Brown Blonde Brainstorm

Discussion in 'Shock Brother's DIY Amps' started by Snfoilhat, Dec 5, 2019.

  1. Snfoilhat

    Snfoilhat Tele-Afflicted

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    IMG_3275.JPG
    IMG_3276.JPG

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    tremolux_6g9_d-fa.png
    FENDERS_6G9_TREMOLUX_01.jpg
    Problem scope:

    My personal thing is full-featured 5W amps, decent EQs, built-in effects, large cabinets. I hardly ever play with acoustic drums anymore, and I don't think I need a 15-20W amp at all.

    Even worse, if you look at all the amps I have now, you'll see every one has the tremolo turned off and the reverb turned up.

    :eek::eek::eek:
     
  2. D'tar

    D'tar Friend of Leo's

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    I don't see any real problem here! Carry on!:cool:
     
  3. Mexitele Blues

    Mexitele Blues Tele-Holic

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    Going with the typical BF reverb circuit, or something else?
     
  4. Phrygian77

    Phrygian77 Tele-Afflicted

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    The 1x12 5881 Vibro Champ I built was loud enough to gig with nearly clean. I thought about doing another one as a head with a compact 2x12, but I'm not sold on the tone of that circuit, not for the clean country stuff I mostly do. It just lacks some of the presence of the other Fender blackface era amps I've built.
     
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  5. King Fan

    King Fan Friend of Leo's

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    I'm with @D'tar -- you don't have a problem. That'll be $250. Please come see me again in a week. :D
     
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  6. Snfoilhat

    Snfoilhat Tele-Afflicted

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    Great question. I can't decide if this should have reverb or not. Tremolo or not.

    A sort of Robrob Blackvibe (https://robrobinette.com/RR763_BLACKVIBE.htm) (is it a Brownvibe if I use the 350k-tapped-70k treble pot? :D), one channel, two channels? :confused:

    High headroom 'pedal platform'? o_O $$$
     
  7. Phrygian77

    Phrygian77 Tele-Afflicted

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    I thought I had posted this already. I'm a bit surprised that Fender ran those 6BQ5 at nearly 400VDC. I think I'd go with 6V6s.
     
  8. Snfoilhat

    Snfoilhat Tele-Afflicted

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    What I read was that the EL84 Tremolux was only in production for about a year, and that the reason was just what you say. The PT didn't work with the power tubes and it was a mess. The Tremolux became the 6L6GC amp that's more familiar soon after.

    When I realized that I have a power transformer already matched for a pair of EL84s with the right mounting dimensions for this blonde Bassman chassis, that planted the seed to try to do a 18W Tremolux. The way it might have been.


    IMG_3280.JPG

    (I'm working in parallel on the graphics for the single-ended Princeton from earlier this year in the gold cabinet)
     
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  9. Phrygian77

    Phrygian77 Tele-Afflicted

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    I think the bias and tail values for the PI should probably be tweaked for the EL84s.
     
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  10. muchxs

    muchxs Doctor of Teleocity

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    I'm working up two circuits that will be packaged one each in a 6G3 chassis. One is a very rare "bargain bin" amp.

    Imagine if you wanted a Pug or a Labrador so you bred a Labrador to a Pug...

    :D

    The front end is virtually a 5E3. It ducks into 6G3 then turns back into a 5E3 at the PI. It has 6BQ5s, fixed bias and a very unique trem circuit driven by a 6AU6. That's 2x 12AX7, the 6AU6, 2x 6BQ5 and a 5Y3.


    If you're using 6BQ5s with an LTP you might want to look at a Marshall 1974 PA.
     
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  11. Snfoilhat

    Snfoilhat Tele-Afflicted

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    I went really thin on the coats of clear for this face plate. Cheapest & quickest yet, and I think it helped me find the edge beyond which the savings aren't worth it. I'm not trying to pioneer the 'relic-ready' amplifier :p
    IMG_3282.JPG

    When it's ready I'll go to a print shop and get the face plate for this new blonde/brown thing done on the big plotter. And add more coats of clear.


    ***


    Starting to tackle the technical stuff. Here is the power transformer I'm working with. It's small. Three secondary windings.

    240-0-240 V on the HT
    6.3 V for a pair of 6BQ5s and a pair of 12AX7s (2 * 0.76 A + 2 * 0.3 A = 2.12 A)
    6.3 V for a EZ81 rectifier (1 A)

    Motorola_SH20N_power_transformer.png
    Questions:

    Can I add another heater load to the regular 6.3V windings and just observe whether the additional filament, like from a third 12AX7, pulls down the voltage supply? And if it doesn't, is that enough evidence that the PT can handle it?

    If that's a bad idea or the voltage does drop, can I run a few tubes (up to 1A) off the third winding originally meant for the rectifier? Keeping that string separate from the others, and adding a virtual center-tap?
     
    Last edited: Dec 7, 2019
  12. printer2

    printer2 Poster Extraordinaire

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    Yes, just add the load and see what you get, won't hurt anything with the amount of current another preamp tube takes. The actual voltage of the heater supply may go down some when the amp is drawing its full load but the change to the heater voltage should not change too much. The 5V supply for the rectifier should have a higher unloaded voltage, might be enough for another tube. Yes with the center tap.

