Tuesday, January 31, 2023


The NT05 is a "LoFi RhythmBox"

It consists of;

-Two voices; "Sine" and "Noise"

-Two 128 step pattern banks

-Eight selectable rhythms

-Two "Pad" envelopes

-One LFO


The Sine voice has a VCA knob, Distortion knob, and Pitch knob. The Distortion knob effects the waveshape of the oscillator. At the low end, the waveshape is triangular. Midway it is Sine, and at full, the oscillator is squarewave. The Sine VCA knob sets the offset of the VCA, and can be used as a volume mix knob when other modulation inputs are not in use. The Sine VCA can be modulated by any combination of the LFO, Pad EG2, and the Sine Pattern bank EG. The Sine Pitch knob sets the offset of the Sine VCO, and can be used as a pitch control when the VCO is not being modulated. The Sine Pitch can also be modulated by any combination of the LFO, Pad EG2, and Sine Pattern bank EG, however, the LFO and EG2 can only modulate one or the other; VCA or Pitch. Likewise, Pad EG2 can only modulate one or the other; VCA or Pitch. When Pad EG2 is set to Pitch, the Pitch knob sets the depth of the envelope. The Sine Pattern EG is triggered by the Sine Pattern bank. The envelope modulates the Sine VCA, and can also modulate the Pitch. The Bend knob sets the depth at which the envelope modulates the Pitch. The decay of the envelope is controlled with the Decay knob. The decay can be modulated by the LFO via the Sine Decay Mod switch, however the decay has to be set longer, as the LFO can only shorten the decay time of the envelope. 

The Noise voice has all of the same VCA, Pitch, and modulation features as the Sine voice minus the distortion knob. The Noise voice is derived from a "LFSR" type pseudo-random-noise generator. The pattern length of the LFSR can be set to one of eight lengths. The shorter lengths are more harmonic, while the longer lengths sound noisier. When the LFSR Select switch is pressed down, the touch pads can be used to select the desired LFSR pattern length. A number below each touch pad represents the corresponding  pattern length.


The two Pattern Banks record and play back 128 steps continuously. There are eight two-channel 16-step rhythms to choose from for inputting into the Pattern banks. The touch pads select the rhythm, and as long as the pad is held, both Pattern banks will record their respective channel. Alternatively, there is a third channel per rhythm that can be substituted to either Sine or Noise Pattern by pressing the Pattern's respective Beat Roll switch. Each of the eight rhythms has a unique Beat Roll that is shared between the Sine and Noise pattern. Both the Sine and Noise Patterns have their own Step Erase switch. As long as this switch is held, the respective pattern will be erased one step at a time. There is also a Clear All switch that will instantly erase both patterns entirely. The Pattern Banks have two settings; Record, and Run. In Run mode, any rhythm input will trigger the Pattern EG's, but will not be recorded to the Pattern. Any rhythms already recorded will be looped continuously. In Record mode, the Pattern will continuously write over itself with any new input, or the looping output. The Pattern Banks are clocked by the Rate oscillator. The speed of the rhythms are set by the Rate knob, but can also be synced to external 5 volt clock signals via the Clk In jack. The internal or external clock source can also be sent out to other devices via the Clk Out jack. The Noise Pattern Bank can also be sent out to external devices via the Seq Out jack. All inputs and outputs are 0-5 volts.


The LFO can be used to modulate the VCA's, Pitch VCO's, and Pattern EG's as described in VOICES. The Rate and Depth of the LFO are controlled with the joystick. The Rate of the LFO can set to high or low via the HI switch next to the joystick. The rate of the LFO can also be modulated by Pad EG1 via the LFO Mod switch. The Depth control of the LFO can be set to bipolar or unipolar via the Offset switch next to the joystick. In bipolar mode, the LFO depth will rest midway when the LFO is fully attenuated. In uni-polar mode, the LFO depth will rest at zero when the LFO is fully attenuated. While the Pad EG1 LFO Mod is engaged, the Depth control sets the depth of the envelope to the LFO.


