Power supply caps (brand).. Favorite...Does it really matter?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by pfrischmann, Feb 22, 2005.

  1. pfrischmann

    pfrischmann Member

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    Hi Guys,
    I'm doing some basic work on one of my Marshalls ('78 JMP) and noticed that several of the Daly 50x50 cans have a blister on top. It's more like the plastic just tightened and lifted off the top.

    I only see about .1-.2 volts of AC on the caps so I'm not sure they need replacing So...

    1. Do I really need to replace them? How do I test to make sure?
    2. If I do, does it make a difference which ones I choose?

    Black gate
    Cerafine
    Nos (Erie)
    Nos (LCR)
    F&T
    JJ
    .....any others???


    Thanks,
    Paul
     
  2. sws1

    sws1 Member

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    There was a thread on this about a week ago.

    Do a search on "F&T JJ" in the Amps and Cabs section. Doug Roccaforte had some feedback. The thread was about ZoSo caps.
     
  3. pfrischmann

    pfrischmann Member

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    I remember that..If your talking about a couple of people having a disagreement about caps and their break-in. I can't find the thread. It may have been nuked.
     
  4. pfrischmann

    pfrischmann Member

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    Yup, It's gone......Anyone care to weigh in on this?
     
  5. RL in Fla

    RL in Fla Member

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    Paul , David Allen's using F&T 's for what that's worth ;) .
     
  6. pfrischmann

    pfrischmann Member

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    Thanks, RL.
    I seem to see F&T popping up a lot.... They look just like the LCRs too. They might be easire to mount.
     
  7. sws1

    sws1 Member

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    Same diameter, but not as tall. I just put an F&T in last night, and they are short and stubby vs. LCR's tall (2" I think)
     
  8. pfrischmann

    pfrischmann Member

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    Did you use the LCR mounting HW or did you have to replace that too?
     
  9. sws1

    sws1 Member

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    I didn't replace an LCR cap. I replaced a Chemicon cap, which was already a replacement.

    But I did measure the F&T, and it appears to be the same dimension as LCR.
     
  10. floobeedust

    floobeedust Member

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    A tech once told me power supply capacitors could have a variance of plus 40 % to minus 20 % and be within the normal spec.......dont know if thats BS or not ?
     
  11. dstengineer

    dstengineer Member

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    It's true that most electrolytic (can) caps have a normal manufacturing tolerance that is very wide. +/-20% is VERY typical and +40/-20 is also common. This means that a 100UF cap is considered to be within "manufacurers" specificaton at any initial test value between 80 and 120UF. This has to do entirely with production/foil handling issues and NOT the quality of the capacitor. Like most things in life it's also a money issue. A cap that comes off the line will be perfectly suitable for most applications even at -20%, so the manufacturers wont scrap them and lose $$. Lastly, caps change value very quickly with applied voltage (this is normal), temperature and time. Given they're place in the circuitry (dc filter) it's not super critical that they be a tight tolerance part.
    Most large/quality capacitor manufacturers show these details in there web page specs.

    Bob Dettorre
    DST-Engineering
     
  12. pfrischmann

    pfrischmann Member

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    Wow,
    Great Answer Bob! Thanks...

    So the next question

    Is there a difference between a $49 50x50 Cerafine filter cap in a Marshall and a $10 JJ in a marshall?
     
  13. dstengineer

    dstengineer Member

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    .. $39. Sorry.. I couldn't resist being a smart... well anyway.

    From my experience over th elast 25+ years as an engineer, amp restorer and guitarirst I can't honestly say I hear or feel a difference. However, I always try to push the best quality part for reasons of reliability and mechanical strength (especially if your amp travels a lot). Mechanical issues are offen a bigger deal than electrical when it comes to vibrations and thermal stress. I've found that the brands common to high end guitar and audio amps (JJ, F&T, etc) tend to be of a generally better quality than the more typical "industrial/consumer" grade parts from Illonois (who are actually a Japanese company), United Chemicon, Panasonic, etc. I think what makes certain variations worthy is the care with wich they are built. Better materials and conrtuction make for a better part. In guitar amps the electrical stress isn't really that large if a properly pick component is used so I've founf that most good caps sound good as well (regardless of where they are made). The really sound issue is using a cheap "off shore" part form the bargain bin that just wont hold up under use and maintain its specifications when energised. And as I tell most of my customers, if having the "best" or most expensive part makes you feel better, then you'll play better.

    Bob D.
     
  14. V846

    V846 Member

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    Bob,

    I know for a while in the late eighties if one ordered Sprague Atoms from Mouser you might get United Chemicon caps which looked cosmetically identical to Atoms. Wonder if Atoms are relabeled Chemicons ?

    David
     
  15. dstengineer

    dstengineer Member

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    Interesting observation. There was a time when the Big name American companies were outsourcing there production to Japan and Mexico. I was in the industrial power suplly design world then and it was a major issue getting good parts. I can say this for certain, you'll be hard pressed to find an American brand that's actually made in the US. This is do to labor costs, pollution laws and a swell array of other political/economic issues. Depite the "where" I still find that the big name US companies (Sprague, Mallory, Cornell) have damn good parts for any application. And for guitar amps the specialty companies seem to be putting some good effort into their builds. JJ, F&T, LCR (who have actually been around for years) are really excelling in reliable afordable parts. I've personally had great results with them all. Now if I can just find a good reliable car!

    BD
     
  16. V846

    V846 Member

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    Outsourcing, that that's word I was looking for! Globalization is a wonderful thing innit? Actually I'm mistaken, think the time frame was more like the mid nineties... senior moment:rolleyes:
    Yeah I like the F&T cans, haven't found a source for the axials in the states yet..
    I've heard Rifa is a good cap for geetar amps but as with the F&T axial haven't found em yet..

    db
     
  17. PaulC

    PaulC Member

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    The F&T axial's can be found at New Sensor, but they're out for the next month or so...

    PaulC
     
  18. V846

    V846 Member

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    Got a project coming up soon, think Ill try those

    thanks Paul

    David
     
  19. V846

    V846 Member

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    Got a project coming up soon, think Ill try those

    thanks Paul

    David
     
  20. glasman

    glasman Guest


    Check with Antique Electronics. They called me a couple of weeks ago to let me know they had the F&T radials in stock. They are not listed on their website as of this morning.

    Gary
     

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