Split-O-Matic prototype board. The u ni t provides a ninverting option for each channel, and a master I. Circuit Description The lour buffer channels are identical; onlv channell is described.
Instrument feed couples through Cl to unity-gain AC voltage follower. ICl-a, whose output couples to level-con trol pot R2, whose wi per lies to a pol a ritv-i nversion block consisting of 51, ICl-c, and associated componenls. Audio coupl es t hroughR7 -C 11 to the 0 u tpu t path. MikO-Malic circuit board. Mix-OMatic schematic. R3 trims multiplier balance.
Ou tpu t of the pa n n i ng network couples to IC1-d, an inverting amp that controls the output level by R Feed the Input a l-KHz sinewave 3Vp-p.
Connect output to oscilloscope. Trim R3 to give a clean, even sinewave at twice the input frequency see Fig. If no Signal generator and oscilloscope are avail- Fig. Distort-O-Matic V prototype board. This procedure takes two people.
First, connect unit to axe and amp. Center R3. Set preamp gain at maximum, R12 fully CCw. Set the output level at desired volume. Now rotate R12 fully Cw. While a helper dea nly picks the lowE-string at the 15th fret, trim R3 for minimum volume. The tone at that point might sound an octave above its expected pitch.
In this condition the box acts as a preamp with gain near unity. R2 varies distortion trorn none to complete. Because the axe output is usually not a pure sinewave, the 40M output is not frequency-doubled; rather, it contains very high levels of distor ion products. The outpu I is doubled in frequency when the input is a pure sinewave, which sometimes happens wah cleanly picked notes above the 7th fret. Hinq-moduieror-Iike sounds occur when the player picks two notes together. Distort-O-Matic V schematic.
Notes Making R3 a lKpanel pot lets the player vary multiplier balance. This gives a different range of sounds compared 10 mixing wet with dry. With R3 at one ex- me the si nal coming off the 4QM is almost clean, taking on a bit of lube-like distortion as R3 is rotated away from the limit. If R3 is taken the other way, past lhe multiplier's balance pain I, the signa I retains a high distortion quotient.
A-Output level trimmed 10 match input; distortion control fully CCw, giving purely clean leed. Scope display should look this way when R3 is properly trimmed. Complex sinewave sums do not emerge frequency-doubled, but extremely rich in distortion products. Distort-O-Matic V circuit board. Envelo-Mauc EM fleshes out the concept in a unique and versatile way. IC1-a output couples directly to a voltage-controlled parametric equalizer comprised of IC5-a, IC2, IC3, and their associated components.
R16 controls output level. IC4-d output couples through R29 to the control parr of the voltaqe-conrrolled filter. The metal tab of the"TO regulator case ties to the 5VOC ground, so isolate the heatsink from the metal case.
If this is not possible, insulate the heats ink lrorn the tab using a mica washer and silicone heatsink compound. The wall wart must supply no less than 8 volts nor more than 12 volts, DC or AC, at a current capacity of at least mao Observe proper polarity when wiring a DC wart.
As a tool of subtlety and extremes, harnessing its potential calls for an understandinq of the controls. All eight pots are so responsive thaI it's possible to build a functional box that seems nonfunctional due to improper control settings Give yourself the bener part of a weekend to learn this box. Labeling the controls is a good idea.
Connect unit to axe and amp, establish desired volume. First, explore the range of the parametric EO working under manual control. Turn boost fully CCw, take R15 Ihrough its range to vary frequency. You shoufd note strong cut that shifts over the approximate range Hz 10 6 KHz. Vary bandwidth to see how this affects adjacent frequencies Next, take R24 into boost territory.
Exercise care, because EM can boost up to 20 dB. With R24 applying full boost in a conspicuous way, ease RS open while plucking a string. The filter's center frequency will move in response to the input signaL How far it moves depends on preamp gain and setting of R5; which way it moves depends on the position of S2. At this point you may nora distortion, due to very Iast attack and decay.
