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5e3 Neil Young sound - destroying tubes? Which output transformer

Discussion in 'Amp Central Station' started by tzurby, Apr 5, 2021.

  1. tzurby

    tzurby TDPRI Member

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    I am tryining to nail the Neil Young sound, and for me, what I get is good enough (I should have recorded a bit louder):


    This is a 1955 5D3 Deluxe converted to 5E3 specs many years ago by my tube tech. The signal chain is:
    1974 Les Paul Standard, MXR Compressor, 1955 Fender Tweed Deluxe (converted to 5e3, has a smaller OT than later 5e3's), resistive load box with 50k line out and isolation transformer, Binson Echorec II, TC Electronic Hall of Fame 2, CMI (Marshall) with 1970s 4x12 cab plus 1958 Fender Tweed Deluxe.

    However, I realized today that the amp destroyed one of the two Visseaux 6V6 tubes.
    [​IMG]

    I changed the power tubes to vintage RCA 6V6. They sound nice too.

    Now, I wonder if the amp (and the tubes) can handle this massive load of distortion. For the tube experts on this forum, here are the voltages:

    [​IMG]
    Apart from pin 1 and 6 of the first preamp tube (Mullard 12AX7) the voltages are quite normal, it seems to me.

    Also, I wonder if Neil Young switched to 6L6 and an Schumacher 125A1A output transformer, which can be found in late Tweed Deluxes and early brownface Deluxes (it should look like this), not for tone but for safety reasons.

    Am I save with using the amp in this configuration? Or will I kill tubes and possibly the original 1955 OT (not a Triad 106).

    Also, I just finished a DIY Deluxe Kit with Hammond PT and OT. Sounds nice with 6L6 tubes too, but no Neil Young tone sag. The reason for this project: I will keep the 1955 Deluxe original and intact, trying to get that sound with the DIY Tweed Deluxe.

    I am considering changing the OT on that DIY amp. Should I go for the brownface Dlx OT (MMs claims to have "cloned" it with the FBDO)? Will I get sag with this OT? Or should I go with any of the Triad 106 clones and keep the amp with 6V6 tubes instead of an 6L6 configuration?
     
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  2. no doz

    no doz Tele-Meister

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    if i remember correctly, NY's 5E3 was converted by his tech to run 6L6 tubes, and I believe the PT was swapped out for a more powerful one as well. runs at 18W instead of the standard 15

    you could try installing some screen resistors on your power tube sockets, they could help prolong your tube life. the original 5E3s didn't have them so they are rarely present on most of the 5E3 kits out there, but as far as i understand it they became a fairly standard industry practice towards the end of the 50s. i have 3W 470R resistors between pins 1 + 4 on V3 and V4 of my 5E3 and have had no issues with power tube failure thus far despite constantly playing with a very similar tone to yours
     
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  3. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Good idea. On the voltage question, what’s your bias in percent dissipation, and what measured resistance do you get on that 250R cathode resistor? And what’s your heater voltage pin-to-pin?
     
  4. That Cal Webway

    That Cal Webway Friend of Leo's Silver Supporter

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    Neil Young's longtime Excellent amp/ gtr tech Larry Cragg,

    Look him, and if he has a website or whatever you may be able to contact him.

    I just found this on his venerable Fender tweed from Guitar Player magazine in the 90s interview with Larry.
    Larry's always been free to do lots of very good interviews thru the years so you should be able to find the info just on interviews alone and features:


    "I have fans pumping a lot of air into the back of the Deluxe, since we rebiased the amp to use 6L6s."

    .
     
  5. bumnote

    bumnote Tele-Holic Ad Free Member

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    I read somewhere he prefers cheap Chinese tubes...have no idea if that's true or not.
     
  6. schmee

    schmee Doctor of Teleocity

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    I really wonder if that isn't just a mechanical failure of the tube and nothing to do with being overdriven. Old tubes sometimes lose vacuum, turn white and break all on their own in a stock situation. That one didn't seem to turn white or lose vacuum, but.... hmmm...

    I would be tempted to be very careful about using old Output Tubes if you want to protect your OT. They can test and seem fine but fail and take it out. A set of NOS RCA 6V6's took out the original OT in my 65 BFDR shortly after installing and biasing them. A big flash and a destroyed OT.
    I went to JJ's in all my 6V6 amps and never looked back.
     
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  7. tzurby

    tzurby TDPRI Member

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    Oh, I did not now this - or I did not remember. I read my files, and it can be found here.

    O.K., I will install a fan. I found this website.
     
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  8. tzurby

    tzurby TDPRI Member

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    I will do that. No 3W 470R resistor at hand. I will order. 2W is not enough?
     
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  9. tzurby

    tzurby TDPRI Member

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    The rististance on the cathode resistor is 242R.

    "bias in percent dissipation"? I do not know.

    I applied Rob Robinett's "Tube Dissipation Using Cathode Resistor Voltage Drop" method.

    And I got this: [​IMG] ... is 11,1 watts and 79,3%

    Is that what is needed?

