TTP ATX1 Analog VCO Instruction Manual

: May 15, 2024
: TTP

Table of Contents

TTP ATX1 Analog VCO
Features
Installation Instructions
QUICK START ART PATCH
SWITCH MODES
AUTO TUNING
SPECIFICATIONS
References
Read User Manual Online (PDF format)
Download This Manual (PDF format)

TTP ATX1 Analog VCO

TTP-ATX1-Analog-VCO-PRODUCT

Features

Analog VCO with 4 classic waveforms (sine, triangle, saw, pulse)
ART Mode
1V/Octave Mode
LFO Mode
Single input for both ART and 1V/octave
Dual frequency controls for precise tuning
FM input
PWM control with external CV
Crossfade between waveforms manually and with CV
Sync input
Gate out for ART

Installation Instructions

FIRST STEP – INITIAL TUNING

Please note, this manual uses Octopus, however all tuning function are available from other ART controllers as well and are not limited to Octopus.

TTP-ATX1-Analog-VCO-FIG-1

ATX1 is a smart analog VCO that learns your setup environment and the case it is in.
In order to get the best performance from ATX1 we highly recommend doing an initial tuning to give the VCO a baseline recording of its new home.
Place the ATX1 and Octopus in your case. Turn on the case and let it warm up for about 30 minutes for a small/medium case (like Mantis) or up to 1 hour for a very large case.
When fully warmed up, patch ART1 out from Octopus to the ATX1 ART in jack.
Click the ATX1 button until it turns Red showing it is in ART mode.
Now hold down the AUTO TUNE button on Octopus till the display shows INT TUNE message, then release the button. At this point the ATX1 will start to tune itself, the LED will first turn off and then start blinking yellow as it tunes.
Wait until the LED comes back solid red. This process can take anywhere from several seconds up to several minutes. Do not interrupt the process. Once complete ATX1 can be used normally and only needs quick Auto Tuning from time to time.
The Initial Tuning procedure is recommended to be done when the ATX1 is moved to a new case or environment or if regular Auto Tuning (see later in the manual) takes a long time. Now let’s start the first patch.

QUICK START ART PATCH

(Requires Octopus)

Set ATX1 to ART mode by pressing the Mode switch until the LED is Red.
Turn the Frequency knob to the middle (noon) and the Fine knob fully left (counter-clockwise) and also the FM knob fully left.
The pitch of the ATX1 Audio Out should be very close to Middle C (261.63 Hz).

TTP-ATX1-Analog-VCO-FIG-2

Connect a computer running DAW/MIDI software using a USB cable or hardware MIDI with a 5 pin MIDI DIN cable to Octopus.
Set the output of the DAW channel or MIDI hardware to MIDI channel 1
Set Octopus to MONO 8, click the settings button to edit. (see Octopus manual for settings)
Patch ART OUT channel 1 from Octopus to ATX1 ART In, select ART on the ATX1, RED light.
Patch Audio Out to a filter or VCA.
Patch Gate Out to an envelope generator (ADSR, AR, etc) and envelope out to filter or VCA.
Play notes on the DAW or MIDI device, you should see the MIDI In light on Octopus flashing and the ATX1 gate out LED flash too with the notes playing.

TTP-ATX1-Analog-VCO-FIG-3

Important note about Tuning and AUTO TUNE

ATX1 has two types of tunings, INITIAL TUNING and Auto Tuning. Both should be implemented only after a decent system warm up time.
INITIAL TUNING had been discussed in the beginning of this user manual and is usually done once to serve as a starting tuning base and can be indicated by yellow flashing light.
AUTO TUNE is done from time to time to correct the tuning to the current environment.
It uses the Initial table to slightly adjust the tuning for the current temperature. This is the most common form of tuning. Auto Tune can be done by holding down the red button on ATX1 or by sending an Auto Tune command from Octopus. Auto Tuning should take several seconds up to about a minute and flash red light. If it feels like it takes too long then you most likely need to redo the INITIAL TUNING again to build a new tuning base.
Please read the section of this manual for more information on Auto Tuning and also Initial Tuning.

SWITCH MODES

ART – RED

ART is a high speed digital protocol developed by Tiptop Audio that replaces 1V/Oct pitch voltages with reliable and stable numeric values. ART also carries other performance data from MIDI control sources.
Frequency knob offsets the octave in relation to the incoming note values. Full left is 1 octave down, in the center no octave shift and full right moves the pitch up one octave.
Fine knob sets tuning offsets. The left half of the control detunes the pitch up to about 1 semitone. The right half of the control sets semitone intervals from +1 to +12 (octave up).
These two controls combine to allow multiple ATX to create chords and rich detuned sounds. Be sure to check the Fine knob in case the ATX1 feels like it is not playing in tune as it can shift the ATX1 from the expected pitch very slightly!
The Gate output is active in ART mode only and can be connected to envelope generators that control VCA levels, filter cutoffs and so on.
To make multiple ATX1 play the same notes use a Stackcable or passive mult to send the ART signal to all of them at the same time. Only one ATX1 Gate Out needs to be used since it will be the same for all modules connected this way.

