Brownface tonestacks?

Discussion in 'Shock Brother's DIY Amps' started by JohnnyCrash, Jan 12, 2020.

  1. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,025
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA
    I’m planning a Bassman build.

    It will have a 6G6-B for the Bass channel.

    I’m tempted to go with something unusual for the Normal channel. Maybe a brownface Concert’s tonestack? IDK.

    I was originally thinking of (and still leaning towards) a two channel amp for clean/dirty (with a PPIMV at the end), but the other brownface amps can grind too. Maybe it’ll be a two channel ROCK amp with a lead and rhythm channel... now I’m not sure what I want out of this amp anymore!



    Anyway, what brownface tonestacks would you want to try and what are the differences (if any)?
     
    Greggorios likes this.
  2. jsnwhite619

    jsnwhite619 Friend of Leo's

    Age:
    35
    Posts:
    2,644
    Joined:
    Sep 10, 2013
    Location:
    Georgia
    It may come down to desired volume output. Like I said before, the 6g6-B I had a chance to play may have been the sweetest amp I've ever played through. But, I've never played a gig in my entire life that I could have used it at the level I was playing. And in true Fender fashion, a roll back on the guitar cleaned up nicely. So, you'll already have a fat clean and awesome overdrive in the same channel already, dead stock. But, that master volume idea would be helpful for sure.
     
    JohnnyCrash likes this.
  3. FenderLover

    FenderLover Poster Extraordinaire

    Posts:
    5,093
    Joined:
    Jun 11, 2009
    Location:
    Minnesota
    Check out post #11 below for differences in blackface/brownface response. Bass is not shown because there wasn't a noticeable difference. The real difference is in the treble response. When at zero, the brownface will cut the treble more severely. Those tapped pots used on the brownface are hard to find and expensive. Given what you get out of it, not really worth the pursuit to me. It's one of those things - if it was so good why did it go away so fast? YMMV:
    https://www.tdpri.com/threads/quad-6v6s.822833/#post-8314259
     
  4. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,025
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA


    There are several brown era tonestacks. Which one are you referring to with “tapped pots?”
     
  5. FenderLover

    FenderLover Poster Extraordinaire

    Posts:
    5,093
    Joined:
    Jun 11, 2009
    Location:
    Minnesota
    The big brown brothers. The smaller brownfaces had single knob tones. The tapped pots are seen in brownface schematics on the treble pots (6G16 Vibroverb, 6G6A, 6G6B Bassmans, Bandmaster)
     
    Last edited: Jan 13, 2020
    JohnnyCrash likes this.
  6. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,025
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA


    I’m looking at using a weird one then: the 6G12-A Concert.
     
  7. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,025
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA
    ... also, the 6G6-B uses special pots?
     
  8. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,025
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA

    Nevermind, I see it now... in the Normal channel.

    I’m using the 6G6-B Bass channel and I’m thinking the 6G12-A Concert tonestack for the “Normal” channel.
     
  9. Snfoilhat

    Snfoilhat Tele-Afflicted

    Age:
    38
    Posts:
    1,262
    Joined:
    Apr 8, 2016
    Location:
    Oakland, CA
    Take this with a grain of salt -- I haven't played a real Fender with this tone stack, nor seen a SPICE model or tone stack calculator or bode plot or anything -- but to my ears the brown Super/Pro/Vibrolux/Concert/Twin/ etc etc tone stack common to the -A versions of all those 6G* amps sounds indistinguishable from the post-1963 tone stack everyone agrees sounds mid scooped and is the stereotype of clean Fender.

    The 350-tapped-70k pot and the 3 nF cap are different components and the arrangement is a little different, but the mid cap, bass cap, mid resistor, the source and the load from the next stage are the same. To me it sounds just as scooped and so basically the same. There is a weird meme(?) or common wisdom that all brown amps have more mids than later Fenders, and I'm not sure I understand where that comes from.

    I got my 350k-A tapped at 70k pots from Weber. They are 16mm (smaller cases than typical amp pots) and the shafts are smaller than 0.25" so USA knobs need a bit of tape or a shim to fit well. The bushing and hardware are strange, smaller than 3/8". So kind of a pain but I remember them being (3 years ago) only a few dollars. Imported I guess.

    Looking forward to seeing what you build and your feedback on how it sounds!
     
    Wally likes this.
  10. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

    Posts:
    11,025
    Joined:
    Mar 12, 2005
    Location:
    Fullerton, CA


    It’s official: my eyesight is horrible.

    I kept seeing “250k” when the schematics in fact said 350k.

    Looks like it’ll be a blackface tonestack for my Normal channel...
     
  11. Wally

    Wally Telefied Ad Free Member

    Posts:
    33,910
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    I have a BF amp that has those tapped treble pots....unique prototype 1x15 Pro...without a serial number in the chassis, even. I have asked in various forums what the effect of those tapped treble pots is on a technical level and have never gotten an answer. I do know that this Pro is different from other BF amps in the mids.....not drastically different..but there is something going on there that the ear hears.

    I caught your introductory thread on this build, Johnny. Imho, there is nothing about the Concert that harkens back to the 5F6A Bassman but for the phase inverter, output section and the speaker format. That said, in a build one can take that later tone stack as in the big 6G and BF amps and manipulate the gain, slope resistor, and tone stack values to move toward that big tweed sound. if you are building two channels, I highly recommend this approach.
     
    JohnnyCrash likes this.
  12. Wyatt

    Wyatt Tele-Afflicted

    Posts:
    1,122
    Joined:
    Nov 3, 2004
    The 6G6B Normal is nearly identical to the 6G12A tone stacks. IIRC, only difference is .02 vs .047 at the Mids. Having tried both in Vibroclones, the .02 offers a little more mids, but it's not night and day (but worth testing for personal taste).
    • The 6G6B uses the .047 mid cap that would be used through the BF Fenders (except the Super Reverb)
    • The 6G12A uses the .02 Mid cap that is used through the larger Brown Fenders (and the BF Super Reverb)
    As FenderLover's data points out, the Blonde/Brown tone stack can be dialed to match the AB763 tone stack. That means the stock 6G6B offers all the tones of the larger Brown Fenders, the Normal channel of the AB763 BF Fenders, plus the bass option. It's very versatile. A single 6G6A or B was the amp used for bass and guitar on more tracks by the Beatles than any other amp or amp model, from around Rubber Soul onward.

    A 70K tapped 350K pot can be bought from Weber, Hoffman or others for ~$2.50. It's a budget piece, probably by Alpha, but it is available. Or some people pair a 250K pot with a 68K resistor.
     
    Last edited: Jan 14, 2020
    JohnnyCrash, FenderLover and Wally like this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.