Advance decay to abOUI 9 o'clock; ba rely open the a t tack can trol, and this distortion should subside. Once you have a handle on how the box works, lake attack and decay through their ranges and note the effects of delaying each.
The user will find it rewarding to explore EM's effects pre- and post-distortion, to accentuate or mute distortion products under dynamic control. OC--Offsets in the filter limit internal headroom to about 22Vp-p.
Overload is possible: 3Vp-p au! Envelo-Matic Circuit Board. I t Fig. Envelo-Matic schematic. Envelo-Matic prototype board. C5 helps keep the carrier from feeding back through the FM port. IC3 output drives an ultrasonic transducer. Receiver: The ul trasonic sensor couples directly to input of IC1-d, a non inverting preamp whose gain va ries Under control of pot R IC2-a output couples directly toa precision fullwave rectifier made up IC1-a, [C2-b, and their associated components.
IC2-b output couples dlrectlv to a lowpass filter made up 01 IC2-c and associated components. This filler lets the player attenuate low-frequency ani-facts as described below. IC2- doutput couples directly to inverting amp IC2-a. The audio signal couples through RC16 to the output path.
R25 varies the output level. Encoding, sending, and decoding an axe feed creates two effects. Rrst, overdriving the frequency modulator yields rich distortion whose personality varies with carrier frequency and drive level. In addition, the ultrasonic signal picks up spuriae in transit that decode in ways rangingfmm mildly interesting to practically cool.
Place the transducers on a table, apertures facing, a few inches apart. Secure them with tape if necassarv. Power up OMS, slowly turn up the amp's volume; trim R6 until audio is heard At this point the audio should sound distorted. Take modulation drive control R21hrough its range. The lower the drive level, the less distortion and sustain; the higher the drive level, the greater the distortion and sustain.
Next, explore the effect of altering carrier frequency R6. The device exhibits a fairly wide sweet spot, as well as marginal areas at the extremes of pot rotation where the distortion threshold rises, giving a punchthrough effect. Distort-O-Matic VI schematic. Move the transducers to the point they're atmost touchlnq, vary receiver gain and note the effect on sound.
Now move the transducers about a toot epart, Take R16 through its range and note the effect ofputling distance between the transducers. With transducers aboutB" apart and a strong signa I established, move your hand over the pair about 2" above them: note the whoosh due to spuriae from ultrasonic echoes off the moving hand. Turn R23 tufly CWand note the change in tone. It may be necessary 10 turn up the amp's bass control to perceive the subsonic element of this signal.
The transducers don't have to face each other. Put them about 3" apart but facing the same direction. Now you have a tiny sonar system capable of detecting movement of objects in the bea m. Place I he pair " from, say, a speaker cone. Movement of the cone registers in the ultrasonic mix. Transducers' leads can solder directly 10 the board if desired. Similar transducers sometimes surface in surplus channels; most transducers described as "KHz resonant" should work in OM6.
Non-resonant transducers, or those that resonate at a frequency other than 40 KHz, will not work. The transducers may register other sources of u I trasonicenergy, such e. Top: TypicalKHz ultrasonic transducers. Lead soldered to case should tie to circuit ground.
Distort-O-Malic VI circuit board. The external input couples to S1's other throw; 51's pole teeds the signal through el0-R18 to the input of IC4, half an NE configured as a voltage controlled amplifier whose output is taken off pin 10 and couples through RC7-R19 to IC6-a. Signal couples through RC9 to the output path. The net signal path is noninverting. Control Path: lel output couples directly to a precision fullwave rectifier made up of IC2-a, -b, and associated components.
The resvlt of the control path is for the output of IC3 to approach ground in the absence of a primary input signal. In this state the gain of IC4 is essentially 0, so any signal present in the secondary audio path does not reach the output. A primary input signal generates a positive voltage conducted through IC3 to IC4, causing gain to rise to a maximum ot 1 when IC3's output swings to lIS positive limit.
The setting of RS controls Fig. Modu-Malic prototype board. R" ne. Modu-Matic schematic. Initial settings: all pots fully CCw, Sl either position. First, trim the DC offset of IC4. A significant change in supply voltage will require retrimming R Untrimmed feedthrough i.
