Robin

You can use the 6.3v center tap (green & yellow) to ground OR the 2-100 ohm resistors as an artificial center tap, but not both.   Good luck, enjoy.

I have NOS 5Y3s that output 50 volts lower right out of the box compared to a new manufacture 5Y3 or a SS rectifier.     I put a 1/2 power attenuator in all my 2Stroke inspired builds these days and it works well, allowing you to dime the amp (for tone) and have an output of around 2 watts.  It’s still loud though  🙂

Hi Jordan, I use the carling switch for that, Antique Electronics # P-H494, You might also consider a Carling 3 position switch P-H520 to add a Mute/Standby function to the On/Off switch. It’s a great way to add that switching option without having to drill another hole in the chassis and adding another switch.

I can’t tell from the component board because the leads are on the back but it looks like it goes to the power tube socket as the cathode bias resistor, bypassed by that cap next to it. All my 2Strokes have a 500r/ 10w resistor bypassed with a 25uf/ 50v cap. The attached photo shows my very first 2Stroke layout, it works great.

I agree with Andy, it’sounds like it might be parasitic oscillation. Can you post a photo of the whole chassis? Pushing the leads around with a chopstick might reveal a problem.

That will do it, with a squeal in a new build or OT replacement, that’s the first thing to check.

Did you find a six for your amp?

Jensen Falcon Jet 12. Eminence Cannibals Rex is good too but from what you said, I’d try the Jensen Falcon Jet.

Here’s the schematic for the switchable rectifier, build it on the back of the rectifier socket, using the 4 unused lugs. 1N4007 diodes work great.

Greetings,
You could try changing the cathode bypass caps (C8 & C9). Remember you’ll have halve or double the value of the cap to hear an appreciable difference. You could also try lowering the plate voltage on the preamp tube to get a bit less headroom and add more grind. Also, you could easily add a solid-state full-bridge rectifier. It’s…[Read more]

I hope some of you were able to enjoy the free 4 week “introduction to tube amps”, webinar hosted by Gerald Weber, it was really good with a lot great info shared.

I hope some of you were able to enjoy the free 4 week “intoducition to tube amps”, webinar hosted by Gerald Weber, it was really good with a lot great info shared.

I hope some of you were able to enjoy the free 4 week “intoducition to tube amps”, webinar hosted by Gerald Weber, it was really good with a lot great info shared.

I hope some of you were able to enjoy the free 4 week “intoducition to tube amps”, webinar hosted by Gerald Weber, it was really good with a lot great info shared.

February 16, 2017, Tonight is the third “Tube Amp Webinar for the Novice” meeting presented by Gerald Weber. Last week there were over 90 attendees. Tonight night Gerald will discuss the different sections of a Fender Princeton circuit and explain how each one works and how they go together. The Power Supply, Preamp Section and Output section…[Read more]

Looking good! I can’t see your grounding scheme from the photos but isolating the power supply grounds from the input/preamp side will help keep the amp quiet. Run the grounds from the filter caps to the power supply side of the chassis, maybe to a lug on one of the power transformer mounting screws. And the preamp grounds together on the…[Read more]

Follow the instructions in this link: http://www.geofex.com/ampdbug/pwrtrans.htm
It is possible that the PT is blown but it’s also possible that it’s something else in the power supply, a bad tube can cause damage to other components. When a fuse blows, it’s not because the fuse went bad, use the light bulb current limiter you built when you…[Read more]

From time to time, the question of how to get more headroom with a Two Stroke comes up.
As the Two Stroke design is very much in the vane of a “black face” style amp, it’s never going to be as clean as some other designs. But the new Tung-Sol 7581A may offer a significant delay in the onset of breakup and provide a cleaner tone at higher…[Read more]