ACOUSTI-Q Tube Preamplier/Blender USER'S MANUAL 1.0 Copyright © 2001, PreSonus Audio Electronics, Inc. ALL RIGHTS RESERVED TABLE OF CONTENTS 1 1.1 1.2 2 2.1 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.2 2.2.1 2.2.2 2.2.3 3 3.1 3.2 3.2.1 3.3 4 5 Overview.................................................................................. 1 Introduction ............................................................................... 1 Features .................................................................................... 2 Controls & Operation................................................................ 4 Front Panel................................................................................. 4 Gain Controls/Blender.................................................................. 5 Notch Filter ................................................................................ 6 Equalizer.................................................................................... 7 Master ....................................................................................... 9 Metering .................................................................................... 9 Back Panel ............................................................................... 10 Output..................................................................................... 10 Tuner/Amp ............................................................................... 10 Effects Loop ............................................................................. 11 Connections ........................................................................... 12 Instrument Input/Blender .......................................................... 12 Vacuum Tubes .......................................................................... 12 Replacing The Vacuum Tube ....................................................... 12 Wiring Scenerios ....................................................................... 15 Technical Specications ......................................................... 16 PreSonus Limited Warranties ................................................. 18 i OVERVIEW 1 1.1 INTRODUCTION Thank you for purchasing the PreSonus ACOUSTI-Q Tube Preamp/Blender. This preamp was designed using state of the art components to deliver crystal clear audio for an innite period of time. We believe the ACOUSTI-Q Tube Preamp/Blender to be an exceptional sounding unit and an exceptional value. Please contact us at 1-800-750-0323 with your questions or comments regarding this product. PreSonus Audio Electronics is committed to constant product improvement and believes the best way to accomplish this task is by listening to the experts on our gear, our valued customers. We appreciate the support you have shown us through the purchase of this product. Please pay close attention to how you connect your ACOUSTI-Q to your system. Improper grounding is the most common cause of noise problems found in studio or live sound systems. We urge you to scan this manual before hooking up your ACOUSTI-Q to familiarize yourself with its features and applications. Good luck and enjoy your ACOUSTI-Q! 1 1 OVERVIEW 1.2 FEATURES The following is a summary of your ACOUSTI-Q's features: Dual Input Stage Your ACOUSTI-Q contains two separate dual servo preamps with separate volume controls. This award-winning design provides ultra low noise performance and wide dynamic control for both preamps giving the ACOUSTI-Q the ability to boost the desirable signals without increasing unwanted background noise Blender Control Separate volume controls are provided for mixing the input signals. This is accomplished by way of a dual concentric volume control for blending incoming signals to the 1/4" TRS input jack. 12AX7 Tube The input signal is routed through a 12AX7 vacuum tube after the Master output. This design applies the aural enhancement capabilities of the tube on the input while minimizing unwanted audio artifacts. 12V Phantom Power The ACOUSTI-Q has +12VDC Phantom power available to the Ring of the 1/4" TRS input. When the Phantom power switch is engaged, +12VDC power is supplied for use by mini-condenser microphones installed in some acoustic instruments. Use caution when engaging the Phantom power switch as a loud transient may occur. Phase A phase reverse switch is provided to enable the user to invert the phase of the input signal. Engaging the phase switch can compensate for different connector hook-ups. Varying the signal's phase may also be used to achieve an intentional `out-of-phase' sound. Experiment! Notch Filter The ACOUSTI-Q has a Notch lter on the front panel for isolating and controlling low frequencies that may be prone to feedback. 2 OVERVIEW 1 Equalizer The ACOUSTI-Q Equalizer section has a pair of dual concentric potentiometers. The left inner control is a sweepable Mid-Range control and allows the user to select a frequency from 250Hz to 5kHz while the left outer control cuts/boosts the selected frequency +/- 12dB. The right side inner control, which is labeled Brilliance, boosts or cuts (+/- 12dB) 8kHz and above while the outer left side control in the Equalizer section, which is labeled Bass, boosts or cuts (+/- 12dB) 100Hz and below. Master Section The Master section of the ACOUSTI-Q contains a Mute switch and a dual concentric control for use in setting the level of the Main output and the level of the Cut/Boost feature*. The Mute feature is provided for use in conjunction with an external tuner. Engaging this switch mutes the Main output while allowing the signal to remain present at the -20dB AMP/TUNER output. *Activation of the Volume Cut/Boost feature requires use of an optional external footswitch which also provides footswitch operation of the Mute function. The footswitch may be purchased at your authorized PreSonus Dealer. 