Tube/valve questions for a newbie

Discussion in 'The Workbench' started by BLG, Aug 2, 2020 at 3:07 PM.

  1. BLG

    BLG New Member

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    I bought a used DSL40C and I frequently get kind of a dull/faded/hollow sound out of it. So I started thinking about changing the tubes to see if that helps. That just lead to a whole lot of confusion that I'm hoping for some help with. Originally I was planning on replacing all of the tubes, but when I went to my local Guitar Center the only tubes they had in stock were Groove Tubes 12AX7s so I bought 4 of them and replaced all 4 existing tubes with those. I think it sounds better but I'm really not sure. So I figured that the preamp tubes must be where most of the tone comes from (especially since I live in an apartment and can't crank the amp at all). That said, I put a volume pedal in the effects loop so I can crank the volume knobs almost all of the way and still lower the sound level to an acceptable level. So my questions are:

    1 - Does the volume pedal in the effects loop really help give me the same (or similar) sound to what I would get if I could really crank the amp? I'm sure it's not the same, but am I at least helping achieve the same thing? (I may ask this question in a separate post).

    2 - I just read about V1...V4 in the pre-amp tubes so now I'm totally confused. Should I consider different tubes for different positions among the 4 pre-amp tubes? Or was it fine replacing all 4 with Groove Tube 12AX7s?

    3 - Is there any way to try different tubes (manufacturers/models) without spending several hundred dollars on several different sets? I'm guessing not since once you plug it in you own it. The possible combinations are practically endless. Just wondering how other people have gone about trying different combinations out.

    4 - How much of a tone change could I expect replacing the power tubes (EL34 I think), especially given my apartment situation? Part of this goes back to question 1. And if I do replace them what manufacturers/models should I try? I'm going for a Slash/G&R tone here with my Epiphone Les Paul (hopefully soon to be replaced by a Gibson Les Paul).

    5 - Am I really limited to 12AX7/EL34 for the preamp-power tubes or should I consider other models as well?

    Thanks in advance!
     
    Last edited: Aug 2, 2020 at 3:13 PM
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  2. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    1. No the volume pedal doesn't really allow that. If it is apartment volume then a very limited signal is going to the power section. Thus it is not saturating.

    Possibly you have another issue. You mention "frequently" you get this. So that means not always. Any other effects hooked up? What channel, both?

    Hard to tell from what you are describing if pre tubes will help. Nompoint in changjng power tubes for tone differences at that rate.
    You gotta try em 1 at a time. V1 and V2 will make the biggest diff tonally for you.

    You can use any 12A_7 tube but most will give you less gain. It is designed for AX7s
     
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  3. anitoli

    anitoli Well-Known Member

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    As far as throwing differnt 12*** tubes in there this is a little advice from an amp builder:

    Q: Can I substitute a 12AT7/12AU7/etc. for a 12AX7?
    A: Yes and no. While they are the same pinout, the tubes are very different with regards to internal plate resistance, bias current, gain, etc. It won't usually hurt anything to substitute them, but it is not a fair tonal comparison if you don't also change the cathode and plate resistors to optimally bias the tube. A straight swap without regard for circuit operating conditions will lead to incorrect conclusions regarding the characteristic tone of the tube.

    Go here and read for a bit. You WILL learn alot:

    http://www.aikenamps.com/index.php/technical-q-a
     
  4. BLG

    BLG New Member

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    This only happens in the gain channel and yes - it is intermittent. I have a lot of pedals. My chain looks like this: Boss Tuner-> Boss compressor->Boss Noise Suppressor-> Amp in -> Effects loop-> Arion Chorus-> Boss Digital Delay->Boss Reverb->Boss Looper->Ernie Ball MVP Volume pedal->Effects return. I can turn off the effects loop to take all of those out of the equation and usually the sound doesn't improve. (Again I said "usually", so I haven't been able to identify a pattern that is reproducable). Thanks for the reply - I really appreciate it!
     
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  5. BLG

    BLG New Member

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    I assume that V1 and V2 designate the position of the tube? There's a rubber ring around "V1" (and only around V1) - is that correct? I'm assuming that they go from left to right (V1 - V4) starting with the one with the rubber ring on it?
     
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  6. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    Uh I woildnt think tubes will help a whole lot. Start with zero pedals. None anywhere and see what it does.
    If it is intermittent it could ppssibly be a tube issue but they usually don't manifest like that. Is it when any other pedal is on? Compressor? Only on OD channel could indicate a tube issue, V1 or V2 but if you changed already and it didnt fix the issue it is not tube related. You really need to play enough to see if the issue disappeared. If not don't bother with yet more tubes. I get that type of hollow sound all the time in parallel effects mode using digital multi effects. Latency issues.
     
  7. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    V1 is tube furthest from power tubes. One w rubber ring, yes.
     
