Raytheon 12ax7

Discussion in 'Amp Input - Normal or Bright' started by zeeter, Mar 16, 2013.

  1. zeeter

    zeeter Strat-O-Master

    Messages:
    802
    Joined:
    Nov 2, 2011
    Location:
    Philadelphia
    Got my order for 2 Raytheon 12AX7 tubes today:

    Super Reverb RI:
    Steps taken:
    Raytheon in V2 and V4 - Loud hiss\hum
    Raytheon-1 in V2 and Tung Sol in V4 - normal hum
    Raytheon-2 in V2 and Tung Sol in V4 - Loud hiss/hum

    Good harmonic test on Raytheon 1
    Harmonic test on Raytheon 2 failed - no sound through the speakers

    Gently sanded the posts in Raytheon 2 but received the same results.

    Used the same tube in V2 in a Deluxe Reverb with no noticeable hum/hiss. At first I did hear it, but it went away after around fifteen seconds. Also, I did hear a harmonic when tapping it within the DRRI.

    Do these need to burn in at all? If so I'll let it go for a while, but since one is not producing harmonics when tapped I'm pretty sure it's bad.

    The hum/hiss was there whether the guitar was plugged into the amp or not. Strange that the same tube would work fine in a DRRI and not a SRRI.
     
  2. zeeter

    zeeter Strat-O-Master

    Messages:
    802
    Joined:
    Nov 2, 2011
    Location:
    Philadelphia
    C'mon...nobody?

    Adendum, when turning the DRRI up all the way I heard the same hiss/hum. Not the normal up at full volume sound you'd expect, but more like that hissing and humming.
     
  3. OLDGREYGIT

    OLDGREYGIT Senior Stratmaster

    Messages:
    3,731
    Joined:
    Feb 7, 2011
    Location:
    Surrey
    Got a Raytheon in V3 in my Swart.
    It's the tremolo driver/bias.
    Very quiet, low noisefloor, and supplies a mighty throbbing.
     
  4. zeeter

    zeeter Strat-O-Master

    Messages:
    802
    Joined:
    Nov 2, 2011
    Location:
    Philadelphia
    I don't think it's a problem with the brand as much as with the tube itself.

    So yours is a 12at7 then? Not a 12ax7?
     
  5. Leebman

    Leebman Strat-Talker

    Messages:
    400
    Joined:
    Feb 4, 2009
    Location:
    E. Yorks
    Are you saying you bought an old tube and it is noisy and hissing and you are wondering why ?
     
  6. zeeter

    zeeter Strat-O-Master

    Messages:
    802
    Joined:
    Nov 2, 2011
    Location:
    Philadelphia
    No, I'm asking if the tube seems like it's bad or if it needs to be worn in a bit as I've never used NOS tubes before.
     
  7. Leebman

    Leebman Strat-Talker

    Messages:
    400
    Joined:
    Feb 4, 2009
    Location:
    E. Yorks
    Tubes vary with the amount of hiss and hum they produce even new ones it is unlikely to get any better with burn in more likely it will get worse over time. It doesn't necessarily mean its bad it may still function with in spec. The problem buying nos tubes is they have all been picked over many times and what are left are the rejects, some of which are still better than modern tubes. You have to pick your supplier carefully and hope they know what they are doing. Same with modern tubes the stuff that hits the open market has already been rejected by the major amp building companies.
     
  8. zeeter

    zeeter Strat-O-Master

    Messages:
    802
    Joined:
    Nov 2, 2011
    Location:
    Philadelphia
    Interesting. So it's pretty much hit or miss, huh? The one works great. The other one works in the deluxe and I'm guess it's because less power is going through it. The guy I bought it from said they both tested at 130/130, and we know nobody on the internet lies at all.

    I have four more coming in. Two Raytheon 12ax7 and two Telefunken 12at7 tubes. I guess we'll see how that goes. Might see about returning the one.
     
  9. zeeter

    zeeter Strat-O-Master

    Messages:
    802
    Joined:
    Nov 2, 2011
    Location:
    Philadelphia
    Got a 2nd set of Raytheon tubes yesterday just before rehearsal. Put them in my SRRI and it was music to my ears. Literally and figuratively.

    Paid $20 less for these tubes. The original seller said he'd give me my money back plus shipping for the one bad tube. I should have said their both were bad as the newer ones are nearly silent compared to the one that I thought was good from the original delivery.

    I have them in 2 and 4. Put a Tung Sol in V1 as that's supposed to have some effect on the sound. Some people even take V1 out so that it doesn't affect V2 and V4 at all. I just didn't want to keep a Groove Tube in there which is why I put the Tung Sol in there.

    Waiting on my order of two Telefunken 12at7 tubes. Should be here today. I'm planning on putting them in V3 and V6 - though there's debate over how much they actually affect the tone in V6. Might just keep the Fender tube (probably a licensed groove tube) in there if it doesn't affect the tone at all.

    Edit: Also just ordered a couple of RCA black plates from the 1950's. Normally these go for over $100 but these were $50, so I'm guessing they'll be decent but not superb.
     
    Last edited: Mar 22, 2013
  10. arithon

    arithon Strat-O-Master

    Messages:
    648
    Joined:
    Aug 20, 2012
    Location:
    Milwaukee
    Do you have contact cleaner? You can put some on the metal ends of the tube, let it it sit a while then wipe off with a paper towel. Oftentimes this helps with NOS tubes because sometimes they have some corrosion on the contacts.

    I would also try firing some compressed air up into the tube socket in the amp, they do get dust and crap in there and that can effect things.
     
  11. zeeter

    zeeter Strat-O-Master

    Messages:
    802
    Joined:
    Nov 2, 2011
    Location:
    Philadelphia
    I ordered an RCA tube off of Ebay and put it into my Deluxe V2 with a Tung Sol in V4 and I can't believe how great it sounds! Even better than the Raytheons.

    Now if I could just get some decent 12at7 tubes. I ordered some Telefunkens but they sound horrible. I may just buy new for those as they're important, but not as critical as V2 and V4.
     
  12. midifarm

    midifarm Commercial Suspension

    Messages:
    1,795
    Joined:
    Jan 31, 2009
    Location:
    Minneapolis
    Find someone in town and have them tested. Sounds like a dead tube. If Raytheon made the tube, it should be mil spec and good to go. Telefunkens are NOT the way to go for guitar amps. Mic pres yes. They won't be as musical as you're expecting.
     
  13. OLDGREYGIT

    OLDGREYGIT Senior Stratmaster

    Messages:
    3,731
    Joined:
    Feb 7, 2011
    Location:
    Surrey
    I agree! I found the Telefunkens very 'hi fi', clean, precise and a swine to overdrive in a pleasant way. (That's how they are supposed to be).
    There are a bunch of Mullard 12AT7's on Fleabay Uk at good prices.