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  • #16
    Originally posted by Enzo View Post
    The old days saw caps with typical tolerance of +80/-20%. SO a typical 16uf cap can measure as high as 28uf and still be within spec. There is nothing with a critical value in a guitar amp.

    I recommend 22uf caps because they are a standard value, and available anywhere. 16uf is not a standard value. It might have been 50 years ago, but then I was just a college boy, and gas was cheap. So not only will it be easier and cheaper to go with 22uf, it won't even be outside the original specs. Modern caps are much closer tolerance.

    Will it change the sound of the amp? Probably, but not because of the value of those couple caps. it will change because it will now have new fresh caps. He likes the way the amp sounds with bloated, off-value, worn out caps. Nice fresh new caps are going to make the amp sound different. Will it make a Deluxe sound like a MArshall or something? No not at all. But it will sound more like a new Deluxe rather than an old tired one.
    +1
    In fact, that +/- was typically on the + side. So those old 16uf caps were commonly 20+uf. I always go with 22uf for it's availability. Which comes with selection options so your not stuck using some boutiquy thing that may be mediocre, but is labeled at 16uf to indicate it's "specialness". 22uf all day
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #17
      I'll double check the 25/25. The reading was way off in circuit but the final check was with them out of circuit. It could be my eye's as I posted about them in a in a previous thread.
      It's all about the bass. Lock in the groove and stay out of everyone else's way.

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      • #18
        It's his choice. Antique has bot 16uf and 22uf listed. Yes the 22's are a bit cheaper.
        It's all about the bass. Lock in the groove and stay out of everyone else's way.

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        • #19
          Measured both in and out of circuit. Going to check again tomorrow just to see could have been my eye's. They do play tricks on me from time to time. Sometimes it's a PITB. The are going to be replaced anyway.
          It's all about the bass. Lock in the groove and stay out of everyone else's way.

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          • #20
            Kind of like the blind listening test.
            It's all about the bass. Lock in the groove and stay out of everyone else's way.

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            • #21
              In fact, that +/- was typically on the + side. So those old 16uf caps were commonly 20+uf. I always go with 22uf for it's availability. Which comes with selection options so your not stuck using some boutiquy thing that may be mediocre, but is labeled at 16uf to indicate it's "specialness". 22uf all day
              Have you ever seen one of these old caps that measured more than 20% above rated value? Me not.
              - Own Opinions Only -

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              • #22
                Originally posted by Helmholtz View Post
                Have you ever seen one of these old caps that measured more than 20% above rated value? Me not.
                Well, ok... I've seen an 8uf that measured 10. So that's 20% (though not above). I can't remember about other's as specifically except that they always seemed to be AT LEAST the posted uf value and usually higher by a tad. But there were also old caps I never measured because they were getting replaced anyway. So I can't say about any decrease with age. It's not like we can measure them the way they were I also have a limited ability to measure value because I don't have a proper bench tool. I just use my 87 which has a limit of 4.7uf. I put another cap in series with the one I'm measuring and math the result.
                "Take two placebos, works twice as well." Enzo

                "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                "If you're not interested in opinions and the experience of others, why even start a thread?
                You can't just expect consent." Helmholtz

                Comment


                • #23
                  Originally posted by Chuck H View Post
                  Well, ok... I've seen an 8uf that measured 10. So that's 20% (though not above). I can't remember about other's as specifically except that they always seemed to be AT LEAST the posted uf value and usually higher by a tad. But there were also old caps I never measured because they were getting replaced anyway. So I can't say about any decrease with age. It's not like we can measure them the way they were I also have a limited ability to measure value because I don't have a proper bench tool. I just use my 87 which has a limit of 4.7uf. I put another cap in series with the one I'm measuring and math the result.
                  Well I certainly know about decrease with age. In many applications the lifetime of the equipment is determined/limited by the filter cap. We did real lifetime testing (i.e running hundreds of SMPS over years at max. ambient temperature) and checked samples for C and ESR at intervals. The end-of life criterion was C down to 60% of rated value.
                  - Own Opinions Only -

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                  • #24
                    Oh, I wasn't saying it doesn't happen. I was noting that those older caps I've bothered to measure seem to be as much or greater than their rated value. If caps lose value with age then I would expect they were higher when new. I shot high.
                    "Take two placebos, works twice as well." Enzo

                    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                    "If you're not interested in opinions and the experience of others, why even start a thread?
                    You can't just expect consent." Helmholtz

                    Comment


                    • #25
                      If caps lose value with age then I would expect they were higher when new.
                      They surely were. But the results are rather individual. C decrease is influenced by operating hours, temperature and the quality of the seal.
                      The caps I had to replace (because of high ESR and leakage current - I usually just go by the too low Q-value) were often down by > 20%.

