The Asheville Music Tools ACV-1 is an analog chorus and vibrato pedal that also covers slapback delay, flanging and more experimental time-warp territory, all from one modulated BBD delay line. Asheville Music Tools calls it a Chorus/Vibrato Time Warping Device and describes it as capable of "shimmering comb filter swirls, luscious true pitch vibrato, glitchy textures, ringing metallic pipe tones, and even a faux reverb"1. It is the second effect in the company's line of time, phase and frequency modulation pedals, following the AFG-1 Analog Dynamic Flanger2.
The circuit is built on a classic chorus architecture: a 1024-stage X-Vive high-voltage MN3007 BBD reissue chip as the delay line, a vintage-style compandor for noise reduction, discrete transistor 5th-order anti-aliasing and reconstruction filters, a VCA feedback circuit, a discrete high-impedance JFET input stage, and an analog clock VCO with a temperature-compensated exponential converter. The maker says the pedal uses over 350 selected components, including premium audio-grade op amps and high-tolerance, non-microphonic capacitors, and that it was engineered by Hawker1.
What the ACV-1 does
At its core the ACV-1 is a modulated analog delay. The Time knob sets delay from 3.1ms to 59ms, expanded to 155ms with an expression pedal, control voltages or the LFO1. An LFO then wobbles that delay time to create chorus or vibrato: the Rate knob runs from 0.1Hz to 14Hz, or 28Hz with CV control, and the Amount knob sets LFO depth from OFF up to 60% of the full Time sweep1. Three LFO waveforms are selectable, Triangle, Sine or a slewed Square wave, which changes the character of the modulation1.
Because the delay time reaches into slapback range and the feedback path is flexible, the pedal covers more than chorus. The maker lists the effect types as chorus, vibrato and slapback modulation, and the Tone control, which sits inside the feedback loop, can be turned counterclockwise for muted warmth or clockwise for what the maker calls bright punchy chorus or flanging sounds1.
Controls
| Control | What it does |
|---|---|
| Time | Delay time, 3.1ms to 59ms, expanded to 155ms with expression, CV or LFO1 |
| Rate | LFO rate, 0.1Hz to 14Hz, faster with an expression pedal1 |
| Amount | LFO depth, from OFF to 60% of the Time sweep1 |
| Mix | Center detent at 50%; adjusts from full wet to full dry1 |
| Tone | Tilt filter inside the feedback loop, about 740Hz center; high +5dB to -10dB, low +4dB to -7dB1 |
| Feedback | 0 to near infinite; capable of self-oscillation1 |
| Phase switch | 180-degree phase shift of the wet and feedback signals1 |
| Expression switch | 4-position rotary assigning CV/expression control to Time, Feedback, Rate or Amount1 |
| Bypass footswitch | Effect on/off1 |
The Phase switch is worth a note for chorus players: flipping the wet signal 180 degrees out of phase changes how the wet and dry signals combine, which shifts the pedal between chorus-style and flanger-style comb filtering1.
Expression and CV control
The ACV-1 takes synthesizer-style control seriously. A TRS jack on the pedal works with either a standard expression pedal or a control voltage source, with a CV range of 0 to 5V. The ring of the jack supplies a current-limited 5V output and the control input is on the tip1.
A 4-position rotary switch assigns that external control to Time, Feedback, Rate or Amount. The maker notes that all external controls are additive to the front panel knob, extending the range rather than replacing it, so a knob set partway up plus an expression pedal sweep can reach beyond what the knob alone allows1. Pedal of the Day highlighted this synthesizer-inspired control scheme in its 2024 review, which found "the look, feel and sounds created by the ACV-1 Analog Chorus Vibrato are all quite impressive"2.
External CV also unlocks the longest delay times: the range grows from the knob's 59ms maximum to 155ms under CV control1.
Feedback and self-oscillation
The Feedback control runs from 0 to what the maker calls near infinite, and the pedal is capable of self-oscillation using the tone control or the EXP/CV input coupled with knob position1. In practice this means the ACV-1 can move from subtle chorus into ringing metallic tones and faux reverb, the textures the maker lists among its capabilities1. The Tone control's placement inside the feedback loop shapes those runaway resonances as they build.
Power and connections
The ACV-1 runs on a standard 9V DC center-negative supply with a 2.1mm x 5.5mm barrel connector. Current draw is under 150mA, with 70 to 90mA typical and up to 250mA at startup1.
The startup draw of up to 250mA exceeds the pedal's running current. A power supply rated only for the typical draw may struggle at switch-on, so plan headroom accordingly1.
Input impedance is greater than 1MΩ and output impedance is 1KΩ max, or 5KΩ max in buffered bypass. Maximum input level is +14.25dBµ (4.0V RMS) and maximum output level is +14dBµ (3.9V RMS), which gives the pedal plenty of headroom for hot signals1. Noise reduction is handled by a 2:1 broadband compandor with 10dB high-frequency emphasis1.
The bypass question deserves its own answer: an internal slide switch, reached by removing the cover, selects between true bypass, which takes the pedal entirely out of the signal path, and a classic JFET buffered bypass that the maker says prevents noise and signal loss in longer effect chains. The input preamplifier's discrete high-impedance JFET stage can also be used as an always-on buffer1.
The ACV-NOS edition
The ACV-1 also exists as a limited edition, the ACV-NOS Edition. The standard ACV-1 remains the maker's regular-production version at $397.001.
Videos
collector//emitter
Mark Johnston
ambienttrash
Sources (2)
- ACV-1 Chorus/Vibrato Time Warping Device, Asheville Music Tools
- Asheville Music Tools ACV-1 Analog Chorus Vibrato, Pedal of the Day, 2024-05-18
