Brookshire Sound Design
If you find this documentation useful, please send Gary an email and let him know your appreciation.
Bill Halsey advises that a replacement power cord for the ST-11 may be acquired from Ken's Electronics in Kalamazoo, MI.
Your new Strobotuner is a result of many years of research and experience in building electronic tuning devices.
C. G. Conn pioneered highly accurate tuning devices many years ago with the introduction of the STROBOCONN. Wide acceptance of the Stroboconn led to the development of the light-weight Strobotuner which for years has been the standard of the industry. Modern transistors and integrated circuits have led to this advanced model Strobotuner - the most reliable and accurate machine yet produced.
The ST-11 is designed for use on 120 volt, 60 Hz. household power supplies commonly used in North America. If the tuner is to be used in Europe or other areas where different voltages and power frequencies occur, a special export model must be used as serious damage and erroneous readings will result. When traveling overseas with the ST-11 local power availability should be checked to determine compatibility with the ST-11 tuner.
Your new model is built with the most modern and efficient components available. There are no tubes to burn out, weaken, or create heat. The Strobotuner is assembled with solid-state parts. 1t is actually a digital computer that maintains its accuracy indefinitely using a small amount of electrical power. The Strobotuner is designed with nine integrated circuits assuring many continuous hours of accurate use. As a result of the sophisticated circuits the Strobotuner is accurate within one cent (1/100th of a semitone).
The Strobotuner works on an optical illusion known scientifically as the stroboscopic effect - so the name STROBOTUNER. The stroboscopic effect is responsible for the apparent backward rotation of objects such as wagon wheels seen in motion pictures when the wagon is clearly moving forward. This same effect causes the wheel to appear to slowly rotate forward or even appear motionless when the wagon is going "full speed" ahead.
Your Strobotuner operates in a similar manner only the "wheel" in the tuner is a motor driven disc like the one shown in figure "A" above.
A synchronous motor turns the disc at 12 different speeds depending on the note setting of the SELECTOR KNOB. The disc is made of plastic which light will show through. Neon lamps are placed behind the spinning disc and are the source of the orange glow when the tuner is running. The neon lights actually go off and on (too rapidly for the eye to see) at exactly the same frequency as the tone played into the microphone. When everything is exactly synchronized, (neon lights and the spinning disc) the stroboscopic effect is shown as a semicircle of motionless lines around the disc. If the tone is sharp the lines will appear to revolve to the right or clockwise. If the tone is flat the lines in the disc will appear to rotate to the left or counter-clockwise. If in tune the lines will appear to stand perfectly still.
The stroboscopic effect has remained over the pears the most convenient and accurate method for visually displaying musical intonation.
Operating your Strobotuner is simple. And to get the most accuracy and best operation from the machine, a little time should be invested in becoming familiar with it. Developing the habit of following the sequence of instructions below will insure the proper operation and calibration.
Look at figure "B" above and become familiar with the names of the controls. The storage compartment contains the microphone, microphone stand, microphone cord, plug, and power cord. Notice how alt of these parts fit neatly into the compartment. They must go back into this small area in the same way as they were packed at the factory. Pull the storage compartment door open and take out the cords and microphone.
Connect the power cord to the plug-in on the back side of the tuner. Connect the other end of the power cord to a source of electrical power suitable for your model tuner.
Insert the microphone plug into the receptacle on the front of the tuner. If you wish to use the microphone stand, merely insert the microphone into the flexible holding clips on the top of the stand similar to figure B.
It is important to calibrate the Strobotuner before each use. Turn the FUNCTION KNOB to the CAL position as in figure C. Doing this turns the tuner on and sets the machine for calibration. Be certain that the pilot light is on. If it is not, check the power cord connections and the source of electricity.
The disc seen through the indicator window should be rotating. Do not be concerned if the disc starts spinning slowly at first - this is perfectly normal.
Since the tuner has all solid-state circuits, no lengthy warm up is necessary. Sixty seconds after FUNCTION KNOB is turned on, the machine is fully stabilized, and the calibration procedure can proceed. Study the indicator window in figure D below.
