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Hi guys

I'm not sure how to title the thread for my question, so it (the title) may be confusing. I'd like to know more about circuits. In the Lightning (since I have the layout and a successful build of it):

1) Where are the cathode resistors?

2) Where are the plate resistors?

3) Which color of wire on the layout indicates the tone stack?

Plate - the plate is usually connected to a plate resistor which is usually connected to the B+ or power supply voltage. Typical Plate Resistor values are 100K, 150K, 220K. Larger values equal more gain.

The Grid is where the signal enters the tube.

The Cathode is usually connected to a cathode resistor which usually goes to ground. The cathode resistor, along with the Plate resistor, control the gain of the tube stage. Typical values are anywhere from 100 ohms to 10K. Smaller values = more gain.


See the theory document reprinted with permission from Aron from diystompboxes.com for more details .


http://www.trinityamps.com/ForumGallery ... Theory.pdf

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Oh cool, thanks Stephen.

On the Lightning, would the 120 15W resistor be the plate resistor?

That would be the cathode resistor.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Would the cathode be the capacitor connected to the resistor? Where is the plate resistor?

The tubes Cathode is connected to a cathode resistor which goes to ground. The cathode resistor, along with the Plate resistor, control the gain of the tube stage. Typical values are anywhere from 100 ohms to 10K. Smaller values = more gain. The 18 watt uses 120 - 150 ohms

It is common to see a cathode bypass cap connected in parallel with the cathode resistor. The 18 uses 40-500 uf bypass cap. The cathode bypass cap also gives the stage more gain.

By altering the values of the cathode resistor and cathode bypass cap, it is possible to roll off various degrees of bass.

The cathode resistor and plate resistor control the biasing of the tube.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Ok---I think I've got this somewhat figured out.

V1 & V2) the 1.5k resistor and 25uf cap are the cathode resistor and cap.

V3) doesn't have one?

v4 & V5) The two 100 ohm resistors that go from pin 9 to pin 9 are the screen resistors. The 250uf cap and 15 watt resistor serves as the cathode resistor and cap.

V4 & V5) Why does the single resistor and cap work? It runs to pin 3 of V5 then from V5 to pin 3 of V4. If I'm correct about the cathode resistor/cap on V1 & V2, could you wire it similarly? Run pin 3 of V1 to pin 3 of V2 without have the separate resistor/cap for V2?

Since you want the power tubes to work together - you bias them together. You want the pre-amp tubes to work separately - You bias them separately.


Read this Theory document for some good background to Guitar amps by David Sorlien.

http://www.trinityamps.com/ForumGallery ... theory.pdf

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps