Akashic Guitar effects circuit lookup
DRIVETONEACCENTVOLUME

1590B · 4 knobs

Tagboard Effects

Shin's Music Dumbloid SpecialVerified

Based on the Shin's Music Dumbloid Special

Category
Overdrive
Controls
Drive · Tone · Accent · Volume
Build
Vero· 19×13· 17 cuts, 4 links
Layout
Verified · Tagboard Effects marks it as built and working
Tags
Overdrive

From the post

And the "Special" version with the Jazz/Rock switch. If I'd just added a cap I would have tacked this layout on the bottom of the first post, but I've shifted things around quite a bit, gained a row but lost two columns, and with this not being verified I thought it should have it's own thread to keep different version discussions/troubleshooting separated. I think I prefer this layout out of the two as it makes better use of the available space and will leave more room for wires at the sides if you're putting it in a 1590B.

Thanks to Amplified Nation for confirming position of the Jazz/Rock switch which only needs a single contact and so has been listed as a SPST, but use two lugs of a SPDT if you can get them more easily and cheaply.

If you can't find an opamp that clips pleasantly and so can't get round the fizz in your build, then consider making this small modification. Adding a back to back pair of diodes of your choice between pins 1 and 2 means that you'll get diode rather than opamp clipping. It does make it a bit closer to a Tubescreamer but the other changes will still make a difference and some people will think it's better to be closer to a Tubescreamer and sound good, than closer to the original and sound fizzy. Or if you want both options just build the original and add the diodes on a switch between pins 1 and 2.

Schematic

This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Tagboard Effects. No KiCad fragment has been drawn for this circuit yet.

Parts list 27 rows

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RefValueNormalizedTypeNotes
Resistors 8
×810K10kread from the layout by eye
×31K1kread from the layout by eye
×2100R100read from the layout by eye
×1220R220read from the layout by eye
×11K51.5kread from the layout by eye
×1100K100kread from the layout by eye
×1150K150kread from the layout by eye
×11M1Mread from the layout by eye
Capacitors 10
×3220n220nread from the layout by eye
×2470n470nread from the layout by eye
×1100n100nread from the layout by eye
×11u1ufilm; read from the layout by eye
×182p82pread from the layout by eye
×1100p100pread from the layout by eye
×12u22.2uelectrolytic; read from the layout by eye
×122u22uelectrolytic; read from the layout by eye
×147u47uelectrolytic; read from the layout by eye
×1100u100uelectrolytic; read from the layout by eye
Transistors 2
Q1BC548BBC548Bread from the layout by eye
Q2BC548BBC548Bread from the layout by eye
ICs 1
×1OPA2134OPA2134read from the layout by eye
Potentiometers 4
DriveA1MA1MPotentiometerwires labelled Gain; read from the layout by eye
ToneB20KB20kPotentiometerread from the layout by eye
AccentB25KB25kPotentiometerread from the layout by eye
VolumeA100KA100kPotentiometerread from the layout by eye
Switches 1
Jazz/RockSPSTSPSTtoggle, pads Sw1 and Sw2; read from the layout by eye
LEDs 1
D13mm red LED3MM RED LEDon board; read from the layout by eye