Aion Electronics RIFT Manuale - Pagina 6

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BUILD NOTES

Transistor selection

The original Superfuzz usually used 2SC828 transistors, sometimes 2SC537 or 539. There is nothing

special about these transistors, but being early silicons, they were much lower gain than modern

silicons. This makes a big difference in the circuit.

AionFX took measurements of an original Superfuzz as part of the development process for the updated

version of the Rift. The transistors (2SC537G) tested as follows using a Peak Atlas DCA55:

Q1: 124 hFE

Q2: 95 hFE

Q3: 143 hFE

Q4: 62 hFE

Q5: 50 hFE

Q6: 52 hFE

In general, most people agree that the Superfuzz sounds best with higher-gain transistors at the

beginning and lower-gain transistors at the end. If you have only six transistors, it's recommended to

assign them using the following process:

1. The transistor with the lowest gain is used for Q6.

2. The two transistors closest in gain are used for Q4 and Q5.

3. Of the remaining transistors, the highest gain should go in Q1, second-highest in Q3, and third-

highest in Q3.

It's recommended to use the 2N3904 for Q1-3. There aren't very many transistors available today that

get down to the 50-60 gain range, but the 2N3903 is often under 100 and is a great choice for Q4-6.

The Rift PCB layout uses the USA-standard E-B-C pinout (2N3904, 2N5088, etc.) for the transistors, but

an extra pad has been provided on each transistor footprint to support the Japanese E-C-B convention.

If you do use a vintage transistor like the 2SC828 or 2SC945, make sure to adjust accordingly.

Fine-tuning the octave

For the most pronounced octave effect, you want to make sure the Q4 and Q5 transistors are matched

as closely as possible for gain (hFE). Most multimeters have an hFE function to test them. As you can see

from the original measurements above, though, it can still sound great with transistors that are pretty

far off from each other, so don't get too hung up on this aspect of the build.

The octave trimmer is there to compensate for unmatched transistors, and in fact Shin-ei implemented

this trimmer because it was easier and cheaper than sorting for matched transistors. You will get the

best effect if you use the two transistors that are closest in hFE for Q4 and Q5 and then use the octave

trimmer to fine-tune the effect.

RIFT OCTAVE FUZZ