Southampton Pedals - Fifth Gear Overdrive

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Bolsyo
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Post by Bolsyo »

This one has become very popular among bassists. It's extremely similar to EQD Speaker Cranker. I've read people claiming that this one is a lot more controllable and can go lower gain than the Speaker Cranker. Info about the pedal: https://www.southamptonpedals.com/produ ... -overdrive

EQD Speaker Cranker schematic I found:
Speaker Cranker Schematic.jpg
Source: http://drdfx.hu/en/oomph/ (interesting post with analysis of similar boosters btw)

Based on the gutshots below, the differences I can see is:
  • The 1N60P diode with cathode towards ground is replaced with a 1N4004.
  • Gain pot upped from B5K to B10K.
  • Added "Heat" knob seems to be just a pot wired in series with the 10K collector resistor: lug 1 to the 10K resistor, lug 2 to collector, lug 3 unconnected? Not sure about value since it's under the PCB, probably B10K or B5K?
  • A100K volume pot on the output.
  • Added 100r resistor on 9V input for filtering.
Gutshots of different PCB revisions found scattered across the web:
Fifth Gear 2.JPG
Fifth Gear 1.JPG
Fifth Gear 3.jpg
Fifth Gear 4.jpg
There is also a 1-knob mini version, only difference from Speaker Cranker here seems to be the 1N4004 diode, 100r resistor on 9V and B10K Gain pot:
Fifth Gear mini.jpg

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Bolsyo
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Post by Bolsyo »

Finally got around to breadboard one of these, sounds nice on both bass and guitar. Tested it with a strat and tried different heat values. I found 5K a bit subtle, 10K was a lot better. Then a big jump up to 50K just to try the extremes, but it was mostly harsh fuzz territory imo. Then I tried 25K, still too harsh for me. I found 10K gave me the most useful sweep.

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Nocentelli
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Post by Nocentelli »

Bolsyo wrote: 30 Jul 2020, 00:48 It's extremely similar to EQD Speaker Cranker....
  • Added "Heat" knob seems to be just a pot wired in series with the 10K collector resistor: lug 1 to the 10K resistor, lug 2 to collector, lug 3 unconnected
The "heat" control was seen on the Lollygagger Canaglia a couple of years back - A lot of mileage in the Electra:

viewtopic.php?f=7&p=268181#p268181
vanessa wrote: 20 Aug 2007, 17:51 You can't arrest someone for reverse engineering something.

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G.Bisson
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Post by G.Bisson »

Redrew the schematic based on Bolyso's mod descriptions and drdfx's schematic.
GBisson_FifthGear_Schem.png
Here's a stripboard layout I've built and verified.
GBisson_FifthGear_vero.jpg

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