Fender Frontman to Princeton 5F2A/Champ Conversion

Discussion in 'Shock Brother's DIY Amps' started by willholt92, Jul 25, 2019.

  1. willholt92

    willholt92 TDPRI Member

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    Hi All

    After spending a lot of time on this forum looking at amp builds over the past 6-9 months, and being half way through a tweed cabinet build I've been slowly chipping away at all year, I took the plunge and bought a kit from Mojo Tone.

    This came about when I found my old Fender Frontman 15G which I had as a first amp when I bought my very first guitar probably 16 years ago, a lowly Squier Strat.

    Last year I completely reworked my Strat, fully stripped it, repainted Seafoam Nitrocellulose, Handwound Vintage spec pickups, CTS pots, Orange drop cap, bone nut, sanded and oiled neck, Kluson vintage tuners. It's turned out incredibly well and is again one of my go to guitars now.

    When I found the amp in my basement I thought, surely I could do the same to the amp and turn it into an awesome little tube amp. Making what this combo pack should have been in the first place.

    I began looking to see if anyone had ever done this, and I found a few threads with people doing the same, which tells me I'm not barking up the wrong tree. But I didn;t really find a full in depth one in the way I am thinking so I thought I would start a thread.
    Also for the inevitable help I will need from all the great folks on here when it's not working and I cant figure out why.

    Any way, I love the champ circuit for it's simplicity and sound however I wanted to keep the blackface aesthetic and so I decided on the Princeton Circuit to add a tone pot and an extra knob to the front. I read up on a modification many have done to remove the tone pot from the circuit and essentially convert back to a 5F1. However I am planning to do this with a separate pot altoghter hidden as a Voice pot simply on and off.

    Currently I have received the kit and began disassembling the Frontman to begin mocking up the chassis. As I work in design I have spent most of my time thus far designing the front and backplates when not working on my other projects. (I have told my self I will not properly start this until my tweed cabinet is finished due to me having far too many proejcts on going)

    Here's a few pictures this far FullSizeRender (3).jpg

    I couldn't resist changing the front logo for the proper Princeton style one.

    FullSizeRender (6).jpg

    FullSizeRender (8).jpg
     
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  2. willholt92

    willholt92 TDPRI Member

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    The graphics have been a lot of fun for me to work on, my plan is to mock up the chassis positioning of the components in plastic sheet to make sure everything fits as it should and no parts are fouling each other or anything stupid like that.

    Once this is confirmed I can get the sheet metal parts drawn up in CAD and my friend has a laser cutter and press break to help me make the chassis.

    I will keep the front panel classic Princeton Black face, 2 inputs, Volume, Tone and the Voice switched pot, then the jewel light.

    I am planning to move the on/off switch and fuse to the rear of the chassis along with the speaker jack. I can't see this causing any issues, unless someone can tell me otherwise?
    The additonal depth of the Frontman cab should allow enough room for the tubes to hang down behind the board.

    IMG_9512.JPG

    I printed the graphics and double sided taped them to some plastic sheet I had lying around in our workshop. Then I can use a hole drill to make the different holes for various components.

    IMG_9654.JPG IMG_9655.JPG

    IMG_9656.JPG

    Here you can see the front panel mocked up, I also bought some chassis support plates for the top to give the classic blackface look. I'm just hoping I have enough room at the edges of the chassis to get the screws through and not hit the PT as it is looking a little tight.

    IMG_9657.JPG

    Back panel mocked up and holes started to be drilled. Yo ucan see left to right. Power cable/Fuse holder/On Off switch and Speaker Jack.
    I have ordered my spekaer too for the mock up, a Jensen Cr8 for starters, although having used Celestion Eight 15 in my Blackstar HT1 I might try one of these at a later date.

    IMG_9659.JPG

    I hope to start this proejct properly in the coming weeks, but it will depend on when I get my finger out and finsh my tweed project. Which is here if anyone is interested.
    https://www.tdpri.com/threads/tweed-cabinet-build-and-some-distractions.956833/

    I'd be interested in anyone's comments or if anyone has seen anything catastrophically stupid please do tell me.
     
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  3. King Fan

    King Fan Friend of Leo's Ad Free Member

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    I envy your ability to build a cabinet, but especially to produce faceplate mockups and then the real thing. That’d be cool.

    Enjoy the build.




    Sent from my iPad using Tapatalk
     
  4. jvin248

    jvin248 Poster Extraordinaire

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    .

    I have a beat up off-brand 10watt amp that I'm planning on chopping down to a mini-head. I'll leave it solid state.
    There are a few images of people taking the Fender/Squier 10W amps apart and making a mini head and matching full stack cabinets for it.

    Your project looks like a fun one.

    .
     
