Considerations about tubes importance

Discussion in 'Amps and Cabs' started by gbtommasi, Jan 30, 2008.


  1. gbtommasi

    gbtommasi Member

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    Hi guys,

    yesterday i pulled a couple of groove tubes 12ax7M (mullard replicas) out of my marshall head, and replaced them with a fine couple of real Mullard 12ax7, almost new that i bought from ebay for a very cheap price.
    Well, I already put a couple of Siemens in the power stage, and could appreciated the results if compared with stock tubes.
    Yesterday i could once more appreciate an impressive difference in the sound.
    I put one Mullard in the first position and one as phase inverter before the power stage, and suddenly my round, silky, thick sound became rounder, even more silky and thicker.
    What a change! I would not say it's better, just it's different (incidentally, it is better for me).
    So this brings a consideration along on which i'd like everyone could say his opinion: mine is that tubes are almost 50% of the sound in a tube amp, and, even for past experiences i had, i say that a poor sounding amp can have great benefits from a tube replacement, given that you have selected and fine tubes available.
    What do you think?
     
  2. Dave L

    Dave L Member

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    Well, in my opinion changing tubes definitely can yield good results, and the right tubes can really fine-tune a tone. With that said, changing something like speakers and/or cabs can make an entire world of difference.

    Another thing to discuss is that different amps seem to react differently to tube changes. I feel that my Riveras are very sensitive to tube swaps, but some amps I´ve had in the past didn´t change their tone all that much with new and different tubes. I wonder what aspect of the design of an amp dictates this? Of course, I might just be hearing things.
     
  3. Blue Strat

    Blue Strat Member

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    50% may be pushing it, but even 10% (assuming there's a way to measure % improvement in tone, which there isn't because not only is tone subjective, % improvement is subjective as well) can be enough to turn an amp that's going to Ebay into a keeper.

    It depends a lot on which particular tubes you're changing from and to. In your case, I would have to say that the 2 examples (especially the GT-Ms made prior to 2008) might produce a radical change.
     
  4. Blue Strat

    Blue Strat Member

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    Definitely true and there are probably numerous aspects that would affect this. One big difference is that brighter speakers make tube changes much more apparent than darker speakers. If a speaker is not letting the full frequency spectrum be heard you're a lot less likely to hear changes.
     
  5. frank62

    frank62 Member

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    Different amps like different tubes. An NOS Mullard may make a dramatic difference in certain amps and very little in others. One thing you can be sure of is a good NOS with outlast most current production. In a Blues Junior for eample the RI Tungsols worked as well for me as any NOS preamps tubes i have tried. NOS Teslas worked best for the power. This is only one amp and a few different tubes so there are no absolutes when talking tubes. The sound or tone one is after is so very much a personal thing but the fact NOS will last much longer is reason enough.
     
  6. gbtommasi

    gbtommasi Member

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    Indeed, there are many factors which may contribute to change the character of an amp, yet i experimented the effect of swapping tubes on different amps.
    ten years ago i bought a 76 silverface twin, which came with all its original tubes, pre and power. After some months, its old Silvanya eventually died, and i replaced them with a quartet of GT, and the amp was no more the same. I eventually sold it... same for a Marshall JMP MKII (a 77 master volume), which changed drastically when its old, original tubes blew and i replaced them with a lot of different tubes, but i was unable to recreate that magic which had made that amp so special to my ears. Until i plugged a couple of Siemens into it...

    so that's it, i am convinced that good tubes (read: NOS) can improve almost any amp on the market, or at least, change it
     
  7. rockon1

    rockon1 Member

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    +1 Some amps sound completely different(especially replacing the V1) while others seem much less affected. The difference can be startling to hardly noticable. Bob
     
  8. hamfist

    hamfist Member

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    This has been my experience too.
     
  9. Guinness Lad

    Guinness Lad Silver Supporting Member

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    Tubes to me are like guitar strings, you can change the sound quite a bit but generally you cannot turn a bad amp into a great one. I have a bunch of tubes I keep on hand to dial amps in that I like but I have never been able to coax greatness out of an that just didn't have it.
     

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