GIBSON GOLDTONE
GA-15
GA-15RV
GA-30RVS
OPERATING
INSTRUCTIONS
GA-15
INTRODUCTION
The Gibson “Goldtone” GA-15, GA-15RV & GA-30RVS are no nonsense, compact, purist
valve guitar amplifiers. They have the minimum controls necessary to produce a good
range of sounds, from clean to overdriven.
However, with the addition of such features as a switchable gain boost, stereo effects
loop, pseudo-stereo reverb, and a stereo power stage, the “Goldtone” GA-30RVS model
takes the range as far as it could possibly go.
The circuit topology has been based on traditional guitar amplifier designs, with new
ideas incorporated where beneficial.
The preamp and power stage sections are 100% valve. The valves used are:
“Goldtone” GA-15
Two ECC83/12AX7’s and two EL84/6BQ5’s run in Class A.
“Goldtone” GA-15RV
Two ECC83/12AX7’s and two EL84/6BQ5’s run in Class A.
“Goldtone” GA-30RVS
Four ECC83/12AX7’s and four EL84/6BQ5’s run in Class A in stereo (two EL84’s per side).
REAR PANEL CONTROLS
“Goldtone” GA-15
“Goldtone” GA-15RV
“Goldtone” GA-30RVS
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Input (“Goldtone” GA-15 only)
A single jack socket is provided for connection to your instrument. This is a high
impedance input which allows for perfect matching to both passive and active guitars.
Inputs - Hi & Lo/Link (“Goldtone” GA-15RV & GA30RVS)
Two jack sockets are provided for connection to your instrument.
The HI input is a high impedance, high sensitivity input. This can be used with both
passive and active guitars and, depending on the level of output from the guitar and the
VOLUME setting, allows the amplifier to be driven hard into overdrive, if desired.
The LO/LINK socket can be used in two ways. Firstly as a lower impedance, low
sensitivity input, for use with high output guitars when the user wishes to keep the
overdrive under control. Alternatively this socket can be used as a LINK to chain together
two amplifiers, simply plug your guitar into the HI socket, take an output from the
LO/LINK socket and plug this into the HI input of the next amplifier in the chain.
Bright switch (All Models)
The BRIGHT switch adds more high frequencies when selected. It works in the traditional
way, therefore as the volume control is increased the effect becomes less apparent.
Volume (“Goldtone” GA-15 & GA-15RV)
This sets the overall volume level of the amplifier as well as the tone and the amount of
overdrive. From low to about halfway, depending on the output level of the guitar used,
the sound should remain reasonably clean. Increasing the control further will
progressively increase the level of distortion in the sound, obviously being a valve amp it
will respond to the player’s dynamics and use of the instruments volume.
Volume / Pull Gain (“Goldtone” GA-30RVS only)
This is a push/pull potentiometer. Pushed in the control acts like a normal volume control
on a typical non-master volume amplifier, therefore it sets the overall volume level of the
amplifier and has a huge effect on the tone and the amount of overdrive. From low to
about halfway, depending on the output level of the guitar and which input socket is
used, the sound should remain reasonably clean. Increasing the control further will
progressively increase the level of power amp overdrive in the sound, obviously being a
valve amp it will respond to the player’s dynamics and use of the instrument’s volume.
Pulling the control out activates the additional valve preamp stage therefore effectively
turning the control from a VOLUME into a GAIN control. This extra gain stage makes it
possible to produce a fuller overdrive sound especially when turned up as this blends
preamp distortion with power amp distortion. With the control pulled out the extra gain
stage is also footswitchable. This enables the user to footswitch between clean and dirty
sounds.
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Setting the VOLUME at about 12 o’clock gives lovely warm clean sounds which can then
be switched to a nice, not too saturated overdriven tone.
