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VFE_SPS_Dragon
VFE_SPS_Dragon
F
DYNAMIC OVERDRIVE
X Type:
Build Level: Intermediate
Based On: VFE® Dragon™
From the
VFE
website:
"Tubescreamer. Rat. Klon. OCD. Tim. KoT. What do all these beloved drive circuits have in
common? They all cut bass before distortion, and cut treble after distortion. This basic recipe is the
backbone of many of the dirt pedals you use. Enter the Dragon, a dynamic overdrive designed to
give you ultimate power over the pre-gain bass cut (HPF) and post-gain treble cut (LPF). Precisely
tighten or fatten up your low end, smooth out the top end or add sparkle. Go from a transparent
tone to a focused mid boost to push through a dense band mix, or just use it to light your favorite
drive on fire."
The SPS Dragon includes the TrueSoft 3.4 switching PCB with the voltage inverter. You will need
additional parts and information included in the TrueSoft doc to complete all VFE_SPS projects.
LEVEL, DRIVE: Self-explanatory.
HPF: High pass filter control to cut low frequencies (pre-gain).
LPF: Low pass filter control to cut high frequencies (post-gain).
COMP: Dynamic control over the two mosfet clippers that create the overdrive one. The center
position uses the least amount of clipping. The CCW and CW positions blend in different
amounts of clipping via the series mosfets.
IMPED: This trimmer sets the input impedance to the effect. Set high for single coils (CW), med
for high output humbuckers (middle) and low for active pups (CCW).
SLOPE: This switch determines whether the HPF and LPF act at -6dB or -12dB per octave.
LED: Controls the bypass LED brightness.
Terms of Use:
You are free to use purchased VFE_SPS_Dragon circuit boards for both DIY and small commercial operations. You may not offer VFE_SPS_Dragon PCBs for
resale or as part of a "kit" in a commercial fashion. Peer to peer re-sale is fine, though.
Technical assistance
for is available via the
available to respond via email in a timely and continuous manner, and (2) posting technical problems and solutions in the forum creates a record from which other
members may benefit.
All copyrights and registered trademarks are property of their original owners. Any mention of trademarked or intellectual properties in this documents is purely for
comparative purposes.
Overview
Controls
madbeanpedals
forum. Please go there rather than emailing me for personal assistance. This is because (1) I'm not always
Last Updated:
April 26, 2024 11:19 AM
© 2024
madbeanpedals

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Summary of Contents for madbeanpedals VFE SPS Dragon

  • Page 1 DYNAMIC OVERDRIVE X Type: Last Updated: April 26, 2024 11:19 AM Build Level: Intermediate © 2024 madbeanpedals Based On: VFE® Dragon™ Overview From the website: “Tubescreamer. Rat. Klon. OCD. Tim. KoT. What do all these beloved drive circuits have in common? They all cut bass before distortion, and cut treble after distortion.
  • Page 2: Parts Layout

    Parts Layout VFE_SPS_Dragon pg. 2...
  • Page 3: Component Values

    Component Values VFE_SPS_Dragon pg. 3...
  • Page 4 Trace Layout VFE_SPS_Dragon pg. 4...
  • Page 5 B.O.M. Resistors Caps Diodes 0.1u LED1 0.1u Transistors 150R .22u BS170 1.5k .33u BS170 100R 150R Quad amp 1.5k 4.7n Switches 2.2M .22u On/On/On 220R Footswitch Momentary Trimmers Pots P3AB C10k/100k 220R D100k P5AB C10k/100k W200k D100k VFE_SPS_Dragon pg. 5...
  • Page 6: Shopping List

    Shopping List Value Type Rating Spacing 100R Carbon / Metal Film 1/4W 150R Carbon / Metal Film 1/4W 220R Carbon / Metal Film 1/4W Carbon / Metal Film 1/4W 1.5k Carbon / Metal Film 1/4W Carbon / Metal Film 1/4W Carbon / Metal Film 1/4W 2.2M...
  • Page 7 Build Notes The Dragon uses some specialized pots which are available at Stomboxparts: C100k/C10k: https://stompboxparts.com/pots/16mm-dual-gang-pot-short-pcb-leg/ D100k: https://stompboxparts.com/pots/16mm-potentiometer-short-pcb-leg/ W200k: https://stompboxparts.com/potentiometers/16mm-potentiometer-short-pcb-leg-center-detent/ • The surface mount version of the Dragon uses a OPA4134 IC, which is only available as an SMD package. You can sub in a TL074 or any other quad amplifier that can handle 18v or more. •...
  • Page 8: Circuit Voltages

    Circuit Voltages TL074 BS170 42mV 43mV 46mV 9.19 0.00 BS170 0.00 0.00 0.00 0.00 0.00 -8.99 -406mV -457mV -457mV 9.44vDC One Spot supply Current Draw: ~50mA Knobs @ 50%, switch down Split-rail design VFE_SPS_Dragon pg. 8...
  • Page 9 125B Drill Template VFE_SPS_Dragon pg. 9...
  • Page 10 Build Pic VFE_SPS_Dragon pg. 10...
  • Page 11 Schematic VFE_SPS_Dragon pg. 11...

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