Performance was notattected, because the unit usually operates with attack or decay past minimum, which puts teedthrough well into the Infrasonic. Users wishing to trim feedthrough can follow this procedure: Set attack and decay at minimum, primary and secondary output levels at zero.
Apply a Hz sinewave to the primary input; adjust preamp gain to give 5Vp-p at ICl output. Place scope probe on output of IC2-c, adjust R5togive maximum amplitude short of clipping.
This gives about 3Vp-p of ripple in the control voltage. Move scope probe to pin 10 of IC4, [rim R14 for minimum leedthrough. Trrm R26 to give desired preamp gain. Turn R2S fully CCW to kill the primary feed, turn R17 fully CW to open the secondary audio path; slowly open RS while plucking a string and note that the secondary feed is heard only while a primary input exists.
Take R9 through its range and note the effect of delayed attack. Maximum delay is -4 seconds. Return attack to minimum. Take RS through its range to hear the effect 01 delayed decay. At maximum decay, the secondary feed continues to be heard tor -4 seconds after cessation of the primary signal. Turn amp volume down, switch Sl to 'internal' a pop accompanies switching , return amp volume to desired level.
In this stale, attack and decay operate on the primary input. The nature of clipping strips the signal 01 dynamic range. By feeding the line-level output of the luzz box into Modu-Matic's secondary input, fuzz can be made to track instrument dynamics as tightly or as loosely as desired. Connect the secondary feed to some odd sound source: a digital sample, FM intersiauon hiss, etc.
The secondary effect takes up to several seconds to emerge atter playing commences, or as long to decay once playing ceases. Advancing attack creates a delay between picking the string and the emergence of sou nd from the amp-an automatic guitar swell.
Fast decay heightens the effect. Notes Modu-Matic is optimized for a 15V supply. Significant departure form this voltage is not recommended. Use of a regulated 15V supply allows omission of 05, and replacement of Rl 6 wi lh a 7. While the primary input accommodates instrument-level to line-level feeds, the secondary input is designed only for line-level feeds, and high ones at that, preferably averaging at least 2Vp-p.
Modu-Matic circuit board. Circuit Function Signal feed couples through C3 to noninverting preamp lei-a,. IC1-a I output couples to IC1-b, a unity-gain invening amp. If RZ are changed such that the SVFs exists predominantly in the leedback loop, gain reducrlon results from reduced feedback Impedance lor frequencies passed by the SVFs.
All four filters possess independently variable center frequency R5 and bandwidth R7. ICl-c output couples through AZ8-C8 to the unbalanced output, the signal path at that point is noninveninq. In this state the box acts as a preamp whose gain depends on setting of A1S. To avoid interaction, at leas! Quad Parametro-Matic schematic. Notes Despite 13 pots, wiring PM2 presents no particular problem if you rake your time.
Color-coded wire eases the process: one color for all the bandwidth POlS, one for all the gain pots, a third for frequency pots. Twisting wire pairs helps, as does labeling each lead with a small piece of masking tape. Instability will result under certain conditions; for example, maximum preamp gain coupled with maximum gain of overlapping bands placed on the same frequency, plus maximum output gain.
This totals more than 60 dB. Aside from avoiding sug:t an unmusical setting, separate the input and 6lnput leads. Make the pot leads short. The SVFs used in PM2 differ from the one used in Pararnetro-Maric by sneaking the signal in through the path normally used to control bandwidth, allowing bandwidth control bv a single rather than a dual pot see Ref.
Preampgain resistor R15 can be a trlrnpot, fixed resistor, or panel pot. Quad Parametro-Matic prototype board. Quad Parametro-Matic circuit board. The signal path is noninvening. Both sinewave paths possess enough gain to clip if their levels are advanced to maximum, giving quasisquarewave control pulses.
Tremolo-Matic II prototype board. Tremolo-Matic II schematic. Next, trim the primary sine generator. Connect Qpe probe to IC1, pin 8. Move scope probe to IC1 pin 7, trim R28 as above fOr the secondary sine generator.
