Does anyone have an idea how to test for microphonic or bad tubes?? I really don't fancy forking out cash for a big old AVO Valve Tester type of machine. Tubes are costing me a fortune lately. I use 6L6's and 12AX7's. Thanks!!
The best tube tester is your amp... trust me on this.
...obviously a dedicated tube tester is also very handy tool and you don't need to get an AVO.... those are really expansive.
You could get a cheap emission type tube tester but a device like is not very accurate... it's more like an indicator GOOD/BAD and even than the result is not 100% accurate.
You can spend a little more (still a lot cheaper than AVO) for a vintage transconductance type tube tester. Those will deliver even better results.
Learn about vintage tube testers here...
http://www.tone-lizard.com/Tube_Testers.html... but if you want to mach tubes or search for balanced preap tubes you will have to get a modern type device.
..a device like this
http://www.maximatcher.com/but there are many other available as well... this is only one example.
BTW it just happens that I have AVO CT160 on my bench at this moment... I borrowed it from a friend... and let me tell you this thing is just to complicated. I don't like it... for that kind of money, I would definitively buy some modern type tube tester.
I also have a very old cheap Precision tube tester... very easy nice and simple tester... but like I said not very accurate.