aion HADRON DYNAMIC OVERDRIVE Manual - Page 5

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BUILD NOTES

Variants

The Eternity has dozens of variations, many of which were given names such as Burst, Kanji, Roadhouse,

D-Mod, etc., but most of which were not named at all and just sold as the Eternity.

The parts list in this project comes from an early version of the original Eternity that was traced in 2007,

which Sean from Lovepedal verified as being a "V3".

The Eternity Burst can be built by changing out the following parts:

C5: 150n → 220n

R6: 470R → 330R

D2: jumper → 1N914

Drive: 100kB → 500kB

Some variants also had 20k for R4 (which sets the minimum drive level), 1MB for the Drive control

(which increases max available gain at the expense of fine-tuning at lower gain settings), or 2kB for the

Tone control.

IC selection

The exact IC is not known since the markings are sanded off in original units. However, based on

reviewing the photos and comparing the physical IC package, the consensus in the DIY community

is that the original Eternity used either an LM833 or LM1458, with others suggesting the LF353 as

another possibility.

Early versions of the Eternity shipped with an additional TL072 (unsanded) so the player could swap it

out if they wanted. Chip-swapping in the Eternity became something of a cottage industry in the early

years after its release. Forum discussions were endless, and there were even people on eBay selling

packs of alternate Eternity chips. It's not idle speculation, either—it's a simple enough circuit that chip

selection really does make a difference in tone.

Any dual op-amp will work here, so feel free to experiment. Others have had great luck with the

NE5532, OPA2604, NJM2043DD (marked as JRC2043DD), and NJM4560D (marked as JRC4560D), or

TLC2262.

According to the manufacturer, other variants of the Eternity used different op-amps. All of them

were sanded down, so nothing is known for sure beyond that, but it's possible that several of the above

suggestions were used "officially" at one point.

Power supply resistor

The 330R resistor in series with the power supply will drop the voltage to the pedal and is part of the key

to the sound. Some variants of the Eternity used 390R here. However, due to the slight ~0.2V voltage

drop from D1 that was not present in the original, it's recommended to stick with 330R.

HADRON DYNAMIC OVERDRIVE