Tube Amp Archive

I've heard of better way to turn a push pull amp into a quasi single ended is with a pot or mute switch that turns off the control grid signal to one of the power tubes. That leaves the idle current flowing through both halves of the OT (and both tubes' current through the single cathode resistor in...

I suppose my issue with the supplied answer is why isn’t current from the 6V battery flowing through the 3 ohm resistor and the 2 ohm resistor. It seems this path has been ignored. My memories of how to apply Kirchoff's voltage law are pretty distant too, maybe someone else can help with getting th...

The first tone control section looks at least a little bit interesting. The parallel fixed mid boost and scoop sections with a blend pot isn't something I remember seeing anywhere before. Most of the design is pretty plain though. There's no negative feedback in the power section, which isn't unique...

There are so many things I like about this build that I feel bad that my comment about it is a suggestion for an improvement in the layout. One of the specific things I like (and I'm planning to do the same thing): the divider between the transformer and the audio signal path. One detail that has ro...

I've been comparing inverter stage spice simulations the last couple days (definitely going to go look for #124 next), so I spiced this choke tail pair last night, but now that there's obviously some interest I should probably jump on the bandwagon and post about it too. The last time (and first tim...

Amazing thank you, is the capacitor necessary? I see so many amps without it but have one I can put in if needs be. Any Tonal affect I would hear whilst playing if it’s not there versus is there? The cap provides frequency compensation, which like you've already noticed isn't used or talked about m...

A good place to start is the datasheet for the resistor you plan to use. The model in Aiken's schematic is pretty easy to find. https://www.vishay.com/docs/30201/rhnh.pdf Page 3 has a lot of relevant info: Vishay RH resistor wattage ratings are based on mounting to the following heat sink: RH050: 12...

I found this paper helpful https://www.valvewizard.co.uk/Grounding.pdf Merlin recommends using a ground reference at a point in the circuit that minimizes the power supply current flowing past/through the ground connection point. Specifically: connect the ground reference at the cathode of the inpu...

I just found a really thorough introduction to Thermal Resistance and Heat Dissipation, and I wish I had found this a few years ago. basics_of_thermal_resistance_and_heat_dissipation_an-e.pdf If the Texas Instruments pdf above was too specific for your tastes, this Rohm Semiconductor lesson covers a...

No. If you don't want to take my word for it, listen to Texas Instruments. Here's a lesson from them in how to understand some of the numbers that show up on nearly every single heat generating solid state device data sheet. These same numbers also tend to show up on high powered resistor data sheet...

Something like the dissipation of the single triode within the same envelope of a dual triode tube ECC82.png Franco No, the inside of a vacuum tube isn't a very good comparison. (I could elaborate, but it would take a paragraph or two.) More like 10 watt resistors mounted in air dissipating 9 watts...

Sorry about the double post. I mostly wanted to second what bepone said, for emphasis: From other oscilograms.. it is difficult to interpret your oscilograms, without the schematic and explanation where did you conect and how did you measure.. I can see in your pics something that does look like it'...

I did take some pics of the noise today: IMG_5927.JPG This is the filament waveform without any filtering. I forgot to take one of the line all by itself but they're practically identical. The line being obviously just scaled up from what you see here. Okay, I went back to your first post and found...

The noise is just present on the power line without the amp hooked up. Its pretty much always there and I'm not really sure whats causing it. Can you post a pic of how noisy the wall voltage is without the amp plugged in? You might've missed the bullseye when you described it, but it could still be...

With the voltage split equally between two MOSFET's in series, the voltages on the X-axis will be one-half and the power at each step will be one-half. The power will still peak at the mid-point, but it will be half the single MOSFET power. English isn't my language, please can you explain this thi...