iSP Technologies THETA PRO DSP Owner's Manual

INTRODUCTION

Congratulations on your purchase of the THETA PRO DSP™. The THETA PRO DSP™ was

designed to provide the ultimate sonic performance possible in a Guitar DSP based processor; all
controlled on the floor, with simplicity of use and programmability. The THETA PRO DSP™ is based
on state of the art Digital and Analog circuit design and technology and features ISP Technologies

proprietary algorithms for all THETA PRO DSP™ functions. The THETA PRO DSP™ also features

the patented Decimator noise reduction system for the highest level of noise reduction and
transparency available. Also included on board is a SONG mode allowing the guitarist to arrange
presets into 124 songs with 4 preset patches per SONG. Please read this manual carefully for a
through explanation of the THETA PRO DSP™ and its functions.

IMPORTANT SAFTEY INSTRUCTIONS

Please read the following very carefully before operating this unit

 Read ALL instructions carefully before using this unit. Keep these instructions for future reference. Heed all

warnings and follow all instructions.

 Do not use this unit near water, in the rain, or where there is moisture. If this warning is ignored a serious

electrical shock or death may occur.

 Do not attempt to service this unit. No user serviceable parts inside. Refer servicing to qualified, ISP

approved personnel. Servicing is required when the unit is damaged in any way, such as power adaptor is
damaged, liquid has been spilled into the unit, the unit has been exposed to rain or moisture, does not
operate normally, or has been dropped.

 Care should be taken to avoid spilling any foreign objects or liquid into this unit. Avoid exposure of this

equipment to dripping or splashing and ensure that no objects filled with liquid, such as vases, are placed on
the equipment.

 Only use accessories or attachments that are specified by the manufacturer.
 Failure to follow these instructions may void the warranty.

NO USER SERVICABLE PARTS INSIDE. REFER SERVICING TO
QUALIFIED ISP TECHNOLOGIES SERVICE PERSONNEL.

The lightning bolt triangle is used to alert the user to the risk of electric shock.
The exclamation point triangle is used to alert the user to important operating or

maintenance instructions.

POWER REQUIREMENTS
This unit requires the connection of the external AC Power Adaptor to a 120 volt AC
outlet. Do not attempt to connect this unit to any power source other than the one
supplied with the THETA PRO DSP. The THETA PRO DSP will typically draw on
the order of 1.5 amps of current from the AC power adaptor when in use.

Quick Start

Refer to the Figures shown for the hardware drawings which show the locations of
the switches, knobs, and jacks when reading the following, or even better, just look
at your unit.

1. Connect the guitar to the IN jack, connect the STAGE OUT jack(s) to a power

amp such as the ISP Stealth which is connected to a guitar speaker cabinet, OR
connect the DIRECT OUT jacks to the input of a mixer, OR connect the
PHONES jack to headphones or earbuds (or connect all three). With a mono
system, the output(s) can be set to mono in the global parameters later. The
STAGE OUT jacks can be connected to a conventional guitar amplifier, but this
will not yield optimum results, since most guitar amps will further shape and
distort the sound.

2. Connect the supplied 9V AC power adaptor to wall power, then to the POWER

input on the Theta Pro. The unit will power up and recall Preset 1. Pressing the
RECALL 1 switch will display the Preset 1 title.

3. With the Preset title displayed, adjust the INPUT LEVEL control on the back

panel so that the LEVEL 0 LED (red) just flashes when playing hard, then back
off the INPUT LEVEL control slightly so that the 0 LED does not light. Short,
infrequent flashes of the red 0 LED are generally not audible. Adjust the STAGE
OUT LEVEL or PHONES LEVEL controls to taste. The DIRECT OUT levels can
be controlled by the global DIRECT TRIM parameter which affects all presets,
and by the OUTPUT LEVEL parameter within each preset, which affects all
outputs, but is the level specific to each preset. Note that the LEVEL LEDs only
display the raw input level when the preset or song titles are displayed
(FUNCTION turned fully counterclockwise). If any other parameters are
displayed, the LEVEL LEDs will display the maximum of the 4 output DAC
(Digital to Analog Converter) levels.

4. Play!

5. Presets can be selected by pressing the PRESET down or up switches, then
the RECALL 1 switch. Holding the PRESET down or up switches will result in
progressively faster scrolling through the preset titles. The RECALL 2 switch
will immediately increment one preset, and the RECALL 3 switch will
immediately decrement one preset. These can be used to step through the
presets to try them out. The RECALL 4 switch will jump back to the last
previously recalled preset, easy to remember since it is the last switch on the
right. If the preset title is displayed (if FUNCTION is set fully
counterclockwise), the VALUE knob can be turned to scroll through the preset
titles. Pressing the RECALL 1 switch will then recall the selected preset.

