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Summer project...

Discussion in 'Shock Brother's DIY Amps' started by dougsta, Apr 10, 2021.

  1. dougsta

    dougsta Tele-Meister

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    I scored a SS Fender Frontman 212R for £50 (it actually works and has no issues other than it sounds like a SS amp).

    So now I have a summer project to convert it to a tube amp, the electronics should be straight forward. I'll wind the transformers and a choke. To keep the budget low I'll use old USSR clones of 12au7/12at7/12ax7 (I already have a bunch I got for £1 each) I also have 2 of the USSR 6L6 clones 63pS, maybe good for a 40 watter. I'll reuse the spring line but drive it from a constant current tube circuit.

    I'm thinking it will take a lot of lipstick on this pig to get it to look like a Twin Reverb though. A lot of work on the faceplate and it's missing a knob.

    summer project 2.jpg
     
  2. 985plowboy

    985plowboy Friend of Leo's

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    I’ll watch
     
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  3. NSB_Chris

    NSB_Chris Tele-Meister

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    Are you going to put in the vibrato part of the circuit?
    You could leave that out and add a tube driven effects loop. Put the FX return pot on the back panel. Then you could put any vibrato or other time based effects in the effects loop. Keep the original faceplate.
     
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  4. Mark617

    Mark617 Tele-Meister

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    Def keep the face plate. Sorta like hiding what’s under the hood . I look forward to seeing your project
     
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  5. Harry Styron

    Harry Styron Friend of Leo's Gold Supporter

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  6. dougsta

    dougsta Tele-Meister

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    Excellent idea, I wasn't sure about the extra vibrato channel, a lot of work to keep it when I already have a multi effects pedal.

    Maybe I can do something to customise the faceplate logo.
     
  7. dougsta

    dougsta Tele-Meister

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  8. radiocaster

    radiocaster Poster Extraordinaire

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    Those preamp tubes are wired differently from 12A*7. If you might want to use both in the future, you need to add a switch for both types for each tube.
     
  9. dougsta

    dougsta Tele-Meister

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    Yes, indeed, when the filaments are on pins 4/5 I find it easier/neater to wire in a chain. I've done the switch thing on my champ type build as I have some ECC85 valves from the '60s, they use pins 4/5 and a screen on pin 9 just like the USSR triodes.

    IMG_8347.jpg
     
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  10. dougsta

    dougsta Tele-Meister

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    Here's some photos of the the project amp.

    FM1.jpg FM2.jpg

    I'd like to do some changes on the right side, add a dwell pot next to the reverb pot, move the foot switch jack to the rear and move the pilot light further to the right.
    On printing a new logo.
    A friend who runs a print shop came round the other day with his 'critical' windows 7 accounts computer for me to fix, I asked about printing white ink on a black background and he said you require specialist printers to print white ink. He could print black on white plastic stickers. Got his system up and running again so owes me a favour. He also has a vinyl cutting device, basically a CNC craft knife. I just have to do the artwork.

    fender-vintage-reissue-series-65-twin-reverb.jpg
     
  11. printer2

    printer2 Poster Extraordinaire

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    Could try selling the old chassis whole unless you were using it for the tube amp. May not get much but it may help.
     
  12. dougsta

    dougsta Tele-Meister

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    I've got the crazy idea of using the chassis!
    Now, the main issue is the shape. The side profile of the rear of the chassis isn't rectangular, I'll have to make a cut and bend to 90 degrees and join it back together, aluminium so could use rivets/nuts/bolts.
     
  13. dougsta

    dougsta Tele-Meister

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    I removed the chassis, unmounted the PCB and mains transformer. Didn't lose any parts, all in a plastic box with a lid.

    Here's my chassis 'solution'.

    Make 2 long cuts along the length of the chassis, one at the back and one at bottom. Make a 90˚ bend half way down the back. Make a 30˚ bend in the bottom part and join together with nuts n bolts or rivets, should make it stronger for mounting the heavy transformers.

    chassis solution.jpg
     
  14. dougsta

    dougsta Tele-Meister

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    Here are some better photos of the chassis prep:

    Removed the back plastic sticker, modest heat from a plumbers torch helped.

    IMG_8380.jpg

    The rear sticker came off in one piece, I can reuse part of it if needed.