    My trailer project will be on hold after today so I will get back to the 6BQ5 amp I am building. My amp will not as pretty as your amps though. There were some high voltage hifi amps around at the time. I have a Scott amp that used the high voltage equivalent of the tube, don't remember the number. I think Harmon Kardon did one to or maybe I am just thinking about the 12AB5.
     
    Last edited: Dec 7, 2019
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  13. printer2

    printer2 Poster Extraordinaire

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    Looked for this amp on Youtube, only one I could find.

     
  14. BigDaddy23

    BigDaddy23 Tele-Meister

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    Tim Rogers from You Am I uses one of those......I’ve seen them live many times and that amp sounds glorious. From memory he just uses a boost pedal every now and then to give it a kick.
     
  15. Snfoilhat

    Snfoilhat Tele-Afflicted

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    If I'm gonna say this anywhere on TDPRI, I guess I'll say it in the thread I started: I think that amp sounds bad with the volume up.

    Also, hey, is it too much to ask to include a few seconds of the tremolo in a 4 minute demo of the 'serviced, quiet, awesome-sounding, collectible' Tremolux? o_O

    If you need me I'll be in Bad Dog Cafe griping about gear demos with my fellows :p
     
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  16. BobSmith

    BobSmith Tele-Meister

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    Could you explain a bit about how you’re doing your faceplates or where you take them to? I’m in Bay Area and looking for a place. Not much luck for reasonable price so far...
     
  17. Snfoilhat

    Snfoilhat Tele-Afflicted

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    re: face plates. I think we're right on the cusp of ordinary people being able to access college/library/retailer CNC milling or additive manufacturing or some kind of etching on an inexpensive, walk-in basis. But I'm not there just yet, and I don't want to help pay off the big capital investment of a small trophy shop's equipment at $50-100 per face plate just for my personal amp collection.

    All that is to say, my process is very inexpensive but my not stand up to 40+ years of use like professionally made aluminum. Mine are essentially stickers.
    Make the graphics in GIMP/photoshop.
    Print on the lightest, cheapest paper at the local office supply place that has a wide format printer/plotter.
    Spray a few light coats of shellac onto the back side so that the paper doesn't absorb the glue I'll later use and get blotchy.
    Spray many light coats of shellac onto the front.
    Cut the outline (e.g. 18.25" * 1.9" for a princeton reverb chassis)
    Gorilla glue the face plate to the chassis with the chassis clamped face-down to my work bench. This is essential for getting a paper-based face plate to lay flat, not get wrinkled, not look like paper. Gorilla glue has just the right body (it foams as it cures) and elasticity and open time to get the face plate lined up just right while getting it clamped between the bench and the chassis.
    I might do some very light sanding to knock down gloss or flatten the clear coat.
    Last, cut out all the holes with an xacto knife.
    Takes a couple days and < $10

    @BobSmith if you're in San Jose, is there a Tech Shop? I haven't kept up with them, but years ago I assumed that eventually we'd all be manufacturing amp stuff in small batches in a place like that. Good luck
     
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  18. peteb

    peteb Friend of Leo's

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    That guy gets some nice sounds. It sounds good, it sounds like Jimi.


    I tried out a 61 Tremolux in a store once, Emererald City Guitars. I thought it sounded brittle. It wasn’t really the sound for me.

    Soon afterward I tried a Blackface Tremolux. That amp had the sound I was looking for. Not brittle, softer sounding with a smooth transition into overdrive sounds.
     
  19. Skydog1010

    Skydog1010 Tele-Afflicted Platinum Supporter

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    What's Tremolo? (I ask while swimming in Reverb) BF and Tweed for me 100% of the time. Unfortunately for me my budget keeps me linked to SS, low power tube BF amps are a fantasy for me, 5, 10, 15, 20, 22 watt is plenty of mojo for my playing. Wish I felt comfortable building an amp, and had access to electronic parts or parts kits to get the job done right.

    An $1100.00 amp kit doesn't really interest me when I can buy a 90 dollar modeller by Fender with a five warranty and it sounds relatively decent. I'm just rambling on here about trying to be reasonable with my GAS money.

    Bought a Mexican Blues Junior that someone had modded, and it was IMHO as loud as a Twin Reverb, with no way to get any decent tone from it without my ears bleeding. I happily gave it away, I believe when the trading stopped on that amp and a Trio+ pedal, I actually paid almost $1k to dump them both.

    Poor management of trading stuff on my part, but I just can't seem to find a sweet little tube combo BF with a single 12 that I can justify for my bedroom playing.

    Wish there was a really Santa.
     
  20. Snfoilhat

    Snfoilhat Tele-Afflicted

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    Single-channel schematic, leaning heavily on Robrob's single-channel reworking of the Vibroverb. Still a few consequential decisions to make, like whether to use global NFB (?), switchable cathode bias (?), and a few little details like in the bias voltage supply, bright cap or not, more or less silly graphics.

    Close readers will note that the power amp is not precisely the 6G9 or any Fender. It's close to a complete p-p EL84 power amp offered by Merlin Blencowe in his preamp book, which he uses as an example of a modernized power amp tuned to minimize blocking distortion (maximizing 'good' distortion when overdriving).

    Single-channel_tremolux_6G9_8DEC2019.png
    F_faceplate_birds_8DEC2019.png

    Thanks
     
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