Do It Yourself (DIY) paradise for tube and SET project builders.
Message Sort: Post Order or Asylum Reverse Threaded
On Capacitors..
68.226.79.216 |
||
Posted on April 24, 2016 at 07:45:43 | ||
Posts: 1800
Location: Omaha NE Joined: September 8, 2006 |
OK, I'm a late convert to the importance of capacitors. We recently modified a Dynaco ST-70 with our standard mod except the customer opted for Russian K-40Y paper in oil coupling caps, instead of the standard good quality film caps. The difference was startling. With the K-40Ys the amp dropped all character-it just seems to pass music. I've read about how caps depart from ideal. There's resistance, inductance, and they can be modeled as a capacitor in parallel with a number of RCs. While I've never seen a good explanation of this phenomenon, I suspect it has to do with a little leakage into and out of the dielectric, and with electrostatically wrenching electrons inside the dielectric around a little (which would lead to both the little capacitances and the little resistances as the electrons are moved and then resistively relax back into place). Some inductance is unavoidable in the leads. That leads me to the question. Has anyone tried expensive, volumetrically inefficient vacuum capacitors? They should have no dielectric-related misbehavior. Maybe good for RIAA equalization? Or coupling caps if you like room-sized amps? It also occurred to me that due to their size and shape they might be microphonic. |