Guitar Splitter, Getting too much hummmmm!

Okay, So I've been reading the forums and gaining as much knowledge as possible.  I set out to do my first project.  Its a guitar splitter with two transformers for running two separate amps with a DI out as well.  Heres the schematic.
http://www.geofex.com/FX_images/splitter.gif

So I've got it all put together and I'm getting a decent signal when playing through it but Also getting a really loud hum.  With the power off the hum is gone, also when the guitar volume is turned down the hum is gone as well.  Touching the strings makes an audible difference in the hum as well. 
Does this on every output jack including the DI, same exact hum from each, so this tells me either a grounding issue or something with the opamp right?

I'm using a 2134 instead of a 134 so I just grounded the input pins of the unused side of the opa. 
I've got +9 and -9 on pins 8 and 4 respectively.  I've got 0v at the output pin on the opamp.


I checked my resistor values again and all look right.  Only thing I can think of is that for the 2.2mF cap, I ordered this http://mouser.com/Search/ProductDetail.aspx?R=ECW-F2225JBvirtualkey66720000virtualkey667-ECW-F2225JB
which is a 250v and seems way overkill by the size of it.  I went ahead and put it in but I'm wondering if this is causing my hum.
Should I get a smaller voltage cap and replace it?

Thanks and excuse my noobishness,  I'm still learning and want to get some good practice before I start on bigger projects.

Since the hum is gone when the power is turned off, I suspect that the screening of the input wires is insufficient.
The input impedance is very high (> 1 M.ohms), so it is very easy to pick up unwanted signals!
I would certainly use a metal enclosure for this circuit! (Connect the case to the 0 V. or ground of the circuit.)

The Iso jacks must be isolated from the chassis and each other. You cannot mount them in a metal box if you are using the standard 1/4" jacks that automatically ground to the enclosure. You must use jacks that are insulated from the chassis, or mount them in a plastic box.

regards, Jack

RuudNL said:

Since the hum is gone when the power is turned off, I suspect that the screening of the input wires is insufficient.
The input impedance is very high (> 1 M.ohms), so it is very easy to pick up unwanted signals!
I would certainly use a metal enclosure for this circuit! (Connect the case to the 0 V. or ground of the circuit.)

Click to expand...

Is there anyway to test this out before I buy a metal enclosure? 

I know that with the circuit energized, when I touch the ground on the input jack with my finger, the hum decreases alot.  When touching the ground and in clean mode on the amp the hum is almost bearable, but on high gain it is still very noticable.

If you connect the input to ground (=shorten the input) and the buzz is gone, it is the screening!

Ok,  I shorted the input and hum is completely gone!!  Woot,  You guys are so cool!  So I guess I will find a metal enclosure and isolate the jacks with nylon washers and heatshrink.  Is there anything else I can do to help with the interference?

You could use this type of jack if you are using a metal enclosure.
This is an easy way to keep the output jacks isolated.

Would using shielded wire for the input help against this problem as well?  I would use shielded wire for both input wires and connect the shield to ground at the circuit board?

Not using shielded wire for high impedance inputs is asking for trouble!
But the best remedy to avoid hum and unwanted signals is a Faraday shield in the form of a metal enclosure.

Ok, cool so I will get some 2 conductor shielded wire and a metal case and I should be good to go, right?  I guess it is common practice to always shield these wires, is that why there is no reference to it in the schematic or does the schematic usually address this?
Thanks for all your help.

Right! The schematic diagram only shows the circuit. The designer assumes that builders will know that they should use shielded wire for the (high impedance) input, or keep the wires to the input jack very short.

kool thanks.  ;D  Hopefully all goes well and I can work my way up to an 1176 build.

Use a regular 1/4" jack for the input side so that the metal box will be grounded, but use the isolated jacks for the output.

Many pedal builders do not use shielded wires and all goes well as long as the circuit is not very high gain.  Look inside any Boss pedal and there are no shields.  It's probably better if you do use shielded, but as long as you get the outputs isolated, I think your problem will be solved.

-Jack