Blues Jnr - dime the master or not?

Discussion in 'Glowing Bottle Tube Amp Forum' started by spenno, Jul 2, 2019.

  1. Commodore 64

    Commodore 64 Friend of Leo's

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    Sure put a 3W resistor there.
     
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  2. opticnerv

    opticnerv TDPRI Member

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    I changed a resistor on the board to get a constant lower-than-spec bias. You could also install a trim pot and use a multimeter to ensure the bias is at a tube preserving output. A 12AT7 in the position next to output tubes keeps drive/distortion down and, to my ears, helps with tone. But I fiddle with all the preamp tubes to get what I like. Also switched out some stock caps for Orange Drops and some other stuff I don't remember. Replaced the Eminence speaker for a Celestion Vintage 30. Upgraded the stock 18g speaker connection (wire from jack to speaker terminals) to 14g. Typically I set master about 1/3 - 5/8 open and adjust volume to.....the volume I need. Pedals add grit, girth, delay and modulation.
    Anyhoo - I love the sound of this amp.
     
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  3. peteb

    peteb Friend of Leo's

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    Did the EL84 short and take the under spec ed screen resistor with it?


    Not sure if that’s the case or not.



    Since cooling the bias would require voiding the warrantee, in the mean time you could use some military grade power tubes. They should easily last the warrantee period, and then you could adjust the bias.
     
  4. peteb

    peteb Friend of Leo's

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    Did the EL84 short and take the under spec ed screen resistor with it?


    Not sure if that’s the case or not.



    Since cooling the bias would require voiding the warrantee, in the mean time you could use some military grade power tubes. They should easily last the warrantee period, and then you could adjust the bias.


    7189 or other?
     
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  5. jrblue

    jrblue Tele-Afflicted

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    Wally and optiknerv make good points true to my experience (though I use a PJ). I love these amps if they're used well -- ask Jeff Beck -- and adjusted and/or modded to suit the player and to eliminate some of the stuff Fender did that can make them sound less than great for some users. I got one of the first ones made -- maybe 1996? -- and modified it in steps over the years as I got used to it and its potential. Optiknerv's comment about running some lower-output tubes in the preamp section is excellent. I did that, ending up with a 12AU7 (!) in the first position and a 12AT7, as optiknerve did, as the second tube. Though this seems like a radical move, in practice the amp remains loud, but the usable clean and clean-ish tones are more abundant, and the tone overall is just beautiful. I get compliments everywhere. I also put in a bigger OT, and that changed everything brilliantly; the low end is tight, deep, and hefty. I did many small mods in the circuit. Many are available online, and the deal is to make sure you pick good ones that do what you want, and not just mod because you can. Though snobs look down on these amps because they're not expensive enough and do sort of have a built-in tone when stock, but you can unleash them easily. I think Beck toured with them not to promote Pro Juniors, but to remind everyone what music is and where it comes from. If you need a boutique amp to create great sounds, you're not much of a musician. And the crowd doesn't applaud your choice of amp. Enjoy your Blues Junior!
     
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  6. bftfender

    bftfender Friend of Leo's

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    yes & some more yes. Just coming back to some Fender amps after Marshall run,,the plexi teaches tubes up then chan vol to adjust. I applied this now to my fenders & so wish i knew this before..i let some gems go though i never should of.( had a 66 Super bone stock & a 64 i think vibro something...1 owner..kick..kick myself..just didnt know how to use it right !!
     
  7. Strato50

    Strato50 Tele-Afflicted

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    Usually they arc at the socket. Quick fix I e watched my tech so is scrape a little between the socket pins and bam no more arcing.
     
  8. jamesepowell

    jamesepowell Tele-Meister

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    Agree completely. It's part of the joy of guitars & amps & pedals.

    My students (high school English): "Hey mister, what do you do on weekends?"

    Me: "The never ending search for tones."
     
  9. 1300 E Valencia

    1300 E Valencia Friend of Leo's

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    The "VOLUME" control allows you to adjust how much signal goes into the front of the amp. The more you turn UP this knob, the more distortion you get.

    The "MASTER" control allows you control the overall LOUDNESS of the amp, regardless of how clean or distorted the signal is coming from your guitar and pedals.

    If you want the maximum CLEAN sound, turn the MASTER UP all the way, and use the VOLUME control to adjust how loud you want it.

    If you want distortion from the amp, either by itself or in combination with pedals, turn UP the VOLUME knob to the desired amount of distortion ("overdrive", "pre-amp clipping", "dirt", whatever you choose to call it), then control the overall LOUDNESS with the MASTER.
     
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  10. Wally

    Wally Telefied Ad Free Member

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    ^^^^^this......or......my preference.....push both of these gain controls toward the upward end of their range and control things with your pick attack and/or the guitar’s controls. I find it to be a good training exercise to run an amp waaaay on up the dial and demand of the picking hand some control. This will demand that the player NOT hit strings hard unless that distortion is wanted. For playing as opposed to training??? I still like an amp turned up to a certain point to get the richness and liveliness at any volume. Where on the dial??? It depends on the amp and it’s controls. Vintage Marshall’s?? I find that if they can’t be turned up past halfway, there is little point in turning them on. My Super Champs?? I prefer them with all three gain controls dimed....and play wonderful cleans at lower volumes that way...or screaming harmonic overdrive, too. Ommv..."
     
