Bastl KASTLE v 1.5 Manual

INSTRUCTIONS 

Kastle is a mini modular synth and as in every 

modular synth the sounds are programmed by connecting outputs to inputs. Outputs 

are labeled by a silver outline around the patch points. Inputs don‘t have the silver 

outline. Feel free to also connect inputs with inputs and outputs with outputs. Nothing 

bad will happen. And sometimes something interesting can happen with strange 

connections!

0 

Find a microUSB cable or go to your nearest store and buy 3 AA batteries. You can 

catch Pokemons on the way, though you don‘t have to, but the important thing is that 

on average you will burn 50 calories. Also, not shipping the batteries to you from us is 

environmentally friendly. 

Connect the USB cable to a powered 5V USB socket or insert the batteries to the 

battery compartment the right way - as indicated on the battery holder.

Flip the power switch to the USB or BATT position based on which power source you 

are using. There is a LED close to the LFO RATE knob which should light up. If it doesn‘t 

it means the USB socket is not powered or you connected the batteries in a wrong 

way or they are completely depleted.

1 

Use the OUT jack to connect your headphones or an audio cable from your 

speaker system. The main output of the complex oscillator is routed to the OUT jack.

2 

Turn the OSC PITCH knob to adjust the PITCH of the main oscillator. A modulation 

signal can be connected to the PITCH MOD socket and the PITCH MOD knob controls 

the amount of the modulation.

3 

Turn the OSC TIMBRE knob to adjust the PITCH of the modulating oscillator. 

A modulation signal can be connected to the TIMBRE MOD socket and the TIMBRE 

MOD knob sets the amount of the modulation.

4 

Turn the WAVESHAPE knob to adjust the 3rd parameter of the sound. A modulation 

signal can be connected to the WAVESHAPE socket to modulate this parameter. The 

WAVESHAPE also sets the pulse width of the OSC PULSE output.

5 

This patch point on the device can be either used as another signal for your patch 

or when any other output is connected to this output it will be passively mixed with 

the oscillator output and will go to the OUT jack. This is most useful for adding more 

power by connecting the SECONDARY OSC OUT.

6 

The SECONDARY OSC OUT provides alternative waveform based on the second- 

ary modulating oscillator and the waveform can be adjusted by the WAVESHAPE 

parameter. It can be either used to modulate parameters within the Kastle synth or 

patched to the OSC OUT socket to mix with the main waveform or it can be output 

separately via the I/O jack.

7 

The MODE socket lets you select the synthesis mode. The synthesis mode affects 

both the OSC OUT and the SECONDARY OSC OUT.  

○

 When nothing is connected the synthesis mode at OSC OUT is phase modulation 

and at SECONDARY OSC OUT is phase distortion. 

○ 

When a modulation signal plugged into this jack is high (or just patched to “+” 

socket) the synthesis mode becomes track & hold modulation on the OSC OUT and 

formant synthesis

 on the SECONDARY OSC OUT. 

○ 

When the signal connected here is low (or just patched to “–” socket) you are 

in dual noise mode with more tonal character at the SECONDARY OSC OUT. 

See the Synthesis Types section for more information.

8 

To set the MODE socket statically to specific synth mode use the low = ”–” or high 

= ”+” patch sockets. These patch points can be also useful to set the BIT IN pin. “+” 

can be used to offset any modulation signal and “–” connects directly to ground so it 

can be used to connect grounds between several instruments.

9 

The LFO RATE sets the speed of the modulation. The modulation is displayed by 

an LED close to the LFO RATE knob. A modulation signal can be connected to the 

RATE MOD socket and the RATE MOD knob sets the amount of the modulation. This is 

especially useful when creating more complex modulation curves. See Tips & Tricks 

section for more info.

10 

The LFO TRIANGLE socket outputs simple triangle waveform, but it can be 

altered by modulating the LFO RATE or triggering the LFO RST to get some complex 

modulation shapes.

11 

The LFO PULSE socket outputs PULSE wave in sync with the TRIANGLE wave. 

When the TRIANGLE wave is rising the PULSE output is high and when it is falling the 

output is low. This signal can be used for synchronising external equipment.

12 

The LFO RST resets the phase of the LFO to the highest point of the triangle and 

then the triangle begins to fall. This is very useful for creating complex modulation 

curves or for synchronising with external clock.

13 

The STEPPED generator is inspired by the Rungler circuit by Rob Hordijk. It can 

produce 8 different voltages. It generates new voltage twice per period of the LFO 

(every time the direction changes from rising to falling). The voltage is based on the 

current state of 3 bits of internal binary 8 bit shift register. The shift register is shifted 

with every new voltage generated. When this happens - based on the signal at the BIT 

IN socket - the new bit arriving to the shift register remains the same (BIT IN is low), is 

inverted (BIT IN is not connected) or is generated randomly (BIT IN is high). It means 

that when BIT IN is not connected the STEPPED output generates a 16 step pattern. 

When it is low it generates an 8 step pattern. When it is high it keeps generating 

a random pattern and when it is altering it generates a semi-random pattern. The 

STEPPED output is very useful for modulating every parameter in the Kastle synth 

or any external device with the I/O port.

14 

The I/O CV port enables you to connect up to 2 modulation/audio/clock 

signals from Kastle to external gear or to connect any external signal to modulate 

the Kastle synth. The signals are output with a stereo jack and the patch points 

L and R connect either to the left or right channel. To use both channels with a 

modular synth you can use stereo to mono splitter adapter or you can just use one 

channel (L) with a mono cable connected to the I/O jack. When connecting external 

modulation to Kastle please note that the signal will be rectified and Kastle will 

respond only to signals 0-5V.

OSC OUT

LFO

RST

BIT IN

STEPPED

MODE

L

R

OSC PITCH

LFO RATE

RATE MOD

TIMBRE MOD

OSC TIMBRE

WAVESHAPE

PITCH MOD

OUT

I / O

I / O

LFO

LFO

OSC

USB

USB POWER

BATT

2

2

3

3

9

9

9

8

7

2

3 12

13

10

11

6

4

14

5

1

14

0

0

FEATURES v 1.5

© complex oscillator

© 3 synthesis modes on the main output: phase modulation, noise mode,

track & hold modulation

© 3 more modes on the secondary OSC output: phase distortion, tonal noise mode, 

formant synthesis

© PITCH control with offset and CV input with attenuator

© TIMBRE control with offset and CV input with attenuator

© WAVESHAPE control with offset and CV input

© voltage controllable LFO with triangle and square outputs and reset input

© stepped voltage generator with random, 8 step and 16 step loop mode

© 2 I/O CV ports that can be routed to any patch point 

© the main output can drive headphones

© 3x AA battery operation or USB power selectable by a switch

© open source

© possibility of exchanging different LFO and OSC chips

© durable black & silver PCB enclosure

WHAT IS IN THE BOX

© kastle synth    ©10 patch cables    © sticker

© for environmental reasons we are excluding the batteries in the package

SEE WWW.BASTL-INSTRUMENTS.COM FOR MORE INFORMATION.