The Sound Professionals


Dual Channel Microphone Preamp







Congratulations on your purchase of The Sound Professionals dual channel microphone preamplifier SP-PREAMP-5.  This preamp can be used in situations where the signal coming from your microphones need to be strengthened before they are plugged into your recorder or mixer. The ‘plug in power’ feature, built into this preamplifier, can be used to power any microphone that requires a 9 volt D.C. power source.


The preamp is built into an Otter Box 1000 series case and is constructed of sturdy ABS fiberglass reinforced plastic that will protect the internal components from mechanical damage. The output cable is terminated with a standard high quality, right angle 1/8” stereo mini plug.


To access the battery compartment, slide the batteries out of their holder and Install three new 3-volt batteries of the same type (CR2016) noting the proper polarity ( “+” up).


Preparing to use the preamp


Selecting the proper gain range

Your new preamplifier has adjustable gain, in 3 ranges, and is controlled by a small toggle switch. The 9vdc “plug in power” feature is present in all gain ranges. The “0dB” gain range is used for loud recordings, when you don’t need any additional amplification. With this range, the audio signal is not amplified. The “29dB” gain range is used for most recording situations (moderately loud to fairly soft). The “50dB” gain range is used for extremely quiet recording situations.


For best results, use the lowest gain range that adequately drives the line input of your recorder to an acceptable level. Using a gain range that is too high will result in overloading of the preamplifier input, called “Brickwalling”. In general, you want to use the least amount of amplification necessary to obtain a line level signal to drive your recording device.


Using the SP-PREAMP-5  with any Sound Professionals  microphone

If you are using the SP-PREAMP-5  with one of our microphones, simply plug the microphone’s connector into the preamp input jack.


Using the SP-PREAMP-5 in conjunction with other microphones

If you are using the SP-PREAMP-5 with a microphone other than a Sound Professionals microphone, the procedure for its use is the same as noted above. Be sure the microphone is designed to use at least 9 volts DC and has a 1/8” stereo phone plug.


Plug the 1/8” stereo output cable from the preamp into your recorder or mixer’s LINE input. Turn the level control of the preamp all the way down (counter-clockwise) and turn the preamp ‘on’ by flipping the power switch up.


Turn on your recorder or mixer and prepare it for recording. For a recorder, set the recording level by following this procedure:


1.     Set the recording level to the maximum setting in the ‘manual recording’ mode (some recorders are always in manual mode). The recording level should be at maximum for the best overall dynamic range and lowest signal to noise ratio.

2.      While monitoring a source signal, turn up the level control on the preamp (the knob that rotates) so that the recording level meters are set per the manufacturer’s instructions (usually as high as possible without hitting the very top of the scale “0dB”).


You may now begin recording, following the directions provided by your recorder or mixer’s manufacturer. After a few minutes of recording, stop the recorder and listen to the recording you have just made. Adjust the microphone placement and recording levels as needed. Repeat this procedure until you are satisfied with the results. You are now ready to make that once-in-a-lifetime recording!


Remember to turn off the preamp when not in use to conserve battery power.


Care and Maintenance


Your Sound Professionals  preamplifier has been designed and manufactured to provide a lifetime of trouble-free service. When necessary, you may wipe the exterior of the case with a soft cloth moistened with clean water, removing excess moisture with a dry cloth.


Questions and help


If you have any questions regarding the use of your preamplifier or require help with these instructions, please feel free to call us at 1-800-213-3021.