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Question about Jack Casady Bass Center Block.

Discussion in 'Luthier's Corner' started by psychepool, Nov 28, 2018.

  1. psychepool


    Nov 19, 2018
    I do not certain what to write the title.
    Anyway, there is one question.
    I wrote this before.
    Double P bass pickup wiring question.

    Because of that idea, I am forced to surgery on this unique and beautiful bass.
    I upload the plan image to explain it briefly.


    I want to try this.

    Jack Casady is a full-hollow body without a center block, so I have to put some wood inside the body to get a P pickup mount.
    (Fortunately, It has a little reinforcement inside the upper and lower plates for the reinforcement of the strength, which made the floor flat. The work would be a little easier.)

    From here, my troubles begin.
    There are conflicts in two options : Make the pickup mount with a minimum amount of wood or install a large block across the area where both pickups are mounted.
    Please see the picture below.


    Make the mount with minimum of wood pieces is the intention to keep the full-hollow body's characteristics.
    And use the large block is the intention to reinforce the strength of the instrument, add some semi-hollow taste, and prevent the neck dive.

    Of course, I have not used a semi-hollow bass. In fact, it is the first time to use full-hollow bass.
    If you think about the guitar as a base, I expect it sounds a little more solid than now.

    Which would you choose if you do this?
    Would be there any sound differences if you block them with big blocks? Or isn't there any noticable difference?
    May be I will use plywood for do it. It wouldn't be the whole center block that extends from the neck joint to the tail anyway. Would it be a sloppy build?
    I would like to hear your advise.
  2. Basvarken

    Basvarken Commercial User

    Dec 3, 2010
    Velp Rockcity
    Luthier / Gibson Bass Book
    Why don't you make pickup rings? You only have to cut out the shape of the pickups. Mount a ring and work with springs to set the desired height.
    MoeTown1986 and bholder like this.
  3. psychepool


    Nov 19, 2018
    Is there a pickup ring that can mount the P pickup? I also search the pickup rings but there's no ring for mountthe pickup, only just for aesthetic purpose.
  4. xaxxat

    xaxxat Supporting Member

    Oct 31, 2008
  5. psychepool


    Nov 19, 2018

    Did I misrepresent the situation?

    The P pickup is direct mount, so a bottom plate is required for mounting.
    That product does not have a bottom plate, so it can not mount the pickup and looks only for the purpose of covering the visible side for looks good.

    My question is about the pickup mount block under the pickup, not about the routing of the upper plate of this bass. Because it's a hollow body, it is not possible to mount a P pickup which is a direct mount type without a bottom block(plate) to mount.
  6. psychepool


    Nov 19, 2018
    While I wait for an answer, I set the direction to some extent and I am working on it. Thanks for your answer anyway. I wonder if there is a pickup ring that can mount the P pickup separately from whether it is applied to my work.
  7. sikamikanico

    sikamikanico Supporting Member

    Mar 17, 2004
    Hmm, no, your are NOT forced to operate on your JC ;) I question your plans, but hey, it’s your bass...

    Also, as far as I know, JC does have a center block. Is it too deep/low to mount the Ps? I’ve seen one JC with a P, but cannot tell if there’s anything on there to raise the pickup: P-Bass Sound with a Hollowbody Bass

    If you do go forward with your plans (and the center block is not high enough) I don’t know what would work best, but I’d go with a version of Plan A, for a simple reason that a big block would require a big hole to get it inside. What you want (I hope) is to do minimally invasive surgery, laparoscopic even - just cut the pickup holes. Then feed in blocks through pickup holes. I’m not sure how you’d glue them in place, but I guess you can apply pressure from above. Should be enough for your purposes? You won’t have much room to work with, unless you go with an open surgery approach, which will just ruin the beautiful bass...

    But again, I urge you to rethink your plan. There are many cheap P basses you can do this with... or at least use pickups that mount from pickup rings. Or, imo the best plan, keep the bass as is.
    MoeTown1986 likes this.
  8. Beej


    Feb 10, 2007
    Victoria, BC
    The JC bass does have a center block, but it's only full size under the neck and bridge - its routed back thinner between those points. Casady Bass Pickup

    It's probably enough to screw down your P-pickups on, but you might have to add some ears on the top and bottom. I doubt a P rout will cover the original hole from the JC pickup, so you'd probably have to make some sort of cosmetic covering (rings, pickguard, etc). Or just properly fill any cavities you cut on the front and refinish the entire top.
    sikamikanico likes this.
  9. Basvarken

    Basvarken Commercial User

    Dec 3, 2010
    Velp Rockcity
    Luthier / Gibson Bass Book
    Then make a base plate! It doesn't have to be pretty, since it will be inside the body.
    Just cut out a plate out of pickguard material. Drill onze size too small holes for the height set screws. They will tap their own thread into the plastic. And will surely be strong enough to hold the split p pickups.

    If you're handy enough to cut neat holes into the top for the P pickups, you'll manage to make a base plate, right? :thumbsup:

    Use pickup ring screws (see pic).

  10. psychepool


    Nov 19, 2018
    JC is a full-hollowed body and does not have a center block.
    There are additional wooden frames in the center of the top and bottom plates, but it's not "blocks."

    I also know that it is not a wise plan. And I also know that this bass has a very good identity. The low-impedance pickup also has a very useful sound.
    It is believed to be a well completed instrument that is well balanced with distinct concept.
    But with some problems, I got this instrument at a very very low price, and I was curious to do something.
    For that reason, I was able to make this disaster. I also know this is a disaster. :)

    Unfortunately, I wanted to do it quickly and proceeded to Plan B while waiting for an answer.
    I suppose that if I can finish well, my JC will have a more stable structure.
    But I do not have professional equipment, so I think Plan A would have been a lot cleaner to work with. The processing was more difficult than I thought.

    I'll finish it anyway. Again, I also know that this is an unwise plan. Anyway, I'll try to finish it well. Thank you for your advice!
    sikamikanico likes this.
  11. psychepool


    Nov 19, 2018
    "Or just properly fill any cavities you cut on the front and refinish the entire top."
    I'm doing it like this way. There is no proper tool, so the job is very rough. I hope to finish it well.
  12. psychepool


    Nov 19, 2018
    Thanks for the good advice. Unfortunately, work has already been done. The next time I get a chance to do this again, I'll consider it. Of course I do not want that happening...
  13. Beej


    Feb 10, 2007
    Victoria, BC
    no need to do it very roughly, the proper tool would be using a router and a custom-made routing jig to rout the correct size hole with precision into the wooden top. For a p pickup, I would first drill the holes for the ears and then use a router to carve the hole for the pickup. While the hole is open, I would glue down small pieces of wood to the back of the body through the hole, that way you can mount the P pickups directly to those pieces of wood. Because there will still be a large hole left from the original Jack Casady pick up, the best thing to do would be to patch that hole with matching wood as close as possible, and using epoxy to ensure the finish is uniform. After that, you can respray the entire top to match.
  14. sikamikanico

    sikamikanico Supporting Member

    Mar 17, 2004
    Please report results, with pics and all :)
  15. Slidlow

    Slidlow Supporting Member

    Apr 15, 2009
    Oshawa, Canada
    I'm expecting the two bars he mentions under the top are reinforcing the top and when he cuts through them there may be bridge pull and distortion of the top eventually if this a true hollow body.

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