The two Pad Envelope Generators; EG1, EG2, are velocity sensitive, and are triggered either internally by tapping the unit, or externally via the Pad Input jack. The Pad Input jack was designed to accept any manner of input, but responds best to piezoelectric transducers like the one that is built into the unit. While the Pad Input jack is in use, the internal piezo is disabled. The Pad EG's have independent Decay knobs, and independent Invert switches. The Invert switches invert the response of their respective envelope generator. The Pad Input has a Response control knob to set the sensitivity of the Pad or input. The Response knob can be helpful when inputting stronger or weaker signals from devices such as audio signals or microphonic devices.


-Built-in speaker.

-Standard Boss style DC adapter

-Master Volume control knob

-Power on/off switch

-1/4 inch output jack

-6xAA battery compartment

bla-bla coming soon...

Saturday, January 28, 2023



The NTSH is a mini joystick noise synth.

It consists of; 

- one white noise generator

-one square wave oscillator

-one 12db resonant LP filter

-one Sample&Hold/envelope generator

The controls;

The joystick on the left controls the Filter Cutoff and the Pitch of the Square Wave VCO, while the joystick on the right controls the Gate frequency of the Sample&Hold, and the frequency of the Triangle Wave that is being sampled.

The Gate frequency is also the frequency of the Envelope Generator.

The Gate/Attack Time switch will set the Envelope Generator to either Triangle or Saw waveform.

In Triangle mode, the Sample&Hold Gate time will be at 50% on/off ratio. This will cause the modulation to sweep at the Triangle oscillator frequency between samples. 

The Sample&Hold and Envelope Generator modulation sources can each be set to VCO Pitch, VCF Cutoff, or both VCO and VCF together.

The Mixer switch sets the Voice output to VCO, Noise, or both Mixed.

The Mixer switch set to QOSC will turn off the Noise and VCO to the filter, and set the Resonance to self oscillation. The Filter Cutoff sets the QOSC frequency.

In QOSC mode, the Q knob is disabled. In all other modes, it sets the Resonance of the VCF.

The Volume knob sets the output volume level.

The NTSH has a power ON/OFF switch, 1/4 inch output jack, and built in speaker.

The NTSH can be powered by 3 AAA batteries, or with a standard 6-9VDC center positive adapter.

The design;

 The NTSH is smaller in size to other NT boxes by about half. 

The electronics are all analog, and designed from scratch. 

The goal was to design and build a new NT box that was smaller and more accessible for people to buy and support my work. These small boxes are relatively easier to build than the other NT box designs that came before it. They still take several days each to make, but because of their small size and limited function, it is a much less daunting task. I have trimmed a lot of the build time by investing in better power tools for sanding and shaping the boxes, and rather than hand painting the the face-plates, I am using colored acrylic. It costs a bit more, but I just don't have the time these days to do everything by hand anymore. The only drawback is that the colors are pretty limited.

The signal path of the NTSH is pretty basic but it covers a lot, I think. I knew I wanted a white noise generator with a resonant filter. I just love that sound. There wasn't enough space for any kind of sequencer, so I thought a S&H would be nice. The first iteration of the circuit used a bunch of cmos oscillators at different frequencies as a modulation source, because I thought a real S&H would take up too much space, but actually it was the other way around, and the cmos oscillators were difficult to control together in a reliable way. The most difficult but also must interesting part of this build was to come up with as many practical and quality functions as possible with such a small footprint. The end result is such a tight fit in the box, but I think it is perfectly balanced in sized and functionality. The circuitry was also very helpful.. By that I mean, the final circuit seemed to offer up solutions or new features that I hadn't intended using, and usually didn't require too much effort. For one thing, the white noise generator required a charge pump circuit to generate 12 volts to work. However, the current didn't have to be much, so I used the VCO to charge the pump(pump the charge?). Then the S&H gate offered up a perfect synced envelope generator, and the switch to make the gate/attack time 1/1 made both the S&H and envelope so much more dynamic. The Qosc function was something I decided to add after I had already finished the first prototype. It had occurred to me that the self oscillating filter sounded really great without an input signal, and implementing this was literally adding one connection to the Mixer switch! Sometimes things are meant to be.