Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

BUILD: Marshall 18W Single Channel w/Reverb

Discussion in 'Shock Brother's DIY Amps' started by sds1, Sep 19, 2017.

  1. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    Hey gang,

    So here we begin my third build, this time the donor amp is a friend's Fender Blues Junior, a 2xEL84-powered combo with 3x12AX7 and a solid state reverb. In the search for a suitable replacement we decided on the Marshall 18W. The specs evolved over time but eventually I arrived at a build essentially identical to @Fiat_cc 's recent build (see here for more info: http://www.tdpri.com/threads/18-watt-variation.723856/).

    Here are the amp's specs:

    - Marshall 18W single (tremolo) channel
    - 2x6V6 output
    - 1-tube reverb (dwell pot omitted)
    - single input
    - solid state rectifier

    Parts sourced from Mouser, AES, and Hoffman.

    I adapted the layout to a 10" board with filter caps stacked off to the side:

    [​IMG]

    And here are some pics of the donor amp. A small chassis but the Hoffman board is actually more shallow than this, so will be easy to work inside here:

    [​IMG]

    Pots are Gain, Tone, Trem Intensity, Trem Speed, Reverb Level, Master Volume. I found out they make 3-way switch for Off/Standby/Play so I'm pretty stoked about that. The control panel adapt nicely:

    [​IMG]

    Currently looking at how I might weave the RCA jacks in between the sockets there. Looks like I have plenty of room for it:

    [​IMG]
     
    Last edited: Sep 19, 2017
    Fiat_cc, robrob, jasonvilla and 2 others like this.

  2. Bill Moore

    Bill Moore Tele-Holic

    You are using a Blues Junior chassis. The Blues Deluxe is quite a bit larger, (and has a pair of 6L6 power tubes.)
     
    sds1 likes this.

  3. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    Oops thanks, you're right.
     

  4. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    I have one question for the experts, how do I properly omit the reverb dwell pot from the reverb circuit? The dwell pot is a 1M pot coming off the first grid. Is this pot replaced with a 1M resistor to ground, or something else?

    [​IMG]
     

  5. jasonvilla

    jasonvilla Tele-Meister

    100
    Oct 9, 2010
    so cal
    Yup, that's what I did on my jcm800 one-tube reverb build.

    Oh, and I originally built it with the dwell pot but it didn't really do anything for me so I took it out and just used the 1M resistor in it's place.
     
    sds1 likes this.

  6. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    Thanks man. Yeah Chief Architect @Fiat_cc mentioned the same with respect to the usability of the dwell control.
     
    jasonvilla and Fiat_cc like this.

  7. jasonvilla

    jasonvilla Tele-Meister

    100
    Oct 9, 2010
    so cal
    Yea I remember searching the internet for a while and couldn't even really figured out what it did. I guess it's like a reverb master volume... but it was way too similar to the mix control. Did you finish building this? How do you like the one-tube reverb? I played around with mine A LOT. A lot, a lot. I was never really happy with it, but it works.
     

  8. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    Hey man, not yet... waiting for Doug Hoffman to get back from vacation so I can place an order for board and wire. Will update the thread with progress, sometime mid-October. Can't wait!
     
    jasonvilla likes this.

  9. jasonvilla

    jasonvilla Tele-Meister

    100
    Oct 9, 2010
    so cal
    Sweet, I wish you luck!
     
    sds1 likes this.

  10. Fiat_cc

    Fiat_cc Tele-Meister

    Age:
    34
    427
    Oct 8, 2016
    Melbourne, Australia
    Curious what you didn't like about the one tube reverb...
    I was pleasantly surprised by it, and find it better than I had hoped. It certainly doesn't get as wet as some, but I don't need that much verb...
     

  11. Mart the Hat

    Mart the Hat Tele-Meister

    484
    Feb 11, 2013
    Edinburgh, Scotland
    I've used a couple of different 1-tube reverbs, one similar to the one shown and the other using a 12DW7 to drive a high impedance tank with no transformer. (which I liked slightly better) I think they're fine if you're comparing to something like a modern Fender op amp driven reverb, but if you're used to a blackface Fender type reverb, there just isn't as much depth available. It sounds good playing at home, but on stage I've had the occasional "is this on?" moment.
     
    jasonvilla likes this.

  12. jasonvilla

    jasonvilla Tele-Meister

    100
    Oct 9, 2010
    so cal
    Hey man I made a quick vid showing the reverb in my build so you can hear what it sounds like in a higher gain type amp... though i didn't play with much gain. I tried the 12DW7 and a few other tubes to drive it but felt it worked best with a 12AX7.
     
    Zepfan likes this.

  13. Zepfan

    Zepfan Friend of Leo's

    Nov 30, 2013
    Horn Lake, MS
    I like Reverb, but not a whole lot of it and yours sounds just right to me. Like the sound your getting from your amp too. Did you try a 12AU7 for the Reverb circuit?
     

  14. Fiat_cc

    Fiat_cc Tele-Meister

    Age:
    34
    427
    Oct 8, 2016
    Melbourne, Australia
    I reckon that sounds pretty good. My amp with one tube reverb sounds just a bit wetter perhaps, but only a little.
    I'd never use much more than that.
     

  15. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    All the parts are in and I got organized today, gutted the Blues Jr. and made sure the components and layout were still valid. Everything fits great and I'm not seeing any real challenges.

    [​IMG]

    Oh I went thru the Mallory 150's with my new oscilloscope and tried to identify the foil end. It wasn't always a clear winner. The .001uF cap had a lot of noise compared to the others, I'm not sure if that's normal or not. It seems as capacitance goes down the chances of noise goes up.

    Tomorrow I will get the board drilled and assembled. I'm waiting on a new step drill bit to handle 1"+ holes, should be here Thursday and then I can complete the chassis work. I got some silver hammered paint for the chassis this time. I'm going to see if I can't get this completed by the weekend.
     
    PelleOter and Fiat_cc like this.

  16. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    Board done for now. Moving along to some chassis work.

    [​IMG]
     
    dr_tom and Fiat_cc like this.

  17. Fiat_cc

    Fiat_cc Tele-Meister

    Age:
    34
    427
    Oct 8, 2016
    Melbourne, Australia
    I think there is a wrong value resistor in the tremolo section. Should be two 470k in there (yellow purple yellow), but in the photo one looks like 470r (yellow purple brown).
     
    sds1 likes this.

  18. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    Man it took me 30 minutes just to figure out what the hell I did here. I mean, your schematic doesn't have 2 470 of anything in the tremolo....

    These are Richie's improved trem values, and you're correct it was 1M to 470K not 470. My layout is wrong.

    EDIT: oops not even, I got Richie's change correct. The one I goofed on is a stock Marshall value.
     

  19. Fiat_cc

    Fiat_cc Tele-Meister

    Age:
    34
    427
    Oct 8, 2016
    Melbourne, Australia
    Richies improved is 470k and 470k. That's what I've put in my version 2 build. One still looks like a 470r not 470k though unless the camera is playing tricks.
     

  20. sds1

    sds1 Tele-Meister

    Age:
    41
    404
    May 4, 2017
    Orlando, FL, USA
    No you are correct, I was just saying the resistor I got wrong was a Marshall stock value. The Richie change from 1M to 470K, I got that correct.

    Good lookin' out, thanks. I am at the point now where I feel disadvantaged not having a master schematic for my build. The layout just isn't enough for these situations. I guess I will start doing schematics.

    How is v1.4 coming along?
     

IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.