What am I doing to my sound by using 5881s?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Phil M, Jul 29, 2006.


  1. Phil M

    Phil M Supporting Member

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    I have an Allen Old Flame head which is based on the blackface Fender Super Reverb. It also does some other cool stuff because of the raw control and master volume.

    These generally come with 6L6 and a tube rectifier, but mine came with 5881s and a solid state rectifier thing is plugged into the recto slot. I can get blackface sounds with the raw off, but when I use a Les Paul and crank up that raw control a bit, I'd classify the sound as more of a classic Marshall mixed with a little Fender. Is it simply the amp's design, or do the 5881s play a large role here? I'm not really familiar with that tube except that they were in my old Marshall JCM900 and these amp's sound NOTHING alike.

    FYI, I just ordered some new Tung Sol 5881s from Doug Preston. I'm eager to see if they make a difference.
     
  2. Blue Strat

    Blue Strat Member

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    Tung Sol (and most real) 5881s will give you less headroom than 6L6GCs (you must indicate a suffix, to say 6L6 is ambiguous as there are about 5 varieties with different power/sonic attributes).
     
  3. Phil M

    Phil M Supporting Member

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    All the 6L6 amps I've ever used were 6L6GC. Thanks.
     
  4. Blue Strat

    Blue Strat Member

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    All modern amps do use GCs. Some vintage and boutique amps can use other types as well.
     
  5. brad347

    brad347 Member

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    I concur, I knew what you meant but a 5881 is actually a 6L6. It is a 6L6GB or 6L6WGB (can't remember which). So saying "what happens when I replace a 6L6 with a 5881" is a bit like saying "what happens when I replace a preamp tube with a 12AX7?"
     
  6. brad347

    brad347 Member

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    well there you go. I stand corrected... no wonder i wasn't sure if it was a GB or a WGB... it's between them!
     
  7. Phil M

    Phil M Supporting Member

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    No, that would be like saying "what happens when I replace a power tube with a 5881." :AOK

    I spoke with Doug Preston of dougstubes and he was able to tell me what what sound and headroom differences I might expect if I used a 6L6GC or a 5881 in this amp. I know what you mean though, thanks.

    Now here's a question that might have more substance to it: this amp came to me with a little solid state "thing" plugged into the rectifier tube slot. I think it says Sovtek but I've never seen such a device before. I am under the impression that this might keep the sound a little tighter, but I don't remember where I hear that. Would using a tube rectifier make the bottom end too mushy? I remember this could be an issue on some of the old blackfaces I had when they were loud and overdriven.
     
  8. EADGBE

    EADGBE Member

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    Here's an interesting article:

    http://www.guitaramplifierblueprinting.com/rectifiers.html
     
  9. Blue Strat

    Blue Strat Member

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    Solid state rectifiers (which is what you have) increase internal voltages, give more headroom, tighter low and and often make an amp brighter.

    "Too mushy"? For who? No one can answer this for you (if they do, they're lying to you). A tube rectifier will definitely make the low end "less tight".
     
  10. Phil M

    Phil M Supporting Member

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    Of course tone is subjective, but I think you did answer it for me as much as you could, thanks. The amp does sound good and I don't have a burning desire to switch out the SS rectifier. I was curious though.
     

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