Well, I suggested brass but ZM thinks it is Aluminum anodized. Do not have the conductivity of brass but it should be fine otherwise it wouldn´t be used I think in a commercial amplifier.
User 'dimkasta' stated in post 50 that brushing lowers the contact surface, which is true also of course. Polished copper seems to me the best solution but it oxidates also....
A miliohm meter with kelvin probes could tell more, but again I'm sure aluminium or whatever works just fine, as long as screws are tight and washers with teeth are used.
ESR between 0.02 and 0.06 Ohms and Capacity between 30,000uF and 39,000uF
I read somewhere that and the end of life the capacity gets larger and the ESR rises also.
Mallory CGS Series with datecodes from 1988
Attachments
Last edited:
Thank you.
That is mostly correct, capacitance also tends to deminish.
The specs for the new Mallory CGS from roughly the same capacitance and voltage rating are 0.019 ohm at 120Hz.
https://www.google.com/url?sa=t&rct...usg=AOvVaw3-y_BNmkg_zXw4qIw89u09&opi=89978449
Still, I would consider these caps as pretty good, taking their age and the hard work they have done in Class A amps into account which I thought the Threshold is.
They are indeed 35 years old and the Threshold SA/1 is a complementary (push pull) amplifier as all Threshold SA series were (and nowadays the XA Pass Labs Series) marketed as a Class A amp for its 8 Ohms rating which is 160 Watts in the case of the SA/1 (SA/2 100 Watts and SA/3 2 x 50 Watts).
Than I put them back! No, the CGS specsheet says for caps with voltageratings below 150V capacity can be -10% and +75%.
NP stated that those used Mallory's are pretty robust.
Capacity decreases when the capacitor dries out:
"Over time the liquid electrolyte will evaporate, and
therefore reduce the amount of available electrolyte within the
capacitor. As this occurs, regions of the capacitor plates begin
to dry out, resulting in a decrease in contact surface area
within the capacitor. This reduced surface area results in a
decrease to the component capacitance, while simultaneously
increasing the ESR."
Increasing is also a possibility and neatly explained in this paper:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi-77-38Mr_AhV8gv0HHdIoCE8QFnoECA0QAw&url=https://eprints.whiterose.ac.uk/104114/1/IECONv2a.pdf&usg=AOvVaw2bFraAO9vMJn2iD2AKmO7D&opi=89978449
"Over time the liquid electrolyte will evaporate, and
therefore reduce the amount of available electrolyte within the
capacitor. As this occurs, regions of the capacitor plates begin
to dry out, resulting in a decrease in contact surface area
within the capacitor. This reduced surface area results in a
decrease to the component capacitance, while simultaneously
increasing the ESR."
Increasing is also a possibility and neatly explained in this paper:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi-77-38Mr_AhV8gv0HHdIoCE8QFnoECA0QAw&url=https://eprints.whiterose.ac.uk/104114/1/IECONv2a.pdf&usg=AOvVaw2bFraAO9vMJn2iD2AKmO7D&opi=89978449
Thanks for the paper, these were built like a tank. (For Jan: Like a Leopard)
Well then, these are still perfect caps..
Last edited:
The Mallory pullouts still weighed in pretty much to my idea. The electrolytic fluid will probably evaporate through the safety vent very slowly?
But I already bought new caps from 2021 and mounted them in.
My primary question was if it is opportune to mount solid (film) caps over the electrolytic psu caps.
I feel after all that has been stated that there's no need to buy expensive caps and that if I decide to try it I should use motor run caps like these:
My primary question was if it is opportune to mount solid (film) caps over the electrolytic psu caps.
I feel after all that has been stated that there's no need to buy expensive caps and that if I decide to try it I should use motor run caps like these:
Temperature is an important factor. Every decrease from the nominal temp with 10°C doubles the life expectancy. In time this accumulates and the fluid slowly evaporates thrue the vent. Also, in case of malfunction due to e.g. overvoltage the vent will activate not to make the cap explode.
As for the motor run caps: I wouldn't do it but if it makes you feel better,.. 😉
You certainly are correct that expensive caps makes no sense.
As for the motor run caps: I wouldn't do it but if it makes you feel better,.. 😉
You certainly are correct that expensive caps makes no sense.
Thanks. And yes being a Class A amp like a Levinson ML-2 or Krell KRS-100 I had these amps tend to get pretty warm. Levinson and Krell used mainly Spragues (United Chemicon nowadays I reckon) but these did probably not became as hot as the real Class A amps like Aleph single-ended amps and single ended tube amps.