6v6's in Blues Jr.

Discussion in 'Amp Tech Center' started by Scotty 2, May 8, 2015.

  1. teletimetx

    teletimetx Doctor of Teleocity

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    I don't have anything even remotely close to Wally's technical skills; I'm just a player. My point is that, even beyond the technical analysis, the OP will have a subjective response to any sonic/auditory signal, as we all do. He asked what he could expect and while lots of folks have characterized what they feel the main difference between EL84 and 6V6 might be, there are so many variables in the process that it's next to impossible to estimate accurately what the OP might "expect". We'd like to be able to assess the difference with all other things being equal, but that's not easy to do, unless you want to fork over the pesos to buy an amp that can do that for you.

    I have my own opinions on how I respond to classic 6V6 v. EL84 equipped amps, but there's not enough consistency in those responses to come up with something useful for the OP - that's why I suggested he do some field research and come up with his own conclusions. What, it's a bad thing to go play through a bunch of different amps? Plus there are enough knobs to tweak on a Blues Jr, that along with a choice of guitar/pickups, you could probably make a 6V6 version sound like an EL 84. Just saying.

    ...in any event, I gig on a weekly basis with a Blues Jr. and seem to be part of a fairly small minority here that likes it. Come to think of it, at the gigs I play at, the only people who ask about the tubes are other guitar players.
     
  2. mrboson

    mrboson Tele-Afflicted

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    It was designed to fit a spot in the market. Fender has options covering 6V6 territory. I believe Fender wanted to sell a small watt amp as an EL84 amp inspired by the 5F6A circuit. I think Wally already pretty much said that. Fender went further and chose values for components in the circuit to keep the Blues Junior from overlapping other amps that they sell.

    I think people either love it or don't. Mods can be simple (i.e., different values for coupling caps, increased size of filter caps) to add more depth to the bass and reduce the boxyness of the amp. More efficient speaker helps with increasing headroom. But it is still a Blues Junior at that.

    Changing the circuit to 6V6? I guess there are even guys going all the way to 6L6 with the appropriate PT and OT upgrade. Supposedly sounds like a Blues Deluxe at that point. I would just buy a Blues Deluxe ;)
     
  3. Johnny Cache

    Johnny Cache Former Member

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    It should have a tad more clean sound. IMHO after owning 2 BJr's they should have built it with 6V6's not EL84's.
     
  4. muchxs

    muchxs Doctor of Teleocity

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    The Blues Junior is a 1995 design, a 20 year old design. Not bad! Fender's entire combined BF / SF line didn't make 20 years. Marshall changed a whole lot between 1965 and 1995 when the Blues Junior was introduced.

    Historically, The Soviet Union officially dissolved on Christmas 1991. The U.S. vacuum tube industry was effectively defunct circa 1991. Conveniently, several vacuum tube factories were still in operation in the former Soviet Union.

    While Russian type 6P6S is roughly analogous to U.S. type 6V6GT and Russian type 6P3S is roughly equivalent to U.S. type 6V6G... the Russian 6P14P "EL84" equivalent was abundantly stockpiled and became the basis for the ensuing wave of "EL84" amps. They still make 'em fresh every day at the Reflektor plant. EL84s still have the same advantages they're always had... they're inexpensive tubes that make relatively stout power with less supply voltage and less grid excitation compared to 6V6s. Cathode biased 6V6s make around 12 watts while cathode biased EL84s make 18 watts without breaking a sweat.

    "That's one louder, innit?" :D

    .


    .
    How 'bout a limited edition with 6V6 tubes and tube driven reverb?

    How 'bout a handwired 6V6 Blues Junior with tube reverb in the same old black tolex cabinet?
     
  5. bparnell57

    bparnell57 Poster Extraordinaire

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    If there are two tubes made in the dissolved Soviet Union that I trust, it's their EL84's and their metal base 6SN7's. The EL84's are just fine for me even though I have a few Japanese pulls laying around. The 6SN7's are absolute top notch. Some hifi guys would say the best 6SN7's ever made were Russian metal base ones.

    I also use 6P6S tubes in my mono hifi amp (runs em at 420 volts cathode bias for about 12 watts) and they're not too shabby at all. Definitely smoother sounding than the big old JJ's I had in there. Shipping on all surplus Russian tubes is of course a gamble. One of my 6P6S's in that hifi amp has its getter sitting in the bottom of the glass tube just rattling away. Won't short anything if the amp doesn't move. Still shipping beats tubes.
     
