Modify a 1960b 4x12?

Discussion in 'Cabinets & Speakers' started by tremojem, Nov 15, 2011.

  1. tremojem

    tremojem Member

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    I have a Marshall 1960B.

    It has the four 75W Celestians and is rated at 300W, I think, as I have not used it or looked at it in years because a friend has it in his studio . But now my friend needs the space and so I am going to pick it up.

    You can run it in mono or stereo.

    Here is the mod that I would like to do and would like some feedback on.

    It is my intention to use this in stereo and connect each of my two Tremoverbs to it, one on each side respectively.

    In and effort to get a tighter and better sound (maybe some punchier low end), I thought of isolating the left and right side from each other.

    My question is this. If I used 3/4" plywood to insert (permanently affixed of course) between the speaker sets on the left and right side of the cabinet would this yield a good sound.

    This would be like having two vertical 2x12s in one speaker enclosure. I would not change anything about the cabinet. I would just add this separator to isolate each side of the cabinet and then acoustically seal each side. I guess I would use a very small amount of sealant in all the seams and then add some insulation to each side. This would then be two side by side vertical 2x12s.

    But, would this sound good?

    Please help and don't be afraid to tell me what you really think this will achieve.

    I am not a speaker engineer and would really appreciate your help, thanks.
     
  2. shredless

    shredless Well-Known Member

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    I say do it, boogie does the same thing
     
  3. tremojem

    tremojem Member

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    Really?

    I did not know this.

    On what cabinet do they do this.

    I mean I know the Road King cabinet is configured special.

    Cool...I am glad to hear this. I thought I was mad.
     
  4. GIBSON67

    GIBSON67 Well-Known Member

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    Will you be playing both amps at once, or just one at a time, switching between them?

    I don't think it would help any if both amps are running together, but switching between the two sets of speakers there would definitely be a difference.

    I would try your set up before I added any wood and see if you like it first the original way. But it's your box, do what you want, it sounds like you could reverse it if you don't like it.
     
  5. tremojem

    tremojem Member

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    I would be playing both amps at the same time.

    Right amp into right side of cabinet and left into left.

    I was hoping the isolation would make it better, and more distinct or articulate to each amp.

    I have read alot of guys saying to just do the following* to make a 1960b cabinet sound amazing:

    *Caulk all seams, including handles, baffle, everything.

    *Tighten all screws, especially the hardware for the speakers, as they are notoriously loose.

    *Increase wire gauge and solder connections is possible.

    What about insulation...more or less and how?

    So that is all I have for now, let me know what you think.
     
  6. GIBSON67

    GIBSON67 Well-Known Member

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    Have you tried it as-is in the set up you want?
     
  7. tremojem

    tremojem Member

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    Not yet.

    I hope to pick it up this weekend.

    I will open it up to perform an inspection and take readings with my DMM to confirm impedance is correct so I don't blow my amps.
     
    microhead and GIBSON67 like this.
  8. GIBSON67

    GIBSON67 Well-Known Member

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    That's always wise...
     
  9. Ken

    Ken Well-Known Member

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    Seems to me isolating the two sides is a really good idea to eliminate phase or standing wave problems since you're using 2 amps.

    Ken
     
  10. tremojem

    tremojem Member

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    Thanks Ken.

    I hope so.

    I will start with nothing and slowly work by tinkering to get it to where it sounds good.

    Who knows maybe it will sound fine from the get go.

    It is all perception.

    I don't play metal so maybe the concentration on mid/upper mids will sound good to me.

    Although the two combos I have are open back and I do look forward to more focused lows and mids.

    Thanks again.
     
  11. GIBSON67

    GIBSON67 Well-Known Member

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    Let's hear some clips when you start and as you finish.
     
  12. SmokeyDopey

    SmokeyDopey Well-Known Member VIP Member

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    Would it really affect the phase?
    I mean if all speakers are on the same baffle and the baffle is straight...

    If there IS a phase issue, wouldn't it be the same if isolated or not? If there is a phase issue, it should be corrected because at some point standing in front of the amp (even though isolated) the further you stand, the less apparent the separation would be, and since at a certain distance you won't be able to tell theres a separation so.... would you then at that point perceive the phase issue? :hmm:
     
  13. Ken

    Ken Well-Known Member

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    There was a thread a while back that said the DSL was out of phase with some other amps. I also didn't get it so I asked, and it was explained by Clammy IIRC that this means one amp is making the speakers push while the other will make the speakers pull if you're sending the same guitar signal through both via some kind of splitter.

