Hello. I've been a member here for quite some time but have never participated in discussions. I didn't feel as if I had anything technical to offer. I have mostly resourced this forum as a learning tool by reading...a lot. Still, I have a lot to learn. For example, only recently did it really sink in that chasing that elusive "magic" Marshall tone involves many factors, but largely comes down to circuit specs. And of course to complicate things further, the transitional periods make it difficult to say "I'd just like to have the tone from a 1986/7 circuit from 1968". But at the same time, this is what fascinates me and keeps me eager to learn. I plan on building my first amp within the next year, after much research. For reference, I am not a young man, ahem, 50, and I have owned many, many Marshall models through the years (did I mention many?). At the moment, I only have a 1987x and two clones, a Ceriatone bass spec 1967/8 jmp50, and a recent acquisition, a JTM45 from GC, which brings me to the reason for my post. I saw this amp listed for a good price and I've been looking for a decent JTM45 clone. It was advertised as a Union Jack JTM45 and only had one picture of the front of the amp. I went for it as the return process is easy enough to navigate if necessitated. Though it is definitely not a Union Jack, it is well built and sounds really, really good. Like silly good. Being somewhat of a novice when it comes to circuits, can you guys tell me what I've got here? And maybe who built it? From what I have been able to identify, it appears to be a JTM45 circuit but with higher filtering? (2 - 50+50 and 1- 32+32 cans on top, and 1 - 16uF on the board). Sozo caps, carbon comp resistors throughout, Sprague Atoms, F@T and JJ filter caps, Hammond PT and choke plus what appears to be a Heyboer RS spec OT. The transformers seem small but I recently learned that it's not necessarily the size that matters as much as it's minimum handling capacity. In any case, the amp sounds terrific. I'll try to post some clips if I can manage to get a quality recording. The tone, if I were to describe it, sounds full and blossoming, with each note, even in a chord context, getting equal attention. It leans easily to beautiful harmonic feedback when notes are sustained. I've only tried it through a 4x12 with G12M-25's so far. And it only sounds better the louder it gets, with minimal "point of diminishing returns". And it's difficult to dial in a "bad" tone. Thanks for any information anyone is able to provide. I really just curious about the circuit (any variations from the original JTM45) and who might have built it. IMO, they did a great job. Opinions also would be welcome. I know it is not meant to be a dead nuts on replica. And although I am still a recovering vintage and vintage correct addict, these days I'm happy to have the tone, regardless of aesthetics and circuit tweaks.