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6L6 in a Champ 5F1

Discussion in 'Amp Central Station' started by James Knox, Dec 3, 2020.

  1. James Knox

    James Knox Tele-Holic Silver Supporter

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    I have read a LOT of Internet Chatter concerning this Controversial Subject and I noticed by a search that the topic has not been discussed here in a long time.

    I agree fully with the ethos that a Champ with a 6L6 is NOT a Champ. However, cuz Boomers love Champs and there is much more guitar playing at home than gigging these days, I believe the Tweed 5F1 Champ to be a nice, nostalgic, great sounding Single Ended Amp. I love the 5F1 Circuit. I learned how to read a Schematic, Follow a Layout and build and Tweek by building them.

    I have sold a few of my builds and almost always the question come up... can it take a 6L6? I want my Champ to be louder, etc. I’ve been telling guys a Champ is a Champ, it is what it is, get a different amp if you want louder or more headroom or whatever.

    BUT.... after building a Big Bottle 5881 5F2A Princeton and loving it, I am “going back in” with building a 6L6 10 Watt Amp that will fit in a 5F1 Chassis.

    A Couple Considerations are that the 6L6 draws more Heater current so one needs a bigger PT or a SS Rectifier. Also, the OT needs to be upgraded from a 5w to a 10W. Then there is the Power Tube Cathode Bias Resistor and sussing out 5 or 7 ohm OT Primarys.

    So, NOT discussing IF a Champ should have a 6L6. The discussion I am starting centers around building (on purpose) a Louder Champ (10 watt) that is powered by a 6L6 or 5881.

    Here is an interesting starting place...

    AF31AF8F-DFE0-40FC-9755-124E48669DE1.jpeg
     
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  2. ThermionicScott

    ThermionicScott Poster Extraordinaire

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    Bigger PT? Probably not necessary. Can you name a 5F1-style PT that can't feed a 6L6 and 12AX7? ;)
     
  3. otterhound

    otterhound Poster Extraordinaire

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    I bought a new Champ 600 . When I switched to a good used 6V6 , I discovered that it had come from the factory with a Chinese 6L6 . It wasn't any louder , but it now sounds better .
     
  4. Willie Johnson

    Willie Johnson Tele-Meister

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    I've got the big honkin' JJ 6v6 in my Champ 600 reissue; I figure that kind of splits the difference.
     
  5. loopfinding

    loopfinding Tele-Afflicted

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    Kt88 or bust
     
  6. stephent2

    stephent2 Poster Extraordinaire

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    I put 6L6s in an amp (5f11 style) that was designed for 5881s and I eventually overheated the OT.

    My buddy the amp builder told me the problem was the high plate voltage that 6L6s generate and that was the reason to OT overheated. Went back to 5881s and no issues. If you want a tube w/ a bit more juice than a 6V6, the 5881 is a great choice.
     
  7. gabasa

    gabasa Tele-Meister

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    I don't care to make traditional Champs either; mine is anything but. I went through a lot of speakers in it and settled with a 12" Jupiter alnico with paper voice coil former. The speaker has a 100dB sensitivity rating and the amp is plenty loud for band rehearsals. I love it when both I and our other guitar players bring our Champs in, they're my favorite practices!

    I don't know if I'd trade the tone of a 6V6 for the volume of a 6L6. I went with a louder speaker but you have to follow your gut for your own builds. In the end if you have a Knox Champ build you're gonna love it.
     
