Can someone please verify this amp pan layout for me?

[liddokun]

R.G. was kind enough to put up a schematic for a circuit that pans one input between two outputs, which a friend of mine has asked me to build for him so he can pan between 2 amps with his one guitar. 

Can someone please have a look at my layout and tell me if there's anything missing? 


The schematic can be found at Geofex, panning for fun article, 3rd page (Pan Between Outputs).
I'd like to be sure the layout works before I actually start etching.  Maybe because I made the layout I've overlooked some common mistakes. 

[liddokun]

If someone has the time, can you just look at the schematic and look at the layout and see if it's correct?  It'd help me out a lot. 

[RickL]

It looks good to me. I compared the schematic to the layout and couldn't see any problems. I assume the pinout for the TL072 is correct, I didn't check it. I'm not completely certain R5 will fit under the TL072 but I suppose with a tall enough socket it should work, if not it can be tacked on the back of the board.

Any chance you have a copy of just the traces? I wouldn't mind building it in the next couple of days to confirm it works.

[liddokun]

Yep, I can render it as PnP.  I also forgot to add a note to the bottom of the layout that R5 is mounted on the solder side. 

[RickL]

Well, I built it and it works, but there are problems with the layout...sort of.

Looking at the actual layout, the V+ and ground pins are reversed. Pin 4 should be V+ and pin 11 should be ground. Fortunately the rest of the IC is symmetrical because...the PNP image is mirrored...which corrects the problem.

I use the 4ms CBCB method of construction so when I noticed that the PNP was mirrored I simply used the unmirrored version as my pattern...which got the V+ and ground connected as shown in the layout... which is wrong. Once I figured out what went wrong I used some flying leads to wire the V+ and ground pins correctly.

In summary, the layout is wrong but if you use the PNP mask to etch a circuit board you will correct the error.

[liddokun]

Yes,
Thanks for verifying that.  I'm using the mirrored image pnp to etch, so it will be fine for me.  Sorry for the confusion, I normally created my layouts that have IC's with that in mind, that I will later reflect it as a mirror image, so somethings get reversed in the layout. 
Does the circuit work well?

[RickL]

I didn't do any more than just plug it into two amps and confirm that it worked correctly. It doesn't have any noticable distortion and the pot pans smoothly between the outputs. It might sound cool if mounted in a wah shell and used to pan between amps with two different settings or effect combinations.

It seems like a bit of overkill to just split a signal and send two different levels to different amps. A simple active splitter with volume controls for each channel would work as well for that with a much lower parts count. I think you could even make one with a single FET.

[liddokun]

I suppose so, but I didn't want to spend the time experimenting with stuff.  I posted a topic asking for ways to achieve this application, and R.G. came up with this circuit for me.  I will be mounting it in a rocker pedal, and it will be used to pan between two different amps with just the rocking of the pedal.  Though the crybaby's don't go through full pot rotation, so I'm actually using an old Boss wah enclosure, which uses a slide pot.

[liddokun]

Just finished building this one, it's verified by me. Works fine, I put it in a wah enclosure.