Rerurn to Romy the Cat's Site


In the Forum: Melquiades Amplifier
In the Thread: 6 Channel Version of Super Melquiades
Post Subject: Capacitors are like cholesterol - migh be good and bad.Posted by Romy the Cat on: 11/4/2007

 drdna wrote:
The question in my mind Romy is: why?  I will be interested to hear your comment on what your goal was to learn about your system in introducing these and what the results are.  After the extent to which you have described the sound of your system, it will be very instructive to hear your comments.

I have toyed with the idea of using these for RIAA circuits in a phono preamp, since the required pF values are appropriate and they should offer minimal distortion.

Well, prior to personably bitching about capacitors let define what we are fighting in capacitors. Capacitors are like cholesterol: there are good capacitors and there are bad capacitors. The good or bad status is however is not only determined by the type of capacitors but primary by the why how the cap is used. If cap is a coupling capacitor (or PS capacitor) then it is squashed from both sides by differences of DC potentials and the dielectric of the capacitor has been already polarized. The small amounts of AC signal the flows over the cap has not significant strength to repolarize the cap’s dielectric. Why it is important? Because the what AC attacks the cap’s dielectric the dielectric acts like a cone on miniature loudspeaker, crating electro-mechanical vibration and consequentially the microphonic noise. However, in case a cap use no or little DC (as in line-level filter of feedback filter) then each single milivolt of AC forces the dielectric into re-polarization. Better dialectic less exposed to this event but what would be if the dielectric …is vacuum or air? In this case there is no dielectric of any kind. available for re-polarization. I was looking for year the right vacuum cap and all that I have seen with right fixed values were aluminum caps. Now I have eventually found a pure cupper cap. Will it be better than an air cap? I do not know but I will try, and I think this is the only way to answer the question.

Pay, attention the Melquiades nowhere uses the “bad-type” (location) capacitors. Wherever the circuit is called upon such a cap the amp uses RL filters or the caps with no dielectric (air, vacuum)

The Cat

Rerurn to Romy the Cat's Site