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  8. boredguy6060

    boredguy6060 Poster Extraordinaire

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    It’s been five or six years and I don’t have the amp here.
    But I used a Classictone PT and OT.
    The OT was 15w the Bias resistor was 12w the speaker was 15w.
    I wired pin 1 and 8 together and tried 6V6 EL34, 5881 6V6
    I used a 5Y3 and a Weber Coppercap.
    There wasn’t as much difference as you might think between any of them. You get more variation from changing the pre amp tube than the output tube.
    In the end the best sound came from the 12ax7 6V6 5y3.
    The most drastic changes in tone comes from changing the speaker. The Weber 15w 4 ohm was perfect.
    YMMV
    good luck,
     
  9. 2L man

    2L man Tele-Meister

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    I bought Hammond 1750B output transformer for about 8W Champ amp. I have not yet measured winding ratio but its impedance is listed 5482 ohms which is pretty accurate ;) . It has only one 8 ohm output but its construction looks like it is wound to paper... I possiblly use 5881 which I have one new single. I have matched pair of 6L6WGA NOS and I will test one and if it sounds better I buy one more single.
     
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  10. homesick345

    homesick345 Poster Extraordinaire

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    EL34 is what's needed into a champ to get a "bigger champ" sound. Turns just perfect (you won't miss 6L6).

    Preserves impedance loads needed too which is nice - I tried everything so there you go

    (This of course needs a power supply & OPT that can carry the increased wattage)
     
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  11. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    @James Knox , I have a question for you here. I recall you have years of experience with lots of different amps; me, I don't know from 6L6.

    What do you think about the common idea that a 6V6 might be 'sweeter' or 'warmer' while a 6L6 can be a bit 'colder' or 'glassier?'

    Also, for the smart folks here, I assume we could calculate, in output power and dB, how much louder a 6L6 Champ would actually be than a 6V6 Champ? How much of that dB increase would happen in a 6V6 with a hi-efficiency 12" speaker, maybe a bigger OT, optimized cab, etc.?
     
  12. James Knox

    James Knox Tele-Holic Silver Supporter

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    @2L man i just finished a 5F1 with that same Hammond 1750B OT. I am comparing it with another 5F1 I built with an Allen Amplification 10 Watt OT. The 1750B sounds really good and is half the price of the AA OT. I’m trying out combinations of 5Y3/JJ 6V6, 5U4/5881 and GZ34/6L6. My favorite so far is the 5881. I love the tone of that tube. My first experience with it was a 5F2A 5881 Big Bottle Build I did inspired by @jsnwhite619. Currently my keeper amp.

    Are you liking the Hammond 1750B OT?
     
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  13. James Knox

    James Knox Tele-Holic Silver Supporter

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    Now that I have two different builds to compare, I would say that I agree with the “6V6 warmer, 6L6 glassier” ethos, but the 6L6 definitely has more bandwidth, more “wider” sounding. With the 10 Watt OT, the JJ 6V6 definitely is in the 6V6 camp. So far, my favorite is the Tung Sol 5881 Reissue.

    Also, comparing the same Chassis through a Champ sized cab with a Weber Alnico 8 AND a Deluxe size cab with a 12” C-Rex, the bigger bottles definitely bring more to the party. Yes, louder. Not twice as loud, but notably louder.
     
  14. 2L man

    2L man Tele-Meister

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    Nice to hear you like it James! I did stop my 1750B SE build because I am not totally happy with the chassis I made and the PT I have has bit too low voltage for tube rectifier use which I planned to use so I might just use silicon diodes.

    I began building a simple 6V6 push pull where I test active Tube Town FET FX loop kit is it worth installing to bigger builds...
     
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  15. radiocaster

    radiocaster Poster Extraordinaire

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    Makes very little sense.

    First of all, the 5F11 has two 6V6s in push/pull fixed bias configuration, but the bias is not adjustable. Ok, maybe it was a custom build.

    But the plate voltage is a function of the power transformer, not of the tubes. A 6L6 can run on lower plate voltages, in fact many datasheets have specs on how it runs at 250V and lower.

    A mismatched output transformer can overheat though, that part is true.
     
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  16. stephent2

    stephent2 Poster Extraordinaire

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    Ah,.. the internet. If you want to disagree w/ Richard Goodsell, the amp builder, go ahead. But just a heads up, he was correct in his diagnosis.

