PCB Guitar Mania - Noise Terminator (Decimator clone)

[Guybrush]

Hey hey,

Just wondering if anyone here had built the Noise Terminator circuit from PCB Guitar Mania?

https://pcbguitarmania.com/product/noise-terminator/

I've tried twice to build it and both times it hasn't worked (no signal when the pedal is engaged).

I was hoping someone may have made a working build and that I might be able to compare notes.

Cheers as always.

[madbean]

When testing, are you sure that the tip of send and return are connected? IOW, you have signal through to the VCA.

[oeslicoalfin]

Is your 3PDT mounted to the component side of the board? It looks like it must be oriented that way based on the locations of the in/out jack eyelets on the PCB. I know I've made that mistake before...

[Guybrush]

When testing, are you sure that the tip of send and return are connected? IOW, you have signal through to the VCA.

Yeah, they're connected correctly.

Is your 3PDT mounted to the component side of the board? It looks like it must be oriented that way based on the locations of the in/out jack eyelets on the PCB. I know I've made that mistake before...

I think the pads are just the "wrong" way round. I've run short eores from the pads to the jack's on the other side of the enclosure. A little hard to see due to it being a tight fit but the white wire goes from the input pad to the input socket on the opposite side of the enclosure. I don't think it should matter which side of the board is seated.

[Guybrush]

Question: With the G-string 2, do you HAVE to use the Send and Return sockets or can you leave them empty and just hook the pedal up at the end of your chain using the Input and Output sockets?

[jimilee]

Sounds like it's time for an audio probe if you've checked the voltages.


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[madbean]

Question: With the G-string 2, do you HAVE to use the Send and Return sockets or can you leave them empty and just hook the pedal up at the end of your chain using the Input and Output sockets?

You cannot leave them empty with the jack you've used. That's why I was asking before about the send/return connection. In absence of anything in the loop, the send and return must be connected. Since you've used simple TS jacks, you need to insert a patch cable between send and return. Another way to do it is use jacks with switched tips. Switched tip wiring means the tips of the two jacks stay connected unless a patch cable is inserted (which breaks their connection).

[madbean]

Btw- you want to put the Decimator as close as you can to the beginning of your FX chain, not the end when not using the loop. The noise gate works best with the cleanest envelope possible. For my personal Deci build, I did not use a loop. So, mine goes right after my fuzz, which is the first pedal in my chain. It's not ideal but the noise gate works perfectly when the fuzz is off.

[benny_profane]

A general comment here: Some of the soldering looks pretty messy. In particular, the DC jack, the 3PDT switch, D1, and both the board and jack connections for the 1/4" jacks. Another concern is that solid core wiring is prone to short if it is manipulated too much. If you find that you're having issues even after trying the above suggestions, ensure that those points are all okay.

[Guybrush]

Bean - thanks for your help. It's late in the UK where I am but will have a look again in the morning. I don't want to use the send/return loop so will try a patch cable between those two sockets. Noted also about the chain positioning. Thank you.

Benny - Yep it's a bit scruffy in places. I'm confident the connections are sound though. I'll flow a bit more solder onto the 3pdt lugs just to be sure. The wire is all stranded though so snappage (is that a word?) shouldn't be an issue hopefully.

Jimilee - I'm absolutely dreadful at following schematics but I think you might be right.

[jimilee]

Question: With the G-string 2, do you HAVE to use the Send and Return sockets or can you leave them empty and just hook the pedal up at the end of your chain using the Input and Output sockets?

You cannot leave them empty with the jack you've used. That's why I was asking before about the send/return connection. In absence of anything in the loop, the send and return must be connected. Since you've used simple TS jacks, you need to insert a patch cable between send and return. Another way to do it is use jacks with switched tips. Switched tip wiring means the tips of the two jacks stay connected unless a patch cable is inserted (which breaks their connection).

See, I was wondering about that. I scoured the build docs, but not everyone makes informative build docs, like you do. The jacks in the build docs all are the same kind.


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[madbean]

Bean - thanks for your help. It's late in the UK where I am but will have a look again in the morning. I don't want to use the send/return loop so will try a patch cable between those two sockets. Noted also about the chain positioning. Thank you.

Sure thing. Here's a bit more clarification:

In Loop mode, what's happening is that the circuit is taking the direct input from the guitar. It sends that through a buffer. That buffer goes to the SEND jack and also the envelope detector. So, the envelope gets clean signal and then the gate comes after the RETURN jack. So, in this case the noise gate effect is actually at the end of the signal chain but keyed off the clean envelope and then sent to the final output. This is the best case scenario for a noise gate.

If you never intend to use the loop, it's best to put the noise gate at the very front to retain the clean input for the envelope. If you put it at the end, then the envelope detector will be keying off ALL the effects in that chain (overdrive, delay, etc) and may produce false triggers or a very unstable gate. So, it's a compromise in that situation. But, I've used mine for years this way and it works fine as long as the gate goes after fuzz. This is because the gate circuit has a high impedance input, low impedance output - IOW much like a buffer. And, fuzz often doesn't work well after a buffer.

[Guybrush]

Thank you so much for the detailed explanation
Who knew a one knob pedal could be so involved!

Good news: Now that I know how to connect it properly, it works.

Bad news: It adds some crackle to the signal.

When building the pedal I substituted the MPS2222A for a BC547A and the LF353N for a TL072. So my first port of call will be to replace thes subs with the original parts. Fingers crossed that will clear up the crackle.

[oeslicoalfin]

I'm glad it's working, and the 3PDT doesn't go on the component side of the board like it does on some of the other Guitar Mania projects... I think that would've been game over when it comes to desoldering. I hope replacing those subs solves the crackle. I have the THAT chip for this project but never got around to building it on strip board.

[m-Kresol]

I have built a noise gate based on schematics flaoting around too. I found that 2 worked well, while one produces a humming sound at higher gate settings. After lots of swearing I found the IC to be the culprit. I have yet to find another working 2181 though. Where did you source yours?