SPACEMAN EFFECTS: Redstone Germanium Preamp

Yet to build this myself, I quite like the idea behind this - I am partial to anything with bass / mid/high controls for guitar and a germanium transistor.  Bonus points for also including a discrete op-amp, which I've been playing with lately.

Before I looked at the schematic for this, I was playing around with modding a Boss Blues Driver to make the tone stack a real tone stack with external pots and removing the last stage, just leaving the two discrete op-amps.  This is a refined version of where I was heading, so I think I'll park that project for now. 

BOOST STAGE

The boost stage uses a LND150 MOSFET which is common on several Spaceman Effects designs.  It could just as easily have been a JFET-based boost - this is a clean boost to make up for the gain loss at the EQ stage.  A little bit of high-end is also filtered off at this stage, but nothing substantial.  You may not even hear it.

EQ 

It's a fairly standard bass / mid/high tone stack with some tweaked values.  This could be modded to typical values for Marshall or Fender, but there's a decent chance Spaceman went this way for a reason - it looks pretty balanced to me.

DISCRETE OP-AMP

It's a Boss-style discreet non-inverting op amp using two JFETS and a PNP transistor (as found in the Blues driver).  There are a couple of resistor value changes, and the PNP transistor is, of course, germanium instead of silicon - hence the germanium preamp name.  The GE transistor will add some extra flavour, but maybe not much more. 

According to the Dead End FX build docs, a 1T308B transistor is used - it makes sense to use Soviets for a pedal with a large production run.  If you don't have a 308 - try something around 70-80 hfe and low leakage (most Soviet-era transistors have low leakage)  Japanese transistors might also be a good choice.

Potential mod:  As this is just another type of op-amp - diodes can be added across the output of the op-amp and inverting input for some soft clipping.  It works on LTspice, so it should work in practice. I'm definitely going to try this.    

SPACEMAN REDSTONE GERMANIUM PREAMP - VERO LAYOUT

The layout below is missing the soft switching to save on size.  If you don't have ferrite beads, jumper it on the input, or use a low-value resistor in the power section (100ohm).  You could quite happily not use the MOSFET in the power supply section, but I had the room, so may as well keep it in.

The same layout as above, but this one is for a Soviet 1T308 transistor, which uses the less common BCE pinout, as many Soviet-era transistors do - you could always use the one above and bend the legs. Still, I find that annoying, so I made another layout to suit.

SCHEMATIC

I redrew part of the Deadend FZ schematic, as I found it difficult to picture the discreet op-amp.  I have not included the soft switching or fancy power supply in the drawing below.   

VIDEO DEMO

RECKLESS: Little Jim

Another fine circuit from Jonny Reckless, this time he's headed into cranked Marshall territory (hence the name).

Here's the thread on DIY Stompboxes  

RECKLESS LITTLE JIM - VERO LAYOUT

RECKLESS LITTLE JIM - VIDEO DEMO BY JONNY

RECKLESS: Moon LNDer Distortion

Another one from Jonny Reckless - the Moon LNDer distortion, using LND150 MOSFETS.   

All the required details can be found on DIY Stompboxes, including schematics, some suggested mods and a video demo with a few words from Jonny.  

Set drain bias to between 6 and 7 volts by adjust the 10k resistors going to the source of the MOSFETS.

JONNY RECKLESS MOON LNDER DISTORTION - VERO LAYOUT

VIDEO DEMO BY JONNY

SPACEMAN EFFECTS: Atlas III Preamp Booster, Point to Point Layout

I had a few of the FETS leftover from the Spaceman Saturn V Harmonic Booster, and I saw the layout over at Perf and PCB Effects Layouts, so I thought I might try one of these.  

The Spaceman Effects Atlas III is another booster, following the theme of rocket engines in naming (nice).

The switch is a phase switch, it literally just inverts the output phase.  So perhaps mount this on the side, or somewhere out of the road, as you won't be making use of this very often, if ever.   It could easily be completely removed, and I'm sure you can work out how to do that yourself.

SPACEMAN EFFECTS ATLAS III BOOSTER - POINT TO POINT LAYOUT

Just a straight up boost / low gain overdrive from Spaceman Effects - the Saturn V Harmonic Booster.  It's a pretty quick and easy build & does it's job well.

 

SPACEMAN EFFECTS SATURN V HARMONIC BOOSTER - POINT TO POINT LAYOUT

SATURN V ON THE BENCH

Build in progress pic below, which is a little different to the layout, as I changed my mind about where + - V should be after making it (I just flipped them around).  I also subbed in a couple of caps as I didn't have a 27nf or 180nf caps.  I went with the next nearest value that I had, which was 33nf and 220nf.  Probably won't make much difference.  

I also removed the millennium bypass LED circuit, and combined drain resistor values.  The drain had two resistors in series, which has no purpose.

If you don't have ferrite beads, just leave then out.  Makes no audible difference.