Vintage Vault
The AC128 saga


INTRODUCTION: The nanotube

Silicium might be an endangered species. Progress around carbon electronics (nanotube and tripods) and nanotech are going so fast that a well-known Japanese TV brand is issuing next year a flat TV screen using carbon nanotube. Much more than this, in our days of digital technology, it is quite uneasy to find the simplest Silicium transistors essential for fuzz box craft.
In this context, it may seem ridiculous to focus on the old germanium electronic science, which main actors are just fond memories of the past.
Nevertheless, and I am not the only one to think this way,
nothing sounds half as good as a well-tuned germanium distortion device for electric guitar.

This is why today, I would like to introduce you to my old buddy, the AC128 germanium transistor ,
exclusively used in my
handmade Mercer Box and KATAPULT pedals .

Besides being in the famous original Fuzz Face, the AC128 was used in numerous domestic electronic appliance, and certainly one of the most common European transistor. This explains why it is still possible to find nice new-old-stock of these jewels.

They usually come in 3 different types :

1) The real thing

This is both the oldest and arguably the best sounding AC128.
But this wonderful piece of crap has a major drawback : completely random technical data in a VERY wide range. This means that any given theorical design has something like 30% odds to function right away. This fact has 2 consequences:

1- Each distortion device using this same transistor must be modified afterwards to match the theoretical technical data of the set of 2 or more transistors.

2- This a posteriori adaptation must be made while monitoring the tone of the resulting distortion in order not to drift away from the prototype.

It is therefore easy to understand that this kind of transistor is not industry compatible. Only handmade and hand-tuned devices can benefit from this nasty gremlin. Beauty has its price.

2) The hottie

This strange device is exactly the same transistor BUT with a factory mounted radiator, useful in other applications where it receives its 32v possible supply. The AC128 can be as hot as a soldering iron in certain cases with no damage. Compare this to a ts9 chip.

I feel the radiator somehow tightens the fuzz tone, while not in a big way, making it a valuable successor.

3) The modern

Well, somebody may have eventually complained and they improved the AC128 up to nearly fixed data. They also made it smaller, with its thin top-hat modern look.

But, unfortunately, this young component gives a higher even/odd harmonics ratio than its pain-in-the-ass ancestor. So the resulting distortion is , exaggerating, closer to a metal zone than a fuzz face.

They are precious anyway, as they fit in the original fuzz face design without any change and give a very acceptable approximation, even for a purist. They really are pure germanium after all!

4) The little sister

The AC188 pictured here, is a scaled down version of the modern AC128, made for lower voltage applications. And what are our 9v fuzz box ? In fact , this little sister does miracles with electric guitars.

Pushed to their limits, they deliver a full frequency grawl that is hard to beat. A very interesting transistor indeed, the AC188 is too rare to give its full dimension.


Tech Data

EPILOGUE : When supply will dry...

In a very close future, all stocks, including mine, of original germanium AC128 will dry.


After this extinction, that only a few aficionados will notice, there will be no other possiblities to obtain THE original fuzz tone than a used Germanium fuzz box or a digital model.

Make your choice.

From my point of view, I feel my '65 strat deserves more than a red plastic computer that can make believe on a recording, but will fool no one, eye to eye, plugged in an all tube Marshall.

" How well you know me

You've seen me cry

I'm just a shadow

In a rock'n'roll sky "

Deep Purple 1973 "Super Trooper"