Help I need a schematic for the absolute simplest audio amp to test tubes with

[Silvertone Jockey]

I sell tubes on ebay. I like to audition the tubes before selling them in addition to testing for reasons that are obvious. I need to but can't audition a few common types like 6V6 etc because my amps are all 6L6 stuff. So I need the simplest 6V6 circuit (no tone controls etc,) I can throw together that will allow me to listen to the noise floor and make sure everything is as it should be operating wise. Probably doesn't need to be at full plate potential even. Any ideas? TIA

[R.G.]

For a commercial venture, it's easier, quicker and probably in the long run cheaper to go buy a small amplifier that uses 6V6s instead of building your own.

Just curious - are you offering someone a fee for helping you with your business in this way?

[mhuss]

Buy (or build) an old 5E1 champ. One 12AX7, one 6V6, optionally a 5Y3 rectifier - couldn't be simpler. I find these amps very revealing for hearing differences between 12AX7s, but I'm sure the same is true of 6V6s.

[Silvertone Jockey]

Found an easy solution. According to a link I found a .1 6ooV capacitor connected to the plate lead of my tube tester will allow me to listen to the tube with some old school 600 ohm headphones, and or connect my O scope up and look for noise that way. I'm thinking the O scope is the way to go. Thanks for the replies

[Alan0354]

If you test tube, make sure you have a tube extender.........that is one to plug into the amp, and the tube plug into the extender. So you don't wear out the socket in the amp.

If you cannot buy one, build one using this:https://tubedepot.com/products/8-pin...base-only-deep and solder a tube socket on top.

[Silvertone Jockey]

Socket extenders? you betcha, replacing a socket is never fun, pain in the ass especially on a tester. Been there done that more than I want to

[Merlinb]

Just build an ordinary gain stage- no need for an output transformer, just use a plate resistor. Feed it into an audio amp to listen to the noise.