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Tube Preamp Tube Swap?

Discussion in 'Amps and Cabs [BG]' started by ccouch7, Apr 14, 2019 at 5:30 PM.


  1. ccouch7

    ccouch7

    Feb 14, 2009
    I wasn't sure weather to post this here or in the effects section, but oh well.
    I've been looking around and doing some research on this but I thought some
    of you guys might have some first hand experience or opinions on this.
    Of course I will do some experimenting with this on my own, just thought I could
    get some ideas from some of you as I've always used solid state in the past.

    I've been messing around with a Laney IRT Pulse tube preamp lately, it uses two
    12ax7 tubes. I love the tone and it actually has the overdrive tone I've been looking
    for-for a while.
    But it has two channels (regular and hot) and I have to keep the gain knob super low
    like on 1 or 2 on the regular channel for it to have the break up I like.
    I'm looking around at lower gain replacement tubes like-
    12at7 -gain factor of 60,
    12ay7 -gain factor of 44
    and 12au7 -gain factor of 20.

    Any of you tube gurus have any experience or guidance on this?

    I plan on putting this thing on my small board along with a Line 6 HXFX and D.I.

    Here's a link to the Laney IRT Pulse tube preamp-
    IRT-PULSE - All tube high gain T-USB interface

    Thanks
     
    Last edited: Apr 15, 2019 at 6:23 AM
  2. Wasnex

    Wasnex

    Dec 25, 2011

    Some people like subbing in different tube types, but so far I have always preferred 12AX7s in circuits designed for 12AX7s. It's not just about the gain factor, different tube types have different operating points so ideally the circuit typically needs to be rebiased for it to operate optimally with a different type of tubes.

    If the circuit is sensitive to tube rolling, you could try different 12AX7s. 12AX7s come in a lot of varieties and in some amps they sound noticeably different.

    The current production Tung Sol tends to have a lot of gain, but doesn't break into distortion very easy. So if you put a Tung Sol early in the circuit it might have tendency to push later stages into OD, but if you put a Tung Sol later in the amp, it may remain clean and punchy. The Svetlana 12AX7 seems to be at the lower gain end of the spectrum so you could try one of these in V1. In my experience the JJ ECC83S is also at the low gain end of the spectrum, but seems to break into OD fairly early in the amps I have tried it in. JJ also sells a medium gain ECC83MG (medium gain). Another option is the 5751 tube type, which is a low gain sub for a 12AX7.

    12AX7, ECC83, ECC803, 7025 are all pretty much the same tube type. There are a few other model designations (like 6681) as well that are essentially obsolete that you might come across if you are looking at old stock tubes.
     
    gepettus, mikewalker and ccouch7 like this.
  3. ccouch7

    ccouch7

    Feb 14, 2009
    Thanks for the info! That's really helpful and gives me a few thing to look into.
     
    Wasnex likes this.
  4. Wasnex

    Wasnex

    Dec 25, 2011
    I am listening to this video as I write this:
     
    ccouch7 likes this.
  5. ccouch7

    ccouch7

    Feb 14, 2009
    Thank for that! I'm diggin' some of the tones he gets with that baritone guitar with it.
     
    Last edited: Apr 14, 2019 at 11:29 PM
    Wasnex likes this.
  6. MarkA

    MarkA In the doghouse. Supporting Member

    Sep 26, 2008
    Can't speak to the Laney pre - and it depends on the circuit - but I've had decent results, before, when I wanted to tighten/clean things up, using a 12AT7 (of the few I've tried, I liked a JAN Phillips 12AT7 WA) in place of a 12AX7. 12AU7 sounded anemic and weird in a 12AX7's spot.

    Success will depend on the specific circuit and your tastes, though.

    Agreed w/above post that different 12AX7's can behave pretty differently (again, depends on circuit). Haven't listened to above video yet.

    My experience with this is far from exhaustive, so take it for what it's worth.
     
    ccouch7 and Wasnex like this.
  7. ccouch7

    ccouch7

    Feb 14, 2009
    Thanks for the reply, you guys are helping me narrow down my choices for tubes
    to try, so I don't have to pick up 4 or 5 different ones.

    I think an 12at7, a different 12ax7 and maybe something else are in the running so far.

