the 1960's offer true bias adjustment. Silverface Fender™s
from the Fender™ CBS era offer a bias balance control, which balances the
bias between the output tubes, but doesn't really offer full bias
adjustment.
Most Marshall™ amps with 8-pin output tubes offered adjustable bias up through
the 1990's. For other brands of amplifiers, refer to the manufacturer's literature and specifications to see if the bias is adjustable.