3 2 CONTROLS & OPERATION 2.1 FRONT PANEL The front panel of the ACOUSTI-Q contains: POWER OUTPUT LEVEL (dBu) -42 -36 -30 -24 -18 -12 0 293 CUT/BOOST 6 0 1k TUBE PREAMP 10 NOTCH -6 -3 0 3 9 12 EQUALIZER 15 18 24 MASTER 0 0 0 TIP (CH 1) RING (CH 2) +12V MUTE 3(dB) 30 INPUT PHASE TIP GAIN RING GAIN -12 92 +/- 12dB FREQ LEVEL 494 +12 -12 250 +/- 12dB FREQ LEVEL 5k +12 -12 +12 BRILLIANCE BASS -12 -80 LEVEL CUT/BOOST PEDAL +/- 12dB +20 +12 Preamp Instrument (1/4") input (TIP Ch.1; RING Ch.2) Phase Switch +12V Phantom Power Switch Blender Control (separate Gain control for Tip and Ring) Notch Notch Filter Control (Frequency and Level) Equalizer Sweepable Mid Range Separate Frequency Selector and Level Cut/Boost control (+/- 12dB) Separate Brilliance and Bass controls (+/- 12dB) Master Mute (Main out) Level (-80/+20) and Cut/Boost (+/-12) LED Indicators Power Output Level (-42/+24dBu) Cut/Boost Phantom Power Phantom Power (12 Volts) is provided to the RING of the input connector of the ACOUSTI-Q for powering mini-condenser microphones installed in acoustic instruments. These microphones are typically utilized in conjunction with a transducer-style pick-up. The 12VDC supplied by way of the RING portion of 4 CONTROLS & OPERATION 2 the TRS connector is designed to fulll the power requirements of the internal mini-condenser microphone and is not intended to supply the necessary current to replace the 9V battery needed by many types of on-board preamps installed in acoustic instruments. Tip Sleeve Sleeve Ring Tip Ring Cable Wiring Diagram for Phantom Power TRS Plug Tip TIP = Pick-Up Ring RING = 12V DC, Sleeve Mic or Pick-Up SLEEVE = GND 2.1.1 GAIN CONTROLS/BLENDER The ACOUSTI-Q Gain potentiometers give the user independent control over the amount of input signal from the Tip (Ch.1) and Ring (Ch.2). The Blender feature lets you change the characteristics of the ampli3(dB) 30 ed sound of your instrument if it is equipped with both a mini-condenser mic and a pick-up. A variety of tonal shadings are available by simply adjusting the relationship between the signals from the mini-condenser mic and the pick-up. For example, the low end of the instrument's sound can be accentuated by blending the mini-condenser mic level louder than the output from the transducer (pick-up). This setting will typically result in a darker, rounder sound. The mini-condenser microphone will reproduce the sound emanating from inside the instrument, which will have greater bass content than the pick-up, which is designed to reproduce the vibrations from the instrument's body. On the other hand, favoring the pick-up over the mini-condenser mic will result in a sound that is brighter and punchier and will bring out the percussive qualities of the performance. The Blender feature provides a palette of subtle tonal colors for instruments equipped with both a mini-condenser mic and a pick-up. Feel free to paint your sound. Remember to turn the Master level OFF (outer Gain control fully counterclockwise) BEFORE the phantom power is turned ON ­ for instruments equipped with mini-condenser microphones. Powering up the phantom power for the mini-condenser mic with the Master turned up may result in VERY LOUD feedback, which could damage your loudspeakers! LE SS 10 E OR M 5 2 CONTROLS & OPERATION Phase The phase of the signal from the mic may be reversed to change it's sound. The inverted phase results in a signal that sounds more wooden and hollow. This sound is much like the sound of single coil pick-up electric guitars such as the Fender® StratocasterTM. It can be especially effective for rhythm guitar. 2.1.2 NOTCH FILTER The ACOUSTI-Q has been outtted with a Notch lter for controlling feedback without greatly altering the instrument's sound. A Notch lter affects a very narrow frequency bandwidth with minimal overlap into 494 -12 92 +12 adjacent frequencies. This is why a Notch lter can virtually eliminate a feedback problem while retaining an instrument's original sound. The dual concentric control for the Notch lter has an inner knob that selects the frequency to be ltered and an outer knob to select how much the selected frequency is boosted or how much the selected frequency is reduced. Frequency The Frequency control (inner knob) of the Notch lter's dual concentric control is labeled FREQ. The frequencies governed by this control are graduated incrementally from 92Hz (inner knob rotated completely counter-clockwise) to 494Hz (inner knob turned completely clockwise). These frequencies are effective at controlling feedback because they correspond to the speed of the vibrations of specic musical notes (ex. 92Hz=F#) that may resonate (feedback) inside an acoustic instrument such as a guitar. The shape of the instrument, the density of the material from which it was manufactured, as well as the volume that the instrument's signal is being amplied and reverberates inside the instrument all play a role in why an amplied acoustic instrument may feedback. Level The Level control is the outer knob of the Notch lter's dual concentric control. Notice that the markings for this control have a zero (0) at the twelve o'clock (straight up and down) position. With the outer knob set at this position, the Notch lter has no effect on the signal. Rotating the control fully counter clockwise reduces (cuts) the frequency that has been selected by twelve dB (12dB). Bringing the knob back to the top or twelve o'clock position adds back the selected frequency until it is completely restored at the twelve o'clock (0) LE SS 0 293 E OR M 6 CONTROLS & OPERATION 2 position. The Level of the selected frequency can be increased (boosted) by rotating the outer knob of the Notch lter clockwise from the twelve o'clock (0) position. This boost can be by as much as twelve dB (+12). Care should be exercised when boosting the instrument's signal with the Notch lter so as to not cause a feedback problem. The Notch lter can be effective at boosting a decient frequency, however, the Bass control of the Equalizer section of the ACOUSTI-Q should be the rst choice for increasing the low end of an instrument's voice. Setting the Notch Filter for an Acoustic Guitar As stated previously, the Notch lter is controlled by way of a dual concentric potentiometer. The inner knob allows selection of a frequency from 92Hz to 494Hz and the outer knob can cut or boost the selected frequency's level by as much as 12dB. Begin by turning the Frequency selector fully counter clockwise and placing the Level control in the twelve o'clock (0) position. Press down on the lowest string at the rst fret. Continue fretting the lowest string moving up the neck one fret at a time until the resonant frequency is located. While keeping the note on the guitar fretted, turn the Boost/Cut (outer control) counterclockwise about halfway. Slowly rotate the Frequency control from the 92Hz position, clockwise, until the feedback is reduced. Try to zero in on the feedback by very slowly advancing the frequency controller past the point at which the ...