  5. Jake Nelson

    Jake Nelson Tele-Meister

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    Subscribed!!

    [​IMG]

    i to envy the faceplates
     
  6. willholt92

    willholt92 TDPRI Member

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    Thank you, it is the first real cabinet I've built and it's been going well this far, just slower than I'd like. But then life get's in the way of most interesting projects



    Thank you, I have been looking at your project and it fills me with confidence, really nice build by the way.
    The faceplates are a nice way for me to use my design skills and not die doing silly things with electronics haha.

    I'd be happy to help make you some artwork for yours if you like?
    Would just need dimensions of the holes and their positions. I have the closest I can get to Fender fonts and I've created the Princeton/Champ logos from images.

    I then get the faceplates made by a laser engraving company with layered plastic, when etched the white shows through from behind the black.
    Testing everything on paper gives me more confidence when it comes time to get the real things done.
     
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  7. willholt92

    willholt92 TDPRI Member

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    Thank you, yeah I found quite a few of those types of head conversions.
    I will probalby end up selling the Frontman cassis and circuit to someone who wants to do such a thing.
    It's actually quite a nice little amp when using the clean channel, great for pedals.
     
  8. willholt92

    willholt92 TDPRI Member

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    Tiny update.

    Jensen arrived, so had a 5 mintues test fit. Can't wait to get going on this now.
    The jensen is actually a bit higher than the speaker that was in there, glad I didn't wait until the end to buy it, don't want transformers fouling the speaker.

    I have some plywood in the workshop so I will likely make a new speaker baffle from that to get rid of the holes at the bottom which won't be needed with the open back.

    IMG_9956.JPG


    I have taken on another project to buld my friend a decent pedal board so it's been pushed back slightly. Hopefully the board will be finsihed this week.
     
  9. willholt92

    willholt92 TDPRI Member

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    Had an hour last night after work to mock up the front and rear panels and drill the holes with my new step drills.

    FullSizeRender (5).jpg

    Unfortunately I got a few hole sizes wrong, and over drilled the pilot light hole which is a pain because that is one area where I am worried the lamp assembly may foul the bottom of the chassis due to the angle of the faceplate. Any way it worked with some success.

    FullSizeRender (10).jpg FullSizeRender (11).jpg

    I have bought a switched pot for the voice change position IE to cut the tone pot and revert to champ circuit.
    Now I assume this will work for this purpose? I have attached photos of the pot below with the switch in on and off position. And I trust I can wire the cut using this? Unless anyone can tell me otherwise.

    IMG_0007.JPG IMG_0008.JPG IMG_0009.JPG

    I am unsure whether the K rating of this pot will make a difference in the circuit?
     
  10. willholt92

    willholt92 TDPRI Member

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    Hi All

    Now I have finished my tweed cabinet I am now able to spend some time on this (more interesting) project.

    I began to draw up the new chassis for the frontman in advance of hopefully getting it laser cut and folded next weekend.

    My engineer at work is modelling all the components in CAD software so we can test fit the components and see how much space we have. It is beginning to look a bit tight already.

    I have decided that I am going to build my own turret board as the Mojo item is too large to fit, I have the materials ready for this but I wanted to ask those who will know better than I, how much I can realistically reduce the size of the board without affecting any of the components.

    I have borrowed the below image from @theprofessor 's thread. (Sorry, it was quicker than populating my board and trying to get a good photo)

    I have added the red lines to show the unused space on the princeton board, if I removed the material between the red lines on my new turret board, and bearing in mind that using turrets will allow easier mounting of multiple components to one point is there anything that would cause any problems for me?

    I will ensure there is enough space so that caps are not touching one another ect, just want to make sure I'm not doing anything stupid

    Board layout.jpg

    Any input will be much appreciated, have a great day everyone
     
  11. Asmith

    Asmith Friend of Leo's

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    20k is probably not going to work very well in this circuit. Id suggest trying to source the correct value pot with a switch. 1 meg switched pots exist and usually double as the power switch on champs. Also a single pole switch cant completely remove the tone control so if thats an issue for youll have to look at using a separate dpdt switch.
     
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  12. theprofessor

    theprofessor Friend of Leo's

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    No need to apologize! I'm glad the image was helpful!
     
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  13. willholt92

    willholt92 TDPRI Member

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    Ah great thanks for the reply, I'll look at getting hold of one.

    I have seen people use those pots when doing this mod on a Princeton.
    Why is it that this will not totally remove the tone control?
     
  14. Asmith

    Asmith Friend of Leo's

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    Its a spst switch by the looks of it, the tone control is connected to the circuit at 2 points so youd need a double pole switch to disconnect both and seperate it completely. Disconnecting the middle lug of the tone pot would do enough though (I think).
     
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