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The
precision electronic section is entirely hand-built and employs
everything from a vacuum tube for the preamp section to integrated
circuits for the tone sections. The chassis is made entirely
of aluminum and is chosen for its repeatable electrical properties
and superior resistance to the environment. This is preferable
to commonly used steel. The front panel is grained and black
anodized while the main chassis, top and bottom are painted
satin black. All rotary pots and dual concentric potentiometers
are custom made for SWR by Noble, USA. Only four coupling capacitors
are found in the signal path and are employed in the tube circuit.
They are a very high grade, hermetically sealed polyester or
mylar type and come from West Germany.
Features
that are unique from previous SWR products are a user optionable
high pass filter, a mute function on the XLR record out, a dot
bar line level display, a separate headphone amp and a new grounding
system that provides for extremely low hum levels.
NOTE:
We found that when using high power on stage or when several
pieces of rack equipment are housed in the same rack unit, ground
loops can occur through the rack rails themselves which tie
the individual units together - both electrically and mechanically.
This is one reason a "star" type grounding system
is used in the Grand Prix. Basically, this means that each part
of the circuitry has its individual ground routed via a wire
to one common point. From this point, the circuitry is tied
to chassis ground through a buss "jumper." If you
have an elaborate rack system or run high power on stage (such
as 1000 watts or more) and are experiencing abnormal hum, crosstalk,
etc., the buss that connects the internal circuitry of the Grand
Prix to the chassis may be removed, totally isolating the circuitry
from the rest of your system. This should only be done by a
qualified technician (chances are that if you can afford this
type of system, you also have your own technician). Please call
the factory for details!
We
feel that this is one of our finest preamp designs to date and
truly hope it brings a new freshness and quality to your playing.
GRAND
PRIX SPECIFICATIONS
Note:
Unless otherwise specified, all measurements were taken with
a line voltage of 120VAC, Gain and Master Volume full, tone
controls flat and Aural Enhancer at minimum.
CHASSIS
Size: Single rack space (1.75") High x 19" wide x
8.75" Deep
Weight: 5 1/4 pounds
Material: 5052-H32 Aluminum
POWER
SUPPLY
All discreet components switchable for 100V, 120V, 220V and
240V operation.
INPUTS
Input Impedance
Passive/Active Input Jack = 800K ohms
Active Input Jack = 60K ohms
Effects Return Jack = 27K ohms
Gain @ 1KHz
Passive/Active Input Jack = 71.4
Active Input Jack = 14.3
Effects Return Jack = 1
OUTPUTS
Output Impedance
Effects Send Jack = 10 ohms
Line Out Jack = 100 ohms
Tuner Out Jack = 100 ohms
XLR Balanced Record Out Jack =1.5K ohms
XLR Balanced Line Out Jack = 10 ohms
Unbalanced Preamp Outs = 10 ohms
Maximum Output @ 10K and 600 ohms
Effects Send Jack: 9V and 7V RMS
Line Out Jack: 9V and 7V RMS
Tuner Out Jack: 9V and 7V RMS
XLR Balanced Record Out Jack: 10V and 5.5V RMS
XLR Balanced Line Out Jack: 18V and 14V RMS
Unbalanced Preamp Outs: 9V and 7V RMS
NOISE
Equivalent Input Noise: 2.80 microvolts
Signal to Noise Ratio, unweighted -93db
Typical Unweighted Noise reading less than 200 microvolts
DISTORTION
System Distortion (1V RMS, 600 ohm load, 1 KHz) 0.23% THD
TUBE
(1) Specially selected Groove Tube 12AX7A
DOT
BAR DISPLAY
Accurate within .5db
FRONT
PANEL FEATURES
DOT
BAR DISPLAY
The Dot Bar Display indicates the line
level (post tone controls) and is sampled pre- Master Volume.
Having the finite level indication the Dot Bar offers, the user
is able to get maximum signal to noise ratio while performing
and should all but eliminate unwanted clipping of the preamp
section. We recommend using this function as follows:
1.
Set the Gain and Master Volume about 1/4 of the way up (9 -10
o'clock).
2.
Adjust your tone section, Aural Enhancer and any effects you
may be using to their
desired settings. Set the controls on your bass to their desired
levels.
3.
Turn down the Master Volume.
4.