  6. muchxs

    muchxs Doctor of Teleocity

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    I thought I was posting on the "Booze Junior" thread. :rolleyes:

    Bill M. modified a few Blues Juniors for 5881s. A 6V6 conversion is easier. Punch the holes, add octal sockets like you would for 5881s but there's no need to swap transformers unless you want to. Diddle with the bias supply to get the bias right. You end up with less power than a stock Blues Junior but otherwise it's as if the Blues Junior was designed with 6V6s in mind right down to the 1.5k gridstoppers.

    Is it worth it? I expect you'll find there isn't a big difference between "EL84" and "6V6" tone.
     
  7. vanr

    vanr Tele-Afflicted

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    If I were to convert it to 6V6's I would convert it to cathode bias also. Just because I like the feel of cathode biased amps.
     
  8. mitchfit

    mitchfit Tele-Holic

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    for a financially expedient test, find a champ owner who will let you put a yellow jacket EL 84 adapter in it for a test drive.

    hell, even bribe a music store owner with giving him the $60 dollar unit, this is still a lot cheaper than not being satisfied with the 6V6 mod.

    as close to an uncontaminated/controlled experiment as you'll find. this ain'tcher run of the mill A-B test with ~hopefully~ close preamp tubes, circuit values and speaker response.

    note any difference in sound that is achieved.

    note any lack of difference achieved.

    then decide.

    admitted, this is kinda reverse engineering your question, but could save you lotsa american inflationary notes.

    $0.02,
    mitchfit
     
  9. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    Ash vs alder?
    More mids from el84s and scooped mids from 6v6?
    Five less watts from 6v6, but bigger tighter low end?
    Bigger and tighter, can they exist together?

    I have a couple of Marshall 18w clones with the more modern TMB circuit, one is stock with el84s and the other was built with el84s and then converted to 6v6 by the builder before I bought it.

    I'm pretty certain I could not tell which was which in a blind test, though I guess if the 6v6 amp makes less power and they used the same speakers I SHOULD be able to hear the (what? 2db?) difference on 10.

    I was hoping for clearer tighter bottom end from the 6v6 amp, and have used a couple of very nice pairs of RCA black plates, where the el84 18w uses some nice Ei Yugos.

    I'm more sold on the ash vs alder debate than the el84 vs 6v6 debate, in terms of all-else-being-equal-sound-difference.
    (but I'm a guitar tech, not an amp tech)

    WAY more sold on the new production tubes vs well chosen vintage tubes debate.

    If I had a Blues Jr and wanted it to sound better I'd sell it and buy a used 18w clone or new kit.
     
  10. Big_Bend

    Big_Bend Poster Extraordinaire

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    I have a Blues Jr I sent to BillM 4 years ago, and he put in the all the mods - 6V6 tubes, upgraded transformer, tone stack enhancements, new presence knob, and so much more. I also upgraded the speaker (JBL) and reverb tank. It really helped the Blues Jr sound like a souped up Deluxe Reverb, in a very portable package. I've been amazed many times how good it sounds on a stage, holding its own with a full loud band.

    I recommend upgrading a Blues Jr to 6V6 tubes, more clean blackface wonderful tone... whats not to like?
     
  11. flyswatter

    flyswatter Friend of Leo's

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    Super Champ X2 -- 15 watts from 6v6s with more useable features and the same volume as a BJ if you run it into a 1X12 cab.

    For the purists, yes, it has digital modelling features... but just leave it on the clean channel, crank it up to breakup, and you'd never know it was there.

    Also, the reverb won't break the tenth time you use it.
     
  12. Ricky D.

    Ricky D. Doctor of Teleocity

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    If you want to play with tone, the worst possible way to do it is via major amp surgery to change tube sockets and wiring to accommodate different output tubes. Unless you have the parts laying around already and have the DIY knowledge.

    The easiest way to experiment is to get a parametric equalizer. Make a super-bright vintage-style Tele pickup sound (almost) like a PAF humbucker, easy if your ears are good enough.
     
  13. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    It would be interesting to hear how much of the difference in your amp came from all the other mods, and how much came from the power tube swap.

