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Turnabout

FX TYPE: Distortion

Based on the JHS® @™

Enclosure Size: 1590B, 1590B2, 125B
“Softie” compatibility: Softie1&2

© 

2020 

madbeanpedals

Overview

The Turnabout is a variation of the Andy Timmons pedal produced by JHS

®

, which is in turn pretty 

much a clone of the MI Audio Crunchbox. It produces thick, meaty distortion to emulate cranked 4x12 

type tones. The Turnabout offers two additions: an asymmetrical clipping option and a thickness 

control to dial in the low end.

Controls

•  VOL: 

Total output.

•  GAIN: 

From medium to high gain distortion. The gain control is interactive with the Thicc control. 

•  TONE: 

Low pass filter.

•  PRES: 

The Presence control is interactive with the Tone control. Higher values increase the 

overall presence which in turn pushes the tone control into a brighter range.

•  THICC: 

Controls the amount of low end sent to the clipping stage. 

•  COMP:

 LED, Schottky and asymmetrical clipping. LED is the loudest (stock to the CrunchBox), 

Schottky is the most compressed and the asymmetrical mosfet clipping is in-between. 

Terms of Use: 

You are free to use purchased 

Turnabout 

circuit boards for both DIY and small commercial operations. You may not 

offer 

Turnabout

 PCBs for resale or as part of a “kit” in a commercial fashion. Peer to peer re-sale is fine, though.

Technical assistance

 for your build(s) is available via the 

madbeanpedals forum

. Please go there rather than emailing me for 

assistance on builds. This is because (1) I’m not always 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.

Summary of Contents for Turnabout

Page 1: ...presence which in turn pushes the tone control into a brighter range THICC Controls the amount of low end sent to the clipping stage COMP LED Schottky and asymmetrical clipping LED is the loudest sto...

Page 2: ...Parts Turnabout madbeanpedals...

Page 3: ...Values Turnabout madbeanpedals...

Page 4: ...Traces Turnabout madbeanpedals...

Page 5: ...1M C3 100pF D4 D5 BAT41 R4 1k C4 47n D6 1N4001 R5 1k C5 100n Transistors R6 10k C6 100pF Q1 Q2 2N7000 R7 1M C7 1uF IC R8 470R C8 22n IC1 LM833 R9 47R C9 22n Switch R10 4k7 C10 470n COMP On Off On R11...

Page 6: ...2 Ceramic MLCC Mica 16v min 1n 1 Film 16v min 22n 3 Film 16v min 47n 1 Film 16v min 100n 2 Film 16v min 470n 1 Film 16v min 1uF 1 Film 16v min 10uF 1 Electrolytic 100uF 1 Electrolytic LED 2 RED Diffu...

Page 7: ...ommerce com spdt short lever center off 9mm Plastic Shaft Pots 10kC 25kB http smallbear electronics mybigcommerce com alpha single gang 9mm pc mount The 10kC plastic shaft pots are very difficult to f...

Page 8: ...Vox amp or Tele style guitar unless you really WANT to punish everyone around you The Thicc control lets you dial out some of the bass in the stock pedal as well as put in a little extra if you like A...

Page 9: ...Wiring Diagram Turnabout madbeanpedals...

Page 10: ...te and may require tweaking depending on the types of jacks switches and pots you use madbeanpedals This is a tight fit but should work if you use the Lumberg or open frame style 1 4 jacks I don t rec...

Page 11: ...s you use madbeanpedals Shown with Softie 2 relay bypass If you are using one of the mbp 3pdt bypass boards or just a 3pdt switch on its own move the drill spot for the switch a bit lower so you can f...

Page 12: ...the same drill spot for 3PDT switch or move to your desired location Drill only one LED spot Enclosed top jacks are used here but you should also be able to fit open frame metal jacks or the Lumberg...

Page 13: ...Voltages Turnabout madbeanpedals 9 42vDC One Spot Current Draw 6mA IC1 LM833 1 4 74 2 4 76 3 4 35 4 0 5 4 55 6 4 55 7 4 32 8 9 12...

Page 14: ...Build Pic Turnabout madbeanpedals...

Page 15: ...Schematic Turnabout madbeanpedals...

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