Tube advice please...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by custom24, Jan 8, 2008.


  1. custom24

    custom24 Member

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    I bought an old Knight radio set with amp and seperate tuner from thrift store for $10. Looks to from the 50's, maybe 60's, and full of tubes. Here's what I've got, what can I do with them? I have a '65 RI Fender Twin Reverb, I have 2 Orange TT's, and a couple effects w/ 12ax7 preamps. Where might these sound best, what might I expect tonewise in your application? Or should I try To build my own amp? Or should I use the point to point Knight amp for guitar somehow? Follows is a list of the tubes, all seem to be good. Also would wonder if the caps and so forth are of use. It has one HUGE cap (orange) w/ Mallory on it.
    2 Mullard ECC83 12ax7's
    2 GE Electronic ECL82's
    2 Mullard ECL82/ 6bm8's
    1 RCA
    1 RCA 6hr6
    1 rca 6hs6
    1 Mullard 6x4
    1 no name marked 6c9 and also the roman numeral III 621
    2 RCA 12au7a's
    1 RCA 6bn8
    1 Mullard 6be6
    1 RCA short and fat says 6ag11 I think.
    What would happen if I loaded the TT with all Mullards? Would I def need to rebias? Thanks for any help!
     
  2. rog951

    rog951 Member

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    No need to re-bias with the Mullard ECC83s, just pop 'em into the TT and enjoy! From the list, those are the only tubes you'll likely be able to use in your guitar amps...perhaps the 12au7a too.
     
  3. Blue Strat

    Blue Strat Member

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    Looks like the 12AX7s are the only ones useful in typical guitar amps.

    What would they sound like? It would take less time to get an accurate answer by plugging them in and trying them than getting opinions laced with "tonal adjectives" that seldom translate from one person to another;)
     
  4. custom24

    custom24 Member

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    Thanks! I will get to playing with them now. Is it true that one 12ax7 will only make a sound difference- the one in the driver's seat? If so I could pop one in each of my TT's.
     
  5. rog951

    rog951 Member

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    Well, I wouldn't say that the other tubes won't make ANY difference, but usually the first tube that the guitar signal hits will have the largest impact on the amp's sound. In most cases, that tube is the one closest to the guitar's input jack. It might just make sense to use one Mullard in this position in each of your amps. Try it and see! ;)
     
  6. custom24

    custom24 Member

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    Kids just off to bed so I have some elbow room now, I'll give both ways a go. Thanks!
     
  7. custom24

    custom24 Member

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    The Mullard 12ax7's in my Tiny Terror set at 15 w thru Orange 2x12- I thought my Les Paul was Magic. Now I believe my amp is Magic as well!! Very awesome tones, seems to have added a considerable squeeze, might even be harbuoring some secret sauce. My wife wanted to clean hers(Tiny Terror) up a little bit, and the RCA 12au7's did that to a near unbelievable level. Abhorent to me, certainly, but she is my wife, so I trust her taste to an extent. She likes. Me? I think she lost considerable volume and some significant punchiness. Then again, I haven't personally played thru it yet, jury is still out. The clean is good. Not what I'm used to hearing out of this amp, which makes it weird. Previously very slight clean headroom, now with the vol and tone dimed and the gain at around 1:00 she is very clean on a previously filthy head. at 7w she may not seem as clean, I will have to see...
    The significance is so great in my Tiny Terror with the old Mullards that I am going to have to give them a go in my Twin, but I cannot imagine ever finding any better in my house than I am getting thru the Orange right now. I am beginning to shudder at the thought of something happening to these tubes, as I know they would be very hard to replace. Well, thanks again, I am back at it!:dude
    -What am I saying? In my Twin with a strat and a rat- I would think "Maybe..."
     
  8. custom24

    custom24 Member

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    Maybe nuthin, sounds great! Any problems switching out these tubes between the Fender and the Orange on a regular basis? Gently, of course?
     
  9. mc5nrg

    mc5nrg Member

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    The ECL82/6BM8, 12AU7, 6X4 do show up in guitar amps that are outside the more common Fender and Marshall type designs. Univox would be one possibility. The other tubes and the amp and tuner chassis might be of interest to hams, older hi fi and antique radio buffs etc.
     
  10. custom24

    custom24 Member

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    Thank you. I thought so on the first two anyhow. I have put the 12au7a's into one of my Orange heads.
     
  11. John Phillips

    John Phillips Member

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    Try not to. The biggest risk to preamp tubes really is pulling them in and out.

    If you sell all the rest on eBay - they're useful to some people, if not for most guitar amps - you might make enough to buy a couple of Mullards (used ones, anyway) for your Twin. You only really need two, for V2 and V4, if you normally use the Vibrato channel.
     
  12. custom24

    custom24 Member

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    Why is the pulling in and out so bad? I am not forgetting that these ARE 50 years old, which I would naturally take as a significant factor, but what is the harm? I really do not even know all the fundamentals yet, let alone the ins and outs. Thanks John.
     
  13. John Phillips

    John Phillips Member

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    The harm is in the inevitable flexing that the pins get as they go in and out of the contacts. Even if you're careful, and it doesn't happen much, it still happens.

    Do this enough and you will significantly increase the chance of a crack or a leak developing around one of the pins. If that happens, air gets in and your Mullard is as useful and valuable as a blown light bulb.

    Tubes were not designed to be constantly taken in and out of sockets - back in the old days, it was expected that they would be plugged in just once and left there, so there was no need to make the pins strong enough to withstand much more than that.
     
  14. JohnnyL

    JohnnyL Member

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    I just love the thought of getting two Mullard ECC83s for $10.00. Great Find!!!

    Johnny
     
  15. custom24

    custom24 Member

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    Thanks Johnny. I had a lot of asked tell me they would take them if I didn't want them before I discovered what they were lol. G.A.S. gets ugly sometimes. I like them a lot, and will look to get another set. Thanks again for the heads up and I'll pass it forward in the future.:AOK
     

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