Harrison Instruments
Model 151 Theremin User Manual
(Online Version for Instruments with Right-Side Pitch)


Table of Contents

1. Safety Notices <back to contents>

Read all the instructions in this manual prior to using this product. Retain these operating instructions for future reference.

	When this product is connected to an external device such as an amplifier, a shock hazard may be present. To avoid electric shock, do not operate this product in the rain or near water. Do not allow this product to become wet. Do not replace or supplement this product's battery with an external power supply.
	Do not place cables connected to this product in areas where they can cause a trip hazard.
	Do not play this instrument at a high volume, especially when using headphones. Hearing experts advise against the continuous, extended use of headphones.
	Do not disassemble this instrument. There are no user serviceable parts inside. Refer servicing to qualified service personnel.

2. Unpacking and Inspection <back to contents>

The following items are contained in the carton:

1. One Model 151 Theremin
2. Two plastic envelopes with one plate antenna in each (interchangeable)
3. One plastic bag containing four hexagonal nuts for antenna attachment
4. One Duracell 9V alkaline battery
5. One Warranty Registration Card
6. One Model 151 Theremin User Manual

Please retain the carton and all packing materials in the event the instrument has to be returned to Harrison Instruments for service.

Carefully remove the plastic wrapping from all items and inspect them for damage.

If damage is apparent:

• Notify the freight carrier immediately to make a damage claim.
• Notify Harrison Instruments to report the damage and to obtain a Return Materials Authorization (RMA) number.
  IMPORTANT: Harrison Instruments must provide an RMA number for all returns.
• Carefully pack the items to be returned, providing at least an inch of padding around all surfaces. Use the original carton, if it is still intact, or an equivalent. Seal the carton on all edges with packing tape and include the RMA number on the shipping label. Send the merchandise POSTAGE PREPAID and INSURED for its purchase value to the following address:

HARRISON INSTRUMENTS
RMA _____
PO BOX 9012
SILVER SPRING MD 20916

3. Additional Materials Required <back to contents>

The following items not supplied with the theremin are recommended for basic use:

• One adjustable-height microphone stand with a standard 5/8"-27 male thread for attachment to the theremin's 5/8"-27 female threaded receptacle. Use a stand suited to support the weight of the theremin without tipping.
  Example: On-Stage Stands® model number MS9700B.
• One 15-foot shielded audio instrument cable with 1/4" mono phone plugs at each end for connecting the theremin to the amplifier/speaker system or audio mixing console.
  Example: Whirlwind® model number SN15. This item is also commonly called a "guitar cable."
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  NOTE: The 151 is equipped with a standard mono "unbalanced" output capable of delivering an maximum output level of about +2.7dBu, which is compatible with most standard amplifier/speaker combination units. If you intend to use your 151 with an amplifier or mixing console that has a "balanced" (XLR or TRS 1/4") microphone input, then a small transformer, such as Shure® model number A85F, along with an appropriate XLR cable, such as Whirlwind® model number MC20, should be used.
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• One amplifier/speaker.
  
  Examples:
  
  The 5 Watt VOX® model DA-5. A compact, battery powered amplifier/speaker appropriate for small venues, especially useful where mains power is unavailable. It is conveniently equipped with a variety of effects processes such as reverberation and echo.
  
  The 20 Watt Peavey® model KB(R) 1. A small amplifier/speaker appropriate for practice and for small to medium-size venues where the overall volume requirement is modest.
  
  The 300 Watt JBL® EON-15 G2. A large amplifier/speaker for major venues where the overall volume requirement is high and direct, personal monitoring is imperative. When stand-mounted behind the head, this unit, set to low volume levels, is also ideal for practice. In particular, the inclusion of good bass response permits practice in the low-pitch registers.
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  NOTE: If there is a retailer available in your area, it is suggested that you try various models of amplifier/speakers before making a purchase. Many retailers will schedule an appointment for "fitting" an amplifier/speaker to your theremin. Select an amplifier/speaker that suits your performance and practice intentions.
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4. Introduction to the Theremin <back to contents>

The theremin is named for its Russian inventor, Lev Sergeivitch Termen who developed the instrument in the early 1920s. It is one of the first electronic musical instruments, and has the distinction of being played by moving the hands within its proximity, without contact.

Theremins have two physical extensions called antennas. One of the antennas is used to control the pitch of the instrument's sound, and is referred to as the pitch antenna. The other is used to control the volume of the sound, and is referred to as the volume antenna. The pitch and volume produced by the theremin vary according to the capacitance between the hands and their respective antennas. The value of capacitance, in turn, is affected by the distance between each hand and its antenna.

