STATUS ARTIS
// RESEARCH PERIOD: 2004-2023 //
** ORIGINAL ALL-ANALOG fx AUDIO CIRCUIT DESIGNS **
BFP #1 … GERMANIUM-TO-SILICON HARDWARE SIMULATORS
This BFP hits guitarists where it counts, by pushing the world’s most notable vintage dirt circuits into new upper territories of gain all while maintaining signature character, etc … in principle the idea can be used in any design that used Germanium devices but for now I’ve decided to focus on “the basic three” ie., the classic Ge dirt circuits …
super-RM (c)2020 // status: MANUFACTURABLE
range-master / modified treble-booster … evolves into higher gain unit combining variable drive filter with Ge-hardware emulation … for years Gallagher, Clapton, Iommi, May, and others all toured with this style circuit as their single dirty-booster pedal
super-FF (c)2020 // status: MANUFACTURABLE
same idea applied to the early/classic Face circuit … from a tight face job, to blathery saturation, and anything in between – the response can go from featherly clean to bombastic just with picking strength and the circuit responds to the guitar’s volume control as old Ge units do …
super-TB (c)2020 // status: MANUFACTURABLE
BFP #2 … HARDWARE SIMULATOR
The Arbutus Booster is useful as an ON_ALL_THE_TIME non-linear booster in front of old low-gain (not very hot by design) tube amplifiers – turning some combos into seething little beasts … many players have told me they use it this way with their favorite amplifier – it’s part of the overal tone
Beyond the Triode-response emulator shown here I have discovered the existence of two other methods for hardware-simulating the large signal “soft-clipping” action associated with class-A Triode signal transfer. I’m sure there must be other undiscovered hardware solutions to this BFP we don’t know of.
super-TRIODIFIER (c)2012 // status: MANUFACTURABLE
BFP #3 … HARDWARE SIMULATOR
By sandwiching my Triodifier stage between preamp and EQ stages then feeding a 60watt power stage I can get a realistic set of tube-like power dynamics that holds up to a drum kit.
BFP #4 … HARDWARE SIMULATOR
A 5-way parametrically variable high-headroom/high-drive linearization of the Kushner-Plunkett 2-transistor classic WAH circuit; with full replication of (un-buffered) input network loading. The same transfer function can be produced two ways, in both cases a physical (Fasel) inductor is used.
para-WAH (c)2009 // status: POTENTIALLY MANUFACTURABLE
BFP #5 … HARDWARE SIMULATOR
One of the important targets in this tube-vibrato emulator is getting the HP/LP cross-over frequencies just right // one way is to match it to an accurate simulation of the original Fender tube circuit (I used my 12ax7 SPICE modelling). The final way is to verify that the zero-depth response sounds identical to straight signal when bypassed – which the audio clip below demonstrates.
As with some of my other phasors, trems and sine modulators the design features an extended range Univibe LFO circuit, which imparts a very natural analog feel. Notice the almost-phasor like response in anti-phase mode!
Dedicated to the memory of good friend Roly Roper (RIP)
6G-HarmonicTremolo with phase/anti-phase/chop modes (c)2013 // status: MANUFACTURABLE
BFP #6 … HARDWARE SIMULATOR
After years of building refined clones of the Acoustic 360 preamp I came up with a linearized “modern” equivalent that uses the same 1.5Hy Cinemag inductor and producing a somewhat stronger/sharper EQ response. Same 12-position (single-band) cut/boost EQ function with Treb/Bass shelves but augmented with my optical-based ENVELOPE-LOCK limiter block. Features super low-noise and super low-distortion – with
versatile controls.
360-MODERN (c)2014 // status: MANUFACTURABLE
BFP #7 … HARDWARE SIMULATOR
The BIAS MODULATING TREMOLO BFP … Hardware Emulation
Producing high headroom “bias modulating” Tremolo similar in quality to the gain-modulating effect found in the output stage of 6G16 brown-face Fender tube amplifiers (labelled there as Vibrato – not to be confused either with Harmonic Tremolo (see above) appearing in other brown-face models).
The “Unitrem” features an adapted Univibe LFO circuit, which helps impart a strong analog feel to the effect. Version III only uses three transistors in total and easily goes into heavy chop territory without distorting the signal.
UNI-TREM-III (c)2019 // status: MANUFACTURABLE
First discovered in 2005 … here’s what version II from 2011 sounded like:
OPTO-VIBE-II (c)2014 // status: LIMITED MANUFACTURABILITY
I wanted to see how close to the response of a bulb-based Univibe I could get using instead matched opto-couplers and a current-driver, all with the same standard Univibe LFO engine. The control interface I came up with here eventually (spring 2025) becomes part of a solution to what I consider to be the biggest BFP of all time …
Presented below: two examples demonstrating improvements of the common types of ALL-PASS filters found in many commercial phasor pedals.
