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Fender amp techs...2 specific questions...

Discussion in 'Amp Central Station' started by LesTele, Nov 10, 2020.

  1. Wally

    Wally Telefied Ad Free Member

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    In fact, a rectifier tube consists two diodes in the vacuum tube domain instead of the later solid state domain.
     
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  2. Wally

    Wally Telefied Ad Free Member

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    Those JJs are not OEM to the amp.
     
  3. LesTele

    LesTele TDPRI Member

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    good point. I love it just the way it is and wanna keep it without mods
     
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  4. LesTele

    LesTele TDPRI Member

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    So sorry! I meant to say groove tubes not JJ’s. Are groove tubes what fender Puts in?
     
  5. Wally

    Wally Telefied Ad Free Member

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    There you go! Only you can answer some of the questions. If you love the way it has been sounding for you, then ime the amp’s voltages and Biasing need to be measured with the tubes that are there. Buy the same brand of power tubes. Bias the new tubes to the plate dissipation point...play on. If you can do this yourself, do so. If not, then do you have a tech? If not, you need one, imho. A person could adjust that amp of yours while you play and make it sound like trash, ime. A player who gets to know how they like the amp to work has an advantage, and that player will want the amp to perform in the same manner form one set up tubes to the next. contintuity of operational parameters is what makes that happen.
     
  6. LesTele

    LesTele TDPRI Member

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    I’m up for doing It. I will definitely take it to a tech if I get second thoughts though
     
  7. TwoBear

    TwoBear Tele-Meister

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    Sorry about that my screen is cracked and I may have sent a part of a message before I could go back and edit it... I was mentioning those extra Stout 6 V6 as a ways of conveying that new tubes are not necessarily worse than the old glorious tubes that everyone goes on about, which actually quite a few of those were quite glorious, or more to the point just very well made ha. No I wouldn't go to 6v6 without a rebias, although there are those yellow jacket and at least one other company that make those adapters that go in between the existing sockets and the tube and offer the ability to use el 84, and I'm not sure but presumably 6v6 tubes in most amps designed for 6l6 & other eight pin power tubes. I have a set by both makers and have used them in my Marshall 1987 x, it's been a while I'm sure I tried them in my super R but I don't remember. I do remember enjoying them in the Marshall though.
     
  8. TwoBear

    TwoBear Tele-Meister

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    I don't get it or we agreeing or what? Or is it because I said a set of diodes? If so that was because I was thinking of'a couple, up to 4 for the full wave design or the six that you see in some of the bigger twins and Marshalls I think.
     
  9. Wally

    Wally Telefied Ad Free Member

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  10. schmee

    schmee Doctor of Teleocity

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    Lots of good info above. Also:
    -If you do buy a bias tester, get one with an option to show voltage also.
    -My experience with rectifiers is that imports ones may have a short life, but if they are working they will last pretty good. If they fail prematurely it's usually when you first use them.
    -There's nothing wrong with a good set of GrooveTubes.
    -If changing power tubes, I kinda like TAD 6L6's. JJ's are fine also.
    -If the amp has the Ruby or Penta brand pretubes in V1 and V2, I would get better tubes. I personally like Mullard RI.
     
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  11. TwoBear

    TwoBear Tele-Meister

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    And one little thing if you buy some tubes like say you want to get a spare rectifier check it out when you get it don't just put it away like I did because then you pull it out and it flashes on you and it's too old even though it's brand new to get a replacement
     
  12. Wally

    Wally Telefied Ad Free Member

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    Groove Tubes was established by Aspen Pittman in the 1980s, iirc. They are a rebrander as are Ruby, Penta, and others..ARS. GT buys tubes from modern manufacturers, test and grade them and rebrand them with their logo. fender purchased Groove quite a number of years ago, so LO Fender amps come with GT tubes. There are codes on the GT tubes that indicate where the tube was made...S indicates JJ, R indicates Russia...C may indicate China. I do not buy GT tubes. Ommv.
    iF you want what you have in there, order some GT tubes that have the same identity codes and grade numbers. Post pics of the 6L6s if you are wondering what they are.
     
  13. Jared Purdy

    Jared Purdy Friend of Leo's

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    Well this is helpful. Now. I just had a pair of 6V6 tubes installed, and biased in two different amps by an amp tech as I've been led to believe from multiple previous posts I've read, that it's necessary to have the amp biased when swapping power tubes. Not so much?
     
