Well that is something I never gave attention to this way but also it seems logical at the same time. Maybe it comes from the Black Gate caps but the habit became to connect new caps to DC first. Electrolytic caps need voltage to start the chemical process. I wonder what would happen if the OP would take a few Panasonic FC caps, let them connected to a certain voltage and then measure them again. I think we can safely assume the caps would measure much better. Never had bad experiences with Panasonic FC and they are quite a good "universal" type for recapping in amplifiers.
Most of us know the phenomenon that a device with new electrolytic caps changes in sound character after a few hours. Those that have used Black gate caps certainly know this
* Regarding recapping: it all depends on brand and type of caps but many amplifiers I have seen had either caps measuring half the capacitance they should have had, measured 0 µF, had a too high ESR or they were already bulging and leaking. It is NOT a stupid thing to replace 10+ year old electrolytic caps especially in power amplifiers and switching power supplies.
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This is a good example of an unbashed post.
The reported capacitance change is about 0.8%. Even if you consider the last digit as
being accurate this may well be within the accuracy limits of the instrument or its drift.
More likely this is result of a change of temperature. Hold the capacitor in your fingers
with test leads attached and see the displayed capacitance slowly rise.
For me this test shows that the capacitance does not increase.
as_audio thank you for the reports from the OEM biz side. I'm not surprised that they have improved processes , that they can universally target 5% lower than the nominal / printed values. The surprising factor is that the global industry has agreed to this practice. That way they $ave raw resources (the Al foil ) I'm sure the bigger OEMs chemically etch their own foils / If they buy it from another supplier the chemistry variables are still there. foil.diyAudio server HTTPS page
catid=106&pageid=2144416256
this is for bulk E caps
IMO your cap replacement strategy needs to adapt. Specify or Fix the capacitor physical dimensions or lead spacing , temperature and voltage 1st. then sort the resultant by brand etc.
The new capacitors will be marked 30-100% higher than the old ones. This wont work in other circuit applications so be knowledgeable.
catid=106&pageid=2144416256
this is for bulk E caps
IMO your cap replacement strategy needs to adapt. Specify or Fix the capacitor physical dimensions or lead spacing , temperature and voltage 1st. then sort the resultant by brand etc.
The new capacitors will be marked 30-100% higher than the old ones. This wont work in other circuit applications so be knowledgeable.
I for one glad no one "bashed" a post citing personal electrical data. Although I usually choose to ignore it or classify it as 'anecdotal evidence' if they don't include the method of testing it. If we bash those rare posts , i'll soon give this forum up for sure. Besides no one in this thread has expressed outrage on ESR as a ripoff ...
BTW I have an old heathkit audio sig. generator with big electros over 40-50 years old*, still measures fine. I looked at capacitance and leakage. I visited this just last month before I used it on making some other component measurements >LC resonance for a speaker Xover. *these are the original dual caps in a chassis mounted single can type, now that's old.
BTW I have an old heathkit audio sig. generator with big electros over 40-50 years old*, still measures fine. I looked at capacitance and leakage. I visited this just last month before I used it on making some other component measurements >LC resonance for a speaker Xover. *these are the original dual caps in a chassis mounted single can type, now that's old.
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Yes, but at displays in the miliohms range you can not be sure. Did he move the test
leads? Did he use four-terminal testing? It is known that leakage goes down in the
forming process, not sure about ESR, and 60 seconds are probably not enough for a
useful stetement. 'Anecdotal evidence' is a good term for it.
You could devote your spare free time to obtain many current production caps and test them with the best equipment and method when they are new and after they have had DC on them. You could also measure the old caps from recapped amplifiers, measure those too and make a list of brand and series of old electrolytic caps that perform excellent after 10+ years and those that measure poorly (the majority), start developing too high ESR, start leaking electrolyte through the rubber seals etc. This would be groundbreaking and we would have a nice addition to the work of Cyril Bateman . Please note that this research would make further discussions and debating on electrolytic caps hard if not impossible. Audio forums would be empty places with some lonely souls around with only hard facts on a list to choose from. No more passion, no more opinions, empty pages....
It might cost less time to just replace 10+ years old electrolytic capacitors in that single aging maltreated device with some defects that sits in front of you (for new A brand ones with documented specifications). Then you notice that the device does not sound optimal when switched on, you pour yourself a drink and return to discover your work was not in vain. You see/hear a nice repaired and cleaned well sounding device that does not end up in the landfill. You were the one that saved this precious device for future generations. A chance to show pictures and chit chat on an audio forum, you will receive respect from fellow recappers too....and get some flak from people that are afraid to do anything in any device as "the engineers and factory know best". Win-win situation.
Please keep in mind that old caps from reputable brands might have been built better than the cheapos with fantasy names coming from China nowadays. It might be that new cheap audio gear needs recapping sooner than audio gear from the seventies that used high quality parts...
. Please note that this research would make further discussions and debating on electrolytic caps hard if not impossible. Audio forums would be empty places with some lonely souls around with only hard facts on a list to choose from. No more passion, no more opinions, empty pages....It might cost less time to just replace 10+ years old electrolytic capacitors in that single aging maltreated device with some defects that sits in front of you (for new A brand ones with documented specifications). Then you notice that the device does not sound optimal when switched on, you pour yourself a drink and return to discover your work was not in vain. You see/hear a nice repaired and cleaned well sounding device that does not end up in the landfill. You were the one that saved this precious device for future generations. A chance to show pictures and chit chat on an audio forum, you will receive respect from fellow recappers too....and get some flak from people that are afraid to do anything in any device as "the engineers and factory know best". Win-win situation.
Please keep in mind that old caps from reputable brands might have been built better than the cheapos with fantasy names coming from China nowadays. It might be that new cheap audio gear needs recapping sooner than audio gear from the seventies that used high quality parts...
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Which will prevent many forum members from bulling old ladies over the Easter-weekend...
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