The pitch-generating section of many theremins, including the Harrison Instruments Model 151, utilizes a principle called heterodyning, in which the signal from two inaudible, high-frequency oscillators are subtracted electronically to produce an audible difference frequency. One of the two high frequency oscillators provides a steady frequency, while the other oscillator's frequency is varied according to the change in capacitance between the hand and the pitch antenna. The volume-control section also uses changes in hand capacitance to alter the energy in a resonant circuit that, in turn, controls the loudness of the tone.

Many early designs of the theremin featured a vertical rod for the pitch antenna and a horizontal loop for the volume antenna. The 151 features two identical horizontal plates, one each for pitch and volume. The 151 also differs from traditional theremin designs in that the loudness of the tone increases as the hand is brought closer to the volume antenna, instead of becoming softer.

5. Model 151 Controls and Output Jack <back to contents>

The figure below identifies the front-panel features of the Model 151 Theremin. To provide visibility, the labels for the controls are located on the top of the instrument. The OUTPUT JACK is located on the rear panel.

The following table describes the function of each feature.

Feature	Function
VOLUME ZERO	Adjusts the response of the theremin's volume so that the tone is softest with the hand furthest away from the volume antenna and loudest when the hand is just above the volume antenna.
OUTPUT LEVEL	Adjusts the theremin's maximum output volume.
POWER LED	Indicates when the instrument is on, and flashes rapidly when the battery is weak.
POWER SWITCH	Turns the theremin on or off.
TONE	Adjusts the output tone characteristic from a low-harmonic, sine-like wave (fully counterclockwise position) to a harmonically-rich wave (fully clockwise position).
PITCH ZERO	Adjusts the response of the theremin's pitch so that the tone frequency is lowest with the hand furthest away from the pitch antenna, and highest when the hand is just above the pitch antenna.

6. Battery Installation <back to contents>

The figure below is a top view of the Model 151 Theremin. The 9V battery, such as Duracell® type MN1604, is shown in the battery compartment with the cover removed. Note that the battery is installed with its terminals to the right and with its NEGATIVE terminal on top. The battery connector is snapped onto the battery with its wires also toward the top cover. The battery compartment cover is secured with two small slotted screws that may be removed with a standard, small-blade pocket screwdriver. To prevent damage to the instrument from possible leakage or corrosion, do not leave the battery in the theremin for extended periods of non-use. To prevent accidental battery consumption during shipment, the 151 Theremin is shipped with the battery uninstalled.

7. Setting Up the Model 151 Theremin <back to contents>

1. Loosen the BASE LOCKING KNOB on the microphone stand and slide the legs to the bottom of the OUTER TUBE. Tighten the
   BASE LOCKING KNOB.
2. Fully extend the microphone stand LEGS and place the stand on a stable, level surface.
3. If the stand has a LOCKING NUT, turn it completely clockwise so that the COUPLING THREADS are exposed above it.
4. While grasping the INNER TUBE to preventing it from falling into the OUTER TUBE, loosen the stand's height
   ADJUSTMENT COLLAR by turning it counterclockwise. The stand's INNER TUBE is now free to slide up and down.
5. Continue to grasp the INNER TUBE with one hand while lowering the THEREMIN onto the top of the stand with your free hand.
6. Engage the theremin's threaded ADAPTER with the stand's COUPLING THREADS.
7. With the theremin perpendicular (90°) to the stand, slowly rotate the stand's INNER TUBE counterclockwise until it mates with the theremin's ADAPTER. Rotate the stand's INNER TUBE, and not the theremin, until it is tightly engaged with the ADAPTER.
8. If the stand has a LOCKING NUT, tighten it by turning it clockwise against the ADAPTER.
9. Adjust the stand's height so that the top of the theremin is at waist level. Firmly tighten the stand's height ADJUSTMENT COLLAR.
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   NOTE: To prevent damaging the threads on either the microphone stand or the theremin, always engage the theremin to the stand at a perpendicular (90°) angle and support the theremin so that the angle is maintained as the microphone stand's INNER TUBE is rotated into the theremin ADAPTER. Never force the threads and never freely spin the theremin on the coupling threads, as doing so will ruin the adapter. To prevent excessive wear, occasionally place a small amount of light machine oil on the stand's COUPLING THREADS.
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10. The antennas supplied are identical and interchangeable and may be attached with either side up.
    Attach the VOLUME ANTENNA to the left side of the THEREMIN using two of the the four HEXAGONAL NUTS supplied. Hand-tighten the nuts securely. Do not use pliers. Repeat for the PITCH ANTENNA on the right side.
11. Set the THEREMIN's POWER ON-OFF SWITCH to the "OFF" position (down).
12. Insert one end of the (user-supplied) audio instrument cable into the theremin OUTPUT JACK and the other end into the (user-supplied) amplifier/speaker system.
13. Set the theremin's front panel controls as follows:
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    VOLUME ZERO:  Fully counterclockwise (Note: this control has ten turns)
    OUTPUT LEVEL:  9 o'clock position
    TONE:  Middle (12 o'clock) position
    PITCH  ZERO: Fully clockwise (Note: this control has ten turns)
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    Perform the following steps with your hands or other objects away from the antennas:
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14. Set the amplifier volume control to its minimum level.
15. Set the theremin's POWER SWITCH to the "on" (up) position. Note that the theremin's LED is illuminated.
16. Slowly increase the amplifier's volume control to approximately one-tenth of its maximum range.
17. Slowly turn the VOLUME ZERO clockwise until a tone just becomes apparent in the speaker.
18. Turn the PITCH ZERO counterclockwise until the pitch of the tone begins to decrease. Continue turning the control just until tone becomes inaudibly low in pitch.

