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Tech says tubes can't change amp sound

Discussion in 'Amp Tech Center' started by Twanginator, Sep 25, 2013.

  1. Twanginator

    Twanginator Tele-Holic

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    I called a local amp tech recently and asked if he could install new tubes in my son's Marshall JCM-900. I asked him which tubes he recommended and he said it didn't matter because, "tubes are just 5 pins and a vacuum...how can they affect the sound?" He believes all of this talk about tweaking amps by swapping tubes is a rip-off. He has been working on amps for decades and is well respected.

    For the record, the discussion was focused on power tubes for this particular amp and I mentioned swapping JJ KT77's for the currently installed tubes because some "metal players" (like my son) seem to prefer them. Not sure if his comments were meant to imply that this particular type of tube is not worth trying or if the whole concept of tube swapping is over hyped. I didn't press him further because he became a bit grumpy at this point.

    So, is this tech right or is he wanting me to sell me his chice of tubes? Note: He did not mention any particular tube and his prices have always been very reasonable in the past. Just trying to figure out if this guy's advice is trustworthy.

    Thanks for any help on this. I hope this doesn't start a heated debate--not my intention. I have no opinion of my own because I honestly don't know.
     
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  2. telex76

    telex76 Doctor of Teleocity Ad Free Member

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    He just doesn't know.
    I'd find another tech if he doesn't know more about amps than that.
     
  3. Wrong-Note Rod

    Wrong-Note Rod Poster Extraordinaire

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    I've heard a change of tubes, change an amps sound right before my very eyes and ears. We were re-tubing my old Marshall and my tech-friend had two sets of tubes, a set of JJs and a set of... something else I cant remember.

    they sounded similar, but different. The JJs seemed hotter and gave the dirt channel more sustain. The other tubes seemed "warmer and fatter" but the leads didnt have that cream and scream I like, so I went with the JJs.

    Similar, but, yes, different.

    I'd find another amp tech.
     
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  4. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

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    Look at these 6V6's. They all have pins but they are designed differently.

    [​IMG]

    [​IMG]
     
  5. Mike_LA

    Mike_LA Tele-Afflicted

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    Probably a good tech, just doesn't play much thru an amp.
    Preamp tubes have a bigger effect on sound but if you don't really play and listen you won't hear the difference
     
  6. muchxs

    muchxs Doctor of Teleocity

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    There is no black and white answer here.

    Most musicians want answers like,

    "EL34s make it sound like a Marshall."

    "EL84s make it sound like a Vox."

    "Mullards sound 'British'."

    Urban Legend amps all that up until you have people thinkin' they can make a Twin sound like a JCM800 simply by swapping tubes. I can convert a Twin to EL34s. It will still sound like a Twin.

    You can achieve a gain spectrum by changing preamp tube types. Swap 12AU7 for 12AY7 for 5751 for 12AX7. Me, I like 6SL7s. :lol:

    You can achieve a tonal spectrum by swapping power amp tubes, say 6L6 for 6V6 or EL34 for 6V6. The difficulty here is a technician understands the tube's power and load requiremnts. Musicians generally don't. If you stick 6V6s in a high voltage environment they're gonna burn. Load them incorrectly and they cook. This is an area where you can damage your amp if you don't know what you're doing. Check out the recent BillM thread:

    http://www.tdpri.com/forum/amp-tech-center/431119-blues-junior-tube-location-disaster.html

    Simple mistake results in a lot of damage.


    Differences in tone are usually due to manufacturing tolerances. The really great thing about NOS Tung-Sol 5881s is they're astonishingly consistent. They all match within a particular batch.

    Then we get into the new stuff. We talked about the Russian 6P3S the other day. It's supposed to nominally be a 5881. Yet none of the specs line up. Worse, by specification there's a +/- 18ma variation in plate current. Real 5881s just plain hit the numbers.

    The imported stuff tends to be a little more or a little less. Yeah, it will sound different depending on which way it goes.
     
    Last edited: Sep 25, 2013
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  7. BigDaddyLH

    BigDaddyLH Tele Axpert Ad Free Member

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    All Metal sounds the same to me, so he may have a point.
     
  8. blowtorch

    blowtorch Telefied Ad Free Member

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    from muchxs: "Urban Legend amps "

    awesome name for a new amplifier maker
     
  9. PinewoodRo

    PinewoodRo Tele-Afflicted

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    I have an SE5a amp. This is a 5 watt, single-ended valve amp that uses just one pre-amp valve (tube) and one power amp valve. If I change that pre-amp valve - an ECC83 (12AX7) - for a different make, I can hear the difference. The power amp valve not so much a different tone but the break-up sweet spot will happen at a different point on the volume control.
    Just my observation : )
     
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  10. thelowerlip

    thelowerlip Tele-Afflicted

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    :lol:
     
  11. muchxs

    muchxs Doctor of Teleocity

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    Due to manufacturing inconsistencies thy're a little more or a little less. They're not supposed to be. Some NOS tubes are relatively consistent. That means they all sound similar within the same lot.

    If your process is outta control and your standard deviation gets wider and wider... yup, you get different flavors of the same thing.

    How many manufacturers are interested in a consistent product when you'll buy ten and swap 'em around until you find the one you like?
     
