stage of the FX unit and has it’s level greatly reduced so as not to
overload the FX units low energy chip. After the processing is
completed by the chip, the signal strength is returned by a tran-
sistor. So now the nice, fat tube preamp tone is converted to a
thin, wimpy transistor tone. We call this “the tone sucking tran-
sistor FX syndrome”...and we designed a system that cures it!
Our approach is to use two signal paths that are mixed on the rear
panel via the Mix control. Usually, you would mix the dry/wet level
on your FX unit, but for best result with our loop you will now want
to set you FX unit for 100% Wet and 0% Dry. The Send level
would normally be set fully up, unless you are using a low signal
level device such as a foot pedal in which case you might over-
drive the FX unit unless you lowered the send level. Use the
Return jack for the output of the FX device, and the Mix control to
blend in the desired level of FX. The secret is to have the Mix level
set with 98% Dry signal from the internal Soul-o preamp stage
blended with a 2% very Wet FX level (see photo above). This
should give you loads of FX, while letting the original preamp sig-
nal pass unaffected by the transistor tone stage of the FX device.
When using the optional footswitch, you should be able to turn the
Loop off and on without any change in tone...it should be
absolutely transparent when set up in this manner. For some real
flexibility, try inserting a normal foot controlled volume pedal
between the FX return signal path. Now when you increase the vol-
ume controller the FX will gradually come on or off as you like, leave
the loop selector of the footswitch in the “on” mode and simply use
the pedal to turn your FX unit on or off, or anywhere between!
Other Soul-o Series Options
The S75RM and S150 RM (the RM stands for “Rack Mount”) amps
can be inserted directly into your rack system. They may also be
built into various wood cabinets and coupled with various GT speak-
er cabinet to make really great sounding, traditional looking amp.
Here are some of the cabinets and accessories you may want to
consider to customize your Soul-o amp to your specific needs. It
should be noted that all Soul-o cabinets are constructed of inter-
locking lightweight plywood that is braced, power nailed, and
glued. The cabinets are then covered in US made heavy Tolex mate-
rial.
S/FS:
A matching footswitch that selects between Clean and
Scream, selects Both (on or off), and turns the Parallel loop on/off.
LED lights indicate the status of the various selections and it
comes with a 25’ cable terminated in a 5 pin Din connector that
connects to the rear panel of the amp.
Cage:
A metal cage used to protect the tubes. Commonly used if the
amp is to be freestanding, say on top of a recording console. Strong
enough to have 4 rubber feet attached to the top/bottom of the cage
“Tone Tips” for tubes and output stage options
• Gritty, greasy old AC30 tone, but louder, try using EL34’s in
Class A Gnarly. Estimated power from the S75 ranges from 50 to
55 watts depending on EL34 type used.
• Warm & bouncy round old Tweed tone, try any 6L6 type tube in
the Class A Normal mode. Estimated power output of a S75 ranges
from 45 to 55 watts depending on 6L6 type used.
• Newer, tighter, cleaner Blackface Fender tone, try any of the 6L6
types in the Class A/B mode. Estimated power output of a S75
ranges from 55 to 70 watts depending on 6L6 type used.
• Dynamic Metal punch or crunch tone, try a EL34 type, or better
yet the newly developed, high powered GT E34Ls in the Class A/B
mode. Estimated power output of a S75 ranges from 65 to 75
watts depending on EL34 type used.
• Steel clean, ball peen hammer tone, try the KT88s tubes in the
Class A/B mode and plug in your Telecaster with the bridge pick
up...you’ll think you’ve died and gone to hillbilly heaven! Estimated
power output of a S75 ranges from 80 to 95 watts depending on
KT88/6550 type used.
Note:
The S150 amp this can produce over 190 watts RMS...and
can easily damage hearing. So be careful not to stand directly in
front this amp connected to one of our EX412 cabs....you have
been warned!
Speaker Impedance Selector
The GT custom designed
output transformers not
only work with many
types of power tubes,
but also have multiple
secondary windings that
allows for selection
between 4, 8, and 16 ohms speaker loads. These features allow
you to customize your amp and speaker combination to emulate
virtually any classic amp example or invent new combinations. We
believe in the philosophy to customize, and not modify, the basic
components of the amp and thereby give the owner the ultimate in
flexibility. As his or her musical tastes and needs change through
the years, the Soul-o Series amp can evolve with them.
CAUTION:
Always use the #1 speaker jack. The #2 is only for
adding a second speaker. The #1 jack has shorting circuitry which
turns the amp off if there is no speaker connected. Also, the total
load of one, or both speakers should correspond with the speaker
impedance selector.
The Parallel FX Loop
This is the most tonally transparent FX loop you have ever heard,
IF you learn to operate it correctly. When properly set up, this loop
allows you to use any digital or analog FX unit blended in parallel
with your original dry preamp signal without any sacrifice of
tone...which is the case when using a conventional FX loop. That’s
because most guitar amp FX loops are Series types, so the FX are
placed “in series” between the preamp and power stage. In this
design, a relatively powerful tube preamp signal enters the input
