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

5F6G3 Luxman

Discussion in 'Shock Brother's DIY Amps' started by Che_Guitarra, Nov 10, 2017.

  1. Che_Guitarra

    Che_Guitarra Tele-Holic

    596
    Mar 23, 2012
    Perth, Australia
    I learnt something very important with my Princeton build: I should have built a Deluxe. So rather than torture it with more mods, i'm hitting the reset button and starting a new build... employing all the I should have done this, I should have done that lessons I have learnt thus far.

    The plan: Tweed Bassman front end, Brown Deluxe style power section. Maybe SS/tube switchable rectification.

    First and foremost, I want a rough and ready rock amp (not a saggy slow blues amp) that can go toe to toe with a drummer. But I don't want an amp that is so loud it can blow out a candle from 10 feet away. Nor do I want a high gain amp - I'd rather step into that territory via pedals. I also need a reasonable clean tone, as I play a lot of rockabilly, reggae and surf. So that is my sought tone triangle: Sublime to Setzer to Surfaris... and Slayer via pedals.

    Am I asking too much from one amp? I don't think so: my 6G2 is oh so close to being all the amp I need... but if i'm going to upgrade all the trafos to Deluxe spec --> go back to the first sentence of this thread. It would also be nice to have a more flexible EQ, thus my desired integration of a 5F6A front end.

    So here's where i'm at so far. If you see any errors in this schematic, please point them out for me. And if you can suggest any improvements, modernisations, i'm all ears too.

    :)

    [​IMG]
     

  2. D'tar

    D'tar Tele-Holic

    946
    Jan 11, 2013
    WNY
    Watching.....

    I doodled a bassman deluxe the other day with a few mods. The itch to build is becoming unbearable.
     
    Che_Guitarra likes this.

  3. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    IMHO, for the music you point at you need more amp to go “toe to toe with a drummer”. Ymmv....but Setzer and the Safaris demand more headroom, imho.
     
    Che_Guitarra likes this.

  4. jmp81sc

    jmp81sc Tele-Meister

    149
    Feb 6, 2015
    Orange County
    I think you will like the stock 5F6A Bassman. I don't think your Luxman design will be that much different than the 6G2. The stock 5F6A is 50 watts which should give you the headroom and volume you want.
     
    tubeswell and Che_Guitarra like this.

  5. Old Tele man

    Old Tele man Tele-Afflicted

    May 10, 2017
    Tucson, AZ
    With today's lousy tubes, you might want to consider adding (maybe just internal) a bias adjustment pot.
     
    Che_Guitarra likes this.

  6. Commodore 64

    Commodore 64 Friend of Leo's Ad Free Member

    Age:
    42
    Mar 1, 2010
    Kent, OH
    5F6A but with 6V6 is a nice amp. I've used one toe to toe with drummer and a Peavey Classic 30 in a garage country band for about a year. So just enough clean, but also a good overdriven tone.

    Paired with a 2x10 (Celly G10 gold, G10 Greenback) or 1x12 (Celly G12 Gold).

    With the true CF, consider a Sino 12AX7 if you are using new production tubes.
     
    Che_Guitarra likes this.

  7. printer2

    printer2 Poster Extraordinaire

    May 24, 2010
    Canada
    Upgrade the power supply caps to 33-50 uF might help keep things together longer if you find you need a little more clean, not so much more output but less modulation from the power supply. Also remember that 50W is just 3dB louder than 25W. Speaker choice could make up for more of the difference. Agree with the adjustable bias, or put separate bias pots and squeeze every last drop out of the tubes/output transformer.

    I had a thought for my Bassman version, have the 22uF caps in the circuit with 33uF in parallel with the plate and screen caps, the negatives of the 33uF's comoned and then through a switch to the common ground point. One position a little bit looser and the other stiffer like a Marshall Plexi.

