The Amp Garage

Man, for as little as they are on Amazon, ($180 to $260) I'd just buy one: East Tester ET5411A+ https://www.easttester-cn.com/et54xx-a-programmable-electronic-dc-load-product/ They're much more expensive over here, but I have been keeping an eye out for one second hand. Apparently nobody wants to s...

As an experiment, I asked ChatGPT about finding a transistor with a certain pinout and specs I could use. I did this three times on three separate days. I was given 7-13 options each time. First time had one that was correct, second time had zero, third time had one. None of the transistors with the...

power mosfet and heatsink As in, just run the MOSFET in linear mode with the biggest heatsink I can find? I was in a dead rush when I wrote that. But yes, run the MOSFET(s) in linear mode and keep them cool enough not to die. You can get MOSFETs with high enough voltage ratings to test tube power s...

Perhaps elaborate on what you are hoping to 'see' by using an active load, and how you are hoping to measure any change (ie. what scope and sensors are you aiming to use). The reference to 500V indicates this is for testing a B+ rail and its dynamic characteristics ? Is the testing for just step lo...

R.G. wrote: ↑Wed Aug 05, 2026 1:45 am power mosfet and heatsink

As in, just run the MOSFET in linear mode with the biggest heatsink I can find?

Howdy, Looking for an active load for testing some of the switcher supplies I've been working with. I've been using combinations of 10w resistors at the moment, but would rather something a little more elegant that is less sketchy and easier to measure. Heaps available for batteries that can do real...

Don't solder these on.

Crimp them on, as they're designed for. The correct crimpers aren't expensive and they'll do you much, much better than soldering will.

Use a star washer below the nut to ensure they stay on.

https://i.imgur.com/5WhCqA1.png This is the general gist I had - was originally looking at the 6GH8A ala Channel Road, but realised the triode needs a stack of current for reasonable gain so I reckon it's off the table. ECL82 would be an easy choice and threw some values in for the recovery stage b...

The reverb pan is going to be the tricky part. You need one with a drive coil of a suitable impedance value to match up well with the load impedance the drive tube wants to see as a load. The datasheet for the 6BQ5 shows triode connected, it wants to see a 3500 ohm impedance, with a plate supply of...

Howdy, Looking at options for transformerless reverbs, and want to stick with tube driven (1 if possible). There seems to be two approaches I've seen from the searching I've done: Swart/Ampeg - Swart use a 12DW7, with second triode for drive and first for recovery, whereas Ampeg use a 6SN7. Channel ...

This is not an all-in-one schematic, but when I was considering building a standalone SS reverb I found this article interesting/useful. It has a few options for solid state driver circuits for low and high impedance tanks, and also shows a basic recovery schematic. And a bunch of spring reverb inf...

This is probably beyond my ability at the moment but it is interesting. Gerbers are included on the older board, so if you're ok with paying for PCB Assembly you can the boards made, SMD populated and delivered to your door through companies like JLCPCB. Only THT left for you to do then. Thanks -- ...

Hello -- Unfamiliar with the expansive breed of amps in the Marshall/Friedman dynasty. The hands-on closest are the Trainwreck Express and perhaps the ur progenitor tweed Bassman. Unable to offer much except to complement the detailed effort in designs. A tad unclear what value comes from that capa...

didit wrote: ↑Tue Apr 07, 2026 7:35 pm Hello --

Yup, Zero Watt --> https://ampgarage.com/forum/viewtopic.php?t=37748.

Best ..

So with 0.5w from a 12AX7, it could possibly be a PI driving a transformer directly - would be interesting to see what's happening inside specifically

I've had my preamp with a 6N2P-EV running around 320v to the plate resistor for a while - no issues.

Datasheet says 500v at cutoff, so wouldn't be too concerned.