Tubes: Low gain vs High gain?

Discussion in 'The Workbench' started by explorickenbacker, Mar 8, 2013.

  1. explorickenbacker

    explorickenbacker New Member

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    So I was wondering what you guys think would be the best option for my jcm 900 sl-x. I play an equal amount of uber-gain and uber-clean, and I'm interested as to what the differences are between different gain tubes. I have had stock marshalls in it and they've actually sounded great for their age, looking to 'upgrade' though, reccomendations?
     
  2. Ken

    Ken Well-Known Member

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    Read the tube stickies. There's a million opinions on what's "best". Budget comes in to play too because you can spend $10 or $100 on each 12AX7.

    The best thing I can contribute is find out which preamp positions are the most important tone wise for your particular amp and spend the most money for these. In general I think power amp tubes are less critical unless you're playing full volume a lot, but even then on your amp it might be more important than on mine. Be sure to get a matched set of whatever you buy.

    Ken
     
  3. explorickenbacker

    explorickenbacker New Member

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    thanks for the info, but i'm confused as to the tonal differences between high gain and low gain tubes at distortion, are they different?
     
  4. Ken

    Ken Well-Known Member

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    Offhand I'd say your amp has so much preamp gain, you don't need high gain anything. I think the specific answer to your question is very amp-dependent and I don't have an SL-X so wait for an owner to chime in.


    Ken
     
  5. damienbeale

    damienbeale New Member

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    Well, for high-gain, and cleans, you'll probably want something that retains it's composure well. 6CA7 will do this well, in comparison to EL34's.
    Or if you fancy some nice tight bottom chunk, KT77's will add this nicely, with a smidge less midrange than your average EL34.

    Of course, you'll need to check your amp is ready for EL34 operation. Most will be configured to 5881's. I wouldn't really recommend current 5881's so a conversion will be very worthwhile.
     
  6. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Like Ken said your amplifier is high gain and is setup to provide high gain no matter what brand or model 12AX7 preamp tube you use in its slots. It never hurts to have nice strong (higher gain tube) 12AX7 in each slot. But just as important is voicing. You may want clean, compressed, distorted or some combination. You have to find and pick a tube or tubes that create more of the tone you want with your amplifier.

    What is funny is hearing about a guy who wants less gain and distortion so the 12AX7 is swapped for a 12AY7 but then turns the preamp gain or volume up. It may work for his taste but depends on the flavor or overall tone of the tube used. In most cases a nice 12AX7 with the gain or volume turned down does the same. It depends on whether the user likes the voicing of the particular tube. But in the end, the user may get less output or volume from the lower amplification value tube.

    The stock Marshall preamp tubes may sound fine in your amplifier. Other tubes may or may not sound better. The hunt is on. There are lots of people here searching or chasing tone for the "right combination" in their amplifier.

    Like mentioned check out and read the preamp tube thread, its big. The resident guys there can point you into good directions. They may even comment on this thread.
     
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  7. explorickenbacker

    explorickenbacker New Member

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    well like i said, I like the two extremes of the gain spectrum, and I also love my current tube tones, what would you say has the most headroom but keeps the distortion levels the same. Also, is it normal to have amp pots that jump in volume between 4-5 and jumps in gain in my gain knobs at about 3-4, because I really need an inbetween from quite to LOUD!
     
  8. damienbeale

    damienbeale New Member

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    Pot traces are probably knackered. Certainly not uncommon.

    As for "most headroom but keeps distortion levels the same", well, that's not really quite how it works. You might find some nice NOS Sylvania greyplate 12AX7's though if you want a bit more clarity to your distortion, and punchier cleans, but they might not necessarily compress the way you're used to, depends on what those Marshall tubes might be. And they've used all sorts over the years, so who knows.

    As for what will work well in what positions, you're better off shooting this guy a message:
    MARTIMUS MAXIMUS ONLINE TUBES AND OTHER STUFF

    and posting same questions on this thread, where hopefully the same guy (MartyStrat54) will respond:
    http://www.marshallforum.com/marshall-amps/3824-preamp-tubes-who-what-when-where-why-how-487.html
     
  9. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    I see Damien linked some reference and gave you Marty's name. Good.

    How are you getting your uber-clean and uber-gain at the same time from the SLX?
    You cannot really have both with that amplifier while using only the preamp for gain structure; it is a one channel amplifier.
    Distortion or breakup by nature is a lack of headroom. So with a one channel amplifier setup as it is you pick one direction or the other.

    A higher gain or stonger tube will only add more distortion down the line in that amplifier.

    It would probably work best to set the amplifier up cleaner and use a pedal or something up front to get added gain and distortion.
    Or setup for a little extra distortion and back off of the volume up front for cleaner tones. It will have to be a compromise.
     
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  10. MartyStrat54

    MartyStrat54 Well-Known Member

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    The SL-X is not noted for its clean tone. It is a high gain amp for players who spend most of their time needing a strong crunch tone. Playing a one channel amp is demanding and not everyone can do it. All the variables, guitar, pickups and speakers, play into this.

    Using the term "uber" is deceptive, as pointed out by mickeydg5. In reality, to get a really good clean and crunch, a two (or more) channel amp is needed. You might want to trade or sell your SL-X and get a two channel amp.

    Putting a high gain tube in V1 will just mean more crunch available on tap. As stated before, the very nature of design of the SL-X is that of high gain.

    When I recommend tubes for this amp, it is to accent the crunch, not the clean.
     
  11. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Unfortunately it may be normal and is probably a characteristic of the potentiometers used. Straight line or commercial type audio pots do that.
     
  12. explorickenbacker

    explorickenbacker New Member

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    Sorry for the late reply, forgot this thread existed! Anyways I just e-mailed Marty, hope to get a reply soon. Concerning the jump in volume, could anyone give me some advice on how to improve/fix this? It'd be much appreciated.
     
  13. damienbeale

    damienbeale New Member

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    Try new pots first. Should be a 1K logarithmic pot.
     
  14. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    I think you meant 1M logarithmic pot (potentiometer).
     
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  15. damienbeale

    damienbeale New Member

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    Oh sh...


    YES! :applause:
     
  16. sarmation

    sarmation New Member

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    I have a jcm 900 mk3 Similiar to yours.It has so much gain that to do classic rock crunch the gain is on like 2 and thin sounding.
    So I run a 12ay7 %40 gain of a 12ax7.I turn the preamp up now to like 5 to get those classic crunches but its alot thicker sounding that way'¨maybe since the gain is working harder just a guess idea I am no tech.

    I have also ran the 12ay7 is the PI slot and got good results.Ads alot of punch and headroom to the tone and maybe a little more low mids to my ears.
     
  17. EL 34

    EL 34 Well-Known Member

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  18. Georgiatec

    Georgiatec Well-Known Member VIP Member

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    I've found there are no hard & fast rules for this subject that apply to all amps. Best way forward is to roll and listen....when it sounds good to your ears then happy days.
     

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