    IMG_8384.jpg

    The annoying angle at the back

    IMG_8385.jpg

    Cut the back off, used a file to remove metal from the bend, then was able to bend it easily back, smoothed of with a file, no burrs to rip into skin.
    Added painters tape to protect the faceplate.
    Cat not that interested, enjoying the sun.
    IMG_8391.jpg
     
    Last edited: Apr 12, 2021
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  15. Marc Morfei

    Marc Morfei Friend of Leo's Silver Supporter

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  16. dougsta

    dougsta Tele-Meister

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    Seems the odd bend angle needed is 25˚ and not the 30˚ I eyeballed.

    Useable chassis size will end up as 24 1/2" x 6" x 2 3/4"

    IMG_8392.jpg
     
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  17. Preacher

    Preacher Friend of Leo's

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    Love it!!

    I am looking for an old Frontman 15 to rehouse my 5F1 circuit in.

    I kind of want the amp to look like the $25 model, but have tubes and a good speaker in it.

    Two bonuses in my mind of having this.

    1) no one will ever walk out with it as they aren't worth stealing.
    2) it will be fun to have some person mention that I should be playing through a tube amp.
     
  18. buddy_coles

    buddy_coles TDPRI Member

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    That looks good, Dougsta! And good to see your cat has assumed the role of supervisor :lol:
    I think the rubber mallet and wooden former method should work well - my experience recently suggests that the main issue is in clamping the workpiece as tight as possible along the bend line. If you can clamp it well, the bend should end up nice and straight regardless of the level of technology used to bend it... But are you creating a new bend, or just increasing the existing 90 deg one?

    Also, I noticed you mentioned about a printing place that does vinyl laser cut to size - do you know what kind of resolution they can go down to please? I was wondering if it would be possible to get a white vinyl sheet laser cut around the edges of all the letters and numbers for a control panel (so down to about 0.2mm accuracy, probably), then stick it on to a chrome panel and very very carefully peel off the main part, leaving the letters... That may be a bit optimistic, but would be a neat way to get white lettering on a chrome faceplate.

    I found a great website by a German chap (B. Brieskorn) here: http://www.brieskorn.de/int/Guitar___Amps/Amp_Projects/AA1164/aa1164.html
    which has some really detailed plans for a Princeton Reverb scratch build - if you look at the front and rear panel links, they are in pdf format and ready to print on white vinyl paper, which can be done on a cheap inkjet printer at home. I guess it would take some time to make the design, but this technique should work perfectly for blackface amps...+

    Last summer I designed a front panel using Powerpoint (quite laborious but it did the job!) and printed onto A4 white vinyl stickers - it worked very well, even with a near invisible join, and a couple of coats of clear lacquer has added what I hope is enough protection. The faceplate is on the back due to the design, so it's not on the 'bottle throwing' side!

    20200623_092105.jpg

    This started as an extension cab for my Blues Jr, but I had an old 25W solid state amp in a chassis so thought it may as well go in...

    20200623_092038.jpg

    I did the same Powerpoint method for a name badge, printing on to clear waterslide decal paper and again lacquering, though this time with about 10 heavy coats!

    20200621_203650.jpg

    I was genuinely surprised how well it all turned out, especially through a £25 inkjet printer!
     
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  19. dougsta

    dougsta Tele-Meister

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    Thanks Buddy, excellent info.

    I ordered a 5 meter roll of white sticky backed vinyl from this site:

    https://www.mdpsupplies.co.uk/gloss-sign-vinyl/detape650series305

    DT650100305 DeTape 650 - White (305mm 5m) 20% £4.34

    You can cut it to your own dimensions then print on top (laser printer in my case). I'll print a black mask on top of the white to get white lettering/graphics.

    I've used the water slide method for guitar head decals, this is my 'Thomocaster'


    IMG_8374.jpg

    I made the body from a diseased (spalted effect) poplar tree they cut down outside my house, I used a chain saw to 'bookmark' the 2 pieces! I made the neck from a piece of sycamore (basically maple) took ages to dry it out.

    IMG_8116.jpg
     
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  20. dougsta

    dougsta Tele-Meister

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    I cut a 25˚ angle into a length of timber which I then screwed to some scrap oak kitchen worktop.
    I then screwed the chassis to the oak worktop lined up with the 25˚ timber and went at it with a square piece of oak and a 2.2lb hammer, 1st bend done.

    IMG_8396.jpg

    IMG_8397.jpg

    Next I have to make a 90˚ bend in the other piece and join them together.
     
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