Raise the Gain Control to where the +10 LED barely flashes when
striking your loudest note. Do this in several different positions
on the neck. Generally you will find a "hotspot" that
gives the greatest (highest) reading. Play this note several
times while adjusting the Gain Control to achieve the +10 LED
barely flashing.
Once
you have accomplished this, use the Master Volume to determine
your volume on stage. You have now set your preamp in such a
manner that will give you optimum results. The sound man controlling
the board in either live or studio situations will appreciate
this as you are able to give him a good level with minimum noise.
Don't forget that the level at your XLR record jack is governed
by the XLR pad.
If
you change instruments and need the same volume level, you are
able to do this quickly by adjusting the Gain control to a similar
level.
PASSIVE/ACTIVE
INPUT JACK
This input can and should be used if your
instrument has passive electronics (no built-in preamp). Some
pickups such as EMG, Fishman, etc. employ batteries for operation
and will work perfectly using the Passive/Active input. Technically
speaking, this input should be used if your instrument has an
output voltage of 1 volt RMS or less. Consult your owners manual
or ask the manufacturer if you are unsure. Preamps made by Bartolini,
Sadowsky and Rick Turner make a perfect marriage with this input.
NOTE:
If you hear a small amount of distortion and the +20 LED in
the Dot Bar Display is not lighting and your power amp is not
clipping, try using the Active Input jack.
If
you would like to overdrive the first TUBE stage, this can be
done by using a preamp between your instrument and the Passive/Active
input. To obtain optimum sound when trying this, make sure the
+20 LED indicator is not lighting. If this occurs, turn down
your Gain control. The first preamp stage is NOT monitored by
the Dot Bar Display for this reason.
ACTIVE
INPUT JACK
The Active Input jack should be used with
instruments having a built-in (on-board) preamp that will produce
signals over 1 volt RMS. Known basses that should use the Active
input are Kubicki X-Factor and some early Ovation Electrics.
Some really "hot" pickups installed in your instrument
may find this input more compatible. The best judge is your
own ears. Keyboards, drum machines, etc., should use the Active
Input jack.
NOTE:
Using the Active input with passive basses may result in a loss
in high end transients. Players who roll off their high end
starting at about 2K to 3KHz or prefer a "darker"
sound may find this input more to their liking.
If
you hear some distortion on your active bass and are using the
Active input, CHECK YOUR BATTERY!! This will save you and a
service technician a lot of aggravation.
GAIN
CONTROL
The Gain control adjusts the volume of
the preamp section. Since the Gain control is similar to a "pad,"
a small amount of signal will be heard even with the Gain rotated
fully counter-clockwise. Please refer to the information given
under the Dot Bar Display for proper use of the Gain control.
AURAL
ENHANCER
The Aural Enhancer was developed to bring
out the fundamental low notes of the bass guitar, reduce certain
frequencies that help "mask" the fundamentals and
enhance the high-end transients. This effect becomes more pronounced
as the control is turned to maximum. The result is a more transparent
sound and is especially noticeable with a slap style technique
of playing.
A
particularly favorite setting for live situations is at about
2 o'clock. This position of the Aural Enhancer brings out both
the low end fundamentals and crisp highs and at the same time
adds a little lower midrange to help cut through the band.
HIGH
PASS FILTER
The High Pass Filter, activated by pulling
out the Bass control knob until a "click" is heard,
rolls off all frequencies BELOW 30 Hz and allows all frequencies
above 30 Hz to pass unaffected. The 3db down point of the filter
is at 30 Hz and response is down 20db at 10 Hz. At higher volumes,
this feature can be a real speaker saver as it inhibits cone
excursion by disallowing sub-harmonics that can cause the voice
coil to "bottom out" or "jump the gap."
We strongly recommend the use of the high pass filter when playing
at high volume levels. At lower volume levels and especially
when a very "open" or fast sound is desired, leave
the high pass filter in the off position.
BASS
CONTROL
The Bass control cuts or boosts the lower
or bass frequencies. Starting at mid-position, turning the control
counter-clockwise cuts the bass response and turning the control
clockwise boosts the bass response. The design of the bass control
is a "shelving" type with the shelving point set at
about 80Hz.
