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Eurotubes “Pro One” Bias Probe for EL84 power tubes

Our Products: Bias Probes and Multimeters

Price: $139.00

Watts Upgrade:
Cable Exit:

Eurotubes “Pro One” Bias Probe for EL84 power tubes

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Product Details

***Current build time is 3-5 business days***

The ET "Pro One 9” Bias Probe is an "all in one” bias probe for EL84 style power tubes (EL84, EL844, 7189, etc.). It is unique in the fact that it shows you both the plate current and plate voltage simultaneously and it is completely self-contained with no switches, knobs or batteries. Unlike other bias probes on the market the Pro One Bias Probe is designed to allow you to play the amp while the probe is installed. So adjust, play, adjust, and dial your amp in!

*The Watts feature is Back! The Watts option is an upgrade from the base Pro One model. This add-on reconfigures the Plate Voltage display so that it alternates automatically between displaying Plate Voltage and real time calculated Plate Dissipation. This along with the quick lookup chart included in the instruction sheet provides a "math-free" path to getting the bias set on your amp in a safe range.

**Cable Exit: The Pro One comes stock with a "Bottom Exit" probe head i.e. the cable connecting the probe head to the Pro One case, enters the case through it's bottom panel (as shown in the pics). This is great for most players that are using the Pro One while the amp chassis is still bolted into the cabinet (head or combo). Some techs may prefer the "Top Exit" option where the bias probe will mainly be used on a repair bench or with the amp/victim in a cradle. Please note the Top Exit option shortens the length of the probe cable by 1.5".

Application Notes

The Pro One was designed to be the ultimate reference bias tool. Each unit is hand assembled and calibrated in-house. It's powered using an extremely small amount of AC heater voltage. This eliminates the need for batteries or external power supplies of any kind.

The Pro One is built to withstand the operational voltage swings found in high voltage power tube circuits. So unlike other bias tools on the market, you can actually play your amp without removing the probe. This is great if you're experimenting with different idle bias points. (Pleas note we do not recommend leaving your Pro One hooked up to your amp indefinitely...)

The Pro One measures true Plate Current directly in the high voltage plate circuitry. This means you get the info you need with no Screen Current error.

Cathode Bias Note: The Pro One uses the cathode connection as its ground reference for the plate voltage measurement. This means the cathode voltage is already subtracted from the plate voltage and figured into the reading (saving you a step).

The video below explains the difference between bias probe types.

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