8. Playing the Model 151 Theremin <back to contents>

In the above procedure, the theremin was prepared for operation. However, a few more steps must first be performed before it is completely ready to play. First, it is important that the user is familiar with the following concept:

The output from the theremin is affected by the presence of any object, including any part of your body, within about four feet of either of its antennas. This means that your body position and body movement, and not just your hand positions, will affect the output pitch and volume. The player will not have exactly the same stance in front of the instrument each time, and the theremin's proximity to large objects such as furniture or walls will vary from one setup to another. Because of these factors, the theremin must be adjusted to compensate for these variations before it is played, as described in the following procedure.

In steps 1 through 3, the volume response will be adjusted:

1. Stand directly centered in the front of the theremin, with your waist about six inches away. If you are using headphones, allow the cord to droop neatly downward from behind you, away from either antenna. It is important to remain still as you play because the proximity of your torso to the theremin will affect its behavior.
2. Lift your left hand so that it is about one foot above the volume antenna. Note the volume level as your hand is lowered toward the antenna; the volume becomes louder as the distance between your hand and the antenna decrease. Touch the volume antenna with your hand and observe the volume. This is the loudest volume, and it may be adjusted with the OUTPUT LEVEL control. While still touching the volume antenna with your left hand, adjust the OUTPUT LEVEL control for a comfortable volume.
3. Adjust the VOLUME ZERO control to obtain the following response:
   a) The output tone is not present with your left hand away from the antenna (your left arm at your side).
   b) The output tone just becomes apparent with your left hand about one foot above the volume antenna. Note that the volume control distance will become smaller as the VOLUME ZERO control is turned counterclockwise, and larger as it is turned clockwise.
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   NOTE: A smaller volume control distance is suited to rapid staccato passages. Smoothly flowing, legato passages may be obtained with larger control distances.
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   In steps 4 through 7, the pitch response will be adjusted:
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4. Purposely offset the VOLUME ZERO control by turning it clockwise so that a tone will be present, even without the left hand near the volume antenna.
5. Lift your right hand so that it is about one foot above the right antenna (pitch antenna). Note that the pitch increases as the distance between your hand and the antenna decreases.
6. Adjust the PITCH ZERO control to obtain the following response:
   a) The pitch is lowest with with your right hand about two feet above the antenna.
   b) The pitch is highest with your right hand about one inch above the antenna.
   Note that the pitch control distance will become smaller as the PITCH ZERO CONTROL is turned counterclockwise, and larger as it is turned clockwise.
7. Readjust the VOLUME ZERO control to remove the offset that was applied in step 4.
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   NOTE: To obtain more spacing between notes in the alto or soprano range, you may offset the PITCH ZERO control so that a middle pitch is obtained with your right hand away from the antenna. This will result in a smaller total pitch range, but will also provide more space between notes. Alternatively, shifting your stance so that you are slightly closer to the pitch antenna will also cause this offset to occur.

As with any musical instrument, individuals will develop their own particular style for playing theremin. As a general guide, it is suggested that the hands are positioned above the antennas with vertical movement used as the primary means of changing pitch and volume. Some lateral movement of the hands is natural and can be useful in avoiding the monotony of purely vertical motion. However, the player should watch their hands to prevent them from drifting too far from the optimal sensing area. Movements of the individual fingers of the pitch hand, a technique often used by thereminists playing "pole" type instruments, may also be employed when playing the 151 Theremin, although the intervals obtained for the same movements will differ for the two types of instruments.

