Pignose 7-100 External Speaker Mod




About: I'm a guitar playing electronics engineer...

This, my first Instructable, will show you how to add an external speaker jack to the infamous Pignose 7-100 battery powered amplifier. With this mod, you can use your Pignose to drive any size speaker, even a Marshall stack! If you love the sound of your little Piggy now, just wait until you hear it with large speakers.

I assume a basic understanding and ability to solder and drill sheet metal, but beyond that, this is pretty simple.

Step 1: Parts Identification

You will need to purchase a mono switched phone jack, refer to the attached photo. This jack has three terminals, one for ground, one for the signal input, and one for the signal output. With nothing plugged in, the signal in and out terminals are connected together and the audio is sent to the Piggy's internal speaker. With a plug connected, the signal is routed to the external speaker instead of the internal Pignose speaker. This part is available from Mouser Electronics, p/n 161-MJ160M-EX

Step 2: Desolder the Existing Speaker Wires

Remove all of the batteries from the Pignose. Carefully desolder the two wires from the speaker, refer to the photo. Note that the White wire is connected to the terminal marked with a red dot. We will consider this the positive (+) terminal. The other terminal is soldered to the shield of the wire, so this must be ground.

Step 3: Remove the Amplifier Cover

With the Pignose open, the amplifier Module is visible on the right hand half of the box. Remove the four small screws (indicated by arrows in the photo) and put them someplace safe. They are very small!

Remove the sheet metal chassis from the Pignose. You will need to drill a 3/8 inch hole in the top of the chassis.

Step 4: Install the Jack, and Start Wiring It Up...

Drill the 3/8" hole.

You will need about 9 inches of two-conductor wire to connect the jack to the Pignose speaker. I used what I had on hand - some leftover car speaker wire - otherwise known as "zip cord" because the two wires can be split from each other like opening a zipper. Strip away about 1/4" of insulation from each wire. One of the wires in this pair was color coded with a red stripe, so I connected that to the speaker terminal with the red dot (the positive terminal). The black wire is connected from the ground, or negative terminal, of the speaker to the ground terminal of the jack.

Note that at this time, the white and shielded wires are not yet connected to anything.

Step 5: Connect the Last Two Wires

You will need another piece of two conductor wire, about 6 inches or so. This will need to be spliced to the existing white and shielded wires. If your zip cord is color coded, use the red strip (or whatever color you used before) to connect to the white wire. Solder these together and wrap it with a layer or two of electrical tape.

Repeat this with the other wire, again wrapping the connection with electrical tape.

Now, connect the free end of the zip cord to the jack. The black wire connects to ground (along with the ground wire from the previous step) and connect the striped wire (positive) to the remaining terminal on the jack - the one that connects to the tip contact.

Step 6: All Done - Now Test It!

Wiring is now complete! Make sure the jack nut is tightened down securely. Carefully install the sheet metal cover back in place using the four small screws. Insert the batteries, and test out the amp. With nothing plugged into the newly added jack, sound should come out of the Pignose speaker as usual.

Now open the amp case, and plug a 1/4" audio cord into the new jack. Plug the other end into an 8ohm speaker cabinet - any size - and try it out. Good luck, and enjoy.

The attached schematic diagram shows what we just did.

Step 7: Demo Video

Check out the demo video....




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    6 Discussions


    7 years ago on Introduction

    just wondering if you could help me out with a pignose-related question i have...

    i was given a gutted 7-100, so i decided i'd just strip whatever there was of use out of it. one of the components i got out of it is the one of the jacks. could you help me out by explaining what all of the lugs are for? or maybe just how it's supposed to be wired?

    i really don't know what happened to it, but it was torn apart on the inside and had leaking batteries and, i assume, dried soda pooled in one corner. because of all that, i don't know if the wires attached to the jack are even all that's supposed to be there.

    any help would be appreciated.

    2 replies

    Reply 7 years ago on Introduction

    I will give it a shot - this week is crazy for me, so it may take me a few days to give you a detailed response, I apologize in advance. Can you tell me which jack you have a question about? There are three on a stock Pignose: the input jack on the front, the preamp out (also a 1/4" diameter jack) on the back, and the 9VDC power input jack on the back as well(A smaller 1/8th" jack).

    The "dried soda" you see inside could actually be from the leaked batteries.

    When you say it was gutted, does that mean all of the electronics were stripped out?

    I'll get back to you as soon as possible. Thanks.


    Reply 7 years ago on Introduction

    alright, i went back to look and found that i have both of the 1/4" jacks. those are the ones i meant, and should have specified. sorry about that.

    i've dealt with regular guitar jacks, but these things have 6 extra lugs. from what i can see inside, i figured that maybe they work like a jack and a switch... but, i dunno.

    as for the "soda"... yeah, i tasted it and you were absolutely right. (hah! just kidding.)

    on the gutted topic, the transformers were still there and about half of everything else that was supposed to be on the board with them was also there. the speaker was there. the volume pot was there (it's a bit wonky, but it still works)... ummm, that's pretty much all i was able to salvage out of it. maybe if i can clean out the cabinet itself, i'll reuse it.

    thanks, and take your time.


    7 years ago on Introduction

    I created a video to compare the sound of the Pignose speaker to the sound of an external speaker. Please check out the following Youtube link:



    7 years ago on Introduction

    It is not quite the same jack as a switched headphone jack; this one is mono, the 'phones jack is stereo but the concept is the same.

    Actually battery life will be the same, as long as the external speaker you use is rated at 8 ohms impedance (the same as the internal Piggy speaker). As long s the impedance is the same, the amplifier has no idea what it is "seeing", so the power consumption is the same. For example, if you have a speaker cab with four 8 ohm speakers inside, they are connected in a series-parallel configuration. Two 8ohm speakers in series totals 16 ohms, then the other two series connected 8 ohm speakers (16 ohms total again) are connected in parallel so the total impedance is back to 8 ohms.

    The little Piggy will seem louder, and will certainly have much more bass response with the bigger speakers.


    7 years ago on Introduction

    Does that also qualify as the headphone switched output jack? I guess you would wear out the batteries pretty quick if it were to drive some large speakers. Crank that nose up past 11.