Aion Electronics L5 Preamp Podręcznik - Strona 3

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Differences from the original circuit

I kept it faithful to the original Lab Series L5/7/9/11 circuit, only changing the following things.

• The power supply—more on this later.

• Channel switching: the original had two channels with separate jacks for each. The only way to switch

between them was to unplug from one and plug into the other, or use an external A/B box. I combined the

channel inputs so that it has a single input jack and a footswitch to change between the channels.

• Master bypass so it can be turned on/off like a normal pedal.

• Hi/Lo inputs: the original units had two jacks per channel with different gain levels to allow it to be used

with different types of instruments. I made this gain boost selectable with a toggle switch.

• I substituted the CA3094 for a 3080 and added external transistors. The CA3094 is identical to the 3080

except for having an integrated buffer tacked onto the end. Since the 3094 is difficult to find, I elected to

convert the circuit to use the more common CA3080/LM3080. The 3080s are still very easy to obtain.

Usage

Channel 1 is a simple Fender/Marshall/Vox passive tonestack with treble, midrange and bass controls. Since

this portion of the circuit operates at very low impedances only achievable with op-amps (and certainly much

lower than a tube amp), the resistors and pot values are around 20% what you'd see in a F/M/V tonestack

while the capacitors are multiplied by five to compensate. The tone controls are identical to the classic setup in

frequency and behavior.

Channel 2 is a little more complex, with a Baxandall active tone control for treble and bass, a parametric

midrange (which actually extends well into the bass and treble frequencies), and something called a multifilter,

which is a patented Moog invention that uses a set of six fixed-frequency resonant filters to add a very unique

quality to an instrument signal that is unlike any other guitar effect, sometimes described by Lab Series owners

as making their electric guitar sound more like an acoustic. (Look up

A word of advice: don't neglect channel 1 if you're looking for overdrive! Channel 1 is incredibly touch-sensitive

and it reacts fantastically well to your playing dynamics. It's like a classic Fender tube amp, but you can tune

the amount of crunch yourself instead of having to maintain a specific volume level. You'll be tempted to think

of the channels as "clean" and "drive", but that's a mistake.

One of my favorite tones through the amp is achieved by hitting the first channel with a Boss GE-7 EQ

arranged in a "mid-hump" and boosted to +10dB. The distortion/overdrive circuit is located after both channels

have been mixed together, so the same clipping happens to both channels. You just have to crank the first

channel a little louder to trigger the overdrive, and a boost pedal in front will be very useful.

The master volume applies to both channels. With the channel volume essentially controlling the amount of

overdrive, the master volume allows you to tailor the final volume to taste. By leaving the channel volume low

and turning up the master volume, you can get a super-clean sound favored by jazz guitarists. By turning the

channel volume all the way up and backing off the master volume, you can get an overdriven tone with the

same overall volume level.

The compressor is a basic limiter that comes after the master volume. It has just an on/off switch and a

threshold control to set the maximum signal level. Everything over that level will be squashed back down. At

higher threshold levels, it simulates light tube compression, but turn it down and you can get all of the higher-

gain tones without the high volume.

L5 PREAMP

patent #4117413

to read more about it.)