Aion L5 Preamp Clean and Drive Channels

[scheffehcs]

When I saw that the JHS Crayon PCB was finished, I decided to abstain from buying it until I finish all the pedal projects I’ve started (and which have gone untouched for at least a year).

These two were mostly done, just needed to paint the boxes and calibrate the distortion / compression. For the boxes, I did my best Rothko impression. The distortion calibration went fine, but for the compression calibration I could not get a reading with the desired 1.17VAC (the range I got for the Clean channel was .41-1.08 and for the Drive channel .26-.57VAC). Regardless, the compressor sounds fine (in certain situations, see below).

I tried both pedals through the power amp inputs of a Hot Rod Deluxe and a JC-120. The Clean channel, which is supposedly modeled to be Twin-like, is very bright, kind of spanky sounding. It can get fairly overdriven. I didn’t like it all that much.

I thought the Drive channel sounded very good. It was supposedly a novel circuit, not meant to model anything - it has the added mid range frequency control which feels pretty powerful, lots of tone shaping available.

One strange thing is that since the compressor is at the end of the circuit, the master volume has to be up a certain amount (around 8/9 o’clock for me) before the compressor kicks in. On the Hot Rod, that was too loud! I thought the compressor wasn’t working until I plugged it into the JC. With the JC I was able to turn up the master volumes louder and the compressor was doing its thing just fine. I wonder if proper calibration would help - or maybe it’s just a quirk of the way the circuit is designed.

I still haven’t plugged these pedals into a direct recording set-up (I use a Helix). This is the main use that I have for these pedals, I have a feeling it’s going to sound great.

I could probably scrounge up a demo if there’s interest. On to the next unfinished project.

 

[crashguitar]

These look great. I love the Rothko inspired finish.

 

[Smrtokvitek]

The compressor is strange indeed but it was designed like that.

 

[fontoponto]

Is this info from the build doc somehow related to this problem or only related to the input signal strength?

Compressor/limiter trimmer
With the 30mV sine wave signal still inserted into pin 4 of IC3, turn the master volume up all the way
and turn the compressor on (switch in the “up” position). Then turn the compressor knob up to about
2:00 (2/3 of the way up) and touch your probe to the “PCB OUT” pad on the right side of the footswitch
board. Turn the trimmer until you measure 1.17VAC.
This will get you in the range of the original amps. If you’re using the L5 primarily as a pedal, you may
want to set this lower so it’s more sensitive to lower-level signals.

 

[Gordo]

It's a different way of thinking of compression too. On my original amp you can dime the master and with the compressor full up (full COUNTER clockwise) you can pretty much talk over the output. Back the compressor off a tad though and the amp starts to get seriously loud real quick. It almosts acts like a power soak. I didn't find it as extreme on the pedals mostly because there was no power amp involved so it's a slightly different feel.

 

[scheffehcs]

The compressor is strange indeed but it was designed like that.

Yep, good to hear it’s working as intended.

 

[scheffehcs]

Is this info from the build doc somehow related to this problem or only related to the input signal strength?

Since it says to set the signal generator to 30mv, that should produce the correct input strength to get the desired reading. I tried an old analog tone generator as well as my phone and got the same result. I was using a cheap meter at work, and the build docs do say to mention something about using a meter that reads AC voltage the correct way (rms vs p-p). I left the test leads on so I can try again at home with my nicer meter.

 

[scheffehcs]

It's a different way of thinking of compression too. On my original amp you can dime the master and with the compressor full up (full COUNTER clockwise) you can pretty much talk over the output. Back the compressor off a tad though and the amp starts to get seriously loud real quick. It almosts acts like a power soak. I didn't find it as extreme on the pedals mostly because there was no power amp involved so it's a slightly different feel.

Yes, this is the way it behaves, good to know. The interaction between master volume and compression did take some getting used to.

 

[Gordo]

I think on mine I followed the calibration doc to a point where I thought it didn’t really get the spirit of the amp and just dialed it in to a usable setting as a pedal. Does that make sense? If you’re using it as an effect pedal the calibration will be different than if you use it as a preamp.