  12. bloomz

    bloomz Tele-Holic

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    The 3 amps I've changed tubes on for "better brands" (JJ usually) to get rid of what the forums call the "cheap Chinese crap"

    Bugera V5
    Blackheart Little Giant
    Blackstar HT5H

    Couldn't hear a bit of difference.

    I think I'll leave my DRRI just the way it is and buy a pedal instead.
     
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  13. Ed Storer

    Ed Storer Tele-Holic Silver Supporter

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    A well-known local boutique amp manufacturer told me that the tone difference achieved by changing tubes is far less than that achieved by changing speakers.
     
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  14. mabley123

    mabley123 Friend of Leo's

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    Another thing not mentioned is durability.

    NOS blow Modern day tubes out of the water.

    Many of the NOS tubes are rated for a 10,000 hour life.

    Try getting that out of any new tube.

    While its true the RCA's were just replaced ( with same NOS ) in my 69 dual showman.. all the other tubes test more than good enough to leave in. Still a lot of life left in them.

    2 hours a day of playing for 5000 days is 10,000 hours. which is 14 straight years.

    And wont they last longer if amp is not dimed too ?

    NOS tubes are hard to beat. Lives depended on them then.
     
  15. chris m.

    chris m. Poster Extraordinaire

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    I recently changed out some old, worn-out 6L6s for some fresh, new ones. What a difference that made! I thought the amp had poor bass response and was kind of flubby. I was wondering if it was the speaker. I called the manufacturer, Victoria, and they said try putting in fresh power tubes first, since the first thing to go is bass response when tubes are dying. (It takes more power to produce bass). Worked like a charm. I tried a couple different matched pairs of 6L6s, and although I could hear a difference, the differences were very subtle. This particular amp is cathode-biased, so I didn't have to worry about re-setting the bias when I made the change.

    I had a THD Bivalve whose claim to fame is you can switch out power tubes at will and it will self-bias. So I tried all kinds of tubes in it. I can tell you based on that experience that different power tubes definitely had a noticeable effect on the tone, but again, it was fairly subtle. And that was when switching among 6L6, EL34, KT88, 5881s, not just different brands of the same tube. At the end of the day, the THD still sounded like a THD, and I think that is a result of the fundamental design of the amp. As another poster said, switching from 6L6s to EL34s is not going to make a Fender Twin Reverb sound like a Marshall. I sold the THD because although the novelty was cool, I didn't really like its dirt sound no matter what power and pre-amp tubes I put into it. Its clean sound was very good, but not to die for.

    Another big variable is power tube biasing. You can take the same set of power tubes and get a different response and tone character based on how "hot" you bias the tubes. When you switch out power tubes, if you don't re-set the bias for the new set of tubes, much of the difference in tone that you hear could be a result of the new tubes biasing differently, nothing else. Or just the new tubes being "fresher", kind of like when changing out guitar strings.

    I've also switched pre-amp tubes and can definitely hear a difference there as well, but as long as all tubes are working according to spec the difference is fairly subtle unless you are changing spec, such as from 12AX7 to 12AT7. If a tube is going bad, once again you will hear a really big difference.

    All that being said, if you buy a new Peavey or Fender that has bottom-of-the-barrel tubes in it, most report a noticeable improvement in tone with a tube change for something like JJs or NOS vintage tubes. I think, however, that changing pre-amp tubes usually will have a much more noticeable difference. And this is cheaper and easier since you don't have to worry about re-biasing the amp. Just be careful inserting the tubes since there is no guide key and it is easy to bend/break the delicate pins on the ends of the pre-amp tubes.

    Finally, going back to amp design, I suspect that you will hear more of an effect in some amps than in others when changing pre-amp or power tubes.
     
  16. paratus

    paratus Friend of Leo's

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    Some people can't hear a difference.
    Some people can talk themselves into hearing a difference.
    Some can actually hear a difference.

    Knowing which category you fit in can potentially save you a lot of money.
     
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  17. Slickster

    Slickster Tele-Holic

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    "SOUND" is a very generic term ...

    Tubes can change loudness, break-up point, sag, smooth/harsh, maybe even treble/bass

    my amps still "sounds" like my amp ... but it sure "acts" different. I think smart tube changes can make your amp sound it's best at the spot you like to play it.

    The changes are REAL ... and can certainly be heard ... sometimes dramatically
     
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  18. Billm

    Billm RIP

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    Agreed. Most tube swaps amount to about a 1-notch change on one of your tone controls, usually the treble. I've done lots of close listening and tube rolling, and have concluded that if you really want to change an amp's tone, change the guts, not the tubes.

    I get lots of emails saying "What tubes should I use to sound like SRV/Hendrix/Clapton/May, etc." I explain as gently as possible that it doesn't work like that.
     
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  19. Delta Blues

    Delta Blues Tele-Afflicted

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    I call B.S. on what your tech said. I installed a NOS Mullard ECC83 in the V1 of my friends JCM 900 (non-reverb) head and you could instantly hear the distinct bass boost and thick syrupy Mullard tone. Imo a JCM 900 is not the ideal choice for such a nice tubes but I scored a mess of them on the cheap and didn't mind parting with one for my friend.
     
  20. muchxs

    muchxs Doctor of Teleocity

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    Bill then proceeded to engineer every worthwhile change you can make to the guts of a Blues Junior. The coolest change IMO is his upgraded transformer set that enables a change to 5881 tubes.

    Net result is big amp capability in a compact package.
     
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