Two Effects in One Box Questions

[Schappy]

Ive done some searching and have found a few ways to wire two effects in one box with two switches.

Is there one way that is best?
What do you do with all the ground wires?

The layout on GGG shows two boards with multiple ground hookups, however my pcbs only have one ground each.
I usually ground everything to the input jack but with two boards that will be a little too much.

[blooze_man]

If you make your own PCB, make multiple pads on ground and ground everything to the PCB and then the PCB to input jack.

[Schappy]

Is it necessary to connect a ground wire between the two PCBs.
Thats what the GGG diagram shows but looking at Dragonflys diagram from the gallery it doesnt show the boards just the switches.

Do you need to do any power supply decoupling?

Also if I run out of room on my input jack for grounding can I just ground the second PCB to the Output jack and then a wire from output jack to input jack ground.

[jasperoosthoek]

I'm too lazy to search for the GGG layout myself. It's best practice to post any link you refer to.

The usual way is to make a star ground. This is a single ground connection where all grounds go to. Your input jack will probably be the best place. In fact exactly as you originally did it . If it is physically too small then make it larger by adding some eyelets or whatever you find. You can also get a little eyelet board and connect it close to the jack and then run a little wire to it from the input jack.

I don't know if supply decoupling is necessary. That depends on the effects you use. High gain distortion effects might require decoupling. That's something you can easily test: Just hook everything up with switches to individually power the effects. If there is a noticeable difference between powering only the effect you use or powering both effects then you know you need decoupling.

If they are distortion effects that don't draw much current you can connect them to the 9V supply by a resistor. Make it as large as possible without noticeable voltage drop. You can also use an inductor/choke for . A 330uH with a 100uF will give you an additional 900Hz cutoff. Larger inductors can be bulky. These are the size of a 1 watt resistor.

Inductors have a very small DC resistance but form a nice low pass filter with the cap with a 12dB/octave slope instead of the 6dB/octave of a cap and resistor. They work much better in rejecting noise and avoiding cross talk between the circuits. Then connect a chunky bipolar between the effects ground and the original 9V input of the effect. The only danger is that when you turn on the effect the inductor has to charge the cap. So if you make the cap too big (1000uF) you might fry the inductor when the power supply can handle the current.

[Schappy]

Here are the two layouts Im talking about.

http://www.aronnelson.com/gallery/main.php/v/DRAGONFLY-LAYOUTS_0/The-Mod-Zone-_/WIRING_2_FX_IN_1_BOX.gif.html


http://www.generalguitargadgets.com/pdf/two_in_one_wiring.pdf

[jasperoosthoek]

I personally would prefer a star ground. I don't see any benefits to that way of connecting it. They had the grounds go along with the signal from one effect to the other. My jacks aren't grounded so it would be better to connect everything ground to the input ground and have that as a source of reference.

[MikeH]

Whenever I do multiple effects in a single enclosure I take a small piece of vero or perf, 2 rows by how ever many spaces I need, and wire that up to the DC jack.  One row I use as a ground buss, and the other I use as a V+ buss.  Keeps things a little less "Rats-Nesty", and helps avoid ground noise.  When it's all wired up I wrap the little board with some electrical tape to insulate it. 

This method is also handy if you'll be swapping out effects; this way you only have to remove the board you want to swap out.  If they're connected together you sometimes have to pull them all.