    That's kind of the point of this thread, is it the power tubes or the circuit that makes a Deluxe sound like a Deluxe (insert alternate amp type)?
     
  14. cousinpaul

    cousinpaul Friend of Leo's

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    I've gone the other way, subbing EL84's into a 6V6 amp via Yellowjackets. Barring any other mods, I think you could expect the 6V6's to sound a little darker.

    I'd suggest a 5E3 clone if you really want to explore some pushed 6V6 goodness. They show up used now and then for not much more than a BJR.
     
  15. Wally

    Wally Telefied Ad Free Member

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    IF that 6V6 amp was fixed bias, then the Yellowjackets achieve more than a simple change from 6V6's to EL-84's. The YellowJackets also establish cathode biasing, if I am not mistaken. IF you had a switch to take the 6V6 from fixed to cathode bias, you would hear the biggest part of that change to the EL-84's in the yellowjacket socket.
     
  16. cousinpaul

    cousinpaul Friend of Leo's

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    I tried them in a Proluxe, modded to 6V6's in cathode bias. THD makes special adapters for this app. Thanks for the clarification, though. It's been a while...
     
  17. printer2

    printer2 Poster Extraordinaire

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  18. Billm

    Billm RIP

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    It's nice to see that some things here on TDPRI haven't changed! I'm glad to be back.

    Many of you know/recall that I've collaborated with David Allen of Allen Amplification on two output transformer designs and one power transformer. I use one of his existing OTs in my 6L6/30 watt conversion.

    The point made above that the BJr and Blues Deluxe are most similar to the 5F6A Bassman is correct. Everyone who was involved with those designs is long gone, but the lower price for each performance tier has kept the Hot Rod series alive for all these years.

    I can tell you what the 6V6 sounds like in the BJr because I've A/B'd them, with and without the basic mods. First, though, let me say that it's crazy to add octal output sockets without doing the basic mods. The BJr designer, according to lore, sandbagged the BJr so it wouldn't encroach too heavily on the Blues Deluxe. Those pitiful .002uF coupling caps strangled the preamp, unless you were looking for a high-strung, midrangey tone that kind of complimented the EL84s. The values in the tone stack were also limiting and the overall sound was harsh. So...

    The 6V6 is a wonderful tube, with lower heater current than the EL84, because it was originally designed for car radios. As part of the RCA beam power tetrode family, it has similar tone to the others, but it requires more bias voltage than the EL84. The BJr has enough in its +/- 26V supply, and a simple resistor change or better, a trimpot will bias it with the BJr's modest 320V plate voltage. By the way, there's a ceramic octal socket that drops right into the existing holes, so all you need is four small holes for the mounting ears.

    What do you have when you're done? A sweeter-sounding BJr that runs a little cooler than the EL84s. It doesn't sound like a PR or DR, which is not a surprise to those of you who are circuit-savvy.

    That said, almost no one does the 6V6 conversion anymore. People spring for the larger PT and OT and go for 6L6s. 30 watts is eminently giggable for people who don't have a sound tech or a board where they play, and it's smaller and lighter than most any tube amp in the range. Some folks give up a few watts and run 5881/6L6GBs because they like the tone.

    The octal conversion, whether for 6V6s and stock voltages or 6L6s with the heftier transformers, is not easy because it requires cutting the tube board, running wires instead of the ribbon cables to the output tubes, and replacing a couple of caps and resistors. We do it all the time here, so we're used to it, but you've got to be a very dedicated tech or tinkerer to go through the trouble.
     
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  19. Wyatt

    Wyatt Tele-Afflicted

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    Not really adding much beyond what muchxs already said ...but...

    When the PJ and BJ debuted, there was only one 6V6 tube being made worldwide, the Sovtek. The EL84 was much easier to source reliably.

    People forget (or weren't around) that as the '90's started...
    • The last American JAN tubes shipped in the mid-'80's (there was a time when jets like the F-16 ran on JAN 6L6WGB)
    • The unification of Germany closed down RFT in '89
    • The Balkan War closed down EI in the early '90's. The factory was actually bombed by NATO
    Amp compnaies needed supply chains of tubes they could count on for years and that was Mike Matthews/Sovtek, Shuguang and Tesla. At the time none made a real 6L6GC, 6V6GTA, etc.
     
    rickmccl likes this.
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