Matchless Spitfire OT Impedence


I’m currently in the process of doing a Matchless Spitfire build. My concern is regarding the primary impedance of the OT. I’ve read through as many of the threads I could find on the subject but don’t thing I found a definitive answer.

I’ve read several times that part of the “Spitfire” sound is the 4k primary impedance of the OT that Matchless uses rather than the typical 8k for a pair of EL84’s. So I purchased a Hammond 1615A with a 5k primary and 4, 8, & 16R secondaries. According to other threads, this OT has been used by a few people for a Spitfire before.

My question is, do I use the 8R tap with an 8R cab? Or do I need to use the 4R tap with an 8R cab to have 10k on the primary? Not sure how Matchless might have had this setup.

Any help would be appreciated.

Last edited: