SOLVED Here's video of Thermionic Deluxe whistling when I turn the volume pots passed 12. (Happens with or without input jack in)

[kylewetton]

So far I've checked all my resistors*, caps and ICs. They're all where they should be.

*I did at this point notice that I mounted a 22K resistor where at 27K resistor was meant to go, I didn't have any on hand so I made one with 22K and 4.7K in series.

This problem happens regardless of whether I have input in or not, I'm just wondering if anyone can help narrow this problem down for me a bit, it's my first build and it the pedal as a whole sounds great and works great, it's just this issue that seems to persist.

One extra detail that might be related: I initially had this problem 10 fold, but found that I'd missed a capacitor and after adding that cap the issue seemed to go away, all except what we're seeing in this video.

I'd love any kind of insight, thanks team

 

[eh là bas ma]

Hello, welcome !

Assuming there aren't any mistakes or shorts, or wrong values on your build, you could try to insulate IN and OUT wires, either with insulated wires, or keeping these wires as far as possible from the pcb, stuck along the enclosure's sides, with tape. High gain circuits are known to be quite sensitive.

Alternatively, in a similar thread :

So, I finally found my solution:

Either you use a buffer, or you do not twist the cables like I did. After checking in on the German forum of Musikding, a DIY-Kit reseller, I got the hint to untwist and trim the cables both to the Power supply and especially to the footswitch. Done that, closed the enclosure - no signs of that annoying whistle anymore!

Tyrian - Whistling on Volume above 12 o'clock and when Blue/Red Mode engaged - possible issues?

Hi all, first post here, hope I am doing this correct without missing any important information. Setup is: Tyrian plugged into my Audio Interface, running AmpHub just with an IR for soundtesting sake. I have an issue with my Tyrian build, that when I push the volume above a certain threshold...

forum.pedalpcb.com

That said, if this doesn't work, some pics of your build (circuit in the enclosure with jacks and everything, pcb soldering side, pcb components side) will be helpful to find the issue(s).

 

[kylewetton]

Hello, welcome !

Assuming there aren't any mistakes or shorts, or wrong values on your build, you could try to insulate IN and OUT wires, either with insulated wires, or keeping these wires as far as possible from the pcb, stuck along the enclosure's sides, with tape. High gain circuits are known to be quite sensitive.

Alternatively, in a similar thread :

Tyrian - Whistling on Volume above 12 o'clock and when Blue/Red Mode engaged - possible issues?

Hi all, first post here, hope I am doing this correct without missing any important information. Setup is: Tyrian plugged into my Audio Interface, running AmpHub just with an IR for soundtesting sake. I have an issue with my Tyrian build, that when I push the volume above a certain threshold...

forum.pedalpcb.com

That said, if this doesn't work, some pics of your build (circuit in the enclosure with jacks and everything, pcb soldering side, pcb components side) will be helpful to find the issue(s).

I'll try both of these, thanks for the response on this

 

[eh là bas ma]

Here is an exemple : Flemming, having a similar issue, "hacked apart a cheap patch cable" to get a "shielded input wire"

🤘Tyrian Distortion🤘

This is a fairly high parts count build so I was putting it off despite totally wanting to share the finished product. I wanted to keep the purple from the original and come up with something appropriately metal for the graphics. UV printing and machining was done by @amplifyfun . When I...

forum.pedalpcb.com

 

[kylewetton]

I'll try both of these, thanks for the response on this

So, I changed out the input wire for a shielded wire. Grounded the shield to the Jack and insulated it with tape. Unbound the power wires. Fixed up a couple soldering joints etc. unfortunately zero change at all, is there anything that sticks out to you on these photos? Appreciate your eye here

 

[kylewetton]

Another thought I had, all of my bottom row pots are hard pressed up against the board, though they all do have plastic dust caps on them. Would this be of any concern?

 

[temol]

Why shielded input wire only? I' not sure that's the case here, but - there is a signal in the output wire, often with a high amplitude. If the wire is in the vicinity of high-gain circuits, there may be enough coupling. Here, the output wire is quite long, goes next to the 3PDT switch

 

[kylewetton]

Why shielded input wire only? I' not sure that's the case here, but - there is a signal in the output wire, often with a high amplitude. If the wire is in the vicinity of high-gain circuits, there may be enough coupling. Here, the output wire is quite long, goes next to the 3PDT switch

It’s my first build, so the answer to your question is simply “because someone else with the same problem shielded just their input wire ”, I did have the same question.

I noticed that the tone does shift in pitch when I move the output wire away from the board with my hand, but does nothing to disrupt the volume of consistency of the whistle tone

 

[giovanni]

Can you post a picture of the other side of the board?

 

[eh là bas ma]

Another thought I had, all of my bottom row pots are hard pressed up against the board, though they all do have plastic dust caps on them. Would this be of any concern?

No, it wouldn't as long as they are correctly protected by the plastic. A piece of cardboard between the pots and the board would have been just fine too. It's only meant to prevent the pots from shorting the pcb's pads.

Edit 3 : you can take the circuit out of the enclosure, release the pressure on these pots, and see what happens with the noise. This way you'll be sure, and you might notice something else in the process (for exemple, is it still noisy out of the box ?).

I noticed that the tone does shift in pitch when I move the output wire away from the board with my hand, but does nothing to disrupt the volume of consistency of the whistle tone

As Temol suggested, you should try shielding the output wire as well. If this doesn't work, I would try to solder jumpers on IN and OUT jack's lugs, so that none of them are empty. One between both ground terminals, an other one connecting both tip terminals.
Edit 2 : You could also try a different jack's variety.

I built the non-deluxe version, and if i recall correctly, the trimmer controls the 5th gain stage's presence. You can also try to turn these trimmers to see if it does anything on the whistling noise. I am guessing that if your trimmers are on high settings, you are increasing the chances to have such issue.

Edit : Your soldering looks very good, very impressive for a first build, but it wouldn't hurt to start hunting for shorts, especially on those many TL72. I would take my iron and clean all the tiny spaces between pads. Make sure you take your TL72 off the board when you apply some heat around them, to avoid overheating.

 

[temol]

I just remembered something - I have this circuit on the board of my own design and it also squeals. For me, shielded cables are standard, so I can eliminate this issue. I tried different things and nothing helped. Of course, I do not rule out that it is a matter of not very successful pcb design (in my case). From what I remember, I tried buffer at the input, different ICs. I'm using relay switching. The position of the knobs at which the whistle starts depends of course on the setting of the internal trimmers.

 

[spi]

It’s my first build

You picked a pretty ambitious one for a first build.

I had a squeal issue once that turned out to be a bad capacitor. I debugged it by basically touching components one by one as it was squealing until I found one that changed the tone when touched. Replacing it fixed it.

The fact that you noticed this tone change when moving the output wire could indicate the issue is there.

 

[PJS]

What are you using for a power supply? Try a battery clip soldered to a power jack and see if you still get squealing. Some power supplies have enough noise in the power to do this - especially with high gain pedals. A battery will be pure DC though.

 

[kylewetton]

What are you using for a power supply? Try a battery clip soldered to a power jack and see if you still get squealing. Some power supplies have enough noise in the power to do this - especially with high gain pedals. A battery will be pure DC though.

I’m using a Strymon Zuma, I’ll give that a go but I’ve never had a problem with it and it’s only a couple months old

 

[kylewetton]

So I believe this was in fact a wire that had frayed with the 4 or 5 times I took it out and placed it back into the enclosure. It wasn’t on the footswitch, but instead the more packed channel switch. It finally broke off while I was debugging, once I replaced it, all worked well. I also swapped out the input jacks from the fancy enclosed ones to the standard open ones however I can’t be sure that helped or not.