| Jason Hubbard |
I have a choice of capacitors to use in a power supply for an aleph-x amplifier (18.5volts @ 6 amps).
Supply will be a CLCLC setup with 4mh air core inductors.
Capacitors are either NOS 56,000uf which i believe are about 15 years old but still hold a charge OK (i may reform them before use just to be sure) or i can use 3 times as many new 22,000uf snap-in capacitors as the C element of the CLCLC supply.
The volume of the 3 new capacitors is not even close to the big can of the 56,000 capacitor - does this have an effect on the ripple current or any other aspect of the capacitors performance?
what are the pro's & cons of each choice?
any comments greatjy appreciated. |
|
|
| Elvee |
Hi
It is generally preferable to parallel capacitors for large values: this results in a lower impedance; in addition, a smaller capacitor will also tend to have a smaller series inductance than a large one, which can be beneficial to the impedance at higher frequencies.
LV |
|
|
| AndrewT |
Hi,
a CRCRC has very high ripple on the first cap.
CLCLC is slightly better. Try comparing in PSUD2 for first C ripple.
If it is still bad then use multi parallel caps for the first C to improve the ripple capacity. Otherwise it will run hot and fail.
The quality of the output is controlled by the last C. Use your best C here.
Aim for sufficient to support good bass response and good ESR for mid and treble. Again multi parallel may give a solution.
But, check for oscillation when trying parallel caps with low ESR. RC snubbers may be the answer. |
|
|
| Jason Hubbard |
Thanks for the replies.
Andrew - are you saying that i should consider unequal distribution of the capacitance across the CLCLC chain favouring the capacitance of the first C in order to reduce ripple current?
What about needing capacitance in the last C which is the capacitor bank that the amplifier will see?
I recalled that smaller paralleled capacitors were preferred to a single larger one (but there was also an argument in favour of the larger ones which i have since forgotten - anybody) |
|
|
| AndrewT |
Hi,| quote: | Originally posted by AndrewT
CRCRC has very high ripple on the first cap.
use multi parallel caps for the first C to improve the ripple capacity. Otherwise it will run hot and fail.
The quality of the output is controlled by the last C. Use your best C here.
Aim for sufficient to support good bass response and good ESR for mid and treble........ |
| quote: | Originally posted by Jason Hubbard
are you saying that i should consider unequal distribution of the capacitance across the CLCLC chain favouring the capacitance of the first C in order to reduce ripple current?
What about needing capacitance in the last C which is the capacitor bank that the amplifier will see? |
Sorry, you have misunderstood my message.
Improve the ripple capacity of the capacitors is NOT the same as reducing the resultant ripple measured at the capacitors.
The last C most influences the sound quality in the amplifier. This means use good quality caps and of adequate capacitance for the last C.
The first C and the middle C are there to attenuate the hum and little else. The first C in particular feels a LOT of ripple (hum)
Go and re-read my message. |
|
|
|