6. BOOST, PHASER, TREMOLO, CHORUS, FLANGER, DELAY, and REVERB
can be turned on or off by the top row of switches, depending on the settings
within each preset.

7. Pressing the SECOND switch allows access to the WAH on/off, STORE, and
SONG Mode, as well as TAP functions to set the modulation rates and
DELAY time. The FUNCTION knob selects the function such as Preamp,
EQ, etc. The PARAM knob selects the parameter within the function, and the
VALUE knob adjusts the value.

8. Changing a value will light the red STORE LED. To store the new value for
later recall, press the 2nd switch, followed by the STORE switch. Note that the
THETA PRO DSP ships with the Preset 1-100 and Preset 101-200 LOCK set
to ON, so storing to those presets will display a FAIL message. Storing to
presets 201-224 is always allowed. See the section on the Global
Parameters for more information on how turn off the Locks.

9. To copy a preset to a different location, first recall the preset. Then scroll to
the desired new location by using the PRESET down or up switches, or the
VALUE knob (if FUNCTION is set fully counterclockwise). Note that the
preset titles will flash, meaning the preset is not fully recalled. Then press 2nd,
STORE to store the last recalled preset into the new location. The original
contents of this location will be overwritten, so be careful. The unit ships with
100 unique presets written in locations 1 to 100, then repeated again in
locations 101 to 200, we recommend that one of the two banks be left locked
to prevent inadvertently writing over the original presets, at least until the
storage space is needed for new original presets.

10. Read the rest of the manual, it contains much valuable information to get the
most from your Theta Pro DSP!

DETAILED OPERATION:
Refer to Figures above for the hardware drawings which show the locations of

the switches, knobs, and jacks when reading the following. Refer to Figure 2 for
the signal flow diagram which shows the flow of the signal through the unit from
the input to the outputs. The following text explains the operation of the unit
organized by the software functions and parameters, but it also incorporates
explanations of the hardware functions where they are interrelated to the
software. This fusion of both domains together helps to simplify the
understanding of the unit, since everything about a single concept is contained
together. Also, many important operational details are contained in the Quick
Start section, so reading and understanding that section is essential.

PRESET MODE:
This is the default mode when the unit is first turned on. It allows direct recall of
presets by name, adjustment and programming of presets, mapping of switches
and the expression pedal, MIDI Dump and Load, and setting of Global
parameters. The other mode of the unit is SONG MODE, which will be described
later.

Functions and Parameters:
Note that the titles of the functions do not always appear on the display, but most

of them are contained within the first parameter of that function. The following list
of functions are accessed in order by turning the FUNCTION knob clockwise.
The parameters are then accessed by turning the PARAM knob. The values
displayed are changed by turning the VALUE knob.

A) Mixer Function

1. OUTPUT LEVEL (OFF to +10 dB): Controls the output level
feeding all outputs from the unit. This is to allow the presets to be
set to nominally equal levels given different gains, compression,
EQ, and effects. It also allows adjustment to prevent clipping of the
4 channel output DAC. When the Function is turned to display this
or any parameter other than the titles, the LEVEL leds will display
the maximum output level of the 4 DAC channels. The OUTPUT
LEVEL can then be adjusted to prevent clipping of the DAC by
keeping the red 0 dB LED from lighting.

2. DIRECT PAN (0 to 100): Pans the direct signal (the signal before
the stereo effects) from Left (0) to Right (100). The primary use for
this is to have the direct sent to one channel and the delay sent to
the other.

3. BOOST (OFF or ON): When ON, boosts the level of the signal
after the Preamp.

4. BOOST LEVEL (0 to 10 dB): Adjusts the amount of BOOST. Note
that if the preset already has a hot level, too much boost can clip
the output DACs.

B) PREAMP Function

1. PREAMP (CLEAN or DISTORT): In CLEAN, the distortion part of
the preamp is bypassed, so the DIST TYPE, GAIN, and SAG
parameters have no effect, and it is not possible to get clipping
within the preamp section, due to floating point processing. If you
are still hearing distortion, it is probably due to the input ADC or
output DACs being overdriven, or your guitar, amp, mixer,
speakers, headphones, or ears. In DISTORT, the distortion part of
the preamp is enabled, so all the parameters become active.

