6L6 VS EL34

Discussion in 'The Workbench' started by Exotic, Dec 3, 2019.

  1. Exotic

    Exotic Active Member

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    so the seller tells me the amp has 6l6 tubes and groove tubes for preamp . what do these look like? (brand) ,and can u put el34's in slots where 6l6 fit?
    and is one better for crunch than the other? s-l1600 (8) (Mobile).jpg
     
  2. Kinkless Tetrode

    Kinkless Tetrode Well-Known Member

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    I wish I could enlarge your photo, because those look like EL34s not 6L6s.
     
  3. Exotic

    Exotic Active Member

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    interesting ,makes sense actually
    tung sol have brown bases like that
    and 6l6 are shorter and stockier ,the el43's are taller and skinnier .
    maybe he made a mistake
    he also said they are about 7-9 years old ,but have not seen much play time and have been in a studio for 5 years and they have around 90 % life left ,can this be possible?
     
    Last edited: Dec 3, 2019
  4. Kinkless Tetrode

    Kinkless Tetrode Well-Known Member

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    Technically, yes you can use either tube but there are a few things you should check:

    The bias range. 6L6s usually require more negative voltage at pin 5 to bias the amp. A resistor or two may need to changed to put the bias adjustment range right for EL34s.

    A jumper wire from pin 8 to pin 1 on the tube sockets are required for EL34s but not 6L6s. If the amp has these it can still run 6L6s, but most Marshalls have these regardless.

    Screen grid resistors. El34s usually run higher value screen grid resistors. 6L6s will still work with the higher value.
     
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  5. Kinkless Tetrode

    Kinkless Tetrode Well-Known Member

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  6. South Park

    South Park Well-Known Member

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    First off what do you have. Does it work how does it sound. 6l6 are a great sounding tubes . You need to test it out before you even start to mod . You mite have a great sounding amp
     
  7. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Those power tubes in the picture are definitely EL34.
    EL34 have a bit more midrange character, maybe a little earlier and more breakup.
     
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  8. Micky

    Micky Well-Known Member VIP Member

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    In my '57 Champ, I can use any octal base power tube.
    6L6, 6V6, EL34, anything that will fit.

    Some draw more current than others but they all work well.
    Currently I have a 6L6 that is so fat that it just barely fits.

    6L6's are great for clean tones. EL34's break up earlier and sound gritty.
    6V6's are a lot like EL34's but smoother.
    I have another octal base tube for that amp but I can't remember what it is...
     
  9. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    To change the tubes, the amp must be re-set internally for EL-34s.
    You cannot plug the EL34s in without adjusting internally for the different tubes.
    This should be done by an experienced person and involves changing some parts on the circuit board.
     
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  10. Exotic

    Exotic Active Member

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    i can't play the amp till friday when it is supposed to arrive .
    i got it because my jcm 800 is at the second tech into the second week now .
    the seller was most likely wrong about the tubes because he was wrong on at least 2 other things about the amp ,he said it had 3 positions for ohms on the back ,4, 8 and 16 ,incorrect it only has 8 and 16 ,he said he didn't see any reason why u would not be able to switch the power mode switch(25 and 50 watts ) while it was on ,incorrect it needs to be off to do that right?
    so i hope i get one of these amps back soon and i hope the second tech finds out while my jcm 800 is howling when the gain and volume are all the way up while the master is on 0 and why the reverb knob is raising and lowering the volume and while it just plain sounds bad !thanks for all the answers it's very helpful.
     
  11. Exotic

    Exotic Active Member

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    ok so i got the amp today(jcm 900 4500 50 watt dual reverb) and first impressions are pretty good 99/100 . i used it with my x pattern g12t-75's + marshall vintage cab ,and it was ok not as much crunch as i wanted ,but i hooked it up to my jbl+ greenbacks cab and wow much better ,crunchier ,and a bit more treble but i was able to dial it down a bit ,used both modes low and high and i like the high better ,it sounds better ,the only thing the low did was to lower the volume a tad and make it sound less aggressive . good news i didn't blow up the amp so i did not blow up the jcm 800 either ,the cab is wired fine and the speakers are fine .my only gripe is the reverb ,maybe it's not working ,or maybe the reverb effect is way too subtle on this amp or maybe something is wrong with the wires or the pan maybe it was like that or maybe something happened in transit .here's some photos ,pretty intense shipping job IMG_1952 (Mobile).JPG IMG_1953 (Mobile).JPG IMG_1964 (Mobile).JPG IMG_1965 (Mobile).JPG IMG_1963 (Mobile).JPG
     
    Last edited: Dec 6, 2019
  12. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    What exactly is jbl= greenbacks cab? Which model speakers?
     
  13. Exotic

    Exotic Active Member

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    sorry it was supposed to be jbl's plus greenbacks cab it consists of 1 reissue greenback 25 watt ,1 evh speaker says 20 watts but i'm told it's really 25 watt? ,1 jbl grey basket 8 ohm speaker with recone ,and finally 1 jbl orange basket 8 ohm original cone 21302 cone . IMG_1801 (Mobile).JPG IMG_1802 (Mobile).JPG

    the cab clocks in at around 7.8 on a dmm
     
  14. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Ah, D120's and some G12M's. Nice stuff.
     
  15. Matthews Guitars

    Matthews Guitars Well-Known Member

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    What model would this JCM800 be? By chance is it a 4010 combo? Because my friend the amp tech has been getting seriously annoyed by a 4010 that is displaying exactly the same symptoms. He says that model is the worst JCM800 model Marshall ever made.
     
  16. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    A 4010 is a 1x12 combo of 2204 model. :scratch:
     
  17. Exotic

    Exotic Active Member

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    no it's a 2210 ,if your friend finds out what's wrong please be sure to let me know ,and obviously i'll do the same .
    in his own words what does he say the amp he's working on is doing?
     
  18. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Reverb controls volume. Reverb doesn't function properly as reverb. That's the main issue. For the rest I'll have to wait until he's back at work to ask him.

    I have yet to hear a Marshall amp that has what I would call a good reverb system. Fender reverb, it definitely isn't.
     
  19. Exotic

    Exotic Active Member

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    yeah i need to give up on marshall reverb and get a pedal for it .
    if the amp howls when the guitar is turned off ,with the right volume and gain on 10 ,then it's exactly whats goin on with mine .
     
  20. Kinkless Tetrode

    Kinkless Tetrode Well-Known Member

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    So it came with EL34s?
     

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