    Maybe some 1.5k grid stoppers on the 6V6 grids also? I just solder them right to the lug with no lead length on the lug side then I heat shrink over the resistor. Oh heck, 1 ohm cathode resistors for setting the bias. Well there goes the simple circuit.
     
    Che_Guitarra likes this.

  8. Che_Guitarra

    Che_Guitarra Tele-Holic

    596
    Mar 23, 2012
    Perth, Australia
    Yeah - really not too sure what values to run. JJ makes a 40/20/20/20 cap can, so that might be ideal, especially if I opt for switchable SS rectification. Would also free up a bit of real estate inside the chassis, which is always a good thing.

    I'll be bending up the chassis myself, BTW, once I settle on a final plan.

    Speakers? Vintage 30s all the way. Probably in 2 x 12 format.

    As for adjustable bias - that is absolutely going to happen. Seperate bias pots? What an interesting idea!

    And FWIW I do have a longer term goal of building a JCM800 2204. But for now, a grab-and-go deluxe with a pair of vintage 30s should be more than adequate for my current 3-piece-band arrangement.
     

  9. printer2

    printer2 Poster Extraordinaire

    May 24, 2010
    Canada
    I had a nifty method of switching a Plexi front end into a 2204 arrangement. V30's, 100dB, sounds good, 10.4 lbs each, uhh... Well at least you get a 3 dB advantage running the power into two speakers rather than one.
     

  10. Che_Guitarra

    Che_Guitarra Tele-Holic

    596
    Mar 23, 2012
    Perth, Australia
    So you think a better option might be to build a bassman/jtm45, and use an attenuator (or PPIMV) for home friendly volumes? If that's the case I might as well build the amp that most tickles my fancy - a 2204.

    I guess the reason i'm shying away from this option (for the time being) is because it's the more costly path. I already have the trafos and tubes to make a 5F6G3 happen, so a hundred dollars or two in bits and pieces and it's a done deal. A JTM45 (or 2204) on the other hand is going to be a $1500 exercise (factoring in postage costs to Australia, and purchase of a decent attenuator to keep the neighbours on my side).

    Hmmm.
     

  11. Nickfl

    Nickfl Tele-Holic

    681
    May 24, 2016
    Florida
    Seems like a solid plan. For what you seem to be aiming for, I'd probably just go ss only on the rectification (drop the b+ with zeners if you have to) and definitely bigger filter caps (I'd do the JJ 40-20-20 cap can even with the tube rectifier).

    A PPIMV and a "raw" switch that lifts the tone stack ground would be good additions as well. These are cheap and easy modifications that add a lot of versatility to the amp.
     

  12. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    My thought is that neither the Setzer sound nor the surf sound was achieved with the tweed 5F6A circuit. Those sounds live in the large 6G amps....Showman for D. Dale, who might be considered The Godfather of surf, and the 6G6B in particular for Setzer. The BF reverb amps are a big part of surf sonics.
    That said.....the amp you have planned can be used to play whatever one chooses to play through it. There is one rockabilly guitarist who uses 5F8A amps....which is an 80 watt version of what you are planning. The one using the tool is a big part of what can be achieved.
     

  13. Jakeboy

    Jakeboy Tele-Afflicted

    Jul 26, 2008
    Sedalia, MO
    Setzer has admitted to playing tweed Bassmen in the early days as well as his famous 6g6b....

    In today’s quieter bar and club environment , you will have enough headroom, IMO.

    That said, why not just build a Tweed or Blonde Bassman and use a nice attenuator like a Badcat Unleash? You will have your tone at the volume you need and on those occasions where you do need the increased headroom that could blow out that candle, you’ll have it.
     

  14. Che_Guitarra

    Che_Guitarra Tele-Holic

    596
    Mar 23, 2012
    Perth, Australia
    Can anyone give me a confirm on the zener diodes specs needed in a circuit like this?

    Being an unfamiliar component, i'm not sure how to select for the task. And Mouser is giving me 32,000 options.

