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Gonna have my 79 Deluxe Reverb looked at

Discussion in 'Amp Tech Center' started by INFANT, Dec 23, 2018.

  1. Dec 23, 2018 #1
    INFANT

    INFANT Tele-Holic

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    There is nothing seriously wrong with it but I'd like to start gigging with it again and I'd like to get some preventative maintenance done. A couple of years ago I replaced V1 and V2 with new JJ 12AX7s, the PI with an EH12AT7 and installed some new EH 6V6GT power tubes and set the bias. Filter caps were changed about 10 years ago. However, I hardly used the amp over the last few years and like I said, I want to start gigging with it again.

    I was planning on having the filter caps replaced again with some F&T caps and replacing all the original electrolytics as the amp is almost 40 years old. Is there anything else I should have my tech look at while he's in there? There's a bit of background hiss but nothing overly annoying. What I want to do is try to make it as "bulletproof" as possible before I bring it to a gig.

    Not interested in "blackfacing" it, removing the pull boost or snipping the parasitic caps on the power tubes. I really like how it sounds. The amp is basically stock except for the C-Rex speaker that replaced the original Pyle.

    I appreciate any suggestions and thank you all in advance.

    Merry Christmas!
     
  2. Dec 23, 2018 #2
    Milspec

    Milspec Poster Extraordinaire

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    Re-tensioning the tube sockets would be a good idea as they do loosen over time and you don't want tubes falling out as you drag around that amp. I know that you don't want to blackface it, but setting the bias to blackface specs can really improve a silverface amp in my opinion....even if you like the present sound. The difference it made in my '79 Twin was very pleasing and costs very little.
     
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  3. Dec 23, 2018 #3
    rogb

    rogb Tele-Afflicted

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    If you want to make it more "bulletproof", maybe look at replacing the tubes with some USA NOS tubes - JAN spec if possible like 12AX7WA - these are strong and reliable.
    A nice NOS rectifier and some NOS 6V6s. If you get them from a trusted supplier, they will back them up if there are any problems.
    Just spend the money on an electrolytics swap and the rest on well built tubes.
    Just an idea, but it's what I'd do.
    The 2 amps in my sig? All USA NOS except RFT EL34s (left)and TAD 6L6WGCs as power tubes
    2 suggestions are Gregg https://www.hitestguitars.com/

    Brent Jesse http://www.audiotubes.com/
     
    Last edited: Dec 23, 2018
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  4. Dec 23, 2018 #4
    INFANT

    INFANT Tele-Holic

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    Thanks for the supplier suggestions. I'm in Canada and the Tube Store is a 10 minute drive from my house. I'll check to see what they have in the way of NOS tubes.

    https://www.thetubestore.com/
     
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  5. Dec 23, 2018 #5
    schmee

    schmee Doctor of Teleocity

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    The hiss is likely the 100k carbon comp slope resistors and plate resistors in the preamp section. I would replace those. There are a bunch of them in there.
    FWIW I have abandoned the use of NOS preamp tubes due to noise (hiss, crackle, microphonics) issues. I use only Mullard RI 12AX7's now. They are more $ than JJ or EH but worth it to me. I've probably used at least 20 now and not had a bad one yet.
    I want to play not worry about tubes.
     
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  6. Dec 23, 2018 #6
    INFANT

    INFANT Tele-Holic

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    Ya my last tech really recommended these EH tubes for very decent sound and excellent reliability. I’m using a new tech now I’ll see what he says
     
  7. Dec 23, 2018 #7
    rogb

    rogb Tele-Afflicted

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    You're lucky! I had to ship my tubes in from the USA, intl shipping + 24% taxes this end. I still would do it every time for a quality amp. The only one that ever went down was a $20 GE rectifier, after bouncing over frozen roads on my cart last winter.
    I want reliability AND great sound not a Chinese tube crapshoot, and I have bought dozens of JJ, EH and tubes like that. Give me the JAN tubes every time.
     
  8. Dec 23, 2018 #8
    schmee

    schmee Doctor of Teleocity

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    I think they are not bad at all. The JJ pre tubes I dont like. But the EH are fine, although I had a noisy one or two over the years.
     
  9. Dec 23, 2018 #9
    Shidoin

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    A big second on NOS tubes. A set of RCA JAN power and rectifier tubes and you’re pretty much set for life. The RCA’s in my DR Are 50+ years old and still going strong.
     
