Tube Amp Archive

Loop B Opposite Direction: Point C to point D has a rise of 4V and E to B has a rise of 2 x i2.
+4+(2 x i2)=0
2 x i2 = -4
i2= -4/2
i2= -2
So we get the same answer with either loop direction.

Loop C: Point F to point A has a rise of 6V, A to B has a drop of 3 x i1, and C to D has a rise of 4V. +6-(3 x i1)+4=0 +6+4=3 x i1 10=3 x i1 i1=10/3 i1=3.33A Point B: Currents coming toward a point are considered positive while currents going away from a point are considered negative. The algebraic ...

Loop A: Point F to point A has a rise of 6V, A to B has a drop of 3 x i1, and B to E has a drop of 2 x i2. "Rise" is positive and "drop" is negative. +6-(3 x i1)-(2 x i2)=0 We can't solve for one unknown current because another unknown current is also in the equation. Loop B: Point B to point E has ...

We are going to use Kirchoff's Loop Rule and Kirchoff's Point Rule to find the various currents. Kirchoff 1.png Conventional current is used in this exercise, so current flows from positive to negative. The given directions of the currents dictate the resistor polarities. Kirchoff 2.png Point E to F...

Tweaked a little for 415V: Bias Two Cap Tap Timmopher 2.png The DC bias voltage that is developed is fairly sensitive to the AC voltage at the transformer bias tap and that AC voltage never seems to be certain until you fire it up and measure it. Different 6L6GC's require different bias voltages in ...

Preliminary Circuit

What plate voltage are you planing to use?

Stevem wrote: ↑Mon Apr 28, 2025 3:39 pm I don't know about the early 77 100 watt twin stuff because I have 76 master volume 70 watt PR and its my understanding that Fender started both models off with UL at the same time.

Let's see it.

Here are 45W Pro Reverb transformers with '77 date codes.

Stevem wrote: ↑Sun Apr 27, 2025 6:50 pm A 77 twin would have been the 135 watt model and had a UL output transformer so it would have had two more primary leads.

Not that it's relevant to the current thread, but Fender made 100W Twins for the first part of 1977 and then made 135W Twins for the later part of 1977.

The OT and PT are likely from the eighties. The 21009 OT was used on the Twin Reverb II.

solderhead wrote: ↑Tue Jan 21, 2025 5:23 pm ...garbage-in, you should expect to get garbage-out.

I believe that Dr. Emmett Lathrop Brown proved that one to be a total fallacy.

R.G. wrote: ↑Sun Jan 19, 2025 4:19 pm For a multi-tapped output, the primary impedance is as stated ONLY when one and only one resistor of the designed output impedance loads the secondary.

What if you loaded the eight Ohm tap with a sixteen Ohm load while also loading the four Ohm tap with an eight Ohm load?

Langmuir was paid by the U.S. government to pose as a debunker of UFO's amongst other things. He was not a debunker in the strict sense of the word because debunkers take things that are false or at least distorted and exposes them as such. Langmuir took things that were true and tried to convince u...

kev02 wrote: ↑Fri Aug 23, 2024 4:55 pm Can anyone pont me in the right direction for thru hole ferrel ? I have no luck on the web yet .

Are you talking about ferrite beads?

I am laying out an amp with a DC coupled cathode follower where it would make more sense to use two separate tubes instead of both in the same envelope. I can't think of a reason why having the gain stage in a separate bottle from the follower stage would be a problem, but I don't know if I have ev...