Instructables

Step 4: Components

Choice of components are alway contentious for tube amp builders. Some insist that one part or another is integral to the process. Hmmm. Although there maybe some truth, there's lots of bunk, too.

Capacitors, Non-Electrolytic

Many swear by expensive polyester or polypropylene non-electrolytic caps. "Orange Drop" is one common type. I used mylar caps. Here's a secret: mylar caps are polyester, mylar is just a proprietary name.

All non-electrolytic caps should be rated for 600V, since they are usually in the signal path. Small cathode bypass caps can have a lower voltage rating, however.

Capacitors, Electrolytic

Most caps 1uF or greater are electrolytic capacitors. They are a must for the power supply filter caps, and are also often used for cathode bypass caps.

These come in two general flavors: polarized and non-polarized. For this project, the only non-polarized electrolytic used were for the preamp cathode bypass caps.

Cathode bypass caps should be rated for twice the bias voltage. 50V rating is more than enough...

There's a "can" type multi cap photo, just for reference. New multi-caps can be found, but they are expensive, and can be hard to replace. These are an option, and are very common in older amps...

Resistors

Again, some will argue the merits of carbon comp vs. metal foil resistors, etc. If you're a believer, knock yourself out ;-). Normal off-the-shelf resistors work just fine.

Ratings:

Resistor application and ratings

Power tube cathode bias : 5 to 10 watts
Power supply current-dropping :  2 to 5 watts
The remainder : 1/2 watt

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