TAD Bias Master BM4

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Measuring Device For Bias

Four octal socket adapters
For the control of the retirement
At 6L6GC, 6550, EL34, 6V6 GT, 5881, KT88, KT66, KT90, KT100, 7027A
With illuminated display
Made in Germany

30-Day Money-Back Guarantee

3-Year Thomann Warranty

Available since December 2003
Item number 166243
Sales Unit 1 piece(s)

2.444 kr

All prices incl. VAT

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90 Customer ratings

5 60 Customers 4 22 Customers 3 4 Customers 2 2 Customers 1 2 Customers

4.5 / 5

quality

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47 Reviews

TAD Bias Master BM4

Robert814 09.03.2014

This model comes with 4 octal probes, but I ordered 2 noval probes as well so that I can set up EL84's as well as 6V6's and 6L6's etc.
WARNING! - There are no instructions! - If you don't know what you are doing, don't try to use this unless you have a friendly tech to show you. You can download them from the TAD site, only 2 sides of A4 folded into a leaflet. Very basic instructions.
The probes each contain a 1 ohm resistor in the cathode lead, so they are measuring total cathode current (anode + screen grid). Circuit schematic diagrams usually state a bias Voltage (e.g. -37Volts) rather than current. This is a good starting point, but then you need to find the valve manufacturer's specifications from their data sheets. Then you can balance up each side of the push-pull stage.
The readout on the unit is 00.0 mA to presumably 99.9 mA.
A "Chicken head" pointer knob selects each of the 4 individual valves, or the OFF position.
It's really simple and easy to use (as another reviewer has said) and you don't have any high voltage connections to make through a test meter. The real skill is knowing just where to set the current level, which is of course different for each and every valve type and can be slightly tweaked for your preferred sound.

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It`s okay

Amateur Slash 27.05.2017

Unfortunatelly there aren?t too many options on the markt to choose from.
Would have preferred a tool that can measure the plate voltage too.
It does though what it says in it?s title therefore i?m quiet satisfied with this product.
Quality of the material has a bit of a cheap expression.
Color coding or numbering would have been preferable for the cables.

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The Probes are prone to break

Trinityman 05.07.2021

Otherwise good but I've had already 2 pair of busted probes.

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Very handy

Tore Stjerna 14.08.2014

This is a great thing to have around if you use tube amps. Gives a clear mA readout of each tube. The probes are in pairs and have white and red RCA connectors in the other end. I only wish that they had marked the probes so you would know which is which. I've done this myself of course, but I think it should have been like that out of the box.

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TAD Bias Master BM4

Measuring Device For Bias

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90 Customer ratings

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47 Reviews

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TAD Bias Master BM4

Measuring Device For Bias

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90 Customer ratings

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47 Reviews

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