Notice to the left of center on the window that the various bands where tuning will be indicated are numbered 1,2,3,4,5,6,7and 8. When calibrating with the function knob pointing to CAL a semi-circle band of lines should appear in the band labeled number 2. If the tuner is in perfect calibration, the lines should appear motionless.* If the lines are rotating to the right (clockwise), turn the CENTS KNOB figure E also to the right, (clockwise) until the lines stop rotating. If lines are rotating to LEFT turn CENTS KNOS also to left (counterclockwise). In turning the CENTS KNOB right or left, the reference pointer connected to it may not be pointing to zero as in figure F.
*Note: Due to the great sensitivity of the Strobotuner the word "motionless" suggests that the lines should appear as stationary as possible - a very slight movement is normal.
To realign the pointer to zero without disturbing the calibration simply hold the knob perfectly still with two fingers and with one finger of the other hand move the pointer adjustment lug until pointer is straight up and aligned with zero. If the knob itself has not been moved, the line pattern appearing in the window will still be motionless and you are now ready to operate the machine for tuning.
Make it a habit to always calibrate the Strobotuner first before tuning.
Refer to the bands where the note will be seen on the tuner window. All twelve semitones of octave C4 through 84 will be found in the number 4 band of the tuner. All semi-tones of C5 through B5 will be found on the number 5 band of the tuner. Now look at the SELECTOR KNOB figure H.
The knob itself has all twelve semi-tones marked on it, while around the outside of the knob are index lines. We will be concerned with the "C" index now - the others are explained later.
Set the selector knob to the note and index C as in figure H. For example, the note we wish to tune is C on the piano; and since the piano is in the key of C we use the "C" index. Any C on the piano keyboard will be indicated with this setting. C1 will appear in the first band (number 1). C2will appear in band 2, and C3in band 3, etc.
What about another note such as E? Turn the SELECTOR KNOB setting so that E aligns with the C index (Figure I. All octaves of E will now show on the tuner. A little practice in finding notes of the piano on the tuner will help in familiarizing you with the Strobotuner so that it can be quickly and accurately used.
Produce a concert C from any source such as a musical instrument or tuning fork. Direct this tone toward the microphone turning the GAIN CONTROL clockwise so that the disc lights up steadily when tone is produced. The amount that the GAIN CONTROL KNOB must be turned to produce a steady light depends upon how loud the tone is. If the tone is distant or very faint the knob will have to be turned to a higher number, In any case turn the GAIN CONTROL knob just enough to produce a steady, clear pattern.
The actual intonation of any note will be shown as a band of lines in an appropriate band in the window. Correct intonation is shown when the band of lines stands motionless.
When tuning a B5 trumpet for example, the Bb index is used to set the SELECTOR KNOB. Figure J shows the SELECTOR KNOB setting for the trumpet (and other Bb instruments) when tuning the written note C. This setting will show all octaves of the written note C produced by the trumpet.
Figure K shows the selector knob setting when tuning the written note C for alto and baritone saxophone (and other Eb instruments).
Figure L shows the selector knob setting when tuning the written note C for French horn in F (and other F instruments).
Obviously if some other note than C is to be tuned the selector knob must be turned to the proper note AND index for that instrument.
Remember, when using the + 2 setting... notes normally read in band 7 will appear in band 5 - two bands lower. The notes normally read in band 8 will appear two bands lower in band 6, etc.
Special + 2 guide numbers are provided on the Strobotuner window to the right of center. You can see that these numbers indicate which octave is ACTUALLY being shown when using the + 2. Your experimenting with notes comparing patterns with and without + 2 will quickly give insight into this important feature.
Of interest to the hobbyist, pipe organ tuner, and recording equipment enthusiast is that the + 2 feature will allow the Strobotuner to accurately indicate frequencies up to 31,600 cycles - beyond the range of normal human hearing! This is accomplished by setting the function knob on + 2 and reading bands 7 and 8.
lf you wish to study the technique of tuning pianos with the Strobotuner we suggest that you obtain the specially prepared manual, "Notes on the Use of the Strobotuner in Piano Tuning". Ordering information will be found on page 17.
