GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Melquiades Amplifier
In the Thread: Single-stage Melquiades vs. DHT amps

Post Subject: Science or religionPosted by floobydust on: 5/17/2009

Romy,

I have to admit that there are as many differences in film caps as there are in electrolytic caps. You can find varying opinions for and against both based on brand, type and usage. As noted, large value film caps get (physically) large so your options become limited by your ability to either afford them or tolerate the physical mass. This makes most look for an acceptable compromise.

After some period of time, I made some decisions for my smaller 45 and 2A3 SET designs which I've been happy with. Axon brand are actually made by SCR but to their "modified" specifications. I use 3 different types in the circuit. For the power supply I used their HighVolt caps which are rated at 630V and have solid copper leads with violet colored PVC insulation. These are physically quite large. I have them in 100uF, 40uF and 20uF. They have been flawless to date in all power supply applications. For cathode bypass functions, they offer a TrueCap series which is rated at 250V and are more traditional SCR encapsulation and a more reasonable physical size. The leads are basic tinned copper and bare. For signal coupling (of which there is only one in my circuit), I use their Tin Foil and Film cap. These are rated at 630V, have the same leads as the HighVolt caps and quite heavy for their physical size. So far, I'm quite happy with them, but according to my source, they no longer make the 630V HighVolt series and it would seem the Tin Foil and Film types are also falling off manufacturing as well.

If I am forced to use electrolytics, I generally use Mallory CGS or Sprague DX series as these are well made and will perform within spec for very long periods of time. These are also pretty large and are considered computer grade and hold up well to time and high frequency loads. Granted, there are many other brands and types available, but I simply don't have the time to spend testing endless configurations and the cost would also be unreasonable. One of my main goals for equipment is that the components used don't change over time and you can depend on them lasting a lifetime, sans tubes of course.

To open another "Pandora's Box", we could add resistors into the discussion....

Regards, KM

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