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Robin replied to the topic Does 290AX need an artificial center tap? in the forum 2 Stroke Amplifier Design and Building 2 weeks, 5 days ago
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.
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Robin replied to the topic High(er) Voltage in the forum 2 Stroke Amplifier Design and Building 1 year, 5 months ago
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 🙂
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Robin replied to the topic Impedance Switch Question in the forum 2 Stroke Amplifier Design and Building 2 years, 4 months ago
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.
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Robin uploaded a new picture: 86 special 2.jpg 2 years, 7 months ago
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Robin replied to the topic 2 Stroke component question.. in the forum 2 Stroke Amplifier Design and Building 2 years, 7 months ago
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.
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Robin replied to the topic squeal when at high volumes in the forum 2 Stroke Amplifier Design and Building 2 years, 7 months ago
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.
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Robin replied to the topic Squeal in my 5B6 in the forum 2 Stroke Amplifier Design and Building 3 years, 11 months ago
That will do it, with a squeal in a new build or OT replacement, that’s the first thing to check.
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Robin replied to the topic Help with voltages and possible signal grounding in the forum 2 Stroke Amplifier Design and Building 3 years, 11 months ago
Did you find a six for your amp?
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Robin replied to the topic "Best" or good 12" speaker for a stock Two Stroke in the forum Speaker Talk 3 years, 11 months ago
Jensen Falcon Jet 12. Eminence Cannibals Rex is good too but from what you said, I’d try the Jensen Falcon Jet.
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Robin replied to the topic Modding the boost/voice switch in the forum 2 Stroke Amplifier Design and Building 4 years, 3 months ago
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.
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Robin replied to the topic Modding the boost/voice switch in the forum 2 Stroke Amplifier Design and Building 4 years, 5 months ago
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] -
Robin replied to the topic Novice tube amp webinar offered in the forum General Amplifier Discussion 5 years, 11 months ago
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.
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Robin replied to the topic Novice tube amp webinar offered in the forum General Amplifier Discussion 5 years, 11 months ago
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.
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Robin replied to the topic Novice tube amp webinar offered in the forum General Amplifier Discussion 5 years, 11 months ago
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.
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Robin replied to the topic Novice tube amp webinar offered in the forum General Amplifier Discussion 5 years, 11 months ago
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.
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Robin replied to the topic Novice tube amp webinar offered in the forum General Amplifier Discussion 5 years, 11 months ago
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]
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Robin started the topic Novice tube amp webinar offered in the forum General Amplifier Discussion 5 years, 11 months ago
Gerald Weber is offering a free tube amp webinar for the novice for the next few weeks. Here’s the message from Gerald:
Here is the registration email for the free webinar I am hosting. You are invited to attend for FREE.
Free Webinar Hosted by Gerald Weber on Every Thursday in February for those that are wanting to learn how the electrons are…[Read more] -
Robin replied to the topic My Two Stroke build, blogged! in the forum 2 Stroke Amplifier Design and Building 5 years, 11 months ago
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]
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Robin replied to the topic Power Tranny Problems? in the forum 2 Stroke Amplifier Design and Building 5 years, 11 months ago
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] -
Robin replied to the topic Testing Different Tubes in 2 Stroke in the forum Tube Talk 6 years, 9 months ago
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] - Load More