Tube Amp Archive

I started this build over a month ago and just can't seem to find the motivation enough to put a lot of time into it so far (images attached). Also, I definitely over-reached on this one thinking I could cram so many components into such as small chassis. I didn't plan it very well and with the PT a...

I got all the parts together and will start putting it together next week. I bought a 2.2ohm/10w chassis mount resistor (it's tiny) and I purchased the components R.G. recommended. I'm going with the resistor first and measuring voltages one tube at a time to see if it gets close to 6.3v. Even if th...

A bit off subject but I thought I'd go ahead and post the following. I mentioned previously that I purchased an amp several years ago which employed a single through hole bridge rectifier. The guy I purchased it from doesn't play guitar and had a website (now defunct) named Lighthouse 4HT Electronic...

Large watt low ohm resistor is one option. Simple is better. A 2.3Ω resistor will drop 4V at 1.75A. Please note... This is a "classroom" solution to your request. Seldom works out exactly the same on the workbench. I would rather have a handful of 1Ω and 2Ω resistors to experiment with and find a s...

D44H11 , $0.90 each and with a current gain of 100-200 typically over the expected current ranges. Voltage capability isn't needed much in this application, as you're likely to see well under 30V collector base even considering transients. A BZX79-3V3 will give you 3.3V nominal before conducting, p...

That's one reason I was using the "DC parts inside a full wave bridge" contortions - it does not add the filter/pulses losses. R.G., based on your recent reply I'd like to circle back to your amplified zener suggestion. I won't pretend that I am on par with several others here such as yourself conc...

Just an update that I still haven't purchased several needed parts yet. I decided to put on my parts list Sluckey's recommendation for the 2.3 ohm (25w chassis mount) resistor. I also purchased this part https://www.ebay.com/itm/224352155131 prior to asking questions here. I'll probably try this fir...

A 5V zener is all I need? Watts? Let's take take those as two questions. :D If you want to experiment with this approach, you would need a zener and a full wave bridge rectifier. Both need to be able to carry the necessary current and not burn up. Watts is always volts times amps. This is easy with...

If you have 4V to drop, there is a trick that may be simpler than some of these. If you use a full wave bridge rectifier as a series AC element (that in at one AC terminal, out at the other), then whatever you put between the + and - terminals acts like it is an AC element outside the bridge rectif...

I'd get the 200C resistor. The price difference is insignificant. There is nothing wrong with 4A bridge rectifier if you have a way to mount it appropriately. It will be a package with 4 leads. Buying the 200C chassis mount wire-wound. I'm going to mount the bridge rectifier on a terminal strip. I ...

TUBEDUDE wrote: ↑Mon Mar 29, 2021 1:52 am An SiC bridge is mighty efficient and generates lower noise, a short Trr etc.

Thank you. I will purchase a couple.

Large watt low ohm resistor is one option. Simple is better. A 2.3Ω resistor will drop 4V at 1.75A. FWIW, this would be my first choice, too. I'd get the biggest one that will fit, at least 10W. It will get hot and the higher the wattage rating the better. I'd make sure it is reasonably isolated fr...

You could start rectifing, levelling the filament supply with cap and measure it, it should be around 14V but usually is a bit less. To be perfectly supplied the filament of ECL84 should be in parallel with 6.3V but in series they will also work with small tolerance and you could give it a try, gui...

I'd get an appropriate tranny and ditch the buck transformer, rectifier, regulator, filter etc path I've built a few of those already and if this doesn't work out I will go that route and buy a proper PT. However, this is a low-dough, lower than normal voltage, experimental type build. I probably s...

Using this PT: https://www.tubesandmore.com/products/transformer-power-120v-primary-14028105-v-secondary Heaters will run off secondary three 10.5V @ 2A. Build is a push-pull ECL84 tri-pent with 12ax7 preamp. Heaters datasheet shows total of 1.75A needed. Large watt low ohm resistor is one option. I...