noisy OD circuit! HELP

[teledan62]

Hey guys. New to this forum!

Ive been trying to build a 3 in 1 guitar pedal. compressor, overdrive and delay in that order. all in the same enclosure. They all work fine but when i engage the overdrive, its really noisy. i thought it was the circuit i was using so I put in a totally different circuit but still the same noise issue. the overdrive circuit is  the night drive by diyguitarpedals.com.au.

Attached is wiring diagram and photo of circuits! Would be hugely appreciated if someone could pinpoint where my noise is coming from

[GibsonGM]

On your drawing, I don't see a gnd connection back to the power supply from the delay?  A casual look suggests that maybe it's shorting with the DC jack?? Worth tracing that wiring back "in real life" to be sure that's what is happening.  Look how it's switched by the right hand switch; is that just to gnd the input when not in use, and is that actually wired that way?   Welcome to the forum, by the way!

LOTS of things can create noise, esp. in a high or highish gain circuit...your wiring dress, for one thing (should neaten that up    Power supply - what is running this - does it on battery too?

What I try to do is connect all the board grounds together, then go back to power supply from only ONE point.   And I make sure I have a cap to ground where the + comes into each board.   But for GROSS noise, it's not that - it is something loose, missing, not connected, shorting to a piece of wire or the chassis, etc.

But for now, check that ground (check em all!), make sure they all have continuity with your chassis.  Check for wiring errors (most common issue), loose jacks not making a gnd connection, etc.   Parts touching the enclosure on the back of the boards, loose solder connections.  It will likely be something easy - we make errors pretty routinely and get the same issues, ha ha...

[LightSoundGeometry]

a compressor + and overdrive will hum,hiss and make noise naturally - you have to be careful pushing a overdrive with a compressor

for example, I can push a show preamp with my range squeeze, but soon as I push a red napper it gets too loud to use at all.

this could very well be the problem and nothing you did building the pedal

I would of chosen an overdrive with a built in compressor already in the circuit. compressors are tricky animals to use in an effects chained stacked with other pedals

[teledan62]

But the noise is there when the compessor is turned off. The compressor makes no difference to the hum

[Mark Hammer]

So, the Night Drive would appear to be something akin to the Boss SD-1, but without input/output buffers ( http://www.diyguitarpedals.com.au/shop/boms/Nightdrive_schematic.pdf ).  This is not an inherently noisy design. 

At the same time, assuming the schematic reflects what you have on your board, there is a critical capacitor missing in the drawing.  Below, you see the SD-1, and below that you see the TS-9.  For the TS-9, you see a 51pf cap in parallel with the clipping diodes.  This cap trims off the top end as the gain is increased, such that a)  you don't get excessively harsh top end, and b) the treble-taming is introduced where risk of hiss exaggeration is greatest.  In the case of the SD-1, the .01uf cap you see in the Tone-control stage essentially takes the place of the 51pf cap in the TS, albeit in a different way.  Here, the cap provides a fixed treble rolloff to tame hiss and fizz.

Whether one prefers an adaptive treble-cut like the TS, or a consistent-character cut, like the SD-1, either way there is precious little taming in the NIght Drive of the hiss that inevitable comes with higher gain.  My suggestion is to stick a 47-68pf cap in parallel with D2, and that should go a long way towards taming the hiss.  You can probably just tack it onto the copper side without difficulty.

Just why they left it off puzzles me.

[Mike Burgundy]

Welcome!

i thought it was the circuit i was using so I put in a totally different circuit but still the same noise issue.

By this, do you mean you've replaced the night drive with a wholly different circuit (say, a boost, or eq, or whatever), or did you replace it with *another* nightdrive?
There's a big difference - when you're swapping nightdrive's, and the problem stays, that suggests there may be a common error in the nightdrive circuit, or there may be a wiring error specific to that position in the chain.
When swapping in a different circuit, it's more likely to be something specific to that position in the chain...
Have you tried swapping the compressor and the nightdrive? Tried the nightdrive on it's own, not in the box with the other two?

[teledan62]

I started with a aeondrive circuit and that was noisy. I took the aeondrive out and put in the night drive. Still noisy. I havent tried swapping the compressor with the nightdrive but I will try it. But will it even make a difference as the noise is still there with only the night drive engaged?

[teledan62]

Welcome!

i thought it was the circuit i was using so I put in a totally different circuit but still the same noise issue.

I might try the cap

By this, do you mean you've replaced the night drive with a wholly different circuit (say, a boost, or eq, or whatever), or did you replace it with *another* nightdrive?
There's a big difference - when you're swapping nightdrive's, and the problem stays, that suggests there may be a common error in the nightdrive circuit, or there may be a wiring error specific to that position in the chain.
When swapping in a different circuit, it's more likely to be something specific to that position in the chain...
Have you tried swapping the compressor and the nightdrive? Tried the nightdrive on it's own, not in the box with the other two?