I’ll repeat: if tubes, get thee a simple tube tester, nothing fancy, just the basics, test existing, garage sale finds, and new ’matched’ ones you buy:
You must get or find the manual to use one.
here’s an accurate 157. I have one of these, it’s smaller brother 151, and a big fancy Jackson or Hickock (it’s down there somewhere, haven’t seen it in years, because the small accurates ALWAYS matched the big one’s results.
don’t let the beat up vinyl or rusty hinges dissuade you, they used low quality metal and thin coverings.
a clean looking Eico https://www.ebay.com/itm/195518113222?hash=item2d85c9a5c6%3Ag%3A4qYAAOSw58Jjmmud&amdata=enc%3AAQAHAAAAoIxeD9vNoKp%2FRjJpdPhJ8VFC7vjuIELd90KucmbeWwUK7WXF%2BDhESAKfFTWIgiSo53S9SLlBmu3AekVgbaDnGuEQl7R2QXJbqTUM8YV5CjmEHD8uVcs0AD0WCrSDJVFyTlXyTRfDmDL03vegcPBY2wKZlMWLIcPhamo39m1Y%2BNQDPOjgosb7oHZP0gTulw%2B%2BpBKc27UstZLLzaRskk6lzCU%3D%7Ctkp%3ABk9SR9jTzrLAYQ&LH_RPA=1&LH_BIN=1Here’s a Jackson: https://www.ebay.com/itm/354440155415?hash=item5286479117%3Ag%3ACy8AAOSwFotjk3wR&amdata=enc%3AAQAHAAAAoD%2BRhC7yrKfgFDnur%2BlRCvyipFwg2OTpZGeVL1mOGBQ08QtV2HvwN7CyVOmjPPXIYrXwNo80OJHX4iOlZj8wDqOR5BCWzp5O1XC7DVj2CBjpMjXn9sfrf%2BkyioZTQ1%2BBoFBTglqTO5ANwB5sqpmbtMFGaMx49X%2FWMZYjNE91QfhQRQj5wIg9xMlvif%2Bq7S9NuoEpQe0nWUplkCNr5HcOB7Q%3D%7Ctkp%3ABk9SR9jTzrLAYQ&LH_RPA=1&LH_BIN=1