2. DIST TYPE (THETA or VINTAGE): THETA type applies an EQ
curve before the clipper stage that matches that of the ISP THETA
pedal. This is in addition to the settings of the PRE EQ controls.
VINTAGE removes this curve, so that the only pre-distort EQ is
what has been set on the PRE EQ controls. Real vintage amps do
not have much pre-clip EQ, but sound less desirable at high gain
settings.

3. GAIN (1 to 90 dB): Dials up the gain before the clipper stage.
Additionally, there is gain available in the Pre EQ and THETA type
distortion, so that the total amount of gain applied to the signal can
exceed 120 dB! As a point of reference, a typical amp head has a
gain of about 60 dB with the knobs set to maximum. If the GAIN is
set above 60 dB, the compressor will be disabled, even if the
PREAMP is set to CLEAN. To re-enable the compressor, the GAIN
must be lowered to 60 or less, then the COMPRESSOR parameter
can be turned from OFF to ON.

4. SAG (0 to 100): Emulates the sag of the supply voltage rails in an
amp. Higher values result in more sag. As you play harder, the
rails sag down resulting in more clipping of the signal. Play softer
and the rails move higher, resulting in a cleaner sound. This is
most effective with moderate levels of GAIN.

5. OUTPUT LEVEL (OFF to +10 dB): This is the same parameter as
in the mixer function. It is just repeated here for convenience
because as preamp parameters are changed, it is typical that the
output level will need to be readjusted.

6. COMPRESSOR (OFF or ON): Turns on the compressor, which is
positioned before the clipper stage. Compression is useful for
making clean or low gain settings sound louder, as it reduces the
level of loud passages and increases the level of soft passages.
The downside is the more compression used via lowering the
threshold, the more noise is added to the signal. See the GAIN
parameter for an explanation of how it affects the compressor.

7. COMP THRESH (-30 to 0): The lower the setting, the more the
compression.

8. PRE BASS (-15 dB to +15 dB): The level of the pre-clip bass EQ.
Generally for distorted presets this is set to 0 or negative to get a
bass cut. For higher gains, these pre-EQ sections do not so much
affect the tone of the output, but rather affect the character of the
distortion.

9. PRE BASS (40 Hz to 240 Hz): The ‘turnover’ or upper frequency at
which the amount of pre bass boost or cut begins to lose effect.
Frequencies above this point will still be boosted or cut, just not as
much, and as frequency in the signal increases, the amount will
diminish to 0. This is a ‘shelf EQ’ type section that remains
nominally flat at low frequencies.

10. PRE MID (-15 dB to +15 dB): The level of pre-clip midrange EQ.
Generally for distorted presets this is set to a positive value to get a
boost in the mids.

See the graph on the next page for a better understanding of
the operation of a parametric equalizer.

Note: there are three controls that adjust a parametric
equalizer including BOOST – CUT (LEVEL), FREQUENCY or
FREQUENCY SWEEP (FREQ) and BANDWIDTH or OCTAVES
(BW). The graph below shows an EQ response curve with a center

frequency of 100Hz and also at 1KHz. The MID “LEVEL” on the
THETA PRO DSP will adjust the amount of Boost or Cut applied to
the signal. The MID FREQUENCY, “FREQ” adjusts the center
frequency as shown below allowing you to select the center point or
peak frequency you are boosting or cutting. The MID BANDWIDTH
“BW” is the bandwidth of the frequencies being boosted or cut and
is selected as OCTAVES. An OCTAVE setting of .1 will be a
narrow band of frequencies that are affected by the boost or cut
approximately .1 octaves at 3bd down from the peak frequency. An
OCTAVE setting of 2.5 will be a much broader portion of the
spectrum that is affected by the boost or cut approximately 2.5
octaves at 3db down from the peak frequency. This type of
equalization allows much more precise adjustment of tone shaping
than typical Bass, Mid, Treble controls.

11. PRE MID (88 Hz to 6000 Hz): The center frequency of the
midrange boost or cut. It is typically set in the 300 to 2000 Hz
range.

12. PRE MID (0.1 to 2.5 OCT): The approximate width in octaves of
the midrange boost or cut. Beyond this width, the curve will slowly
transition back to 0 if the bass and treble are set flat.

13. PRE TREBLE (-15 dB to +15 dB): The level of pre-clip treble EQ.

14. PRE TREBLE (2000 Hz to 12.0kHz): The lower frequency at
which the amount of pre treble boost or cut begins to lose effect.