Move scope probe to IC6, pin 7. Trim R1B for m. Connect unit to axe and amp; establtsh desired volume. If you elect to run TM2 off batteries, include the rectifier diode shown on the wiring diagram. The prototype photo shows a single-turn trimpot for R7, but a multiturn POI is recommended.
The preamp is configured tor fixed gain SUitable for instrument-level feeds. Replace R35 with a 20K audio-taper pot to accommodate inputs ranging from instrument-Ievelto line-level. TM2 should run at a high internal level for best SIN ratio. Average preamp output of 3Vp-p leaves adequate headroom. Adding a second oscillator to a basic tremolo resui ts in more sonic variety than one might expect from the nature of the change.
Patient, methodical experimentation rewards the player with sounds not heard on existing recordings. When mixing rates, initially center the static gain control. In many cases this changes the sound Significantly. The most practical way to recall desirable control settings is to provide nurnbered scales for the controls, and note the settings. Tremolo-Matic II circuit board. IC7-a output couples through C17 to compressor IC2-a, thence through C18 10 a six-stage phase-shift network whose output feeds a highpass filter before being expanded by IC2-b.
Expander output couples through C3-R1S LO IC8-c, which adds or subtracts clean and phase-shifted versions of the signal, depending on setting of Signal couples through AC4 to the output pa tho Control Path: IC6 and associated components form a sinewave oscillatorwhose rate varies Sinewave output couples to R2, which varies level.
R6 varies DC offset at output ot IC1, which ties through R7 to the ganged control inputs of six lype OTAs, each configured as a single-ended vcltaqe controlled resistor; each simulated resistor combines with an op amp to give a variable phase-shift network.
Their need will be determined later. Ol,uF C16, 24 Q. Phase-O-Matic schematic. In this state the box acts as a preamp. Connect unit to axe and amp, adjust R17 to obtain desired volume. Slowly rotate depth control R2 CW and note the sound of vibrato. Phase-O-Matic circuit board. Turn depth all the way down, switch S2 to 'phase: to 'add,' set R19 at about 11 o'clock. Now turn R2 CW and exe the sound of phase, distinguished from vibra to addi.
Significant depare from this voltage is not recommended. Use of an op amp having a greater alive output swing than the TL's results in through too severe fa r t he com ps nde r to ha nd Ie. The preamp's nominal gain of 5. Highpass filtering attenuates much of the feed through, but quieting the box at rest requires added measures, internal companding in this case.
To further reduce noise at rest, POM includes an option to introduce mistracking between compressor and expander patented technique, see Hel. The prototype was quiet enough at rest that this feature was not needed, so R23 and R38 were not insta lled.
Most phase boxes feature variable feedback in the phase-shift chain. Companding makes this irnpractical lor POM. The O. Compressor output also ties through RlO-C13 to the output path. The compression control voltage present at pin 1 lies 10 voltage follower IC2-a, whose output ties to One throw of S2-b. Zener diodes limit maximum compressor output. Expander: Signal input couples through C25 to IC, a noninvening amp configured for gain of 2. IC3-a output lies to pot R14, feeding buffer IC3-b, whose output couples through C20 to expander signal input pin 14, as well as through C22 to treble emphasis network RC21, to one throw of a.
When 52 selects 'internal,' the expander's control voltage is a buffered version 01 the compression control Voltage, and the expander's rectifier input is open.
Expander audio output couples through CR11 to the output path. Compand-O-Malic Lite prototype board. Connect ICl output and expander output to oscilloscope.
Feed the input a 1-KHz sinewave lVp-p. Adjust R14 so that compressor input and expander output levels match. Compand-O-Matic Lite schematic. C ompand-O-Matic Lite A-Composite of response to tone burst. Compressor output would clip at headroom limit, but for action otzener diodes; short duration 01 clipping makes it Inaudible. Expander output shows minimal deformation.
B-Composite 01 a tone burst more typical of music. No clipping; expander output closely resembles compressor input. Envelope bounce is more noticeable at low levels, but still not enough to require trimming which uses the same method as the VCA feedthrough trim.
