@gregtheis if you’ve already received replacement fuses from the factory and the problem persists, than there’s one of a few issues at play here. As others have stated, Synergistic fuses are built to a very tight tolerance. They don’t blow unless there’s an issue. In this case, are you using a fast blow fuse but should be using a slow blow fuse? If so, that’s the problem (I see that you specified slow blow so this is not the issue). Otherwise, as Old Heavy Mech stated, you likely have one or more dried out capacitors and so a massive surge at start up. If this is the case, you are also burning through tubes faster than you should. It’s not a big deal to change out caps in a tube circuit, and one big bonus, you’ll get better sound as well as longer lasting tubes when you do. Lastly if none of these suggestions sound palatable to you, we will make certain you get a full refund through your dealer.

Yours and music,

Ted Denney III

Lead Designer/CEO Synergistic Research Inc.