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http://www.unclespot.com/sigcap.htmlการต่อ
The signal caps should be wired so that the inner foil points toward the output and outer foil points toward the input. The way this is figured out is this: the outer foil was sometimes identified with a printed band on older caps and normally is on the left side of the capacitor when reading the printed information on the cap.
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If you wire the outer foil to the output side,
the sound will be muffled and rolled off. If in doubt, try reversing the leads.
ข้อแนะนำบางอย่าง หลีกเลี่ยงการใช้ Cap ยี่ห้อเดียวกันในแอมป์ตัวเดียวกัน ให้ใช้ผสมกันเหมือนปรุงอาหาร

Also, avoid using the same brand and type of capacitor throughout the amplifier. Mix and match capacitor brands and types (oil, film, paper, etc.)

you would add spice or seasoning in your favorite dish.
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....the reason why the inner foil is connected to the grid of the output tube:
1. Impedance and reactance are different.
2. This in turn, has an effect on the frequency response going through the cap.
3. In general, most inner foils are on the right side of a cap when reading it. When caps are unmarked, you can run a high frequency pulse through it and measure the response on a scope. The best response is indicated by hooking up the positive probe of the scope to the inner foil.