5
by Tommy_Archive
I've owned a few of these 50 watters master volume with this circuit, in this order: vertical input JCM 2204, vertical input JCM 4104, and a JMP. I've also played through two horizontal input 2204.Here are some facts: They all use the same PCB and are technically the same circuit. The transformers changed during this time and the cap types changed. There have been a few cap value changes as well. Some of the JMPs have slightly lower plate voltages. Here is my opinion: I think the JMPs sound a little less bright and a little looser. The horizontals sound the loudest to me and are also the brightest. I had to clip the bright cap in all of the JCMs. My JMP I run with the treble and presence all the way off and it sounds fantastic to me.I love the look of the JMP the best and it weighs a little less. BUT, I only have one because it fell in my lap for the same price as a JCM. If I was looking for one, I'd personally get whichever one I could find cheapest. The sound differences are NOT night and day. In fact, a retube and bias would probably make up more of a difference than the cap/transformer differences. You're probably going to want to clip that bright cap though. Especially if you use single coils and the HIGH input. Maybe not if you like humbuckers and the low input. Also - 6550s are brighter than EL34s in this circuit.Speakers make a HUGE difference. Excellent advice. No way would I run a 4x12 with Vintage 30s with this amp. Would be brutally piercing.Here's the Tommy setting with the bright cap and single coils: 0 - 4 - 6 - 0 - 6 - 5 - HIGH input.