Start up testing is covered in the Mellow Tone Kits YouTube Build Series. You mention checking some of the basics which is good. But the most important is to plug the tubes in and check your B+ voltage, make sure it’s close to spec and most importantly stable. If you have a scope and signal generator you can pass a signal through the Pre and check for a clean signal out, otherwise plug the pre into the R8 (Pre IN), turn the Pre volume to zero and turn on the R8. If the R8 is quiet with no volume then turn the Pre volume up to half – still quiet, go full volume – still dead quiet, then congratulations you built to the design and layout of the original Universal 6/12sn7 Kit Preamp. If noise or sound issues go back and see where your build deviates from our design. Hint: ground topology is critical for a quiet design.
Please let everyone know how it went, including pics.
Cheers
Jim
