Aion Andromeda v. ODR-mini — loss of high end?

[Semilog]

Yesterday I completed a build of the Aion Andromeda clone of the Nobels ODR-1. Pedal worked first try, and the pots generally do what they should. However, the Andromeda doesn't have the same high-frequency clarity or punch that my ODR-mini has, at either 9 or 18V for either pedal. This is the case even with the Andromeda's Spectrum knob all the way up vs. the mini with Spectrum at ~ 1 o'clock. I mostly play a guitar with 'buckers, so this is a problem.

This is my 7th build from an Aion board (all successful), and I measured the value of every component as I populated the board (including the pots), so I'm reasonably sure this is not a build error.

Any suggestions as to where I might start tinkering to get a high end bit closer to the ODR-mini?

[GGBB]

Welcome to the forum.

I believe the ODR-mini circuit is not identical to the original ODR-1, and the Andromeda's bass control makes it different than both. The mini supposedly has "tighter" sound which means the bass is cut a bit so that it sounds brighter. It's probably similar to the new model ODR-1BC with the bass cut switch engaged. The Andromeda bass control lowers gain in the part of the feedback that handles the low frequencies. I haven't seen a schematic for the Nobel's bass cut so I don't know what they've done but an obvious candidate would be reducing the 2µ2 cap used in the first opamp's feedback section (Andromeda C5) - maybe to 470n - or just try turning down the bass.

[Semilog]

Yes, have messed with the bass cut a bunch already. Will give the cap sub a try. 

[Semilog]

So I tried the capacitor swap kindly suggested by GGBB, and that did change the response of the bass cut pot a bit, but did not markedly change the treble response.

However, the Aion circuit contains a couple of extra clipping diodes (D6 and D7) vs. the ODR-1. There are even a pair of pads that can be bridged to cut them out of the circuit. Doing this makes the pedal sound a lot more like the ODR-mini, and more to my taste.

Still, the overall midrange-treble equalization with my (admittedly, somewhat idiosyncratic) rig is not as nice as with the ODR-mini. A bit muddier and mid-rangier. Not a tone that I prefer... though the Aion circuit might be preferred by people with more traditional sensibilities and single-coil PUs.

The search continues...

[GGBB]

Try a smaller cap to ground on the input - C2 - to let more top end enter the circuit.

It would be interesting to see the actual circuit of the mini to understand what Nobels did to remove the buffered bypass. That could account for some sonic differences between it and the original as well as the Andromeda if it's done differently.