Mad Bean Pedals Turnabout User manual

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 lter.
• 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 ne, 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 benet.

Parts Turnabout
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Values Turnabout
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Traces Turnabout
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B.O.M. Turnabout
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Resistors Caps Diodes
R1 1M C1 22n D1, D2 LED
R2 1k C2 1n D3 BAT46
R3 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 22k C11 100uF Pots
R12 22k C12 100n TONE 10kC
C13 10uF PRES 25kB
THICC 25kB
VOL 100kA
GAIN 100kB

Shopping List Turnabout
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Value QTY Type Rating
47R 1 Metal Film 1/4W
470R 1 Metal Film 1/4W
1k 3 Metal Film 1/4W
4k7 1 Metal Film 1/4W
10k 1 Metal Film 1/4W
22k 2 Metal Film 1/4W
1M 3 Metal Film 1/4W
100pF 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, Diffused 5mm
BAT46 1
BAT41 2
1N4001 1
2N7000 2
LM833 1
SPDT 1 On/Off/On, Solder Lug
10kC 1 PCB Mount, Plastic Shaft 9mm
25kB 2 PCB Mount, Plastic Shaft 9mm
100kA 1 PCB Mount, Right Angle 16mm
100kB 1 PCB Mount, Right Angle 16mm

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Parts Guide Turnabout
LM833N:
https://www.mouser.com/ProductDetail/926-LM833N-NOPB
The LM833N should be available at smallbear, as well.
BAT46:
https://www.mouser.com/ProductDetail/511-BAT46
http://smallbear-electronics.mybigcommerce.com/diode-schottky-bat46/
BAT41:
https://www.mouser.com/ProductDetail/511-BAT41
http://smallbear-electronics.mybigcommerce.com/diode-schottky-bat41/
2n7000:
https://www.mouser.com/ProductDetail/512-2N7000
http://smallbear-electronics.mybigcommerce.com/transistor-fet-2n7000/
SPDT (On/Off/On):
http://smallbear-electronics.mybigcommerce.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 difcult to nd right now. Suggest subbing in a linear pot (B
taper).
16mm Right Angle Pots (100kA, 100kB):
http://smallbear-electronics.mybigcommerce.com/alpha-single-gang-16mm-right-angle-pc-mount/
Thinline DC Jack:
http://smallbear-electronics.mybigcommerce.com/dc-power-jack-all-plastic-unswitched-2-1-mm/
Enclosed Mono:
http://smallbear-electronics.mybigcommerce.com/1-4-in-mono-enclosed-jack/
http://smallbear-electronics.mybigcommerce.com/1-4-in-mono-enclosed-switchcraft-111x/
Lumberg Mono:
http://smallbear-electronics.mybigcommerce.com/lumberg-1-4-compact-shrouded-mono-jack/

Notes Turnabout
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• To understand the best way to use the Tone and Pres controls think of it this way: the Presence
control is what you use to set the maximum range of the Tone control. It’s what you will change
rst when plugging in different guitars or to different amps. Then the Tone control is used
continuously to set the amount of ltering you want for a particular sound. Darker amps and
guitars with humbuckers will generally have a higher Pres setting than say, a 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. At lower Thicc settings, the maximum amount of distortion will also be reduced.
So, in general, when you want to get the lowest gain amount possible out of the Turnabout you
are going to turn down the Thicc and Gain controls and set the Comp switch for the least amount
of compression (the LEDs). The Thicc control also lets you shovel some mud out of neck pickups,
too.
• The clipping LEDs will light up when they are selected so if you like blinky lights you can mount
one or both externally.

Wiring Diagram Turnabout
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1590B Drill Guide Turnabout
Note: Drill Guides are approximate and may require tweaking depending on the types of jacks, switches and pots you use.
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• This is a tight t, but should work if you use the Lumberg or open-frame style
1/4” jacks.
• I don’t recommend using any of the mbp 3pdt boards for this enclosure.

1590B2 Drill Guide Turnabout
Note: Drill Guides are approximate and may require tweaking depending on the types of jacks, switches and pots you use.
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• 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 t everything properly. Drill only one LED spot!
• Lumberg style jacks are used here but other styles may t using the same drill
locations.

125B Drill Guide Turnabout
Note: Drill Guides are approximate and may require tweaking depending on the types of jacks, switches and pots you use.
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• Shown with Softie 1 relay bypass. Use 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 t open-
frame metal jacks or the Lumberg style.
• You could also use side jacks but you’ll need to move the Softie1 drill spot
down. If you use side jacks with a regular 3pdt instead of the Softie simply
pick your drill spots for the jacks.

Voltages Turnabout
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• 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

Build Pic Turnabout
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Schematic Turnabout
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