Table of Contents
Advertisement
Quick Links
Advertisement
Table of Contents
Summary of Contents for Slightly Nasty 2251
- Page 1 M O D E L 2 2 5 1 M U LT I B A N D F I LT E R VC A I N G A I N VC A O L OW B A N D H I G N O T 1 5 0 5 2 0...
- Page 2 M u l t i b a n d F i l t e r PHYSICAL FORM FACTOR: Loudest Warning / 4U WIDTH: 3NMW / 75.5mm HEIGHT: 175mm DEPTH: ~40mm from panel front inc. components PCB: 70 x 75mm, Two-Layer Double Sided CONNECTORS: 4mm Banana IDC power connector pinout.
-
Page 3: Table Of Contents
Extra VCA CHOOSING COMPONENTS Bill Of Materials (BOM) Choosing Components CONSTRUCTION Construction Overview Physical Assembly CALIBRATION Calibrating the 2251 CONTROLS Controls REFERENCE PCB Guide This document is best viewed in dual-page mode. C i rcui t Ove r v i ew... -
Page 4: Introduction
R E S . F R E Q. The Model 2251 uses the Loudest Warning 4U format for the front panel, and S L I G H T LY N A S T Y follows Eurorack electrical and power standards. All front panel components are PCB mounted for easy wiring-free construction. -
Page 5: Circuit Overview
The 2251 is really a fairly basic module in terms of architecture, with a filter core surrounded by some simple buffering and CV processing elements, along with a bonus utility VCA. -
Page 6: Signal / Res Cv Inputs
Resonance CV Input Signal Input Exponential Converter C i rcui t Over v i ew... - Page 7 M u l t i b a n d F i l t e r The 2251's audio input is buffered by an inverting amplifier stage built around U301D, that also drops the amplitude of the signal from the full 10v peak-to-peak level of modular signals to just under a quarter of that.
-
Page 8: Filter Core
M u l t i b a n d F i l t e r The filter core in the 2251 is a state-variable topology, which uses a pair of integrators (U201B and U201C) with feedback into a summing amplifier (U201A) to create an analogue computer that solves a second-order differential equation. - Page 9 C i rcui t Ove r v i ew...
-
Page 10: Extra Vca
M u l t i b a n d F i l t e r Because the LM13700 ICs contain two OTA units each, and only three are used in the filter itself, there's still one left over which can be put to good use. In this case the extra OTA is used to implement a general purpose VCA with basic functionality. -
Page 11: Bill Of Materials (Bom)
R101, R102 560R R212, R213 R202, R204, R207, R215, R217, R218, R223, R225, R310*, R506, R508, R511 *3300ppm/C Tempco if temperature stability required R312 R201, R203, R205, R221, R222, R224, R512 R209, R211, R219, R507 R404, R406, R502, R505, R509 R206, R216 R303, R309 100K... -
Page 12: Choosing Components
All resistors should be metal film 1% type, and capacitors are normal electrolytic and film types. While the vast majority of uses for the 2251 will not require accurate or stable pitch tracking, those who want to make the exponential converter as accurate as possible will need to either select a matched pair of BC560 PNP transistors or use a BCM857DS matched transistor IC. -
Page 13: Construction
M u l t i b a n d F i l t e r The majority of construction can be performed like any PCB build, starting with the lowest-profile components (resistors and diodes) and working through to the taller ones (Capacitors, transistors, etc.). The simplest way to populate the board is simply to work through the BOM, doing each component type and value in one chunk before moving on to the next. -
Page 14: Physical Assembly
M u l t i b a n d F i l t e r Assembling the finished PCBs and front panel is very simple. Begin by fitting the M3 hardware to the panel-side PCB. screwing the hex spacer tight to hold it all together. -
Page 15: Calibration
While setting the scaling for the exponential converter is normally a fairly critical adjustment in something like a VCO, in the case of the 2251 it is much less important given that the frequency CV is also scaled by the input attenuverter. - Page 16 M u l t i b a n d F i l t e r knob down to the "150" mark and check the frequency there. Adjust the Freq. Scale trimmer (RV306) until the frequency reads around 150Hz, then go back up to the "1.8k"...
-
Page 17: Controls
The audio input to the filter. I N P U T F R E Q. R E S . S L I G H T LY N A S T Y SLIGHTLY NASTY JACK COLOURS Bipolar signal output BLUE Bipolar signal input YELLOW... -
Page 18: Pcb Guide
A s y m m e t r i c S l e w L i m i t e r M u l t i b a n d F i l t e r LOWER BOARD - TOP LOWER BOARD - BOTTOM P C B Gui de... - Page 19 A s y m m e t r i c S l e w L i m i t e r M u l t i b a n d F i l t e r LOWER BOARD - TOP LOWER BOARD - BOTTOM P C B Gui de...
- Page 20 w w w . s l i g h t l y n a s t y . c o m...
Need help?
Do you have a question about the 2251 and is the answer not in the manual?
Questions and answers