    The two 6V6 measure 34,6mA and 32,4mA. So these tubes are not matched close, correct? This is pretty cold with 307V Plate-to-Cathode Voltage (pin 7 to 8) (according to Rob Robinett's Bias website). I could lower the value of the cathode resistor in order to run the tubes a bit hotter?

    "heater voltage pin-to-pin"? I don't know how to measure.



     
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  10. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Sorry, didn't mean to make this confusing. You're right to use Rob's calculator, and your calculations are OK. TLDR: if we choose to think of the 6V6 as a 12W tube (you want to be conservative to save your tubes), and if I read your voltages right, then your plate-to-cathode voltage on your hotter tube is 328–17 = 311V, and if your resistor is actually 342ohms, you're right in thinking your tube is dissipating nicely less than 100% (which is plenty safe for cathode bias) -- I get 86% at worst.

    So you're not burning up your tubes by excessively hot plate voltage or bias (lots of 5E3s run up to 110–115% very safely -- they're self-biasing).

    Which brings us to the heater voltage. Any voltage above 6.3VAC is putting unneeded strain on tubes -- the heater is basically a light bulb filament, and running it over spec will burn it out sooner. To measure pin to pin, you set your MM to VAC and put the red probe on one heater lug, the black probe on the other. This is often done on the lamp, where access may be easier than on tube sockets.
     
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  11. no doz

    no doz Tele-Meister

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    rob robinette on this topic in another thread:

    "I feel that 5W is preferred but a 2 watt 470 ohm in a 6V6 amp is good enough. With your choices I'd go with the 470 ohm 2 watt grids."

    http://www.tdpri.com/threads/robrob-5e3-screen-resistor-value-rating-question.741115/

    sounds like 2W might work if you've got them! i'd check rob's site for a diagram on how to wire them up properly, can hunt down the diagram i used if you need
     
  12. dan40

    dan40 Friend of Leo's

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    How many hours were on the Visseaux 6v6's? Do you run the amp wide open fairly often? Using a loadbox or attenuator to run the amp wide open will increase the wear on the power tubes and it's not uncommon to have a failure while doing so. Adding screen resistors will offer a bit of extra protection to the tubes. Lower wattage resistors (2 watt) serve double duty and act as a fuse if the screen pulls to much current. Higher wattage resistors (5 watt) will hold up to a bit more abuse before burning out. This is nice if your in the middle of a gig and don't want your amp to go down because of a blown resistor. If protecting your vintage transformers is top priority, the lower wattage resistor will fail sooner in the event of another tube failure.
     
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  13. tzurby

    tzurby TDPRI Member

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    Pin 2 on V3/V4 and pin 9 on V1/V2 are connected to the chassis/ground. Which is normal for 5D3 Deluxes. I measure nothing between ground and pin 7 and pin 4, respectively.
    [​IMG]
    (It is just the housing of the Astron electrolytics.)
     
  14. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Cool. I love it when we can save the 'jacket' on the old caps, and those look super nicely done.

    I don’t really think you have a voltage problem, so I’m not trying to push this. Just trying to answer your concern if your amp was hard on tubes in some way. Of course you have single-strand heaters, I didn’t think of that. In that case you can measure heater VAC from the heater lug across the tube to its ground lug, or from the lamp lug to the chassis. Amp on, tubes in, it should be more than 'nothing', maybe around 6-7 VAC, or your tubes wouldn’t heat up.

    96BC7FE2-734B-4158-8429-B18A7A430552.jpeg
     
  15. tzurby

    tzurby TDPRI Member

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    I got it. It is pretty low: 5,87 VAC. Too low?

    I assume the Visseaux 6V6 with the glass broke simply died of decrepitude.
     
  16. dan40

    dan40 Friend of Leo's

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    I was gonna mention above that your plate to cathode voltage looked a bit low for a Deluxe. I was thinking that it may be normal for the older, 5D3 transformer but your posted heater voltage also seems a bit low. Are you plugged straight into the wall or are you using a variac to lower the voltage? Either way, I doubt that it has anything to do with the tube going bad.
     
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  17. burntfrijoles

    burntfrijoles Poster Extraordinaire

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    I am no amp or tube guru but I've been able to get a good Neil Young tone with my PRRI and a 5F6 pedal. I previously had a Lovepedal High Powered Twin but the 5F6 did just as well. Also my Tone King Gremlin "lead" input has that Tweed sound it gets crunchy really quick.
     
  18. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Good for you. Probably not too low for the heaters; if you allow +/- 10% (but take away the +), -10% gets down to 5.67. But the questions about wall voltage from @dan40 are smart. Is Berlin 240V mains?

    All in all, I think you’re right, your amp's voltages are probably not killing your tubes.
     
  19. tzurby

    tzurby TDPRI Member

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    I measure 222V here in Berlin. I use a variac. I just measured, and the amp sees 111V. I could go to 120V. Should I?
     
  20. tzurby

    tzurby TDPRI Member

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    I found another possible cause why the Visseux 6V6 broke. The load resistor on the load box I use is an 2r7. I measure 3,3 Ohm.
    [​IMG]

    As far as I know, a lower speaker load (the OT wants to see 8Ohm), is good to protect the OT but causes stress for the tubes. Correct?

    Should I change to a higher value for the load resistor?
     
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