Best Tubes for a Magnavox-era Ampeg V4B

Discussion in 'Amps and Cabs [BG]' started by Mannishboy, Apr 16, 2019.

  1. Hi All!

    Yesterday, I purchased a Magnavox-era Ampeg V4B amp (with a beat-up, behemoth, 2x15, folded-horn, caster-less V4B cab.)

    Being constantly worried that I'll disrupt a gig with my gear going down, I feel I need to buy a set of "back-up tubes" (as well as carrying my 3.5lb Quilter Bass Block 800 for a spare.)

    This brings me to my question:

    Figuring in I play a wide selection of music (everything but metal), and price vs. performance, what would you guys recommend? Here's a list of all the tubes I need:

    (2) ECC83/12AX7
    (1) ECC82/12AU7
    (1) 12DW7
    (1) 6K11
    (4) 7027

    Extra points for the retailer with the best prices...

    Any and all opinions are most welcome. Thanks!
  2. IMG_20190415_231227_449.jpg
  3. IMG_20190415_231227_448.jpg
  4. Wasnex


    Dec 25, 2011

    I believe the amp is pretty hard on output tubes, and unfortunately not a lot of companies are making good 7027s. @beans-on-toast has recommended the Tung Sol 7027A or 7581A.

    Here's a related thread: What V4B tubes?
  5. beans-on-toast


    Aug 7, 2008
    I’d buy a couple of 6K11’s if you can swing it as they aren’t being made and getting rare. They’re an expensive tube.

    You don’t need NOS for the other tubes.

    I recommend either of the the Tung-Sol power tubes. You might want to stick with the 7027A if you want original performance. The 7581A has more headroom. A tech should check and re-bias the power tube set in the amp when you change them if necessary.

    Good price,
    They also sell the Tung-Sols.

    They sell the 7581A at Antique Electronic Supply as well. The 6K11 costs a little more there.

    Note, it’s best to test the new tube set in the amp, playing for several hours when you get them. If there’s an issue, you’ll catch it under warranty.
    Mannishboy, Wisebass and Wasnex like this.
  6. Jim C

    Jim C I believe in the trilogy; Fender, Stingray, + G&L Supporting Member

    Nov 29, 2008
    Bethesda, MD
    Why change the tubes?
    Old doesn't mean bad.
    Also, if they are original, it is unlikely you will find a better quality tube.

    I had a V4B for something like 40 years.
    It was nearly new when I bought it used in 1974.
    I sold it with the original tubes and they sounded great.

    Agreed having a spare 6K11 is a good thing as well as a spare 12AX7 in your gig bag just in case (your guitar player needs it).
  7. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Washington, Utah
    John K Custom Basses
    i'd recommend the tung sol 7027A's.
    i just put a matched quartet of tung-sol 7581A's in my 67 showman and it sounds great.
  8. Wisebass


    Jan 12, 2017
    Lost in Space
    Hi Mannishboy :)

    Happy NAD!!! :hyper::hyper::hyper:


    :D Repeat with me:

    "I will not open my amp to repair it' s guts, to change tubes or to do soldering jobs on stage"

    Nobody comes to your gig for that! ;)

    :thumbsup: That' s the way to go if you don 't want to…

    I have nothing to add to the posts about tubes (wasnex and beans know what they are talkin' about!)

    Just one thing :D:

    Better change that! :laugh:

    may the bass be with you


    Mannishboy likes this.
  9. webmonster


    May 19, 2013
    New Zealand
    Mmmm! Interesting - so the tung sol 7581a has more headroom than the tung sol 7027a ?
    Mannishboy and beans-on-toast like this.
  10. CRich0205


    Feb 17, 2013
    I had a 75 or 76 for about a year now too long ago. It was still going strong in the original tubes. Sounded great but I thought I needed an svt instead. Now I can’t grt that sweet power tube grind at sane volume levels. Cool amp but if you have a backup head I would think that would be good.
    Mannishboy likes this.
  11. beans-on-toast


    Aug 7, 2008
    That’s what I’ve found. Read the details here, note this is for the reissue Tung-Sol 7581A.

    Tung-Sol 7581A Audio Tubes -

    In general, you can obtain better headroom performance with any tube if you specify a matched set with a late onset of distortion. Many tube resellers can select tubes to meet this requirement. If they can’t, find a better reseller. If you want lots of distortion, specify a set with early onset of distortion. I often go with average onset of distortion.

    But headroom also depends on the health of your amp. A power supply that sags too much or can’t recover quickly enough from a sudden demand will distort at lower volume levels. Better performing tubes won’t help in this case.
    webmonster and Mannishboy like this.
  12. dan1952

    dan1952 Commercial User

    Jun 27, 2012
    Anderson IN
    Artist Endorsement with Supro Huntington Basses / Owner, Dan's Music, Inc..
    I'd check with @agedhorse to make sure, but I don't think new tubes are the most important thing to be concerned with at this point. This amp is old. Before doing anything else, you should get it to a good tech and have the filter caps replaced and the amp completely checked out. I wouldn't even turn it on again until this was done.
    Mannishboy likes this.
  13. klejst


    Oct 5, 2010
    Omaha, NE
    The more important question is...
    Is a Magnavox-era Ampeg V4B best for metal???!
    Wisebass and Mannishboy like this.
  14. I plan to get it up to Kevin Silva at Uncle Alberts asap. That said, the guy I bought it from is pretty "nitpicky" about his gear, so I'm not afraid of playing it as is.
    I noticed the preamp tubes looked to be the original Magnavox. The power tubes are JJ's.
    I should have done a TB search before posting, but I was so excited to get it. I just figured that there's so many of the reissues out there that I needed to specify the Ampeg era of this amp to get the best info y'all could give me.
    Oh, and I have nothing at all against metal (It's just too physically punishing for this old man's hands!) The closest I get is doing Paranoid one or twice a week...:bassist:
    Also, LEMMY RULES!!!!!!
    Arthur U. Poon, Wasnex and dan1952 like this.
  15. dan1952

    dan1952 Commercial User

    Jun 27, 2012
    Anderson IN
    Artist Endorsement with Supro Huntington Basses / Owner, Dan's Music, Inc..
    Kevin is great. And, BTW, put some casters on that 2x15 cab before somebody gets hurt!
    Mannishboy likes this.
  16. Kevin's the best and well worth the 3-4hr. drive...
    Yeah, I'm slapping some Harbor Freight casters on it and probably selling/trading the cab off. While it sounds great, it's too damn big to fit in the back seat of my '96 Fleetwood Brougham! I'll gig the V4B with my tweeterless Bergantino NV610...
  17. Jim C

    Jim C I believe in the trilogy; Fender, Stingray, + G&L Supporting Member

    Nov 29, 2008
    Bethesda, MD
    Congrats to the OP
    What was the purpose of this thread again?
    Mannishboy likes this.
  18. Spare set of tubes recommended for a Magnavox-era Ampeg V4B. That's it...
  19. Wasnex


    Dec 25, 2011
    A good tube amp tech should have a tube tester. The JJ 7027A is being operated above it's plate voltage limit in this amp, so they may not hold up well. I would probably run them until they start having problems and then buy a set of the Tung Sols.

    If the small signal tubes sound good and test well, leave them alone. Nothing wrong with buying a spare of each. Probably the most important spare to buy would be the 6K11. They are not going to get any cheaper. The Magnavox schematic I looked at showed a 6CG7 as well...should it be on your list as well?

    If the amp runs quite and makes good power, it is unlikely to need a full cap job. If the amp has been played and maintained regularly. I wouldn't be surprised if your tech gives it a quick once over and sends it home with a clean bill of health.