It is not uncommon for beginning thereminists to become tired from holding their hands in position for extended periods, although they usually become accustomed after several sessions. Repeated, abrupt, jerking motions should be avoided because such motions may cause stress and injury to the joints. Since some repositioning of the body while playing is inevitable, it is recommended that the thereminist periodically check the response of the pitch, making sure that the lowest pitch is attained for a hand distance of about two feet. The high resolution and smooth operating character of the 151's PITCH ZERO control allows quick corrections to be made during a performance. While standing is traditional, the theremin may also be played comfortably while seated. In this case, a short microphone stand should be used with the 151 Theremin.

There are many practice methods available for the thereminist. The ability to recognize the actual pitch of a note (e.g. "A" or "A#") is not required, but the ability to maintain and repeat the interval relationships between notes is important. It is recommended that the beginner start by playing along to a recorded melody while concentrating on obtaining the corresponding hand positions. In initial exercises, it is desirable to concentrate just on the pitch hand, while simply maintaining a fixed distance with the volume hand. The ability to use the volume hand to emphasise individual notes and provide the all-important dynamics of loudness will be attained intuitively once the student is comfortable with pitch control.

The rapid, cyclic motion of the pitch hand to create vibrato is a common technique. In this manner, the optimal desired pitch may be included within the extents of the vibrato range, therefore attaining the "perfect" pitch, at least momentarily. Vibrato typically spans the range of a quarter-tone to a full-tone interval and is an effective way to enhance technique. However, the ability to attain correct pitch with practically no vibrato is also a desirable skill. The same cyclic motions applied to the volume hand can also be used effectively for tremolo.

Recording your theremin sessions is an invaluable tool for improvement. After several practice sessions, it is suggested that the student play back a solo of moderate length and observe the accuracy of the pitch intervals and ability to maintain the desired key. Improvement may also be attained by accompanying other instrumentalists. It is suggested that beginners find group opportunities without a vocalist, since the theremin may likely be used to play melody and possibly "compete" for the vocal range. One of the advantageous features of the 151 Theremin is its capability to produce bass tones, which may add a valuable element to the overall mix. While the theremin is often used for lead lines, it can also be used effectively in harmony or as backup.

The prospect for adding special effects to the theremin is limitless, but it is recommended that beginners first concentrate on playing "dry," perhaps with a small amount of reverberation added to provide presence. Reverberation also provides a small amount of persistence that some players find useful for attaining accurate intervals. While, historically, the theremin has been used to provide non-melodic sound, as in the stereotyped use for "special effects" in film, it is also capable of providing the means for articulate, accurate melodic work, given proper attention and adequate skill.

9. Grounding and Portable Operation <back to contents>

A proper earth ground is essential for the 151 Theremin to operate predictably and provide the benefits of its full pitch and volume sensing distances. In mains-powered installations, the theremin receives its ground through the audio instrument cable that connects the theremin to the amplifier/speaker or mixing console.

Portable operation does not provide the convenience of such a direct ground connection. However, the proper configuration of the audio instrument cable that connects the theremin to the amplifier/speaker can readily provide an adequate substitute. To achieve this, it is recommended that the cable, such as the recommended 15-foot Whirlwind® model number SN15, be laid in an approximate circular pattern immediately around the feet of the theremin stand and the player. Spread the cable out in a small area immediately in the vicinity of the stand to ensure that there is adequate capacitive coupling, and therefore grounding of the theremin, to the surface shared by the player and the instrument. The exact lay of the cable is not critical, but it is important not to "bundle up" the excess cable in one spot.

Note that specific adjustment to the VOLUME ZERO and PITCH ZERO controls must be made each time the theremin is relocated. Part of these adjustments address differences in the effectiveness of the grounding among different locations. For example, the optimal settings of the ZERO controls will change by several full rotations for a 151 played in a recording studio in a steel-frame and concrete building, compared to one played through a battery-powered portable amplifier/speaker on a wood stage situated on a dry, sandy terrain.

Although many portable amplifiers provide multiple instrument and mic inputs, it is important that your portable unit be specifically dedicated to the theremin alone. This is because the variations in ground coupling from other inputs, for example, a guitar that is being moved while played, will affect the pitch and volume of the theremin.

Do not place cables connected to this product in areas where they can cause a trip hazard.

10. Tone Control <back to contents>

The TONE control on the 151 Theremin provides a wide variety of sound qualities. When fully counterclockwise, the theremin's tone will be sinewave-like, mostly devoid of harmonics. The fully clockwise setting of the TONE control will produce a wave similar in qualities to a full-wave rectified sinewave, which is harmonically rich. Between these two extremes, a variety of tone qualities are available, including some that are similar to many other types of theremins.

CAUTION: Low-pitched tones, especially sinewaves, do not seem loud, but they may produce sufficient power to cause damage to amplifiers and loudspeakers. When setting up the theremin, always start with your amplifier/speaker system volume control settings at low levels to prevent damage. It may be desirable to use an equalizer and/or limiter at the theremin's output to match the performance of your audio system.

NOTE: The degree of pitch accuracy attained by any particular thereminist, actual or perceived, may vary depending on the tone of the theremin. In some instances where a high-level accompaniment or high ambient noise is present, the thereminist may elect to adjust the tone for a more sine-like quality so that most of the sound energy is in the fundamental region, therefore making it easier to attain the correct pitch. Many other factors also contribute to what tone may be most appropriate; for example, a sine-like tone, dissimilar to the sounds produced by most conventional instruments, may "stand out" too much in a mix, creating a sense of incompatibility with other instruments.

11. Model 151 Theremin Specifications <back to contents>

12. Troubleshooting Guide <back to contents>

13. Model 151 Theremin Warranty and Repair Service <back to contents>

Harrison Instruments Two-Year Limited Warranty

Harrison Instruments Corporation ("Harrison Instruments") warrants this product to be free from defects in materials and workmanship for a period of two (2) years from date of purchase, PROVIDED, however, that this limited warranty is extended only to the original purchaser and is subject to the following conditions, exclusions and limitations hereinafter set forth:

This limited warranty shall be void and of no effect, if:

1. The first purchase of the product is for the purpose of resale; or
2. The original purchase of the product is not made from Harrison Instruments; or
3. The product has been damaged by accident or unreasonable use, neglect, improper maintenance, or other causes; or
4. The serial number affixed to the product is altered, defaced, or removed; or
5. The product's enclosure is opened by any party not authorized by Harrison Instruments.

In the event of a defect in materials or workmanship covered by this limited warranty, Harrison Instruments will repair the defect in materials or workmanship without charge or replace the product, at Harrison Instruments' option, provided however, that in any case, all costs of shipping for the purpose of shipping the product to Harrison Instruments for repair are paid by you, the purchaser.

THE WARRANTY REGISTRATION CARD SHOULD BE ACCURATELY COMPLETED AND MAILED TO AND RECEIVED BY HARRISON INSTRUMENTS WITHIN FOURTEEN (14) DAYS FROM THE DATE YOU RECEIVE THE PRODUCT.

In order to obtain service under this warranty, you must:

1. Contact Harrison Instruments and obtain a Return Materials Authorization (RMA) number.
   
2. Ship the defective product, FREIGHT PREPAID and INSURED for its purchase value, to:
   
   HARRISON INSTRUMENTS
   PO BOX 9012
   SILVER SPRING MD 20916
   
   
3. Include a complete, detailed description of the problem.
   
4. Include a complete return address.

If the defect can be remedied under this limited warranty and other terms and conditions expressed herein have been complied with, Harrison Instruments will provide the necessary warranty service to repair or replace the product and will return it to you, the purchaser.

Limitation of Liability

Harrison Instruments' liability to the purchaser from any cause whatsoever and regardless of the form of action, including negligence, is limited to the the amount of the original purchase price of the product that caused the damage or that is the subject of, or directly related to, the cause of action.

Harrison Instruments does not assume liability for personal injury or property damage arising out of, or caused by, any or all alterations or attachments to its products, nor does Harrison Instruments assume any responsibility for damage to interconnected non-Harrison Instruments products that may result from the normal functioning and maintenance of Harrison Instruments products.
.
UNDER NO CIRCUMSTANCES WILL HARRISON INSTRUMENTS BE LIABLE FOR ANY LOST PROFITS, LOST SAVINGS OR COLLATERAL, ANY INCIDENTAL DAMAGES, OR ANY CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE ITS PRODUCTS, EVEN IF HARRISON INSTRUMENTS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
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THIS LIMITED WARRANTY IS IN LIEU OF ANY AND ALL WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR USE.

14. Contacting Harrison Instruments <back to contents>

Contact Harrison Instruments by e-mail at
sales@harrisoninstruments.com

or in writing at:

HARRISON INSTRUMENTS
PO BOX 9012
SILVER SPRING MD 20916

(Back to 151 Theremin product description page)

Publication Number 151UM-1
Rev. 3  08-01-2014

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