[gta02-core] Caps for bass fix (ECN0022)
openmoko at mazikeen.demon.co.uk
Wed Aug 19 13:28:06 CEST 2009
On Saturday 15 August 2009, Werner Almesberger wrote:
> Joerg and I discussed the choice of capacitors for the bass fix on
> #gta02-core. Some conclusions:
> - as explained in ECN0022, the capacitor should have about 100 uF
> - ceramic is unsuitable because of harmonic distortions
I'll qualify this in case anyone gets the wrong impression. High-k dielectrics
like X7R have extremely high distortion levels. Low-k dielectrics like C0G
have exceptionally low distortion, but aren't available in values bigger than
> - Tantalum seems to be the best choice
Distortion from tantalums is typically >10x that of a low cost polar aluminium
electrolytic. What makes them the best choice?
Cyril Bateman's articles on capacitor distortion are well worth a read.
Article 6 covers capacitors in the range we're looking at here.
More information about the gta02-core