IMPROVED-STD-OTA (c)2014 // status: MANUFACTURABLE
The key to making OTA phasors sound more focused and swirly in the high range.
TOWARDS AN IMPROVED non-optical/non-jFET/non-OTA 2-STAGE PHASOR (c)2022 // status: MANUFACTURABLE
EARLY RESULTS … exploring a different approach
RECENT DEVELOPMENTS (FALL 2024) …
AUTOMATIC GAIN CONTROL BFP’s
The final frontier, my main design obsession these days …
obtaining a more-complete theory of AGC circuits, incl. 570 compander chipset, DBX, THAT Corp, etc. etc. … how to obtain comparable results using rediculously small hardware footprints … more importantly, how (what) to avoid that makes a dead/dull (un-musical/un-inspiring) sounding audio compressor // and how to figure (proof) it out quickly using a simple test
“ENVELOPE LOCK” FLOATING-GAIN-COMP/Limiter (c)2014 // status: EXPERIMENTAL
LA-2A style minimalist opto-limiter (c)2019 // status: MANUFACTURABLE
LA-2A style “fast” non/opto-limiter (c)2017 // status: MANUFACTURABLE
minimalist OTA style limiter (c)2017 // status: MANUFACTURABLE
Having had success in other forms of non-linear Cv control this is something I had to try – and the feel of this thing is truly amazing. In the process it suggests, or confirms, how the human psycho-acoustic mind seems to prefer one type of response over another (my subjective interpretation here).
This easy to build design provides two of the four main AGC processing responses, and they are the usual kind. Essentially a feed-fwd/back switch-able design that doesn’t require any specialized IC’s. See the not-a-Limiter design below which provides the two other AGC modes.
Incidentally, this design has nothing at all in common with the DynaComp (including the signal path structure) other than using an OTA as controlled amplifier // a new approach to solving the problem this way …
Broadcast-Limiter with 7uS ATTACK/RELEASE times (c)2018 // status: MANUFACTURABLE
This circuit chops up the signal at 140khz and applies the Riemann integral limit in reverse. There is no localized time averaging performed by charging/discharging a capacitor …
NOT-A-LIMITER (c)2022 // status: MANUFACTURABLE
This original design provides two of the four main AGC processing responses, and they are not the usual Limiter and Comp-Limiter kind. Essentially a broadcast signal oriented design from the 70’s adapted to instrument level use without necessitating specialized IC’s.… in the clip below notice the near-infinite sustain produced in one mode!
Signetics had the right idea in getting rid of the noisy op-amp that was included in the NE570/NE571 chips but had they put out an NE57X version with all sections completely decoupled, and without added 20k/30k resistors – even if only including one compander circuit per package – these would likely be widely in use today still. Fortunately, a discrete implementation (and its variations) is not beyond practical reach … an interesting and little explored area of audio circuit design research.
RECTIFIER BFP’s
MAXIMIZING RING … AND PRESENTING A NEW APPROACH
FULL-WAVE RECTIFIER WITH “LOW-BUT-NOT-TOO-LOW” THRESHOLD (c)2019 // status: MANUFACTURABLE
SPLIT-WAVE FREQUENCY DOUBLER (c)2019 // status: MANUFACTURABLE
WAVE-SHAPER BFP’s
Pure Electronic Design Non-Sense …
1-BIT A/D FUZZ of DOOM (c)2019 // status: MANUFACTURABLE
NYQUIST ALISIER (c)2005 // status: MANUFACTURABLE
NEW-TOPOLOGY “GAINY CMOS-INVERTER FUZZ” (c)2017 // status: MANUFACTURABLE
“GLOTTAL WAVE” CONVERTER (c)2018 // status: MANUFACTURABLE
“HARD-MODULATOR” WITH HIGH CARRIER REJECTION (c)2018 // status: MANUFACTURABLE
“SUB-MULTIPLIXER” WITH WIDE-OPEN CHANNELS (c)2018 // status: MANUFACTURABLE
ODD’S and ENDS
Things that don’t fit elsewhere …
ORIGINAL HI-FI COIL DRIVER APPLIED TO “JENSEN JT-DB-E” TX (c)2018 // status: MANUFACTURABLE
ZERO-DEGRADATION OPTICAL STAGE/LIVE MUTE FOR (k&k) PASSIVE PICKUPS (c)2019 // status: MANUFACTURABLE
EPILOGUE // THE “BBD” BFP … re: Analog Delay, Chorus and Flanging
So far, I’ve steered well clear of anything BBD related …
That changed recently after talking to a friend in Germany who delids IC’s, helping clear some of my mis-conceptions about BBD behavior. Which lead to a nice discovery //
–>> **NEW** approach to BBD based signal processing (c)2022-2023 // status: EXPERIMENTAL TBD