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  11. BobbyZ

    BobbyZ Doctor of Teleocity

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    Lots of misconceptions about master volumes and their effect on power tubes. Well they really have no effect on power tubes because they're in the preamp.
    Ok someone is going to bring up the post phase inverter style master volumes and how technically the phase inverter is in the power section. Ok I get that but the power tubes are after that, so shut up. :)
    For all practical purposes master volumes work by choking off the preamp until it distorts somewhere and the power tubes just amplify how ever much of that you want to send them for the volume you need.
    The guy playing in his bedroom with a 100 watt MV is only getting a few watts at best out of his power tubes no matter how high the gain is cranked, because he's got to turn down the MV so mom won't ask him if he even looked for a job today. :)
    (Once you start talking attenuators things change because then you are choking back the whole amp right before the speakers. And those can definitely shorten power tube life cycles.)
    Just think about it this way, non master volume amps are just hard wired inside with the MV on ten.
    Personally I've got two MV amps, one is a silverface Twin Reverb, the only time that MV left 10 was when my daughter's boyfriend played it. (he's a %!!$×$$ drummer!)
    Other one is a 100 watt 2555 Slash Marshall, that one I'll mess with the MV and clipping diodes but always go backed to cranked MV/diode off settings.
    There's no right or wrong, I just don't like master volumes. :)
     
  12. strat a various

    strat a various Friend of Leo's

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    I have a 1972 Twin Reverb. For a while, it was my main amp. I don't get why some folks are so vexed by the Master Volume control. Hundreds of gigs, I set the channel volume at 4 or 5, then turned the Master down to where the amp wasn't too loud for the stage, and it sounded fine. It didn't sound anemic, sterile, weak or any other intimidating adjective. It sounded like a quieter Twin Reverb.

    I think many players hear what the want to hear or what they've been told they are hearing, and are afraid to work the Tone controls of the amp and the Volume control of the guitar to get a tone they understand ... too many preconceptions. Not everybody really needs the same tone the message-board big-shots promote ... but they read the same things over and over, so they start to listen with preconceived notions.

    I've seen many decent amateur players adjust their amps at some new-to-them venue without even listening, because "these are the settings the internet says are right for this amp to get a creamy, brown, lush, saggy, whatever ... " It would be funny, but it's sad. Using your ears, folks. That's the ticket right there ... use your ears, not the magic numbers from the internet.
     
    Last edited: Jul 6, 2019
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  13. Wally

    Wally Telefied Ad Free Member

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    I am thinking that the ‘problem’ with the early Fender MV amps is that they did not add preamp gain at the same time. That was the early Boogie formula. r. Smith took the AB763 circuit and dropped in another gain stage in between the input and the first gain stage of the AB763 circuit....in effect creating a higher gain preamp that had two gain stages prior to the tone stack as in the 5F6A. Unlike the 5F6A, though, the Boogie also had the two gain stages following the tone stack.all of that preamp gain led to a circuit that could be overdriven...and the MV in the Boogie had more obvious usefulness when pushing that preamp gain.
     
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  14. strat a various

    strat a various Friend of Leo's

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    Agreed. I think the biggest problem is players not using the right volume amp for the job. There are two main camps in the guitar player universe ... folks who largely play at home or once a week at the informal gig or wedding/party/festival and players who work professional gigs a lot. Unless you get your tone out of a pedal, if you play many gigs at different venues, you gonna need more than one amp ... a big one for the "Woodstock Anniversary", a medium one for the big dance-hall, a small one for the Blues Bar and the teeny one for the Art Show at the trendy cafe.

    My friend Tony from "Redbone" (rest in peace, brother) went years with one old Blackface Twin Reverb at all kinds of gigs, and sounded great doing it. It's about the player, the style of music, and the requirements of the gig, including the acoustics of the room and the wisdom of the sound engineer.
     
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  15. Wally

    Wally Telefied Ad Free Member

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    Strat a various, I like to put an adjustment on the negative feedback loop. I did so with one SFTR long ago. The fellow who bought it had been playing with the same players for 25 years at that time. He found a use for that NFB adjustment...a use that had not occurred to me. He said that he used it to tune to the room. If he was in a cold venue, he used more of the NFB resistance to warm things up. If he was in a warm room, the tended to lean back toward a stock resistance setting. It is interesting to see how different people use their tools.
    FWIW, his band played a gig as the first band in the lineup for a Doobie Bros band concert in Abilene. The second groups was a well-known group, too. My friend said that both groups tried to buy that SFTR.
     
  16. strat a various

    strat a various Friend of Leo's

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    True dat.

    "If he was in a cold venue, he used more of the NFB resistance to warm things up. If he was in a warm room, the tended to lean back toward a stock resistance setting.' ... i DO A SIMILAR THING WITH THE tONE CONTROLS ON MY AMP AND GUITAR. aMAZINGLY, DIFFERENT VENUES HAVE DIFFERENT ACOUSTICS AND REQUIRE DIFFERENT SETTINGs. bLOWS MY MIND.
     
    Last edited: Jul 6, 2019
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  17. BobbyZ

    BobbyZ Doctor of Teleocity

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    Like I said, "There's no right or wrong, I just don't like master volumes".
    That's a personal preference established way before I got online. My online time was very small until 2011 or so I got when high speed internet. Been playing electric guitar since '78 or '79, acoustic since 1976.
    Worth noting that the original owner of my '76 SFTR used the MV all the time, he gigged the heck out of that amp.(it shows) So I tried it again but went back to leaving it on 10 and just using the volume knob like on my BFTR.
    Anyway that's just how I do it, doesn't make it right.
     
  18. hotrodkid

    hotrodkid Tele-Holic

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    So does that mean el84's cathode biased, let's say like in a Peavey C30 would fair better? I ask because I always hear of C30's running hot. But maybe that is a whole other issue?
     
  19. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Nope - fixed bias can be hot. Cathode bias can be hot. The type of bias doesn't relate to how hot the tubes are being run. You can melt tubes just as well with either, or have them be cold and sterile.
     
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  20. Wally

    Wally Telefied Ad Free Member

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    The Peavey Classic 30 has a fixed biased output.
     
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