Making a sum-Amp/ Ybox (Wyebox)

Likez2Jam

New member
Hey all I found a great project on Instructables. for a sum amp. Only issue is it uses stereo jacks and I only have mono on hand. Anyone know off hand how I would have to accommodate for the ring part of the stereo jack circuit? Not sure what ring would be analogous to? Is the ring a hot or grounded path? I would assume a second "hot" like the tip...So I could presumably put the 10k in the tip path? Or would I have to change the values of the resistors altogether to get the same effect? Screenshot (7).png
 

Stickman393

Well-known member
Little beyond my area of expertise, but I'll take a stab...

Following the link they provide offers a good way to think about doing this for mono unbalanced signals:

Screenshot_20211201-215106.jpg

That stereo-to-mono summing box wiring diagram is what you're after. Basically, connect the rings of two mono jacks, wire as though one mono "tip" is the "tip" on the drawing above, and wire one mono "tip" is the "ring" on the drawing above.

When you're done, you should have all your rings directly connected, a 470ohm resistor between in1 and out, a 470ohm resistor between in2 and out, and another 20k resistor between the tip and ring of "out".

Though keep in mind I'm sure this is designed for line level, low impedance signals...it might act a little funny if you try to feed if a signal directly from passive guitar pickups....your best bet if that's the use case is to use a simple jfet, transistor, or IC buffer circuit before that input. Anything from a synth or after another effect should be just fine.
 
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fractal33

Active member
Hey all I found a great project on Instructables. for a sum amp. Only issue is it uses stereo jacks and I only have mono on hand. Anyone know off hand how I would have to accommodate for the ring part of the stereo jack circuit? Not sure what ring would be analogous to? Is the ring a hot or grounded path? I would assume a second "hot" like the tip...So I could presumably put the 10k in the tip path? Or would I have to change the values of the resistors altogether to get the same effect?View attachment 19346
What are you going to be using this for? Sounds like a simple resistor mixer might do the trick. If you are coming straight from your guitar like stickman393 said you might want to opt for an active version to raise input impedance.

resistor_mixer.jpeg
 

Likez2Jam

New member
I am using it to send an octave down guitar (with the tone rolled off to sound close to a bass) and an Alesis eDrum set to one channel on a stereo in/out looper. That allows the "bass" and "drums" to go to a different out(monitors at this point, but PA when gigging) than my actual guitar signal (guitar amp). That way my clean PA can deal with those frequencies and not muddy my guitar loops. I've been running all to the looper, to a "clean as it can get" amp, and EQing to make a nice loop (like recording/gigging quality, not just jamming) has been a nightmare. hoping independent outs will clean it all up a bit.
 

Likez2Jam

New member
I ended up just buying a 6 pack of stereo jacks and did the instructable, but I'm going to hold onto this if I have to make more for some reason. It has worked well so far. Gotta clean up the soldering/wiring on input 2 to the output (jamming three wires to 1 lug got blobby and messy. ) input 1 sounds good, input 2 is finicky at the moment.
 

Stickman393

Well-known member
Helping hands, solid core wire, needle nose pliers: do yourself a favor and get some of those. Often, getting stuff to stay in place while you solder is a battle, but with the right tools at your disposal getting 3 leads into a single lug on a jack is a cakewalk.
 

Likez2Jam

New member
Helping hands, solid core wire, needle nose pliers: do yourself a favor and get some of those. Often, getting stuff to stay in place while you solder is a battle, but with the right tools at your disposal getting 3 leads into a single lug on a jack is a cakewalk.
Oh yeah totally agree. I was just in a rush to finish so I wired it all in box. So it was cramped spaces in the mini enclosure. I just got sloppy because I was finishing it before some plans I had with friends started. I'm going to take the jacks out now that I know I got the wiring in a "it'll fit" state. Going to solder suck and redo the blob wires.
 
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