harmonic engine-noisy in bypass mode-

[mikef]

Hello! Here is a circuit that may be not suitable for stomp-box material, but having built it and plugging up my guitar and running it to my amp, IT SOUNDS KILLER! The PCB is from https://www.circuitbenders.co.uk/forsale/harmonic/harmonic.html

I am wondering what sort of bypass switching I should implement.I believe I tried Millennial?  or another bypass switching that I could not recall,as I put it on the shelf, because whatever it was, it was quite noisy (Clock noise) whilst the true bypass switch was engaged. Any thoughts? THANKS!

[madbean]

Try using shielded wire for the input and output jacks, and the circuit inputs and outputs. Ground the circuit input and output on bypass. You can do this using the madbeanpedals TB wiring by adding another wire from the top right lug to the bottom left one (these are circuit output and ground, resp.)

Also, keep all your other wiring as short as possible and away from all the input/output wiring.

[madbean]

Also, I would add a pull-down resistor at the circuit output to prevent any switching pop. A 100k from lug1 of VR2_Output_Mix to ground.

Not really sure why they have C3 and C6 reversed. Actually, a bunch of the electro caps have their polarities reversed now that I look at it. This is standard 9v, right?

Looking forward to getting my PCB for this!

edit: just saw they are doing +9/-5v so maybe not.

[mikef]

Brian, as far as I understand the build docs, it is 9v. I have powered it up with my bench power supply to9v and also I have used my ispot power brick on my pedalboard. interesting about the caps........... Thanks for the input!(PUN intended)
There is a thread on thw muffwrigglers forum about this circuit............  https://www.muffwiggler.com/forum/viewtopic.php?t=169236&postdays=0&postorder=asc&start=0

[mikef]

Try using shielded wire for the input and output jacks, and the circuit inputs and outputs. Ground the circuit input and output on bypass. You can do this using the madbeanpedals TB wiring by adding another wire from the top right lug to the bottom left one (these are circuit output and ground, resp.)

Also, keep all your other wiring as short as possible and away from all the input/output wiring.

I was wondering about the shielding on the shielded wire. Are you not  supposed to leaveone end of the shielded wire 'Open' or ungrounded? Seems I have read that somewhere,but could be mistaken.

[madbean]

I was wondering about the shielding on the shielded wire. Are you not  supposed to leaveone end of the shielded wire 'Open' or ungrounded? Seems I have read that somewhere,but could be mistaken.

That's correct. Connect one end of the shielded cable to your common ground and the other end open. Once one end is grounded, the entire shield is.

[mikef]

Brian,
Had good initial results in shielding the input outputs. I am going to move the guts into a taller BB Hammond case to see if I cant shorten up some wires. Thanks!

[madbean]

Brian,
Had good initial results in shielding the input outputs. I am going to move the guts into a taller BB Hammond case to see if I cant shorten up some wires. Thanks!

Cool! I got my board in and have acquired all the parts. Just don't have time to build it yet.

[mikef]

COOL! When ya get around to it,and I know how it is, It will be cool to get yer insights. After I re-case mine, I will do a review.

[madbean]

Got mine built up real quick since I didn't have a lot of time. It's cool but not quite sure how to dial it in yet for guitar. I'm going to make a few modifications to it: output volume control, tone control for the harmonic engine. I think I will add a cap in parallel with the sensitivity knob and put an inductor on the power supply line. It's a bit noisy out of the box but it might quiet down in an enclosure. Luckily, I have the perfect enclosure for it. Not going to do it as a stompbox but as a standalone unit. I'm including all the switched jacks to separate the outputs, too.

[mikef]

Cool! it's a wacky one fer sure. I hope you will post it when ya get it like you want it.

[mikef]

TA-DA! Thanks Brian! It is WAAAAAY more quiet with your bypass switching/shielding suggestions.