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  10. Dec 24, 2018 #10
    BobbyZ

    BobbyZ Doctor of Teleocity

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    I'd definitely replace the electrolytics that are still original. Ten year old filter caps are probably fine, but new F&Ts are pretty cheap and go in fast.
    The one silverface schmatic I just looked at shows a bias pot instead of the balance pot most SF amps had. If that's the case no worries there. If it does have a balance pot a small voltage pot ahead of that does the trick without changing the phase inverter.
    Plate resisters on SF amps were normally 1 watt and not that big of a problem. Actually I seldom replace those on any amp, but I live in a dry northern climate and I think that helps carbon comps.
     
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  11. Dec 24, 2018 #11
    AAA71

    AAA71 Tele-Meister

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    Who you using? Im in Burlington. Curious.
     
  12. Dec 24, 2018 #12
    INFANT

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    Rich Audio in Stoney Creek. I overheard some guys at the Hamilton Long&Mcquade talking about where they send their stuff and I heard McNeilly Road (just a km from where I live) plus I've seen someone from the Creek advertising on Kijiji from time to time. Then the other day I was on the Boss website checking where their certified service centers were located and bingo, McNeilly Rd. I checked the website and he works out of his house (like most of these guys do) but he works on amps, keyboards etc. I called him up and he told me 3 to 5 working days turnaround. He gets all his amp parts from the Tube Store in Hamilton. Sounds like a nice guy.

    My previous tech was Bill Costello of Busen Amps, great tech but slow. The last guy I tried was a fellow from Burlington, Ed Stepanic from Eds Amps. Also very good and I was going to go back to him but when I found this guy nearby, I thought that I would try him. Another guy, Chris Church (advertises on Kijiji a lot), is supposed to be very good but unless you are a working musician and need your amp to support your family, you can wait a few months from what i hear.
     
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  13. Dec 24, 2018 #13
    charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

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    I had a '79 Vibrolux that flummoxed a very experienced tech.
    Weird stuff in the bias circuit.
    Just a heads up.
     
  14. Dec 24, 2018 #14
    INFANT

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    Like I said earlier, the amp is working fine right now and sounds great! I just want to replace the 40 year old electrolytics and the approximately 10-12yr old filter caps and anything else that may appear weak and on the verge of failing. There is a little bit of background hiss that I can live with but if replacing a few old resistors gets rid of it completely, then I'm all for it. It's a 79 silverface with a pull boost....not a collectors item but a good "gigging" amp.
     
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  15. Dec 25, 2018 #15
    rogb

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    If you're gonna change some old CC resistors, Ohmite do a good range of modern CC 5% .5W. On a 79, I'd stick with the CC if possible. You might be able to change to carbon film, which have good tolerances and temperature stability, but I would try some quality CC first, and measure them before I put them in.
    https://eu.mouser.com/Ohmite/Passiv...rbon-Composition-Resistors/_/N-5g9p?P=1z0zldm
     
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  16. Dec 28, 2018 #16
    INFANT

    INFANT Tele-Holic

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    Well I brought it in this morning and this afternoon I got a quote. $225 to replace all electrolytics and 3 preamp tubes. I checked the prices at the Tube Store (where these guys get their parts) and $100 of that is for 5 F&T filter caps and 3 Mullard 12ax7 tubes so I don't feel I'm getting ripped off.

    They feel the resistors are fine and don't need replacement. They were amazed at how quiet the amp was....only seemed to hiss when the reverb was turned up to 10. They will look into this but really, I don't play surf so the reverb stays below 5 anyway.

    Amp will be ready on Saturday so I should be able to use it New Years Eve! Looking forward to getting it back!!

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  17. Jan 2, 2019 #17
    Silverface

    Silverface Poster Extraordinaire Platinum Supporter

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    FWIW when I service similar amps I replace filter caps at 15 years - - service life is generally 15-20 - along with the bias cap. The cathode bypass caps I test and replace if marginal. Most types rarely fail and it's not a disaster when they do. I believe in doing necessary work - and replacing every electrolytic cap just isn't necessary. I do replace the older-type dual section cardboard bypass caps and "Whale" brand, as those types seem to be bad or close about half the time anyway. But Mallorys - almost never.

    The price doesn't sound bad at all though, if he's replacing the filter caps as well plus some tubes.
     
  18. Jan 2, 2019 #18
    INFANT

    INFANT Tele-Holic

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    I got it back on Saturday and it sounds wonderful. I was getting a slight hum prior to the cap job but it's gone. Also some background hiss seems to have been reduced and is unnoticeable at lower volumes. I didn't have a chance to use it on New Years Eve as I was hoping to give it a real test beforehand and didn't get that chance. We should be having a few rehearsals before our next gig so I'm gonna try it out there. However, it does sound very sweet down in my basement with my '75 Tele and my P90 equipped LP Melody Maker. The tech even said that it was one of the nicest sounding DR'S he's ever worked on. That made me happy! :)



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