4 Knob Princeton Filters

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Alvis, Feb 19, 2012.

  1. Alvis

    Alvis Member

    Messages:
    3,223
    Joined:
    Jan 14, 2004
    Location:
    Free Rangin' The I-55 Corridor
    I haven't looked under the hood yet ,but Im guessing they originally used a metal mallory multi section can.....?

    What would be the best/ most "correct" caps to use these days?
    Is there a can made now that can replace the old one , do the old leave the old can in place ,hide new axials under the chassis trick ?

    It's not MY amp ,or I'd probably just hide the axials
     
  2. smolder

    smolder Gold Supporting Member

    Messages:
    13,850
    Joined:
    Jun 16, 2008
    Location:
    Central Rocky Mountains
    I hear some of the experts say the capcans are much more durable than typical filter caps and last much longer. In spite of that, I'd replace it (that's just me). I don't think the brand will have much effect on tone. I think weber makes them, I know electronic supply carries them. A big ass soldering iron ($20 in the plumbing dept of the local true value) is typically needed to get the old one out.
     
  3. guitarcapo

    guitarcapo Senior Member

    Messages:
    2,337
    Joined:
    Mar 16, 2010
    If you find a cap can that's close and all the values are at least higher than what you take out, you should be o.k. with a little extra filtering.
     
  4. vibrasonic

    vibrasonic Member

    Messages:
    1,878
    Joined:
    Dec 16, 2011
    I have a bunch of old fenders with the can caps and never had a problem yet.
    I'm knocking on wood right now!!
     
  5. Alvis

    Alvis Member

    Messages:
    3,223
    Joined:
    Jan 14, 2004
    Location:
    Free Rangin' The I-55 Corridor
    Im generally of that school of leave em there til they hum or leak
    Near 50 years old .......

    Just trying to think of a "vintage" correct replacement
     
  6. phsyconoodler

    phsyconoodler Member

    Messages:
    4,351
    Joined:
    Jul 11, 2005
    Location:
    calgary canada
  7. TweeDLX

    TweeDLX Member

    Messages:
    3,778
    Joined:
    Mar 24, 2008
    Location:
    Port Angeles, Washington
    JJ makes a 40/20/20/20uf cap can that's substantially cheaper than the 4 x 20uf cans. Both are available at Antique Electronic Supply. The JJ may require a slight enlargement of the hole.
     
  8. phsyconoodler

    phsyconoodler Member

    Messages:
    4,351
    Joined:
    Jul 11, 2005
    Location:
    calgary canada
    Correction Tweedy,a HUGE hole enlargement needed and 40 uf is too stiff for the first filtering stage IMHO.
    The right caps are available;no they aren't cheap but they are available.
     
  9. TweeDLX

    TweeDLX Member

    Messages:
    3,778
    Joined:
    Mar 24, 2008
    Location:
    Port Angeles, Washington
    True...I replaced mine a few years ago with a correct spec Mallory type by CDE (brand new) that I found on Ebay. As Smolder mentioned, desoldering the old can is a PITA.
     
  10. Trout

    Trout Member

    Messages:
    7,576
    Joined:
    Jun 23, 2006
    Location:
    Illinois/Far West Burbia
    Done this at least 20 times removing those can caps,

    I just get out a super sharp 1/2 wood inch chisel. A couple taps and I cut off the lugs flush from the bottom.
    Solder is super soft and cuts like butter, the tabs easily shear off with it.

    Now Don't BEAT on it, proper aim and angle matters. A few light taps is all it takes.
    80% of the time the solder is only holding on the inner surface and a couple wiggles and they come right off.
     
  11. guitarcapo

    guitarcapo Senior Member

    Messages:
    2,337
    Joined:
    Mar 16, 2010
    Usually I just clip the twisted tabs at their base with common wire cutter/end nippers. Then the only thing holding them in place is a thin layer of soft solder. If you just pull from the other side they usually break out very cleanly leaving a little solder behind 4 perfectly clean rectangular slot holes.

    Install the new can. Twist the tabs to lock the new can in place. Now you have some nice solder already attached to the chassis so you don't have to heat much to solder the new tabs to it.

    Works great for me.
     
  12. Alvis

    Alvis Member

    Messages:
    3,223
    Joined:
    Jan 14, 2004
    Location:
    Free Rangin' The I-55 Corridor
    Didn't know Antique Elec still had mallory type cans , cool thanks .
    I finally got the amp in my hands , sounds fine ,'cept it needs a better speaker
    No cap replacement today
     
  13. guitarcapo

    guitarcapo Senior Member

    Messages:
    2,337
    Joined:
    Mar 16, 2010
    I used to replace can caps if they were 30 years old or more, but lately I question whether I was just wasting money and trashing perfectly good cap cans. No hum usually. I even made a thread on here asking whether this should apply more to smaller electrolytics under higher temp conditions. Whenever I did replace cap cans I used modern manufacture ones and not "NOS" cans. My thought was that if a cap can was sitting in a box 40 years on a shelf, is that really much different than one sitting inside an old amp in a closet for 40 years? Anyway the amps usually sounded the same before and after... In my thread I was looking for catastrophic episodes of can cap failure that would have been averted. None were forthcoming...or even many stories of these cans failing and 60 Hz hum showing up.
     

Share This Page