Ruby Amp build - Hissing in headphones

[mydementia]

Hi guys.
I just put the Ruby amp together last night and must say I really like the tone.  The thing I don't like is the constant hissing coming through my headphones.  I put the 100uF cap across the output (negative pole to ground, right?) and still have the hiss.  I didn't have a 10ohm resistor in my box of goodies - but I think that is to reduce overall volume (which it REALLY needs) for headphone use - the cap was to reduce/eliminate hiss.  Any thoughts?  Anyone have a good switching layout for headphone or cabinet output use?  The schem from runoffgroove doesn't have the output cap on the hedaphone out...much confusion.

Here's a snapshot of my recent spawn.  I built the MXR Headphone amp last week and was disappointed with the headroom, so I added a 17V charge pump (using the Max1044 layout from GGG) - much better headroom, but overall worse tone than the Ruby.  Now that I have the right volume pot for the MXR (500k log wired backwards) the volume level is good...


Thanks for looking.
Mike

[spudulike]

The 10R resistor and the 47n cap form a Zobel Network - it limits the rising impedance of a loudspeaker due to the speaker coil inductance.

[mydementia]

Okay - I've read up on Zoebel Networks...but I think I'm more confused.
Most of the articles I searched in this forum talked about Zoebel Networks for speaker output.  Based on the GGG circuit and the runoffgroove discussion, it looks like the output network is already in place (looks like G->0.047uF cap->10ohm R->220uF cap to speaker output).  Am I adding a second 'output network' (47uF or 100uF cap (?) and 10ohm R) for headphone use?
Here's the layout I followed: http://www.generalguitargadgets.com/pdf/ggg_ruby.pdf

Thanks again.
Mike