    Last edited: Nov 11, 2020
  14. Wally

    Wally Telefied Ad Free Member

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    Biasing can make or break an amp’s sonics. Have your tech move the bias point around while you can play and hear the difference. I have seen people’s eyes go wide at the difference.

    As for ‘matched’ tubes becoming unmatched, this is why I pay for ‘burn in’ time. The drift of operational parameters occurs in the first 24 or so hours. Burning the tubes 8n and then finding the matches eliminates that drifting problem.
     
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  15. Cali Dude

    Cali Dude Tele-Afflicted

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    Yep, it will need to be biased. Regarding current production tubes, I really like the Genalex Gold Lion 12ax7s (gold pin). I don't have a 6L6 amp, so I can't comment on those.
     
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  16. Jared Purdy

    Jared Purdy Friend of Leo's

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    Wally, I'd love the opportunity to noodle while he adjusts the bias, but he's not letting anyone in his shop. Customers have to make an appointment, go to his house with their amp, knock on the door, and talk to him from his porch. He then takes the amp inside and does his work.

    He told me that amp companies tend to bias hot, and he biases around 60% most of the time. I gave him my 64' Hand Wired PR with a set of new tubes (Tung Sol 6V6, a Mullard 12AT7, and some Tube Store "Preferred Series", which consisted of the 5Y3 and the 12AX7's). All of the tubes that came with the amp were Sovtek.

    When I picked up the amp, he said it was biased by Fender at around 80%, and he biased it at 60%. I like the tone that I'm hearing now. I liked it before too, but I like it better now (unless it's all in my head :eek: ).

    On Monday, I gave him my 57' Custom Deluxe with a NOS Philips 5Y3, a pair of new Genalex Gold Lion 6V6, a Electro Harmonix 12AY7, and a ... hmmm, the 12AX7 brand escapes me right now. I suspect he'll bias it around 60% as well.

    I'll let you know what I think when I get it back, hopefully tomorrow. You can look him up, if you care to. His name is John Fletcher and gets very high reviews in Toronto and abroad.
     
  17. Jared Purdy

    Jared Purdy Friend of Leo's

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    I got my 57 Custom Deluxe back from my amp tech. He told me it was self biasing, and Fender had it based at 100%. He's not a fan of biasing that high as he says it's hard on the tubes. If I had known it was self biasing, I would have just done it myself, but then when he was going over it he found a number of things that weren't tight. This is a new amp, purchased from a retailer. $2800!!!! Go figure.

    He replaced all of the tubes (which is why I brought it to him). I gave him a NOS Philips 5Y3, a new pair of Genalex Gold Lion 6V6GT power tubes, a Mullard 12AX7 and a Electro Harmonics 12AY7.

    Anyways, I'm not sure if I actually notice any difference in the tone, however, what I did notice after playing it for a about 20 minutes was that I could smell something coming from it, that "electrical" smell. I took the back off and watched the tubes as I played it for a while. There was nothing untowards, but the smell was definitely there, and it was not there with the stock tubes. I sent him an email asking for clarification, still waiting for a reply.

    Any ideas?
     
  18. Wally

    Wally Telefied Ad Free Member

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  19. Jared Purdy

    Jared Purdy Friend of Leo's

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    Wally, there's no text in your reply to me??
     
  20. Wally

    Wally Telefied Ad Free Member

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    Lol...how did that happen??? I mean...ya’ll know I am a wordy person!!!!

    cathode biased circuits can operate at 100% of plate dissipation safely...or a bit higher even. Leo Fender used the same 250ohm bias resistor in that amp since the first Deluxe was built in the late 1940s. He went by the RCA book. A cathode biased amp runs hottest at idle. When processing signal, the plate dissipation decreases. In fact, a true Class A circuit must run at 100%. Have your tech explain
    to you why he thinks that 100% plate dissipation is improper in this amp. Tubes are the other variable in that Biasing situation. The tubes actually set the bias with their operational parameters. Know that one changes that bias resistor t9 change the bias, your warranty will be of no use to you. Of course, if he touched any solder joints and is not a .fender authorized tech, your warranty is gone already.
    The smell is something else...I have no idea. If you had installed UOS tubes, one might think that the tubes carry residual oils and dirt that give off odors when heated. side note.....personal thing...but I would have played that new amp as it was sold to me for quite a while before I changed tubes.
     
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