Transcendent Sound

Making Music Better

 

Tube Analyzer

Measures both Transconductance and Amplification Factor at any operating Point from 0 to 300 volts up to 150 mA. Determines dynamic plate resistance.


Why is this important?

The electrical characteristics of vacuum tubes are defined by three tube "parameters" called transconductance, amplification factor, and dynamic plate resistance.  If any two are known, the third can be easily calculated.  These parameters specify how a tube will behave in a circuit.  All design equations require accurate tube parameters in order to be valid.


So why not just look them up in a tube manual?

This is a huge misconception in tube audio.  The values given in the manuals are valid for only one set of operating conditions.  Furthermore, these published operating points are always at very high current levels that are almost never used in actual circuits.  They are shown because the tubes characteristics are better at these currents.   By changing the operating point, tube parameters can easily vary by a factor of 3 to 1, rendering calculations based on published parameters useless.

 

What's an operating point?

The operating point is defined as the voltage applied to the plate and the current through the tube.  It is determined by the circuit designer to yield the optimum performance for any specific circuit.  By altering the operating point, a tubes electrical characteristics can be changed (within certain limits) to best suit any particular application.  If the desired characteristics are not obtainable, then a different tube must be selected.  Tubes are almost never operated at the impractical high current conditions shown in the tube manuals.  These are generic conditions that have no relationship to any particular circuit.


Why is the Transcendent Tube Analyzer better than a curve tracer or tube tester?

Curve tracers do not reveal the specific tube parameters.  They just show areas of operation and relative linearity.  No data is readily made available that can be used with the design equations.  Tube testers only show transconductance at one specific operating point and odds are, it's not at the conditions required for your particular circuit.  With only one parameter known, it is impossible to determine the other two.  Only by testing a tube at the conditions that it will be operated, can its true characteristics be known. 

So the information in the tube manuals is valid but in all probability not applicable to my specific circuit and my tube tester and curve tracer can't provide this information?

Yes, that is correct!


O.K., so what exactly does the Transcendent Tube Analyzer do?

The Transcendent Tube Analyzer provides the tube parameters needed for your exact application.  A tube's operating characteristics can be accurately determined for your specific circuit or equipment.  The heart of the Analyzer is a sophisticated adjustable power supply utilizing a tube-based differential amplifier.  It can be set from 300 volts all the way down to 0 volts.  Voltage adjustment is made through a 10 turn potentiometer for very precise settings.  Many tubes can be operated with as little as 25 volts on the plate and the Tube Analyzer allows for the determination of these parameters at these and other voltage levels.  The ability to set the operating point virtually anywhere allows circuit designer or hobbyist to be able to understand exactly how the tube is operating and take advantage of this knowledge in the design or operation of a circuit. 


Change the way a circuit sounds.

You can fine tune the way a circuit sounds by adjusting a tubes operating point.  The heavier the plate currents, the warmer and more rounded tubes sound.  As plate currents are reduced, tubes sound more accurate with less coloration.  Granted, knowledge of circuit design is required to change circuit operating points, but it can be done.   The possibilities are almost limitless.

 

Features.

Please note:  The following is a detailed listing of what the Analyzer can do.  Any tests that are not listed cannot be be performed.      

The plate current available is as follows:
0 to 200 volts- 150 mA
250 volts- 100 mA
300 volts- 50 mA


For accurate plate current settings, bias voltage settings are made in 4 ranges:
0 to 3 volts
0 to 10 volts
0 to 30 volts
0 to 100 volts


The Transcendent Tube Analyzer will analyze any tube with a pin out that matches one of the following groupings and has filaments rated for 6.3 volts up to 3 amps and the 5 volt 300B and 2.5 volt 2A3.  Tubes with 12.6 volt filaments that can be connected for 6.3 volts can also be tested. It does not test tubes with 10 volt filaments.  Analysis must be conducted within the voltage and current limitation of the unit.  Tubes that are operated at higher voltages can still be tested but at these lower ratings.  The results are still valid.  Conventional tube testers do not display plate voltage settings.

