Ruby amp headphone only mod

[merc]

I'm trying to make a Ruby to use for now as a headphone-only amp.  I salvaged a switch (one with two positions and 6 contacts... what's the word? DPDT?) from an 80's radio and I'm going to run the wires that would normally go to the speakers to the middle two pins, and then two wires to the headphone jack and two wires to later be put into the speaker.

_________
| O   O   O |
| O   O   O |   
  |    |    |
  |    |   No wires, but eventually to a speaker
  |    Signal from board
To headphone jack

My worry is that since a speaker is a source of resistance (I base that on the fact they're rated in ohms) that if I don't have one in series with my headphone jack, something will get too much power and blow.  would the solution be just to add a resistor somewhere, and if so, where?  I'm using the perfboard version.  If necessary, I will put up a pic of the layout.  Just let me know.

[anchovie]

http://www.runoffgroove.com/faq.html

[merc]

Yeah, I knew how to do it.  Personally though, I think I would rather use a switch than the "autoswitching" method, because I was planning on using a closed 1/8 headphone jack salvaged from that radio.  But looking at the schematic again, what would happen if I didn't have a headphone plug in?  Would there just be an incomplete circuit, since I won't have a speaker hooked up?

[anchovie]

Nothing bad would happen. Solid-state amps can happily sit there with no output connection. It's bad for the output transformers of tube amps.

[merc]

That was exactly the information I was looking for.  I was confused since I have read "it's bad for your amp to not be hooked up to a speaker" on some sites while "it's perfectly fine" was on others.  Now I know why.

[merc]

Alright, I've just pulled a marathon working on the Ruby.  Something like 7 hours.  ( I used solder lines to go from connection to connection, so I expect some shorts... might have to redo that.)  My problem is, I don't know how to rig it up without the "autoswitching" method as I like to call it.  I want to turn it on with a switch.  I want to switch between speaker and headphone with a switch.  The layout from guitar gadgets that I tried going by is way too complicated because there are wires everywhere and it's a pcb while I used perfboard.  Basically, it's 1:45 in the morning, my brain has shut down, and I can't think!!!  What's throwing me for a loop is the + and - speaker outs.  I don't know how to rig that to a switch for the headphones.  The layout I'm using is in the link below.
P.S.  For C4, I put the positive lead on the lower trace, C3 I put negative on the right-side trace, and C5 I put the positive on the top trace.  Is this correct?
P.S.S.  So the + wire from the battery goes in the +9v slot, does that mean all the grounds go back to the negative wire from the battery?
P.S.S.S. This is my first build, which would probably account for all of these noob questions 

Thanks for helping me out.

http://www.aronnelson.com/gallery/main.php/v/merc1/render.gif.html

[merc]

I was insanely sleep-deprived when I posted last.  My mind is fresh, and I know how to fix it now:  switch to the pcb form.  My perfboard must just be insanely covered in shorts, since I just did lazy solder tracks for wires.  The battery just about blows when I hook it up, and the thing is such a mess of solder and wire, I can't stand to look at it.  I learned what many of you already know:  Don't work when you're extremely tired or frustrated, and perfboards are a pain!  I'll take a trip to the copy machine and etch a board instead 7 hours of perfboard chaos next time, it would have definitely been faster.

[merc]

I gutted that horror I called a perfboard build and turned it into a much more compact freewired form (alright, so it's still as messy).  It's actually working.  About half is wired up and the other half is still on the breadboard, but it runs.  It sounds amazing out of headphones, but there is one problem.  The sound only comes out of one side of the headphones.  I have a stereo enclosed 3.5mm jack that I picked up at Radioshack (at an outrageous price... price gouging little !!@$%s).  Is there any way to get the sound out of both speakers?

[frequencycentral]

Connect the tip and ring tags of the (stereo) headphone output socket together. 

[merc]

I did that, and sound comes out of both sides, but it is barely detectable, even with the volume and gain all the way up.  I did replace the 47uF cap with a 100uF cap since that's all I could find. Could that be the problem?

[frequencycentral]

There are no 47u caps in the Ruby - they are 47n - thats your problem!

[frequencycentral]

47n = 0.047u

Also, what FET are you using? Ruby specifies MPF102 or 2N5457. A J201 for lower output. Check the GS and D of the FET you're using aren't mixed up.

[merc]

There are no 47u caps in the Ruby - they are 47n - thats your problem!

In a layout I got from General Guitar Gadgets, there was a 47 uF cap used in the headphone mod.  Looking at the schematic posted above though, I don't see a cap.  I'm not so good at interpreting schematics though, so I'll just try tearing out the cap and see what happens.

I'm using a MPF102, and, uh, what's GS and D? I just kind of flipped it around till it worked.  The speakers come in at full volume, so I don't think the transistor is the problem, it's my headphone wiring.

But I've been wrong before. 

[frequencycentral]

I checked GGG, u r rite, there is a 47u, is yours the right way round? With the -ve soldered to the socket sleeve? 100u shouldn't make much diff.

GSD = Gate, Source, Drain

http://pubpages.unh.edu/~aperkins/pdf/MPF-devices/MPF102.pdf

MPF102 data sheet: http://pubpages.unh.edu/~aperkins/pdf/MPF-devices/MPF102.pdf

[frequencycentral]

http://en.wikipedia.org/wiki/Image:JFET_N-dep_symbol.svg

[merc]

Transistor is correctly oriented, and so is the cap.  I wired it up as the layout on GGG shows, and it gives the one speaker complete output, and it sounds perfectly fine.  When I attach the wire from the tip to the ring, I get very low output through both speakers.  Unless...
what if I accidentally attached the wire from the ring to the sleeve?  As I said, I'm not so good with the schematics and I'm not sure if I identified the parts correctly.  My wire is for sure attached to the ring, but it might be attached to the sleeve, not tip.  Wouldn't that just cause an incomplete circuit though?