D-Compressor input superimposed on expander output at 20 Hz constant tone. This represents the most extreme pure-tone test of system; distortion is very low. E-Raw compressor output reveals di stort ion neutra lized by expansion. Power up; 1 he n, whil e switch i ng 51 be twe en bypa ss and compand, trim R14 until no di rference in level is heard between bypass and compand. Turn off amp and Lite. Connect compressor output to input of a noi sy s tamp box, su ch a s a vi n ta g e ph ase shifter.
Feed effect output to expander input. Power up amp and outboard gear. Repeat the levelmatching sequence, note the reduction in noise at rest. Notes Ute is optimized lor a 15V supply, but works satistactorilyoverthe range V Lite's companding system is a chopped version of Signetics' Databook circuit.
Noise reduction compares to that su pp I ied by dbx Type II. Companding works best wi th unity-gain effects. Etfecrswith gain other than one fare best with 52 in 'external' position, the expander running off its own level detector.
OVp-p 1 KHz test tone at the outset 01 the recording facilitates later level match. Compand-O-Matic lite circuit board. Preamp output couples [0 IC1-b, a noninverting amp whose gain depends on settings 01 gain control pots R7-Rl1.
When pots are fully Cw, a series resonant network with one end tied to ground appears predominantly at lel-b's inverting input, raisinq gain for resonant frequencies. Tone-O-Matic II prototype board.
TEO II'! Connect uni t to audio source and target device, such as amp or recorder. Take each boost pot through range and note effect on tone. Notes Preamp output should not exceed 1Vp-rl to avoid overloading the simulated inductors.
Pads on the circuit board accommodate two cap widths. R2 can be a trimpot, a fixed resistor, or an externally mounted pot; the protorvpe used a fixed resistor. Tone-Q-Malic II schematic. The resul r, in a sense, spans the gap between tremolo and analog synth. R44 varies the output level. The signal path Is noninverting. Oscillation rate is controlled by the capacitor selected by l2-posilion rotary switch Function output couples to amplitude control pot R3l, thence through R30 to inverting buffer IC9.
Control vel tage couples through R46 to the control port pin 1 of IC3. Output of the attack network is buflered by IC6-b, whose output is held at the negative limit by the positive potential applied through R IC6-b output couples through R12 to the ba se of I n the a bse nce of a pos i tive vol tage! Tremolo -Matic III sch e matico 87 Tremolo-Malic III supplemental schematic. Tremolo-Matic III circuit board. Slow decay of the primary level detector gives low distortion as notes especially bass decay; but beating may be heard for several seconds before 02 turns ON.
This makes it desirable that the gate close swiftly when the player mutes the strings. The voltage flows through R49, causing 01 to source a negative current that neutralizes the positive cha rge in C6 in less than 40 ms. With gate threshold properly set, TM3 mutes when the player mutes the strings, with no audible lag, yet a 1I0ws uninterrupted decay of held notes and chords.
Ramp and negative ramp sound significantly different, especially at slow rates. These, too, change the sound distinctively. Short the input. Set S3 tor maximum tremolo rate. Description Written with advanced designers the stompbox cookbook mind, this book provides stomp-box builders with 38 advanced effects projects for electric guitar and bass, such as distortion boxes, a full-featured noise gate, studio-grade spot compressor, and echo adapter for three-head stonpbox decks.
Fortunately, Boscorelli includes appendices scattered throughout the book that cover topics like the anatomy of the stompbox cookbook cookbiok box, power supply options, troubleshooting, parts sources, discussions of the various kinds of effects, ideas for cooking up new effects and more. Each the stompbox cookbook includes a discussion of the circuit function, parts list, schematic, PCB etching layout and a physical layout and wiring diagram.
I find the bit on attack and decay envelopes really useful. Be the first to ask a question about The Stompbox Cookbook. The links are dead J-R Sanacore marked it as to-read Jun 19, I think its a great resource for anyone who likes building pedals.
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