     
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  17. Recalcitrant

    Recalcitrant TDPRI Member

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    I put together a 5f1 years ago using a Deluxe size PT. Some may recall Angela Instruments’ goofy free projects. It was loud, as I recall, but it reddened the plates. I switched in a 6L6, which functioned great but sounded boring. Here’s what I’d suggest: A deluxe PT and two 6V6 in parallel. Obviously you can’t use a Champ chassis but you can use 5E3 chassis. I did that and was the sloppiest greasiest funkiest amp I ever heard. I wish I still had it. Ampage had a project called The Swamp Thing, that’s what I used.
     
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  18. wrathfuldeity

    wrathfuldeity Tele-Afflicted

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    Have an oddball se6L6, another oddball se el84 and a se6v6 muchxs champ...perhaps kiwi to bananas to apples. Idk about the in's and out's of the electrons flying about. But ime, in general, circuit > speakers have a greater and more significant influence than preamp tubes and power tubes. I have and do run each amp through the same diy oversized 1x12 spkr/cab. The 6v6 tube is warmer and the 6L6 has more range and more strident. The 6L6 at low volume has a sweet bell like cleans and when cranked to 2/3rds to 3/4th on the volume has a wonderful open saggy grind...which are not available with the 6v6 tube. Verses the well known 6v6 tones of the champ world. And the se el84 is another lovely beast...that has a wonderful punchy low volume and a trashy keef when pushed. Anyway one is not better that the other...they are all great at what they do and its wonderful to be able to change out and keep things fresh.
     
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  19. James Knox

    James Knox Tele-Holic Silver Supporter

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    Trying to figure out how to “balance” a Bias that will allow different kind of tube swaps to yield different Sonic and Volume results. I know that everything affects everything. I know that biasing by ear is more important than biasing for a certain percentage number, like 70% or something. I have gleaned that changing the Rectifier Tube From a 5Y3 to a 5U4G to a GZ34 changes the voltage enough to yield different results with a 6V6 Power Tube.

    So I paired up a 5U4G with a 5881, a GZ34 with a 6L6GB, a 5Y3 with a Tung Sol RI 6V6 and a JJ 6V6. Plays a bit with each pair to see how they sound an feel. Recorded the voltages and used RobRobs Bias Calc to get the numbers. This is with the Hammond 290AX utilizing the 275V taps. Here are the numbers...

    6ED9A5E2-BE86-47EA-9815-086A18B8EA2A.jpeg

    Then I thought what the hey, I should run the Higher 325V tap on the PT and see what the numbers yield...

    5266E457-9371-4C46-8FFF-D0083338A73E.jpeg

    I realized in this exercise, I was confusing the Bias Calc Tube “ranges” (cold, average and Max) as Voltages rather than Current.

    Since taking voltages has been such a big part of my building (just started from ground zero, knowing nothing about building since the Quarantine started) finding out about Biasing is kinda new for me. Looking at current rather than voltage is a paradigm shift. All my builds have been cathode bias til I did my last build, a Fixed Bias 5F10 Harvard. It took me “a minute” to get my head wrapped around that.

    Seems like a lot of the wisdom on this forum is centered around “if it’s not red plating, play the glorious tones” till the tube wears out. I’m cool with that. Bias it in by ear. I’m cool with that. Get your initial bias zone dialed in to the “safe zone” based on the Particular tube and the calculations from the Bias Calc. I think I might not be connecting a dot here... plate dissipation still is a little confusing to me. I know that tube max saturation is different than tube max dissipation. I know that many tubes are more robust (NOS, JJ, etc) and can “take it” better than others.

    So my big question is where do I find a compromise cathode bias resistor value to safely run the different rectifier/power tube combinations, realizing that some combos will be biased cold, some biased hot, and some “just right”?
     
  20. radiocaster

    radiocaster Poster Extraordinaire

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    Well the plate voltage can vary some, but it's that in conjunction with the current that determines plate dissipation.

    I take it the bias is not adjustable.
     
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