    My goal is to bring SS rectification B+ to a voltage parity with GZ34 rectification... which I assume means a 10 to 20W voltage wash-off. PT is a Classictone 40-18017: 330-0-330 @ 120mA, 6.3V @ 3A.
     
    Last edited: Nov 11, 2017

  15. Nickfl

    Nickfl Tele-Holic

    681
    May 24, 2016
    Florida
    I would think 10v, 5 watt zeners would be fine. This is probably about an 80-90 ma circuit, so dropping 10 volts is going to dissipate less than 1w. Even if the current triples under full load, the 5 watt diodes still give you a decent buffer. I like the 5 watt diodes, because they are the non heat sink type, while the larger ones need to be heat sinked to the chassis. Its nice to not have to bolt them to the chassis and easy to run them in series to change the amount of voltage drop. If you want to play it safe you can use 5v, 5 watt diodes and just use more of them. Of course, you should check the datasheet for whatever component you find to confirm.
     

  16. printer2

    printer2 Poster Extraordinaire

    May 24, 2010
    Canada
    If you don't know the voltage drop just put a bunch of 1N400X diodes in series, 0.7V drop a piece. If you don't have a dozen or so kicking around in a drawer then you are not really serious about building. Order the zener when you finally have the amp up and running and know what you want to scrub off. Or even make a Mosfet VVR on a perfboard, when done with it use it on a different project or put it on your test bench.
     
    Commodore 64 likes this.

  17. 5F6Animal

    5F6Animal Tele-Meister

    164
    Jan 4, 2016
    Beaumont CA
    I built a 6V6 Plexi amp (barely modified Bassman)for a friend a few years ago. It’s all he uses anymore. It’s plenty loud in a 3 piece live.

    Just make sure to take advantage of a split cathode on V1.
     
    Che_Guitarra likes this.

  18. Che_Guitarra

    Che_Guitarra Tele-Holic

    596
    Mar 23, 2012
    Perth, Australia
    Been doing plenty of schematic toying the last few days (... SS JTM45, 6V6 2204).

    Reflecting on existing schematics - what's the logic behind extraordinary filter cap values in solid state circuits? A tube rectified circuit might have 60 to 80uF of combined capacitance in the B+ feed... 250uF+ seems par for course in a solid state rectified circuit. Hmmm.


    To me, that suggests switchable tube/SS rectification is a waste of time... commit to one or the other, or duly work out how to engage/disengage capacitance levels, or build an amp that is unlikely to sound very good in one mode.

    Does that sound like a fair assessment?
     

  19. Commodore 64

    Commodore 64 Friend of Leo's Ad Free Member

    Age:
    42
    Mar 1, 2010
    Kent, OH
    Yes. One or the other. Without crazy switching of dropping resistors, bias resistors, or cap values when you switch modes, you must set the amp at some compromise of tone and safe bias settings that accommodate both rectification methods.. And who wants to send 400V across a cheap toggle switch that can be bumped/banged off in the trunk of your car...
     
    Che_Guitarra likes this.

  20. Che_Guitarra

    Che_Guitarra Tele-Holic

    596
    Mar 23, 2012
    Perth, Australia
    I've been umming and ahhing about this all week - I think I have to stick with GZ34 rectification. Ultimately, SS rectification would probably suit me better, but the reality is I think a 5F6G3 will sound great from first fire up; a 1987 @ 20W on the other hand will likely require a higher degree of component swapping and B+ circuitry experimentation to get it right where I want it... i'm not sure I have that degree of patience.

    Otherwise - i'm wanting a very simple layout. A single input - maybe two inputs maximum. Single volume - so that means a ganged or concentric volume pot, or a regular pot and a set-and-forget trim pot (or switch) on the turret board. Treble, middle, bass. Presence too will become a set-and-forget trim pot on the turret board.

    I'll give it another week to mull over the rectification decision; that will lead me into my nightshift rotation at work, and give me the opportunity to bend up a chassis away from the prying eyes of the boss ;)
     

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