MID
RANGE SECTION
The Mid Range section is a semi-parametric
type with both level (cut and boost) controls and frequency
controls. The INSIDE knob is the LEVEL control and the OUTSIDE
knob is the center frequency control. The level control boosts
or cuts (raises or lowers) the tone set by the frequency control.
If the level control is in the flat (center click) position,
the frequency control will have no affect to the sound.
To
assure the user of the flat (out) position of any one tone control,
a center click position has been provided. A twenty four stepped
frequency control has been utilized so the user may always relocate
a desired tone. As you find different settings that are desirable,
you may want to make a note of them.
The
easiest way to get acquainted with the semi parametric is to
raise the level control close to the +15db setting, then rotate
the frequency control from one end to the other noting the change
in sound. Do this with both the Lo Mid and Hi Mid sections one
at a time. Chances are that with each section you will find
a couple of positions that are especially pleasing or unpleasing
to your ear. As these are found, adjust the level control to
the desired amount of cut or boost that is desired. After finding
these positions, make a note of the frequency you have chosen.
The more you do this, the more you will relate frequency "numbers"
to their respective sounds. The goal that can be reached is
to be able to easily find adjustments with the tone section.
FEEDBACK
OR SUSTAIN
The Midrange controls can be extremely
useful in correcting feedback in acoustic or upright instruments.
If you are getting a slight amount of feedback from your instrument,
try the following: Set your volume to a point where the feedback
is just occurring, but not out of control; raise the Level control
of the Lo Mid band to about +8 db; slowly rotate the Frequency
control from left to right. At some point in the rotation, the
feedback should get more intense. This is the frequency area
that needs adjusting. Leave the Frequency control at the position
the feedback gets louder; now adjust the Level control in the
CUT mode until the feedback disappears. You may find that as
you raise your overall volume, you may need to further cut the
Level control to achieve the playing volume you need. We recommend
not reducing the Level control any further than is needed to
maintain sound quality.
If
you were not able to find the feedback area with the Lo Mid
knob, set its Level control back to "flat," and follow
the same above instructions with the Hi Mid band.
By
reversing the technique above, you can achieve greater sustain
in certain areas or on
certain notes. You can also use this technique to correct "hot"
spots or "dead" spots on
the neck of your instrument.
Below
are some suggestions to experiment with:
Midrange
is honky or hollow sounding.....cut the 600-1000Hz range
Treble is harsh and hurts the ear......cut the 1.5K to 2.5K
range
Have trouble cutting through the band.........boost around 200
Hz
Need a little more "punch"................boost around
100-120 Hz
TREBLE
CONTROL
The Treble control is a shelving type
designed tone control whose shelving point is set at 4KHz. This
frequency was chosen for its transparency nature and lack of
harshness. Starting from mid-position, turning the control counter-clockwise
cuts the highs and turning the control clockwise boosts the
high frequencies. A center click position has been provided
to indicate a flat treble response.
EFFECTS
BLEND CONTROL
The Effects Blend control "blends"
the signal sent from your instrument with the sound coming from
your effect. With the Blend control full counter-clockwise,
no signal from your effect will be heard (dry). As you turn
this control clockwise, more of the effect can be heard in the
overall sound. When the Blend control is full clockwise (wet),
no true or unaffected signal is heard other than what your effects
unit provides.
This
type of control and arrangement is very effective in reducing
noise caused by effects units and in maintaining a more natural
sound. Please read the "Effects Loop" section for
more information.
MASTER
VOLUME
The Master Volume adjusts the signal level
found at the Preamp Out jacks and the Balanced Line XLR out
jack. It DOES NOT control the output of the effects send jack,
line out jack, headphones or line position of the XLR balanced
record out jack. The Dot Bar Display reads the signal PRE Master
Volume.
The
Master Volume should be used in conjunction with the Gain control
to get maximum efficiency out of the Grand Prix. Please read
the "Gain Control" section of this manual for further
info and operating procedures.
HEADPHONES
The Headphone section of the Grand Prix
features its own power amp, output jack and volume control.
The headphone amplifier is a small wattage "bridged"
type. Use only STEREO headphones. The use of mono headphones
will short out one of the power sections and could cause a headphone
amp failure. Headphones with an impedance of 75 ohms or greater
should be used.
