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JUGULAR amp guitar


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Hi, I started  this build in 2019 then covid hit, Now it's  2024 and I'm finally finishing it . The top case has 4 working speakers from a Marshall MS 4 micro amp. and the bottom case will eventually  have 4 more, I'm  waiting on a lefty neck and the graphics for the control area sometime this week I hope. The gap between the 2 cases will decrease once I slide them together. I finished all the wiring today and it sound good. I measured the guitar from the top of the neck to the bottom case and it's  58.5"

Jugular amp guitar 2.jpg

Jugular amp guitar.jpg

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Oh the beauty of insanity!

I had to check for MS4 to find out that it's that plastic thingy with 2.7" speakers. So if my math doesn't fail on me you've disassembled four of them for that build. Which leads me to the next question: What is the amp you're using to drive those speakers? And how much does that thing weigh?

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Hi, There is no amp to work those 4 speakers , The guitar has 2 functions ,A normal guitar and it will play from the speakers. When a patch cord is plugged into the plug for the guitar and the other end plugged into the other input for the speakers you can walk to the corner store while playing a song, Then unplug for the stage performance. There is a circuit board that operates the 4 mini speakers. And separate volume and tone for the guitar

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I'd also like to say I didn't  copy the Marshall guitar. When I google Marshall amp guitar nothing came up so I started  the build , I had all the wood work done when a Marshall tour of their factory in the UK came on Youtube. In the video they have a museum and in a display case was the guitar, They also mentioned it was played in the Spinal Tap movie, I've never seen the movie, So I typed Spinal Tap movie Marshall amp guitar on Youtube and there it was.

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7 hours ago, PTModIT said:

There is no amp to work those 4 speakers , The guitar has 2 functions ,A normal guitar and it will play from the speakers. When a patch cord is plugged into the plug for the guitar and the other end plugged into the other input for the speakers you can walk to the corner store while playing a song, Then unplug for the stage performance. There is a circuit board that operates the 4 mini speakers. And separate volume and tone for the guitar

Had to read that three times to understand, hopefully right: So when you say there's no amp you apparently mean there's no big wall plug powered amp inside, but you can plug into one for stage performance.

My question was about the circuit board that operates the mini speakers. That's an amp too! And that's what I am a bit interested about.

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7 hours ago, PTModIT said:

I'd also like to say I didn't  copy the Marshall guitar. When I google Marshall amp guitar nothing came up so I started  the build , I had all the wood work done when a Marshall tour of their factory in the UK came on Youtube. In the video they have a museum and in a display case was the guitar, They also mentioned it was played in the Spinal Tap movie, I've never seen the movie, So I typed Spinal Tap movie Marshall amp guitar on Youtube and there it was.

Not accusing about plagiarism, it was just a remark that everything has been done at least once before. It's not uncommon that people end up doing similar things. Although, the guitar world is an odd world and there's no such thing as plagiarism. In general it seems to be perfectly ok to copy designs and get away with it. That's how it has always been, and while this practice is not commonly accepted in any other product category, it's unlikely to change in the guitar realm.

Btw, the amp guitar was not in the original 1984 Spinal Tap movie, but it was in the 1992 "sequel" The Return of Spinal Tap.
 

 

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Hi, These are the circuit boards inside the micro amp, The first pic is for the volume tone on/off etc, the second pic is to plug in headphones and the third is where you plug in the patch cord for a guitar.

marshall circuit board 1.jpg

marshall board 2.jpg

marshall board3.jpg

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Thanks, that's the amplifier indeed on the uppermost picture. By the looks supposedly salvaged from one MS-4.

I guess the extra speakers and solid wooden(?) boxes make it sound much better than the original micro amp.

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So, if I get it right, your guitar has a regular output jack and it has an input jack to the internal battery powered amp (MS4). You put a patch cable between these to play with the MS4 or you connect the guitar to an external amp, as you would do with any guitar. 

If I was you I think I would do connections internally so that if no guitar cable is attached to the output jack, the internal amp would be in use and if a cable is connected then the internal amp would be bypassed. 

On top of these connections the MS4 has a headphone output. Which, according to Marshall spec, can also be used as a preamp. Do you have that wired in?

Anyway, one thing you need to be aware of is speaker impedance. The load your speakers place should match the amp. It may not be an issue with this tiny amp with moderate volumes but you may also blow the amp if you have a serious impedance mismatch. I don't know the specs for sure but, I believe the amp expects an 8 ohm load. Depending on how you wire all your speakers you may end up with too low impedance.

E.g. I assume the two speakers in the MS4 are 4 ohm speakers. Resulting an 8 ohm load when connected in series.

If you have four 4 ohm speakers in series you have a 16 ohm load. Connected in parallel the load is only 1 ohm. Doing a series/parallel combination you would have 4ohm load. Out of these I assume the first one may be ok for your purpose.

Then, if you are going to have eight speakers, assuming they are all 4 ohm, you can wire two sets of 4 speakers in series (each set results 16 ohm) and connect these two sets in parallel. Which equals an 8 ohm impedance. Golden.

But you want to check the specs and look up for information about series/parallel speaker connections.

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  • 3 months later...
11 hours ago, henrim said:

Apparently 15 in standard scale is 6.8 in universal scale.

Most likely so. My rule of thumb is to divide the amount of lbs into two. That's close enough for most purposes, even cooking.

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