Effect works, but is humming

SanderNijland · February 16, 2009, 03:45:47 PM

I build an LPB2 on a custom made PCB, everything works fine except that the effect is humming. If its just plugged in, but turn off and the amp is set to clean, it hums slightly. If the effect is turn on, it gets louder, also on the clean channel. But if i add some distortion/overdrive, it hums like hell.

I build it according this schematic/layout:

http://www.generalguitargadgets.com/pdf/ggg_cb1_sc.pdf
http://www.generalguitargadgets.com/pdf/ggg_cb1_lo.pdf

I used the following parts (maybe those are low quality ore something and make the effect hum)
Resistors - 1/4 Watt, 5% Carbon Film
Capacitors, Panasonic Low Voltage Poly Film

Voltage's

According to GGG:
Collector 4.7v
Base 0.8v
Emitter 0.2v

My own:
Collector 5.35v
Base 0.7v
Emitter 0.11v

Maby something wrong with some components?

Kearns892 · February 16, 2009, 04:05:40 PM

Not to sound condescending, but first check your grounds, and what are you using for a power source?

SanderNijland · February 16, 2009, 04:07:08 PM

Using a battery, and what do you mean with check the grounds? I checked every wire and i wired it up correctly. Lets me look over it again one more time, just in case...

jefe · February 16, 2009, 04:24:16 PM

Is it all packaged up in a metal enclosure, or is everything still out in the open?

SanderNijland · February 16, 2009, 04:37:33 PM

No enclosure, that can be the problem?

jefe · February 16, 2009, 04:41:18 PM

It sure can! A properly grounded enclosure can block quite a bit of hum.

SanderNijland · February 16, 2009, 04:43:34 PM

And can you explain that a bit more? The " A properly grounded enclosure "

Ripthorn · February 16, 2009, 05:15:39 PM

A properly grounded enclosure is either a metal enclosure with the enclosure connected to ground or a non-metal enclosure lined with conductive foil or paint that is connected to ground. This essentially makes the enclosure like a faraday cage used to block electromagnetic signals from outside the cage.

biggy boy · February 16, 2009, 07:43:49 PM

Watch our for ground loop in your gounding path.

GRD_ _ _ _device_ _ _ _device_ _ _ device_ _ _ _device OK

GRD_ _ _ _device_ _ _ _device_ _ _ _device_ _ _ _device_ _ _ _GND NOT good. This is a Ground loop!

GRD_ _ _ _device_ _ _ _GRD NOT good This is a ground loop!

GRD_ _ _ _device This is good it's the star gound !
| |_ _ _ _ device
|_ _ _ _ _device

Glen

SanderNijland · February 17, 2009, 05:55:20 AM

Thanks guys, going to try this real soon, will report back

News:

Effect works, but is humming