Cornish G2 clone (Aion Cygnus pcb) gain and volume problems

[frank90petrosino]

Dear all,

Im writing about the Cygnus project of Aion electronics
https://aionfx.com/app/files/docs/cygnus_documentation.pdf

I built the pedal starting from the kit buyed on musikding website and replacing the mkt capacitors with wima mkp2 as u can see in the uploaded photos.

I'm having some problems about volume/gain level. The pedal is working but with all knobs at 12 oclock I have a decreaseing in volume and a fatty sound: to reach the same output volume of the direct guitar into the amp I need to put volume knob to 15/16 oclock, and increase distortion with sustain knob to 15 too.
Reading the building notes, as solution to gain issue, aion suggest to put R18=18k and R19=100R (collector and emitter resistors of Q3, the first stage after buffering) if germanium diodes have too low forwars voltage (less than 0.3). However, despite I used OA1154 germanium selected diodes (Vf=0.7/0., I tryed this mod in the first stage as suggested but I didn't obtained enough gain increasing.

Moreover, trying to increase volume in the last stage (Q6) I discovered different values for R34 and R35 finding R34=5k1 and R35=1k as a good compromise but not what I am looking for. I upload an highlighted schematic layout.

I'm trying also changing transistors (BC549C and 2N5088) but the result is the same as expected.
Moreover, checking bias points and comparing values with big-muff bias voltages I discovered more or less similar values except for Q3 collector (4.6V and 8.7V before R18 coming from the layout power section).

Do you suggest me to try some other modification to increase gain and volume?

As last questions, compared to the original G2 I'm discovering too high-cut effect even the tone control is all opened. In the building notes are reported a set of mods:

• C1: 100n → 27n
• C5: 220n → 47n
• C9: 1n → 470pF (MLCC)
• C12: 1n → 470pF (MLCC)
• C13: 220n → 100n
• C15: 1n → 470pF (MLCC)
• C16: 220n → 100n
• C19: 220n → 100n

could I have some advice on what is the most important to increase the tone range and have more brilliance?

Thanks a lot,
Francesco

[duck_arse]

hello, frank90petrosino, welcome to the forum.

we have a few rules here - welcome the first [or early] posters. follow the procedure in the "what to do when it doesn't work" thread, and post all your voltages, at least a link to the circuit diagram, and photos of the thing you have built, component side, solders side and offboard wirings. don't make us come after you, we lose interest quickly when we have to do the work for you.


oh, and be nice.

[11-90-an]

Welcome, francesco, to the forum...

Well to be fair, duck, he *did* send us a link to the specific site, more complete, i think, but well, here's the build doc...

https://aionfx.com/app/files/docs/cygnus_documentation.pdf

For your loss of high-end, perhaps you can do the mods specified in the build doc, replacement of some capacitors, in page 7...

I think your Q3 collector should have higher voltage reading... i echo for pictures of your board and wiring.

Again, there is a guideline for debugging threads, here..

https://www.diystompboxes.com/smfforum/index.php?topic=29816.msg222681#new

[frank90petrosino]

Hi guys,

thanks a lot, I'm new in the forum and sorry if my first post was incomplete. Now I modified with more informations photos and ad highlited schematic.

Waiting for you news
have a good time,
Francesco

[iainpunk]

it kinda is just a dull sounding pedal, with way less high end than a normal Big Muff.
the brilliant bright treble the big muff can produce comes from the mid scoop, which our ears hear as bass and treble boost, without that scoop, you can't have the mega treble,
the other option is cutting everything under a certain frequency with a shelve high pass filter.

to reach the same output volume of the direct guitar into the amp I need to put volume knob to 15/16 oclock, and increase distortion with sustain knob to 15 too.

it depends on the output an character of the guitar, but it sounds like something that is quite normal for a Big Muff-style circuit.

i often see people thinking that the 12 'o clock position on a volume control should be unity, but i have never found an adequate explanation why people think that should be the case. different guitars have different volume levels, so its absolutely impossible for a designer to design a pedal that has unity volume in the middle of the pot's position.
that said, try taking out R37 - 39kOhm and using a 100k volume pot, replacing those two with a higher value would load the preceding gain stage way less, and give at least a little bit more volume.

cheers, Iain

[frank90petrosino]

Thanks Iain for your explanation,

I tryied your suggested modification and I obtained more volume.

Bye,
Francesco

[r080]

Another suggested mod for more high end is to make the value of C7 the same as the value of C3. In other words, you would make the input buffer the same as the bypass buffer.