ASTRO AMP: Astrotone Fuzz, with Analog Man Mods

Perhaps best known as the Analog Man Astrotone Fuzz now, this started life as the Sam Ash Fuzzz Boxx and the same circuit also appears in the Astro Amps Astrotone Fuzz - which is a supremely cooler name, which is maybe why it has stuck.

The original has 47n caps on this input and output, and a larger resistor on on the tone control causing it to be kind of thin and awful (which explains why I threw out my first attempt when I first started building).

The Analog Man version basically fixes a couple of minor deficiencies in what is otherwise a pretty cool circuit.

The fuzz pot acts as a volume control in front of the circuit, and the tone is a high-pass filter at the output of the circuit.   The fuzz section is roughly an Electra distortion - single transistor hitting some hard clippers with a lot of already distorted level.  This is followed by a buffer and the tone and volume pots.

ASTRO AMP ASTRONTONE FUZZ - WITH ANALOG MAN MODS - 0.15" VERO LAYOUT

The layout above was created for looks as well as functionality, hence the links under the board.  It's not the most practical in some respects.

Transistors are Fairchild mushroom tops, roughly ~200hfe.   I also used some interesting looking UK Military spec diodes.  

Before building this I did have it on the breadboard and tested vintage parts against modern ones.  I could hear a difference in sound between vintage and modern, but it was minimal.  It's certainly not worth spending money on vintage parts unless you want it to look more vintage.  Same with the capacitors I used, strictly just for looks.

A lot of the rock here is done by the diodes, so all the usual mods are fun to play with - asymmetric clipping, silicon and germanium paired together etc.  

ASTRO ON LTSPICE

As you can see, the differences in frequency response between the modded circuit and original are fairly dramatic.  You can still get a thin sound from the Analog Man version if you want the original - but it's not nice.   It is however nice to be able to take a bit of bottom end off the fuzz, to help tighten things up before you hit your amp with it.

And here's some fun squiggly lines to look at - this at the base of the second transistor, after diode clipping.  Fuzz pot swept.

Some schematics also show the biasing resistors as 3m3 - as this is such a simple circuit, the value of the biasing resistor does affect the sound.  Especially the first one (R2).

ASTROTONE VIDEO DEMO

I feel like this is a pretty reasonable demo - listen for how clean (or not) the amps are running.   I feel that this effect sounds best running at a decent level pushing an amp.  

ANALOG MAN: NTK Sun Face

I saw this Gray Bench teardown video the other night, and the values looked a little different to what I'd seen on other Sun Face schematics, so here it is.

If you don't feel like watching the video, the key difference: 51k resistor on the collector of Q1.  The rest is all pretty standard for a Sun Face, although it does mention biasing the collector of Q2 to 5v, which is a little hotter than the usual 4.5v that is often referred to for fuzz faces.

ANALOG MAN NTK SUN FACE - VERO LAYOUT

And if you think this is a lot of vero for not many parts, you are correct.   It’s still kind of small, and will easily fit in a 150b enclosure, so why bother making things hard for yourself by crowding a board?  Besides, you’ll need some room to lay the germanium transistors flat.

 

GRAY BENCH SUN FACE TEARDOWN

The full schematic is shown at the end of the video.

ANALOG MAN: Beano Boost

The Analog Man Beano Boost takes the classic Rangemaster treble booster and adds a very useful function — a switched input capacitor that widens the tonal range beyond the original’s treble boost.

Because it’s a single-transistor germanium circuit, the choice of transistor does shape the tone and clipping character, especially at higher gain settings.  That said, you don’t need to hunt down an expensive vintage OC44 to get great results.  Many germanium transistors will work really well in this circuit — just be mindful of noise, as a bit of hiss is common with older germanium devices.

Quite a bit of info here on Analog Man's website 

ANALOG MAN BEANO BOOST - TAG BOARD LAYOUTS

Same again, but with a pot to control the gain - with the 5k pot at around 50% the series resistance is about 3.5k depending on component tolerances.  I think this is close enough to the stock 3.9k - you could use something a bit larger than 1k to get it closer, but it really doesn't make a massive difference.

This is handy for finding the sweet spot for just the right amount of grit in the boost.  Another useful option is to replace the 68k resistor with a pot (100k as an example).  One of the Steve Williams boosters has this addition - minor downside, the pot has DC on it, so it will sound scratchy / crackly.

ORIGINAL BEANO BOOST LAYOUT

This is the layout used by Analog Man, which is the same as a vintage Rangemaster (excluding power filtering & 1m resistors). 

Note that I've done it in two layers, as it's hard to show parts directly underneath each other in this format.  

VIDEO DEMO

ANALOG MAN: Astrotone

A nice simple one - the Analog Man Astrotone, which is pretty much a stock Astrotone, with some mods to make it worthwhile.  

The original circuit is a bit thin and is said to only sound good with the volume right up, making it too loud to use in most situations.  The Analogman mods fix this, as well as making the tone control more useful.

ANALOG MAN ASTROTONE - VERO LAYOUT

ANALOG MAN ASTROTONE VIDEO DEMO

ANALOG MAN: Sun Face Fuzz

A nice easy one - the Analog Man Sun Face Fuzz, which is, of course, just a fuzz face with a couple of trimmers.  One for bias, the other to help pull back on the input level, as a kind of false volume pot cleanup.  

Yes, it is a big layout for a fuzz face...  but it still fits in a small enclosure, so why jam everything on a tiny vero board when you don't need to?  Also, I thought being an easy build, more space might be suitable for those just starting out - less chance of solder bridges.

ANALOG MAN SUN FACE FUZZ - VERO LAYOUT