Aion FX Plexus Overdrive

[VanWhy]

Build Rating

4.00 star(s)

This is the Brown Sound in a Box 2. A circuit that came from the DIY community. I love Marshall tones so I had to build this one.

It's not my favorite Marshall AIAB but it's pretty cool.

My only complaint is that it is super noisy. I can't turn the drive knob up over 3/4 of the way or it starts squealing like a banshee. Not sure if I did something wrong or if it's just the nature of this one.

Went with SMD Jfets. Solder job is not perfect with those but I'm getting better.

Overall it is very amp-like and does get some great Marshall-like tones from it. Easy build too. I just dock a star for the noise.

 

[Brett]

Great looking build!

My only complaint is that it is super noisy.

I haven't build the standard BSIAB2 circuit so this could be completely normal behavior, but if it were mine, I think I'd try a couple things to see if I could get rid of that oscillation/squealing issue.

I'd add a little separation between the IN and OUT wires, they're pretty close right now and running them parallel (separated by the width of your ground wire) isn't ideal in a high-gain circuit. Additionally, a PVC/silicone wire insulation jacket isn't the best at isolating sensitive lines.

Your wires are running beneath the board (which looks very tidy) but could be contributing to noise being injected into your sensitive high-impedance signal (input wire) from traces on the bottom side of the board. Try moving the input wire up and away from the board and other wires. That should help some, and if you need stronger isolation you could try using a shielded cable run from the input jack to the footswitch board.

There's a chance that there's a problem somewhere on the board or this may be completely normal for this circuit, but I'd definitely start with attempting to isolate that input wire to see if that fixes it. Again, it's a great looking build and you should be proud of it!

 

[VanWhy]

Great looking build!


I haven't build the standard BSIAB2 circuit so this could be completely normal behavior, but if it were mine, I think I'd try a couple things to see if I could get rid of that oscillation/squealing issue.

I'd add a little separation between the IN and OUT wires, they're pretty close right now and running them parallel (separated by the width of your ground wire) isn't ideal in a high-gain circuit. Additionally, a PVC/silicone wire insulation jacket isn't the best at isolating sensitive lines.

Your wires are running beneath the board (which looks very tidy) but could be contributing to noise being injected into your sensitive high-impedance signal (input wire) from traces on the bottom side of the board. Try moving the input wire up and away from the board and other wires. That should help some, and if you need stronger isolation you could try using a shielded cable run from the input jack to the footswitch board.

There's a chance that there's a problem somewhere on the board or this may be completely normal for this circuit, but I'd definitely start with attempting to isolate that input wire to see if that fixes it. Again, it's a great looking build and you should be proud of it!

Good call and good points. I think I will try rerouting those I/O wires first. Easy first step. Thanks!

 

[MichaelW]

This is the Brown Sound in a Box 2. A circuit that came from the DIY community. I love Marshall tones so I had to build this one.

It's not my favorite Marshall AIAB but it's pretty cool.

My only complaint is that it is super noisy. I can't turn the drive knob up over 3/4 of the way or it starts squealing like a banshee. Not sure if I did something wrong or if it's just the nature of this one.

Went with SMD Jfets. Solder job is not perfect with those but I'm getting better.

Overall it is very amp-like and does get some great Marshall-like tones from it. Easy build too. I just dock a star for the noise.

Mine is pretty noisy too. But it's a great sounding MIAB. It's got that "sag", very EVH-ish.

 

[Bricksnbeatles]

My first real pedal build aside from a few passive untility boxes and a strip board SHO was a BSIABII kit from GGG back around 2015. No squealing with the gain cranked, though it certainly accentuates any hiss or hum on high gain settings if the tone is fully open. Just the typical noise you would expect from a high gain pedal of the sort though, and a noise gate does the trick.

 

[micmac]

Reading this I remembered that I had built an aion Plexus, too - some time ago. I couldn't remember if it was noisy so I plugged it in and cranked it. Don't think it's noisy. Some feedback if you want it, but noisy it's not.

I didn't play it a lot, but it's a fun pedal, just sat down 20 minutes with it

 

[VanWhy]

Reading this I remembered that I had built an aion Plexus, too - some time ago. I couldn't remember if it was noisy so I plugged it in and cranked it. Don't think it's noisy. Some feedback if you want it, but noisy it's not.

I didn't play it a lot, but it's a fun pedal, just sat down 20 minutes with it

Nice. Glad you got inspired to jam on it. The high gain hiss is pretty normal but mine does squeal in drive is cranked. I'm almost certain i can remedy this though. Either way it rocks

 

[VanWhy]

Update: I rerouted both input and output jacks from underneath the board and the squealing is gone! I'm thinking because of having the i/o jacks so close to the SMD Jfets it was likely causing extra noise. Shielded wire may help a bit more but for know I'm happy with it. Thanks again @Brett for the advice

 

[jcpst]

It's not my favorite Marshall AIAB but it's pretty cool.

What's your favorite so far?

 

[Bucksears]

Just curious: did the OP use J201s, or 2N5457s?
I THINK there's a mod somewhere to reduce the gain. It's a great MIAB, if you can get everything sorted out and dialed in.

 

[VanWhy]

What's your favorite so far?

Probably the Golden Falk. Then the M800.

 

[VanWhy]

Just curious: did the OP use J201s, or 2N5457s?
I THINK there's a mod somewhere to reduce the gain. It's a great MIAB, if you can get everything sorted out and dialed in.

I used 2N5457s. According to the build doc, the 2N5457s are less gain-y and compressed than the J201s.