Silent
practicing or monitoring is available with headphones by turning
down the Master Volume. The Grand Prix was also designed for
use as a stand alone unit for practicing in Hotel rooms, studio
lobbies, etc. or for recording direct to tape without the use
of an external power amp.
POWER
SWITCH
Pressing the Power Switch to the ON position
activates the Grand Prix's electronics as indicated by the red
LED lighting.
REAR
PANEL FEATURES
LINE/DIRECT
SWITCH
In the Line position, the signal going
to the Preamp Out jacks also appears at the Balanced out jack.
The Master Volume, however, does not control the level. The
Level is adjusted by the XLR Pad. All front panel controls (Gain,
tone section, Effects Blend, etc.) except the Master Volume
are functional and will affect the signal present at the XLR
jack in this position. In the Direct position, the Balanced
out becomes an active TUBE direct box and the signal is uncolored
by the front panel features.
When
using this switch, make sure it is all the way up or down and
not in a "half way" position.
BALANCED
XLR OUT
The Balanced XLR Out is a true balanced
output whose level is set by the XLR Pad directly to the left.
The signal appearing at this output is governed by the position
of the Line/Direct switch directly to the right.
When
using the Balanced Out for recording, optimum results can be
achieved by DRIVING THE TAPE DECK DIRECT. Of course, if this
is not possible, the Grand Prix will work in any other situation.
Always try and use the XLR pad to adjust working levels. The
use of input pads on consoles can deteriorate sound quality.
If
you wish to send a Direct and Line signal simultaneously, you
may do so by putting the Line/Direct switch in the Direct position
and use the Balanced preamp XLR out for the Line signal. Just
remember that the Master Volume controls the Balanced XLR preamp
out.
Wiring
for the XLR connector is as follows:
Pin 1 = ground, Pin 2 = +, Pin 3 = - (American Standard)
XLR
PAD
The XLR Pad adjusts the level (volume)
appearing at the XLR connector directly to the right. Volume
increases as the control is turned clockwise.
If
you are in the LINE position and change the Gain control on
the front panel, the level will also change at the balanced
output. You may readjust the record level if necessary with
the XLR Pad without affecting any other function.
A
MUTE function is built into the XLR Pad. Pulling the knob out
until a click is heard activates the Mute feature and "kills"
any signal at the XLR connector. This is especially useful when
tuning up or any other occasion where sending your signal to
the board or "house" is undesirable.
Always
check the position of this switch when using the record out
functions. It can save some stress and panic.
GROUND
LIFT
A Ground Lift is provided for the Record
Out XLR connector directly to the right. In the down (GND) position,
the ground connection to pin #1 is engaged. In the up (GND LIFT)
position, the ground connection is interrupted. The ground lift
switch applies ONLY to this particular XLR connector.
If
a persistent hum exists after trying both positions of the ground
lift function, there is probably a problem with the AC wiring
or just a dirty AC line. We are told this happens a lot in L.A.
between 1pm and 4pm!? If this is the case, we suggest using
an isolation transformer between the Grand Prix and the wall
socket.
For
a few dollars, you can buy an AC wall socket tester. A little
light comes on if the socket is wired correctly. We recommend
everyone having one of these if they value their equipment.
TO
TUNER JACK
The Tuner input jack allows the user to
plug their instrument tuner into this jack and "tune up"
without having to unplug and go back and forth from amp to tuner.
This feature is totally isolated from the rest of the preamp
and will function regardless of the settings of the controls
on the front panel. Being on a side chain (isolated) also avoids
loading down of the instrument causing a loss in dynamic range.
To
use this feature, plug in a shielded patch cord from the Tuner
Input to the INPUT on your tuner. Turn the amplifier on and
you are ready to go. If you do not wish to monitor your sound
while tuning, you may turn down the Master Volume. If you are
in the studio and sending a feed to the "house," you
may want to activate the Mute switch so you won't disturb the
engineer who has been trying to get a drum sound for the last
6 hours!
EFFECTS
LOOP
The Effects Loop is located POST EQ and
PRE Master Volume in the block diagram. The signal level appearing
at the Send jack is controlled by the Gain control on the front
panel. If you are getting too hot a signal to the input of your
effect, reduce the level of the Gain control and raise the level
of your Master Volume to retain similar overall volume levels.
By using the Gain, Master Volume and Effects Blend control in
conjunction with each other, optimum results should be obtainable
with any effects unit.