The following procedure is intended to familiarize the experienced piano technician with the Strobotuner. It is not a course in piano tuning as there are many complexities to tuning which are beyond the scope of this manual.
If the piano is to he tuned to A-440 use the calibration procedure given on page 6.
If the piano is to be tuned to a standard such as a tuning fork simply:
Your Strobotuner is now calibrated to the frequency of the sound source and tuning may proceed.
As an example, assume the octave C4 to B4 is our temperament octave using A-440 standard. Assume also that the Strobotuner is calibrated and ready to use. Tune chromatically upward starting with C4. Watch only band 4 which will indicate all of the 12 notes in this octave. As you proceed from C4 to C#4, you must turn the SELECTOR switch to C# using the C index. Obviously the switch must be appropriately set each time a new note is to be tuned. Since C4 to B4 is your temperament octave you should adjust the string tension so that each one of these notes "stops" the pattern in band 4 only. IF YOU SEE PATTERNS IN BANDS 5, 6, 7, or 8 IGNORE THEM FOR NOW UNTIL THE TEMPERAMENT OCTAVE IS TUNED.
Go back and recheck each note of the temperament octave until you are satisfied that one string of all 12 notes in this octave "stops" the pattern in number 4 band on Strobotuner window.
For example, one string - say C4 - is sounded. This string produces other notes such as C5, C6, C7, in addition to C4. Admittedly, C4 is by far the most prominent to the ear. But the human ear - particularly a sensitive musician's ear - will hear C5, C6, and C7 also.
The job of the meticulous piano tuner would be greatly simplified if when sounding C4, the lesser tones (C5, C6, and C7) were exactly twice, four times, and eight times the tone of C4. This is not the case in the piano tone. As the Strobotuner will show, the higher C's are SHARP when C4 is sounded. It is this physical trait of the piano string (inharmonicity) that makes it necessary to "stretch" octaves to make them pleasing to hear.
You will find that the degree of inharmonicity varies greatly between octaves. In any case the Strobotuner will show when inharmonicity is present - and how much is present.
Merely strike C4 and adjust the CENTS knob clockwise until the number 5 pattern stands still. Then mute out all but one string of C5, strike it, and adjust the tuning pin for that string until the number 5 pattern stands still. Tune all of the octave C5 - B5 notes by striking the C4 - B4 notes an octave below, resetting the tuner CENTS knob and pointer each time. Then strike the C5 - B5 notes with the same respective setting, adjusting tuning pins to stop the patterns in band 5,
Continue your tuning procedure upward throughout the C6 - B6 and C7 - B7 octaves. Use the same technique of striking the note an octave below that which you are tuning. Simply look at the band of lines an octave above the struck note to set the tuner. Then adjust string tension of the note you wish to tune from this setting obtained from the lower note. As your speed increases you will probably omit resetting the Strobotuner CENTS knob pointer and simply read direct.
Earlier model Strobotuners had an absolute high range of B7. However, your solid state model has a number 8 band making a practical C8 to B8 range. This extra band allows C8 to be tuned directly. And the + 2 feature allows you to see the C8 and C7 - B7 pattern more clearly.
This operation of the + 2 feature is explained in detail on page 9 of this manual.
Make sure that the CENTS knob and pointer are returned to zero setting used for the tuning standard and the function knob is on NORMAL. Tune the B3 string until the number 4 band pattern is motionless. This procedure will compensate for any inharmonicity in the B3 string and will make the B3 - B4 octave a pleasant sounding interval. Proceed downward through A#3, A3, G#3, etc., using the number four band pattern to tune to.
Most people who tune organs prefer to tune all octaves of the same note, i.e., tune all octaves of C then reset tuner to C#, D, etc. This procedure saves switching the tuner back and forth from one note to the next frequently. In contrast to piano tuning, the organ tuner does not need to be concerned with inharmonicity and the process of "stretching" octaves can be ignored.
As the image clarity of the above 2 graphics leaves much to be desired, hi-resolution graphics will be provided upon request. Simply send me an email request and I'll send you the hi-res graphics as an email attachment.
Back to Conn Strobotuner Models