                      I was just curious if someone had actually seen old filter caps (still) measuring 50% or 80% above rated.

                      My oldest e-cap data book (Siemens,1961) specifies +50%/-20% for HV types and even +100%/-20% for LV types.
                      Last edited by Helmholtz; 07-12-2018, 02:45 PM.
                      - Own Opinions Only -

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                      • #26
                        Originally posted by Helmholtz View Post
                        I was just curious if someone had actually seen old filter caps (still) measuring 50% or 80% above rated.
                        50/60 years later? ... that would be very unlikely.

                        That said, **maybe** we have "seen" them, but how would we know it?

                        People normally do not measure every cap they see, just for fun, unless them being suspect.

                        Except maybe a guy with a brand new Capacitance meter (or a Network Analyzer for that matter ) who to play with his toy measures *everything* around, even his chocolate chip cookies.
                        Juan Manuel Fahey

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                        • #27
                          Originally posted by J M Fahey View Post
                          even his chocolate chip cookies.
                          I need some 500v chocolate chips cookies!

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                          • #28
                            Except maybe a guy with a brand new Capacitance meter (or a Network Analyzer for that matter ) who to play with his toy measures *everything* around, even his chocolate chip cookies.
                            Well, sometimes I am a little like that
                            At least I always make sure that I understand what I am doing and how the "analyzer" works.
                            The measuring experience thus gained often has helped me in my job as R&D manager. We physicists are a little different (strange?), you know: Curious and extremely eager for knowledge.
                            Last edited by Helmholtz; 07-12-2018, 04:49 PM.
                            - Own Opinions Only -

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                            • #29
                              Well that is a major difference in approach between technicians and engineers. Engineers tend more toward the theoretical, while technicians dwell on the practical. When I decide a cap needs to be changed, I change it, and don't bother spending a lot of time analyzing the bad part. I already know it is bad.

                              As a technician, I am also curious and eager for knowledge. But it is a different sort of knowledge. Just as a symphony violinist has different things on his mind than does a bluegrass fiddler. Maybe the bluegrass guy can't read sheets, but the symphony guy can't jam and ad lib. Both are highly skilled.

                              I have decades of experience handling tools, disassembling and assembling stuff. The engineer has decades of experience running sims and other software. The engineer might toss up a breadboard now and then, just as the technician might look up a data sheet now and then.

                              When I was a kid, electronics was my hobby, and I was all into load lines, and curves, and formulae. As a technician, I have not had the need to draw a load line in 40 years.

                              The engineer might hand a schematic to a technician and say "here, put this together for me." The technician might hand a circuit to an engineer, and say "This goes into oscillation if the power supply drops below 14v."

                              An engineer might order 11.2 ohm resistors (A particular Yorkville/Traynor power amp comes to mind). A technician knows that if his 220k plate resistors have drifted to 290k, that still isn't the reason the amp makes no sound.
                              Education is what you're left with after you have forgotten what you have learned.

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                              • #30
                                Originally posted by Enzo View Post
                                Well that is a major difference in approach between technicians and engineers. Engineers tend more toward the theoretical, while technicians dwell on the practical. When I decide a cap needs to be changed, I change it, and don't bother spending a lot of time analyzing the bad part. I already know it is bad.

                                As a technician, I am also curious and eager for knowledge. But it is a different sort of knowledge. Just as a symphony violinist has different things on his mind than does a bluegrass fiddler. Maybe the bluegrass guy can't read sheets, but the symphony guy can't jam and ad lib. Both are highly skilled.

                                I have decades of experience handling tools, disassembling and assembling stuff. The engineer has decades of experience running sims and other software. The engineer might toss up a breadboard now and then, just as the technician might look up a data sheet now and then.

                                When I was a kid, electronics was my hobby, and I was all into load lines, and curves, and formulae. As a technician, I have not had the need to draw a load line in 40 years.

                                The engineer might hand a schematic to a technician and say "here, put this together for me." The technician might hand a circuit to an engineer, and say "This goes into oscillation if the power supply drops below 14v."

                                An engineer might order 11.2 ohm resistors (A particular Yorkville/Traynor power amp comes to mind). A technician knows that if his 220k plate resistors have drifted to 290k, that still isn't the reason the amp makes no sound.
                                I leave it to engineers to comment

                                My engineers did very well with practical as well as theoretical stuff. One technician with 10 engineers worked perfectly.
                                And my practical experience and skills aren't too bad either.
                                Last edited by Helmholtz; 07-12-2018, 10:48 PM.
                                - Own Opinions Only -

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