The
Effects Loop is designed as a "side chain" (parallel)
function similar to those found on studio consoles. Use of the
effects loop should greatly reduce the noise generated by effects
devices (as compared to in-line effects loops). Additional features
of this type of loop can be found below under the Receive jack
section.
SEND
JACK
Run a shielded patch cord from the Send
jack to the INPUT of your effects unit. This jack may be used
as an additional line level output.
RECEIVE
JACK
Run a shielded patch cord from the RECEIVE
jack to the OUTPUT of your effects unit.
One
unique feature of the Receive jack is the ability to practice
along with pre-recorded music. Insert a tape recorder or other
sound source into the Receive jack (make sure it is a mono source).
Using the Blend control, adjust the level of recorded music
from the Receive jack to the "live" sound of your
instrument. The mixed sound will be heard through the headphones
and also sent to the Preamp Out jacks. This feature, which is
also found on the SWR Redhead and Baby Blue models, has proven
to be invaluable to musicians wishing to play along with audition
and practice tapes.
A
common complaint of bass players is that they are not loud enough
in the studio mix. To solve this problem, run a feed from the
headphone mix or console mix to the Receive jack. Using the
headphone jack, adjust the Blend control to the desired level
YOU want to be in the mix! This can only be done if the Line/Direct
switch in the DIRECT position and your speakers are not being
miked. If you are in this position, you can also make your own
private tape of the session by inserting a cassette deck in
the Line Out Pre- Master jack.
NOTE:
Inserting a plug into the Receive jack activates the Effects
Blend control. The Effects Blend control "receives"
this command through the ground created by insertion of the
plug in the jack. Therefore, results can only be obtained by
using a mono phone plug. If you have a stereo plug only, tie
the ring and ground together.
If
you are not getting any "effect" through your speakers,
etc., check the position of the Blend control and the hookups
of you patch cords.
LINE
OUT PRE-MASTER JACK
The signal present at the Line Out jack
is the same signal being sent to the XLR record out connector
when the switch is in the Line position. It is post EQ and Pre
Master Volume. It can be used as an unbalanced record out or
a send to an additional power amplifier.
PREAMP
OUT JACKS AND BALANCED XLR CONNECTOR
The Preamp Out jacks are the unbalanced
send of the preamp to your power amplifier. Use a good quality
shielded patch cord from these jacks to the input of your power
amplifier. Two jacks are provided in the case you have two mono
power amps or no mono input on your stereo power amplifier.
If you wish to use stereo effects, these jacks should go to
the input of your effects and the output of your effects to
the power amp.
For
a power amp to be compatible with the Grand Prix while using
the unbalanced out jacks, its sensitivity must be 7V RMS or
LESS and have an input impedance of greater than 600 ohms.
The
BALANCED XLR OUT CONNECTOR is a
true balanced output. It can be used to drive power amps having
an XLR balanced input. This type of input on a power amp can
be beneficial in avoiding ground loops or hum problems (reread
the NOTE section on the first page of this manual). If you use
this output on the Grand Prix to drive your power amp, be sure
that it is wired for AMERICAN STANDARD (pin 1 = ground, pin
2 = +, pin 3 = -). If your power amp comes from Europe, check
the owners manual for wiring references. In any case, either
the Grand Prix or your power amp can be rewired for compatibility.
A/C
LINE/MAINS FUSE
The line fuse can open (blow) due to power
surges or high powerline transients. This fuse will also open
in the event of an electronic component failure inside your
preamplifier.
DO
NOT DEFEAT THE PURPOSE OF THIS FEATURE BY USING A FUSE WITH
A HIGHER RATING. IT CAN FURTHER DAMAGE YOUR PREAMP AND VOID
YOUR WARRANTY.
SUPPLEMENTAL
NOTE
Because SWR chose to put the least amount
of components possible in the signal path to retain purity,
turn on and turn off transients appear at all the outputs of
the Grand Prix Preamplifier. For this reason, the Grand Prix
should be turned on FIRST and the power amp turned on second.
Likewise, the power amp should be turned off first and the Grand
Prix second.
Turning
the Master Volume down before turning off the Grand Prix will
all but eliminate transients sent to your power amp and heard
through the speakers if the above procedure is not followed.
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