    Without a center baffle, this would make the sound weak and weird as you'll get a ton of cancellation inside a closed back cabinet. I'd definitely install a baffle for a bi-amp situation.

    Ken
     
  14. tremojem

    tremojem Member

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    Great information guys, BUT...

    I use two identical Mesa Boogie Tremoverbs.

    These amps have a build date no more than months apart.

    Additionally I use a Radial ToneBone JX-2 SwitchBone. This device allows me to split my guitar signal and send it to both amps in the front of the amp.

    I use a G-Major in the FXLoop and all my equipment runs thru a PL-8.

    Everything is properly grounded and IN phase.

    So, yes there will be really no perceivable separation and the only advantage is for me in the studio for inspiration.

    I think I would like a more focused tight low end sound. I am just assuming the baffle would help that.

    Additionally when I use the G-Major to pan it will really sweeten up things.

    Sorry for any confusion.
     
  15. SmokeyDopey

    SmokeyDopey Well-Known Member VIP Member

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    I'm not a physicist or sound engineer, but it doesn't sound right.

    With or without the center baffle, it would still sound weak and thin like Slash's tone (j/k ha!). Because what you're hearing is whats coming out the FRONT of the amp. What happens inside of the cab doesn't affect as much as what comes out directly from the speakers.
     
  16. SmokeyDopey

    SmokeyDopey Well-Known Member VIP Member

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    I think the baffle will just help accentuate the stereo feel, but not do anything with phase issues.

    Like in a recording. It can be way out of phase, but if its in stereo, you may not be able to tell right away, but if you put it in mono, THEN you can tell that its out of phase.


    So in a way.... it would be cool NOT to have the center baffle because if something is out of phase, it would be more apparent.

    Then again by standing back further you would be able to tell as well..
     
  17. Ken

    Ken Well-Known Member

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    Oh yes it does! If two speakers push when the other two pull in a closed back cabinet you lose effciency big time, which means losing punch and tone. The baffle prevents that. It's the same principle as those noise cancelling headphones you can buy for noisey environments. They send the ambient sound to your ears 180 degrees out of phase and you can hardly hear anything. Try changing 2 of your 4 speakers wiring + and - connections and you'll hear a cabinet with 2 speakers out of phase. Tell me if you like the tone.

    How many threads do we have on how the back panel or cabinet wood affect tone? And that's MINOR compared to an out of phase speaker!

    To the OP: I agree using the same type amp would probably eliminate phase problems. But splitting the input signal by itself won't; in fact that's the point. The same input signal gets put out of phase in an amp that's designed with a 180 degree change of phase output to the "industry standard" as the DSL was said to do.

    Ken
     
  18. SmokeyDopey

    SmokeyDopey Well-Known Member VIP Member

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    Oh OK, I got it.. It loses efficiency because its closed and 2 push, the other 2 pull, so I can see how 'punch' comes in to play.

    BUT............ you'll still have an out of phase cab. It will be more efficient! And you won't lose the punch but it will still be out of phase.


    EDIT: (Adding to the post)

    Basically my point is the baffle would be like, in a recording situation, putting the recording in stereo and mono.

    Lets say the recording is out of phase. Well... pan it hard left and right (stereo) and it won't be there, it will sound perfectly fine.
    Sure it sounds fine that way, but its wrong, it has to be corrected.

    This would be the baffle; like panning hard left and right. The panel will help, but that phase issue still needs to be corrected.
     
  19. Ken

    Ken Well-Known Member

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    Huh? If you run two amps where one is out of phase with the other through what is now effectively two 2x12 cabinets, you won't notice unless you're right next to it. It will be more efficient than the same cab with no baffle of course. Or is that what you're saying?

    As to your edit: you only notice the phase issue if you mic it, or are standing very close. Across a room I doubt you'd notice. And yes, either amp by itself would sound fine. as to "fixing" it, you would reverse the + and - wires on one side if you knew your two amps were 180 degrees out.

    Ken
     
  20. SmokeyDopey

    SmokeyDopey Well-Known Member VIP Member

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    Well... in that case by standing far across the room it won't be that noticeable.. then why bother with the center baffle? With all the room's reverberation, it would be "covered up".


    FUCK YOU KEN, FUCK YOOOOOOUUUU!!!!!!!!!!
     

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