LR Baggs Acoustic Reference Amplifier - Manual (Page 9)

6) notcH
This amplifier incorporates the garrett null anti-feedback notch filter found on many of our preamps. sonically it is virtually invisible
and it can be used to sweep the primary feedback range of the guitar (60Hz - 320Hz) to cut out a frequency that is causing feedback
or ringing. This control can also be disabled and taken out of the signal path by turning the knob all the way to the counterclockwise
position. you will feel a click as the filter is switched out.
To appropriately set the notch, turn up the guitar until it starts to feed back slightly and then turn the control from counterclockwise to
the clockwise position slowly. As the notch hits the trouble frequency, the feedback will stop.
7) pHase (inveRt)
Press this button to invert the polarity of the signal. When the button is out, the speaker will be in phase with the input signal. The phase
relationship that is most important is the movement of the guitar top in relation to the movement of the speaker in the amplifier. A phase
relationship changes approximately every 4 feet that you move relative to the speaker so you must set this control according to where
you will be standing as you play. A correct phase relationship will sound best and be least likely to feed back. We recommend trying both
phases each time you set up as it will often change at each venue you play.
8) Bass
The bass control is a 12dB boost/cut centered at a frequency of 100Hz. For help with setting the eQ see “Helpful eQ settings” in the TIPs,
TRICks AnD HoW To’s section.
9) loW miD level anD fRequencY
The low mid control has two adjustable concentric knobs. The top knob controls the 12dB boost/cut. The bottom knob selects the
frequency at which you boost or cut. you can sweep from 200Hz (full counterclockwise) to 1kHz (full clockwise). The most common uses
of this control will be to dampen some of the low midrange frequencies on a muddy-sounding guitar or to boost a little of the lower
midrange frequencies on a thin-sounding guitar. For help with setting the eq see “Helpful eQ settings” in the TIPs, TRICks AnD HoW To’s
section.
10) HiGH miD level anD fRequencY
The high mid control has two concentric adjustable knobs similar to the low mid control. The top knob controls the 12dB boost/cut. The
bottom knob selects the frequency at which you boost or cut. you can sweep from 1kHz (full counter clockwise) to 5kHz (full clockwise).
The most common uses of this control will be to cut some midrange frequencies on “nasal” sounding guitars or to boost frequencies up
in the 5k range to bring “zing” back to lifeless strings. For help with setting the eq see “Helpful eQ settings” in the TIPs, TRICks AnD HoW
To’s section.
11) tReBle
The treble control is a 12dB boost/cut centered at a frequency of 10kHz. For help with setting the eq see “ Helpful eQ settings” in the TIPs,
TRICks AnD HoW To’s section.
12) ReveRB
This knob sets the level of the onboard spring Reverb effect (has no impact on the fx loops). The control will not allow for 100% wetness
but does allow enough reverb to be “too much”. For more details regarding this feature please read the “spring Reverb” notes in the
ABouT section above and the “How to get the Most out of the spring Reverb” instructions in the TIPs, TRICks AnD HoW To’s section.
13) masteR vol anD clip leD
The master volume, located in the upper right of the control panel, will be used to set the level of the sound coming out of the speaker.
The main output also has a limiter on it (see “speaker limiter” in the TIPs, TRICks, AnD HoW To’s section). The clip leD will light as the
limiter begins to engage. There should not be much of a sonic change caused by the limiter. It simply limits the volume to keep from
overheating the speaker driver.
As well, the master vol is also used to control the headphone volume when you have headphones plugged into the Headphone output
(the speaker will be disabled at this time). The master vol can also be set up to control the level of an extension amplifier or powered
cabinet by way of the line out (see “Daisy-Chaining Amplifiers” in the TIPs, TRICks AnD HoW To’s section).
14) auX vol anD clip leD
The aux volume control, located in the lower right of the control panel, will be used to set the level of the auxiliary input on the back of
the amplifier. This input is either 1/4” (TRs summed stereo) or RCA jacks (for an MP3 or CD Player). A clip light is also supplied to show the
maximum possible level. There is a lot of headroom on this particular input so you may put in a very large signal and never see the leD
light up. The control is located on the front of the amplifier for easy access.
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