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  8. Sg-ocaster

    Sg-ocaster Active Member

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    As said first eliminate pedals and get the amp/guitar working right....then add in pedals.
    As far as tubes you really should try different ones. I learned by buying up cheap used tubes to flavor test then bought nos of my favorites....you can also ask tube dealers.....kca nos and dougs both come to mind as knowledable guys who can steer ya in a good direction....both nos and cp tubes.
     
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  9. ricksdisconnected

    ricksdisconnected Well-Known Member

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  10. South Park

    South Park Well-Known Member

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    Lets ad to the confusion. The most important tubes Are the power tubes the bias most be set right for it to sound right . The preamp tubes do two things ramp up signal and roll off frequency’s. Amp builders voice a amp with tone caps that go to ground . Changing tubes will not change much might sound a little different for the most part. It Is the combination of gain and roll off That is what you get
     
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  11. avspecialist

    avspecialist Member

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    First I agree with SG-ocaster , eliminate the pedals and any other variables. Just plug in your guitar and use the amp for varying amounts of times, possibly sometimes 15 minutes others 1/2 to and hour or so to try and track down a time frame when the dullness occurs. I would write down on paper the start and finish time of playing the amp to have a record of use. This will help you visualize how and when the issue occurs. From my experience, preamp tubes change the flavor of how the amp sounds. But as South Park says, the power tubes need to be biased properly. This will also change the sound. when you do not enough bias the amp sounds anemic and thin sounding, too much bias and the amp compresses and distorts quicker, not to mention you could fry your tubes if you go to hot. For example, most people bias their amps to 70% power tube dissipation. I found for me I’m about 80% dissipation to get the proper balanced sound. I now do my own bias adjustments myself after a lot of reading on how to do it. Also, have you tried other patch chords to see if the one you are using is intermittently shorted, as well as different guitars. It’s really all about a process of elimination by listening to other members experience and advice.
     
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  12. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    Bias will not be intermittent though. It will sound like it sounds. It is still very important, granted.
     
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  13. avspecialist

    avspecialist Member

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    Yes you are correct, I was just trying to be thorough with my explanation.
     
  14. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member VIP Member

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    :welcome: To the forum
    I have a pair of the Dsl40c’s
    What I have done preamp tube wise is
    V1 12AX7 your flavor
    V2. 12AT7
    V3. 12AX7
    V4. 5751
    This tube placement allows me to run the red ultra gain lead 2 with gain up to 5 without it getting muddy/ fizzy.
    The green crunch channel can now have more bite, and thump when you are able to get some volume.
    I have numerous clips in the DSL CLIPS ONLY thread, all of them are recorded with my IPhone, and any of the clips after January 2020 are with this tube swap.
    Cheers and enjoy your amp, I love mine.

    Mitch
     
  15. BLG

    BLG New Member

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    Thanks for all of the great replies and suggestions. I have biased the power tubes. I can't remember exactly what I biased them to, buti found a great YouTube video that lead me to a site that had all of the desired values for a given amp/set of tubes. So I don't think that's the issue. I will definitely take your advice and plug in directly and try to log my results.

    Thanks again!
     
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  16. Chris-in-LA

    Chris-in-LA Well-Known Member

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    You cannot switch out the power tubes for different types in most amplifiers unless you mod part of the circuit. Your amp is most likely stuck with EL34’s for now. Preamp tubes are different and you have already gotten some suggestions about possible substitutes.
     
  17. RobS

    RobS Active Member

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    you mention that you biased the amp, what was it at before you biased it and where did you leave it at? did you have to adjust it much?

    you may want to leave the multimeter (if thats what you used) connected whilst playing it so if & when it plays up for you you can see if maybe the bias has drifted etc?

    lots of pedals in your chain, hows the power supplied to them all? is it coping?
     
  18. BLG

    BLG New Member

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    I used http://www.tedweber.com/webervst/tubes1/calcbias.htm and with a plate voltage of 450 to get a value of 38.8 mA and I think one side was about 36 so I brought that up to 38.8. Sure - I can leave the meter attached and try again.

    I have a Joyo power supply with 8 outputs - that's how I power most of my pedals although I have about 2 separate power supplies that came with the pedals. It was a relatively cheap power supply so no idea if that's an issue.
     
    Last edited: Aug 6, 2020 at 2:04 PM
  19. BLG

    BLG New Member

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    Hey Mitch. Can you post a link to your clips? I searched for "DSL CLIPS ONLY" and got about 5 pages of results and couldn't find DSL CLIPS ONLY
     
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  20. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member VIP Member

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    It’s right here on the forum, the thread was started by my buddy Solarburn dsl50, in the Marshall amps page
    DSL CLIPS THREAD ONLY it’s at the bottom of the page.
    I don’t know how to bring it here because I am not so good at pulling links sorry
    I also have clips in the Show Me your Riffs thread, and also in the giant
    The Official Marshall DSL40C information thread all of them are here on the forum..
    Cheers
    Mitch
     
    Last edited: Aug 6, 2020 at 9:34 PM

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