Tube Amp Archive

Update: moving the input jack around with its wires changes the pitch of the squeal

I've managed to build the (pre)amp but there is a problem. Besides the nice sounding distorted guitar signal there is a high pitched squeal as well. Here are some things I managed to discover so far: Knocking on the tubes with a wood stick has no effect Noise completely stops when the input is short...

Hopefully not too late, Mojotone carries a PT that may work nicely. 250v 120mA and 6.3v 1.5A https://www.mojotone.com/GA-5-Reissue-Rocket-Reverb-Unit-Power-Transformer I live in Hungary so ordering from Mojotone would be quite expensive, one of the Hammonds mentioned earlier will do the trick. Than...

You can get all kinds of numbers out of a simulation, and sometimes they are useful. Do you have an accurate model of the transformer heater winding? If not, I would try it in hardware to make final adjustments. A regulated supply would be the best way to hit the voltage exactly. I've found a few f...

Achtung, your heater supply will deliver around 9V, its again the RMS vs. peak thing. 6.3VAC is 8.9V peak, but there will be two diode drops and significant ripple voltage that will lower the average DC level. I think it will come out about right, if the heater winding has an appropriate AC current...

https://www.hammfg.com/electronics/transformers/power/229 Check these lil guys out too! If you are alright using a 2nd transformer for your filaments, these dudes still have all the HT current a pile of 12ax7 will ever need. A trim 325dc after full wave rectification and filtering, still plenty of ...

that power transformer is a monster if you are just running a few 12ax7s... id consider going with a smaller one from the 200 series (or 300 series if you need a 220v primary). something like the 369BX (300vct @ 86ma) with a fwb rectifier would get you about 420 volts unloaded... not that the two 1...

The output impedance is going to be a little higher than ideal without any kind of buffer. That being said, it sounds like you have a fair bit of pedal experience and might be familiar with how to use a buffer when needed. So depending on what you're plugging into you might be just fine without any...

Hi! I bought Merlin Blencowe's "Designing Tube Preamps for Guitar and Bass" book and I want to build his ultra high gain design found on page 259. Since this is my first high voltage build (I've build pedals before) and I made a few modifications to it based on the book itself I'd like to get your o...