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Dating Ampeg Blueline SVT, tube opinions?

Discussion in 'Amps and Cabs [BG]' started by beebassdude, Aug 25, 2012.


  1. beebassdude

    beebassdude Supporting Member

    Sep 29, 2008
    Sterling, VA
    So i just picked this guy up in a trade today, gonna figure out if i wanna keep this or my VR and sell the other. im trying to figure out a date, and all i can find without pulling the amp apart (dont wanna do that) is a code on top of a transformer (ETC 298601) and the old schematic in it. It was definitely at one point an original 6146 tuber, since has been converted to 6550s. so my two questions are:

    1. with the pic of the schematic and the transformer code, can i get a decent date on this?

    2. if it was once a 6146 tube amp, is it worth it to have my tech reconvert back to these tubes or just stick with the 6550s?

    thanks!

    photo1-2.

    photo2-2.
     
  2. beebassdude

    beebassdude Supporting Member

    Sep 29, 2008
    Sterling, VA
    nvmd, opened it up, its a 1970 blueline. no tube relay socket, pots are 1377004. early 1970 so it would seem. pretty cool.
     
  3. TheDialog

    TheDialog Supporting Member

    Nov 23, 2008
    Baltimore
    Legit pics?
     
  4. beebassdude

    beebassdude Supporting Member

    Sep 29, 2008
    Sterling, VA
    didnt get a picture of the pot, but i saw it. i didnt wanna remove the entire chasis, so i just took it about halfway out and could see two of them with a flashlight. heres the amp tho.

    photo21.
     
  5. TheDialog

    TheDialog Supporting Member

    Nov 23, 2008
    Baltimore
    Trade your Bird?
     
  6. beebassdude

    beebassdude Supporting Member

    Sep 29, 2008
    Sterling, VA
    yup, no hits on it and i figured i can flip this if i want (probably much easier) and i needed another 112 cab for my bee rig.
     
  7. Seans

    Seans

    Jul 4, 2008
    Herefordshire, UK
    Looks nice and right for an early 70 with 6146b, although some early 70's had the Valve relay too, serial number on chassis or back plate?.

    We need to see under the chassis, ''Beans'' will hopefully be by shortly and be able to give you an idea what's involved in converting back.. But I would say def back to 6146.
     
  8. I have heard a few 6146 amps, not Ampeg, but they sounded great. Not sure how much the conversion would cost but if it's reasonable I think you would be happy with the results. I know of one amp that used a single 6146 and it supposedly put out 80 watts.
     
  9. I know this is possibly the worst time for it, but ummm...

    So, how did your date with your amp go? :D
     
  10. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    Dang do you still laugh out loud uncontrollably every single time someone cuts a fart too? JK :smug:
     
  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Very nice looking amp.

    The case is dead giveaway that it is an early model. The edges are sharper than on the 71 and later models.

    One way to tell of it originally had 6146 tubes is to look for a hole, with possibly a grommet in it, at the base of each power tube. The 6146 tubes have a wire and cap that connects to a plate electrode on top of the tube.

    I would start off with a good cleaning. This includes the case, chassis, transformers, and the circuit board and all the electronics, including the pots and jacks. This is the most time consuming part of getting the amp back into shape. If the amp is original, there are a few components that should be checked out. This includes the plate and cathode resistors, the power supply resistors and capacitors, and the diodes. You'll want a three conductor power cord. I like to remove the speaker out cable and replace it with a jack on the chassis.

    There are different levels of restoration. You could stop here and leave the 6550A's in place. Especially if they are NOS GE tubes. Converting the amp back to 6146 tubes is very easy. There is some rewiring at each power tube socket and the plate wire needs to be added. On some amps you'll find an new (or additional) heater (6.3V) transformer was added to meet the higher current requirements of the 6550 tubes. The 6146W requires 1.25A vs 1.6A per tube for the 6550. It doesn't hurt to leave this transformer in place if you have one. About an hours worth of bench time is required. There was also a minor wiring change in the 1970 and later models in the power supply that differed from the 1969 revision. You don't want to undo that.

    I guess that I'm saying that the amp needs a lot more work than just converting it back to 6146 power tubes to bring it back to original spec. I would get to know the amp and see how you like it with the 6550A tubes in place. The differences with the 6146's in place are subtle. As a purist, I might want to convert it but a lot of folks wouldn't hear a difference.

    These are great amps and well worth the investment to restore them.
     
  12. Why yes, yes I do. Is there a problem with that, good sir? :D
     
  13. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    Nope, no problemo at all, I refuse to grow up and loose my sense of humor too!
     
  14. beebassdude

    beebassdude Supporting Member

    Sep 29, 2008
    Sterling, VA
    serial number on the back chasis is 102514.

    i didnt think the serial numbers on these old ampegs helped in terms of dating? i guess they do haha.
     
  15. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I don't know if I'd reconvert it back, but I do love my 6146b SVT. If you're doing it as a fun project and don't mind eating the expense, then have at it, but I don't know that the 6146b's give you much more than the 6550's. Having said that, I've never been able to do a direct AB with a 6550 SVT so what do I know? ;)
     
  16. beebassdude

    beebassdude Supporting Member

    Sep 29, 2008
    Sterling, VA
    thanks for the opinion jimmy. question for ya as well since youre an ampeg man. i have 2 8ohm cabs that ive been running with my VR, switched to the 4ohm tap. i cant do that with this blueline, as i think if i plug in two cabs it will default to the 2ohm tap. problem is both my cabs only have one input so i cant daisy chain them. im assuming ill have to have some sort of tap mod done to the amp to run it the way i want to? lemmie know!
     
  17. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    It would probably be easier to just drill a second hole on the cab and install a parallel jack, or build a parallel connection box, than to modify the head.
     
  18. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I'd rather get a little box to plug both cabs into to make a 4 ohm load and run that into the amp. You should be able to get one...I don't know who makes it but I've seen boxes built for that...maybe Radial?
     
  19. jastacey

    jastacey Supporting Member

    Feb 8, 2009
    Houston,Tx
  20. beebassdude

    beebassdude Supporting Member

    Sep 29, 2008
    Sterling, VA
    Could somebody post what that box is called? If guitar center
    has one ill go out and snag it now.
     

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