    Thanks again for the help and insights!
     
  8. TinIndian

    TinIndian

    Jan 25, 2011
    Micco Florida
    He covered it above, but a 5751 would the 1st thing I'd try. If I remember correctly it has 30% less gain than a regular 12AX7.
     
    Alivefor5, Wasnex and ccouch7 like this.
  9. ccouch7

    ccouch7

    Feb 14, 2009
    Thank you sir! So that's it then I'm gonna get a 5751 and a 12at7 to try first.

    I actually e-mailed Laney about this, asking about the 12AY7, 12AT7 or 12AU7 for bass.
    They got back to me quick, this was their reply-

    Thanks for the enquiry.
    You can try any of those tubes in V1 position without any modifications, I think swapping V2
    also would be too much but you can try it.

    So I'll try those two in V1 and see/hear what happens.
     
    Last edited: Apr 15, 2019 at 6:16 AM
  10. Roland GR 88

    Roland GR 88

    Sep 16, 2013
    Whitby
    Current Vacuum Tube Manufacturers:

    #1 Location China; Shuagang
    Brands and Sub Brands:
    Sino China, Shuguang, Golden Dragon,
    Rebranders: Mesa, Ruby, TAD, Groove Tubes, PM Components, Valve Art, Peavey, Fender, ......

    #2 Location Slovak Republic: JJ Electronic
    Brands and Sub Brands:
    JJ, Telefunken Black Diamond
    Rebranders: Mesa, Ruby, TAD, Groove Tubes, PM Components, Valve Art, Peavey, Fender, ......

    #3 Location Saratov Russia: Reflektor Corporation
    Brands and Sub Brands:
    New Sensor, Electro Harmonix, Mullard reissue, Tung Sol reissue, Sovtek, Genalex Gold Lion, Svetlana (not real Svetlana),
    Rebranders: Mesa, Ruby, TAD, Groove Tubes, PM Components, Valve Art, Peavey, Fender, ......
     
  11. mattwear

    mattwear

    Aug 7, 2006
    Wellington, NZ
    Following this thread with interest but I’m confused about one thing. Stupid question... What is meant by “high gain” when referring to tubes? Does high gain mean high headroom before distortion, therefore a clean sounding tube? Or does it mean a “high gain” distorted early overdrive sounding tube?
    The latter I’d have thought was low gain because it produces less clean gain before distortion. Can anyone please clarify?
     
    BOOG likes this.
  12. Roland GR 88

    Roland GR 88

    Sep 16, 2013
    Whitby
    High gain means earlier breakup, low gain equals more headroom.
    Power tubes are often rated as low, medium or high gain as well.
     
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  13. mattwear

    mattwear

    Aug 7, 2006
    Wellington, NZ
    Seems counter intuitive, but thank you.
     
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  14. Lammchop93

    Lammchop93 Supporting Member

    Feb 4, 2007
    Louisville, KY
    it's hard to tell, and the differences are subtle, but I did a comparison video using a single 12ax7 tube in my Orange Terror Bass, and tried a variety of tubes.


    The Ruby 12ax7 was pretty low gain, but the JJ 12At7 was the lowest gain of all of them.
     
    ccouch7 likes this.
  15. ccouch7

    ccouch7

    Feb 14, 2009
    That's a cool comparison vid, sounds good, thanks for posting it here!
     
  16. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    TinIndian and ccouch7 like this.
  17. nilorius

    nilorius

    Oct 27, 2016
    Riga - Latvia
    This is too complicated for me. I can only say that i own hartke tx600 2 tube preamp d amp - amp and i like the sound it gives.
     
    ccouch7 likes this.
  18. ccouch7

    ccouch7

    Feb 14, 2009
    beans-on-toast likes this.
  19. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    There are a lot of options.

    For the purpose of a test, in this case, it makes sense to go with the JJ from a reputable dealer that tests tubes before they ship them.
     
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  20. TinIndian

    TinIndian

    Jan 25, 2011
    Micco Florida
    Yes Vintage tubes can get pricey. I picked an NOS JAN Phillips 5751 about 6 years ago and at that time it ran me about 30.00.

    You might check this guy out too.
    Search results for: '5751'
     
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