1V/Oct- Yellow

This is the standard Eurorack 1 volt per octave analog voltage used for pitch. ATX1 tracks well over many octaves but this mode is only included for legacy compatibility.
Frequency sets the coarse pitch of the VCO
Fine allows for more precise tuning of the pitch.

LFO- No light

Sets the VCO range much lower than 1V/oct and ART range. Applying CV to the ART jack still works to change the frequency. The ATX1 will go from very slow cycles and up to audio range in that mode.
Frequency sets the coarse frequency of the LFO
Fine allows for more precise tuning of the LFO speed.

FM INPUT

Analog voltage input to change the frequency of the VCO. Works in all 3 modes.
The knob controls how much of the incoming voltage modulates the frequency.
In ART mode the FM is limited in range for vibrato effects.

PWM

This control varies the pulse width of the pulse waveform in percentage of the ‘on’ time (duty cycle) from a few percent to almost 100% and due to tolerances on some units can go above.
The knob works to manually set the width and the CV input is offset from that setting.

WAVE MIX
ATX’s output waveform can continuously vary from Sine to Triangle to Saw to Pulse using this control. The external CV input allows modulation of the waveform which can have filter like effects as the harmonics are changed.
SYNC IN
Inputting an external VCO will cause ATX to hard sync to the start of the external waveform. This can create some harsher sounds than just the standard waveforms or FM.
GATE OUT
In ART mode this output sets the gate high for a note on and low for the note off of the same pitch. The ART patching architecture puts the Gate out on the oscillator to tie that oscillator to it’s envelope or anything that voice is driving. That help maintain clear polyphonic patches.
AUDIO OUT
The waveform mix output.

ART CONTROL VALUES:

ART signals can contain more than pitch information. Below is a list of controls ATX1 responds to (i.e. from a MIDI source using Octopus).

Pitch Bend

ATX can do pitch bend up and down from a MIDI controller. MIDI CC 21 sets the range form 1 to 12 semitones.

Control Change

Portamento Time (CC 5): sets how long the glide between notes Pitch Bend Range (CC 21): the number of semitones the pitch bend control uses.
Values are 0-11 for +/-1 to +/-12 semitones. Values 12 and higher are wrapped around to the 0-11 range. Default is +/- 12 semitones.

AUTO TUNING

ATX1 is an analog oscillator and might need slight tuning adjustments to match the electrical rails and ambient temperature of your Eurorack case. ATX1 has internal tuning tables based on temperature.
There are two different tuning options: Auto Tune and Initial Tune.
Auto Tune is done from time to time to correct the tuning to the current environment.
It uses the Initial table to slightly adjust the tuning for the current temperature. This is the most common form of tuning.
ATX1 can run the Auto Tuning in two ways

Octopus (recommended) sends Auto Tune or Initial Tune messages. This can be done to multiple ATX1 at the same time. Press the AUTO TUNE button on Octopus and the display will show TUNE NOW and the button LED turns Green. Press the button again and the display changes to AUTO TUNE and the button LED turns off.
ATX1 will now tune.
Hold the SWITCH Mode button down in ART mode for Auto Tuning.

When Auto Tuning runs the mode switch LED will flash RED to indicate it is moving through the frequency range. It will blink slowly at first since low frequencies take time to measure and tune. As the frequency increases the flashing will also increase in speed.
The LED will turn solid RED when tuning is complete. (note that ART messages sent to ATX1 during tuning might be ignored).
Initial Tuning is first done at the factory to establish a baseline tuning table. In some situations your case/environment might not match the factory tuning parameters very closely and the factory tuning is not accurate. If you notice the following, an initialization of the tuning data might be necessary:

Auto Tune takes a very long time to complete (more than 1-2 minutes)
Pitch is only accurate for a short period of time after tuning
You moved ATX1 from an enclosed case (Mantis) to an open case (HEK) or to a case or location with much higher internal/ambient temperature.

To replace the factory tuning allow the ATX1 to warm up for 30 minutes and then have the connected Octopus send an Initial Tune message (hold the Octopus Auto Tune button down for several seconds until the display shows INIT TUNE).

During Initial Tuning the mode switch LED will flash YELLOW (not RED) to indicate ATX1 is performing Initial Tuning and not the regular Auto Tune. This process takes longer than the Auto Tune since the internal table is cleared and the VCO must be tuned from scratch.
Tuning does not require removing modulation cables attached to the ATX1, however if possible it is recommended to keep just the ART and audio plugged when auto tuning and especially if Initial Auto Tuning is performed.
For best performance it is recommended to house the ATX1 in an enclosed Eurorack case like Mantis where heat builds up internally and helps maintain a fairly constant temperature.

Firmware Updates:

ATX1 has an SD card slot on the rear circuit board used to update firmware. Use a MSDOS FAT32 formatted card for the update.
Unzip the firmware update file. It will be called image.hex. Copy to SD card Power off the case with ATX1, remove the module from the case (keep power cable attached!) and insert the SD card.
Hold the front panel button down and power on the case. When LED flashes release the button.
Once the update is done ATX1 will run the updated firmware code.