   

Type A- directly heated triodes:  300B, 2A3
Type B- octal dual triodes: 6AS7G, 6080, 6SL7, 6SN7
Type C- octal pentodes: 6CA7/EL34, 6K6, 6L6GC, 6V6, 6550, 7027, 7581, 8417, KT66, KT88
Type D- sweep tubes: EL509/6KG6
Type E- 9 pin low mu triodes: 6C19PI
Type F- 9 pin dual triodes, 12.6 volt: 12AT7/ECC81, 12AU7/ECC82, 12AX7/ECC83, 12AY7, 12AZ7, 12BH7, 12DW7/ECC832, ECC99, 5751, 5814, 5963, 5965, 6189, 6201, 6681, 7025
Type G- 9 pin dual triodes, 6.3 volt:  6AQ8/ECC85, 6BQ7, 6DJ8/ECC88, 6922, 6GC7, 6H30PI, 6N1P
Type H- 9 pin pentodes: 6BQ5/EL84, 6CW5/EL86, 7189


Test Pentodes as Triodes!

Pentodes make excellent low cost triodes.  Tube parameters for triode connected pentodes are largely unpublished and unavailable.  With the flip of a switch, the Transcendent Tube Analyzer converts the Type C, D, and H pentodes to full triode mode for complete analysis.  This feature opens up an entire realm  of applications that previously were hidden from view.


Dual Triode Matching!

With a flip of a switch, each triode half in a dual triode can be instantly compared for all parameters.  This allows for precise matching in critical applications. 

Determines Dynamic Plate Resistance, Transconductance and Amplification Factor!

All design equations use either transconductance and plate resistance or amplification factor and plate resistance.  In either case, plate resistance is needed.  By measuring both amplification factor and transconductance, the plate resistance is then determined by dividing amplification factor by the transconductance.  Tube testers do not provide this vital information.


Manually Plot Characteristic Curves

By setting the bias voltage at any desired level and sweeping the voltage from 0 up to 300 volts, plate current measurements can be read off of the internal meter.  Plot the data on a sheet of graph paper and a characteristic curve can be drawn.  Set the bias voltage voltage to another level and repeat the process to draw another curve.  By taking readings at small intervals, very detailed curves can be generated. 

  

How are measurements made?

Measurements are displayed on a 3 1/2 digit, digital readout.  Plate current (mA), and transconductance (mA/V) are made in ranges of 20 and 200.  Amplification factor measurements are made in ranges of 20, 200 and 2000.   Plate voltage is displayed in one range of 300V.  Bias volts are displayed in ranges of negative 3, 10, 30, and 100 volts.

Another misconception in tube audio is that transconductance can be measured by slightly changing the bias voltage and measuring the corresponding change in DC plate current.  This will result in invalid measurements.  Transconductance and amplification factor are AC parameters.  The Transcendent Tube Analyzer provides for true AC testing to determine these parameters.


A precision sine wave is injected into the grid of the tube under test.  For transconductance, the instrument measures only the resultant AC current that flows through the tube.  It ignores any changes in DC current.  For amplification factor, the instrument measures the resultant AC voltage produced at the plate.  For maximum accuracy, all AC measurements are processed through a "True RMS" conversion circuit.  To further enhance accuracy, the True RMS circuit rejects most hum and noise that could alter the reading.   Amplification factor measurements are limited to 100 mA of plate current.


What About Calibration?  Is Special Test Equipment Required?

The Transcendent Tube analyzer has been designed to use its own internal circuitry for calibration.  Kits can therefore be assembled with all of the accuracy of a factory assembled unit.  No special test equipment is required.

 

Works Anywhere In the World!

The universal power supply in the unit works on 50/60 Hz from 100 to 120 volts and 200 to 240 volts.  That's the whole planet.  Power cords are detachable for county matching.





Better Than a Curve Tracer

Better Than a Tube Tester

Test Most Audio Tubes

FULL KIT:  $699