Trace Acoustic TA40R, TA80CR, TA60CR, TA40CR Operating Instructions Manual

OPERATING
INSTRUCTIONS

ACOUSTIC
INSTRUMENT
AMPLIFIER

TA40R / TA40CR

TA60CR / TA80CR

INTRODUCTION

TA40R / TA40CR / TA60 / TA80

This range of portable amplification has been based on the preamplifier design of the Trace Acoustic
TA35 amplifier. The TA35 has been replaced by the TA40 - the only difference between these units is
a power upgrade from 35 watts to 40 watts rms.
The principle difference between the amplifiers is the power output and loudspeaker configuration.
The TA80 has power output stages delivering 40 watts rms each. These drive into 1 x 10” and 2 x
5” loudspeakers respectively. This configuration was found to be preferable to one 80 watt output
stage as the two power amplifiers each feature their own dynamic correction, enabling more
accurate reproduction of the total range of frequencies produced by an acoustic guitar. The open
back cabinet design produces a loud, more open sound that projects in a manner similar to that of
an electric guitar amplifier.
The TA60 is something of a departure from the standard Trace Acoustic range. It is a 50 watt
combo, delivering its power into 2 x 8” loudspeakers and a high frequency tweeter. This speaker
configuration gives a sound with more emphasised bass and treble frequencies, which is
particularly suited to those players who prefer a more ‘produced’ sound from their acoustic guitar.
By careful control of the equalisation and notch filters, a loud and natural sound can be obtained,
with accurate reproduction of the percussive attack of the strings and pick / fingers.

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Input/Input switch

There is a single INPUT jack socket that will perfectly match ACTIVE instruments with their own
internal preamp and passive instruments with just a PIEZO pickup or transducer by selecting either
type with the switch adjacent to this socket.
With the input sensitivity set to PIEZO (switch out) the input impedance is extremely high i.e 4
million Ohms. This will perfectly match any PIEZO device giving a clear and accurate response with
no degradation to the signal.
With the input sensitivity set to ACTIVE (switch in) the impedance is much lower 47k Ohms and the
sensitivity much lower. This will match instruments with a built in preamp without fear of clipping
the input. If however your active instrument has an insufficient level of output to light the LEVEL
LED (as some do) then it is perfectly alright to switch back to the PIEZO setting to increase the
sensitivity to a level that works best with your instrument.

Input gain/level indication

The GAIN control should be set in conjunction with the LEVEL LED. When correctly set the amplifier
should perform with very little background noise. It is therefore important to set the GAIN control
correctly using the following method:

1. Plug the instrument into the input jack and select the appropriate INPUT sensitivity.

2. Play the instrument in the style that you would use it e.g. strumming, finger picking etc.

3. Increase the GAIN control until the LEVEL LED is lighting quite often.

4. Decrease the GAIN control so that the LEVEL LED is only lighting on peaks.

5. If the LED cannot be made to light whilst playing then do the following:­If your instrument is an ACTIVE one then either turn its own level control up further or switch the
INPUT sensitivity to PIEZO and try again.

FRONT PANEL CONTROLS

GAIN LO-TRIM HI-TRIM NOTCHINPUT 1 INPUT PHASE

OFF

PIEZO

ACTIVE

IN PHASE
REVERSE

CHANNEL 1

GAIN LO-TRIM HI-TRIM NOTCHINPUT 2 INPUT PHASE

OFF

PIEZO

ACTIVE

IN PHASE
REVERSE

CHANNEL 2

BALANCE

CHORUS

DEPTH LEVEL MASTER

LEVEL

CHAN 1 CHAN 2

SPEED

REVERB

POWER

PULL - SHAPE

TA40CR

LEVEL

LEVEL

IN

OUT

IN

OUT

PULL - ONPULL - ON

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If the instrument uses just a piezo pickup then you will have to leave the GAIN control set on
maximum as this is the best setting you can achieve.

N.B. as the LEVEL indication is driven from after the equalisation circuits, it may be necessary
to re-adjust the GAIN control once the equalisation has been altered.

Phase switch

The ‘PHASE’ switch has two distinct uses, firstly, by reversing the phase of the signal,
feedback from the guitar can very often be considerably reduced, this is dependent upon
the position of the player relative to the amplifier and the switch may need to be either
“in” or “out” depending on player position and the frequency of feedback. This is an ideal
way of reducing feedback as it introduces no change at all to the sound of the
instrument. However this will only work if the amplifier to player distance is fixed as is
often the case with a performer sitting down next to their amplifier.
The second use of the PHASE switch is with the dual pick up system where reversing the
phase of one channel can enhance the effectiveness of the dual pick up depending on the
position of the microphone within the body of the instrument. Again this can also
minimise the chances of feedback.

Description of how the ‘Phase’ switch reduces feedback

If the distance from the instrument to the amplifier is fixed i.e. the player is sitting down
next to or in front of their amplifier then the speakers reproducing the sound of the
instrument set up a series of standing waves, the length of these standing waves is
dependent upon their frequency.
Now as feedback from acoustic guitars is always at fairly low frequencies then the
standing waves associated with it are quite long. If you happen to be sitting at the node
(i.e. the most sensitive spot) of one of these standing waves then feedback is quite likely
to occur as the wave will tend to excite the body of the instrument into resonance.
If however you are sitting at the antinode (least sensitive spot) the feedback will be
unlikely to occur. By simply reversing the phase of the signal through the amplifier you
are in effect reversing the positions of the nodes and antinodes within the standing wave
and consequently changing your relative position in relation to the amplifier i.e. switching
yourself from sitting in a node to sitting in an antinode and thus reducing the likelihood
of feedback occurring.

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