For total and instant control over a range of clean and overdriven tones we recommend
turning the VOLUME control all the way up. Without the extra gain stage switched in the
player can then back off the volume on their guitar for clean sounds, turn up fully for
some crunchy, responsive power amp overdrive, and then kick in the extra gain stage for
thick lead tones with lots of sustain.
Tone (All Models)
Unlike other single tone controls on other amplifiers, which act merely as a treble roll off,
this control works in a different way. It is a dual gang potentiometer which controls two
functions simultaneously. In the fully anti-clockwise position the midrange is dominant in
the sound, turning the control clockwise decreases the mids while at the same time
increasing the higher frequencies.
Start with it in the 12 o’clock position and try different settings with or without the
BRIGHT switch to find the settings that you like. Bear in mind that as the VOLUME is
turned up the BRIGHT switch has less effect.
Reverb (“Goldtone” GA-15RV only)
This single control is for adjusting the amount of reverb effect in the sound. The effect is
produced by a three spring reverb tray inside the cabinet.
Reverb (“Goldtone” GA-30RVS only)
This single control is for adjusting the amount of reverb effect in the sound. The effect is
produced by a three spring reverb tray inside the cabinet. However, due to a simple but
extremely effective modification to the signal between the reverb tray and the stereo
power stages, what you actually hear is a huge pseudo-stereo reverb that seems to fill the
whole room. It is even more noticeable when using extension cabinets.
Footswitch Socket (“Goldtone” GA-15RV only)
This socket is for connecting to a latching footswitch and allows the user to turn the
reverb effect on or off during performance.
Footswitch Sockets (“Goldtone” GA-30RVS only)
These sockets are for connection to latching footswitches. The first one is dual function
and operates the extra gain stage (with VOLUME pulled out) and reverb. The second
turns the effects loop on or off if used.
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Effects Loop (“Goldtone” GA-30RVS only)
This has sockets for SEND, LEFT/MONO RETURN and RIGHT RETURN as well as a
switch for SERIES or PARALLEL configuration.
The SEND is for connection to the input of effects units and can drive floor type battery
powered effects pedals or 19” rack type studio effects units.
The RETURN sockets are for connection to the outputs of effects units. If a mono effect
unit is used then use the LEFT/MONO RETURN.
The SERIES/PARALLEL switch alters the configuration of the effects loop.
In SERIES mode the whole signal comes out of the amp, into the effects unit and then
back into the amp, whereas in PARALLEL mode the effected signal is mixed in with the
original dry signal, thus retaining tonal purity of the dry signal.
The choice of which mode to use will depend on what kind of effects unit is used and
what overall effect is desired. Generally if time delay effects are used, such as delay
(echo), chorus, flanging, phasing, etc., then the PARALLEL setting is usually preferred. If
volume or EQ related effects are used, such as overdrive/distortion, compression, graphic
equalisation, wah-wah or volume pedals, or if a multi-effects unit is used with a
combination of time delay and volume related effects, then it is usually best to set the
switch to SERIES. There are no rules, it is best to experiment and see what you prefer. If
PARALLEL configuration is used then, if possible, it is recommended that dry/direct signal
from the effects unit is turned off.
The effects loop is not activated unless a jack plug is inserted into the LEFT/MONO
RETURN socket. The loop is then footswitchable if a suitable latching footswich is
connected to the appropriate footswitch socket.
It is also possible to use the “Goldtone” GA-30RVS purely as a stand alone mono/stereo
power amp.
To do this set the loop to SERIES configuration, this will effectively eliminate the preamp
and plug signal source(s) into the RETURN socket(s).
External speaker output (“Goldtone” GA-15 & GA-15RV)
This is provided so that the user can connect the unit to an external 16Ω speaker cabinet,
such as a 4 x 12, for a different sound. This is useful for both live and studio use and can
radically change the sound of the amplifier. Try it at a high volume into a 4 x 12 and you
will not believe you are playing a 15 watt amp!
When the jack is inserted into this socket the internal speaker is disconnected. Always
ensure that the amplifier is correctly loaded when in use.
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