Ok the wires that are circled in bright green are the wiring routing errors I need to adjust. I did notice yesterday that when I moved the green input wires I could slightly adjust the level of hum so I really want to reroute wires in that area. Also which caps are the coupling caps. I would like to check for leakage but am not exactly sure which one to check. Thanks Curt

Coupling and tonestack caps are the smaller yellow Sozos. Check voltage on the side closest to the potentiometers. I doubt you find any AC here but check it anyway. Use mV setting on your instrument.

The green input wires are of course very sensitive and capture hum and noise, especially when your amp is open. I always use shielded wires from input jack to V1 (connected to ground at the jacks). And I put the 68k grid resistors directly at the tube socket. But I guess the orthodox guys wouldn't call me a real Marshall builder

Also the green wire that goes from the board to V2 is very hum and noise sensistive. I sometimes use shielded wire here to (shielded at one end of the wire) But when you put your amp in the cab these cables shouldn't cause problems.

(If you want you can build a dead silent Marshall, but you have use some special solutions.)

By the way - do you have any unwanted hum or noise sources close to the amp when you are working with it? Computer? A fan maybe? Fluorescent lamps? A washing machine on the other side of the wall...?

/G

I'm curious if you tried to chopstick that purple presence wire away form that white wire going to the other tone pot (is it the mid control?)? It's right below the board near the bias pot. I know the instructions say that this purple wire should be away from the other tone controls.

with the amount of the hum that I am getting could this just be a wire routing problem? To me is seems like a couple of wires to close could not produce such massive feedback. What is your opinion on this? I will still reroute wires tonight but I think this may be more involved.

When I chopsticked around, I never was able to significantly increase or decrease my hum, so I agree with you. It's probably something else. I was only asking about the purple presence wire, because mine was never as close to the tone controls as yours is and I couldn't move it closer due to the routing. I know it's specifically mentioned in the Metro instructions, so maybe it does have an effect.

I am also only able to hear your soundclip in my computer's internal speakers right now, so it's hard to tell. It does sound similar to what I had though. My solution was weird though (as discussed above). And also, as mentioned above, it wasn't unusually loud with the chassis sitting on the table.

That oscillation is way up there. A few other things for you to look at:

You need to address your 5k6 swamp resistor mounting. They should be soldered right up on the tube sockets leaving no lead visible. Hopefully you have a good soldering setup that lets you work fast. Hard to believe, but this makes a big difference. A lot of little things do.

Wire routings:
The orange and green bias splitter wires in relation to the OT wires, and the purple nfb wires... both of 'em. Again, little things... where these are routed makes a big difference.

Make sure all of your solder connections are solid. A cold solder joint could be your culprit.

Here's a shot of how those swamps need to be mounted...

What would the best may to reflow the soder joints? High heat and fast or low heat for a while. I have a nice soldering station so either should be fine. Just want to avoid leaving any cold solder joints. When I checked I had continuity throuh the board but could i still have a cold joint?

Faster is better. I normally set my station somewhere around 850 degrees. Yes, it is possible to have a questionable solder joint and still read continuity.

You may already know this, but just in case you don't:
When you touch up your connections, be sure to flow fresh solder on them. Don't just heat up the existing joint. Let your soldering station get up to operating temp and stabilize, and keep the tip clean. Flow some solder on the tip first then hit your joint and apply more solder if necessary.

I had a bad hum with a batch of Tung Sol reissues in V1. Not sure what you had there but just a heads up.

I had JJ's in there but I also tried a set of Groove tubes in there as well and the hum did not go away. The groove tubes are good since I run them in my other amp.

Also this noise only happens when there is a guitar plugged in. Dont know if this helps or not. It is quiet when the guitar is not plugged in. Could this be a grounding problem?

OK, make sure you are using a good cable. try a different cable and a different guitar.

Guitar maybe acting like an antenna. Check your ground at both ends i.e. output and input jacks, try different guitar & cable for process of elimination. Also, make sure your not around any fluorescent lights which drive tube amps crazy.

OK I can do that. I was using my les paul but I was using a really crappy cable. Could this make that much of a deal? I guess I can pull out the monster cable. For testing purposes I also have the input jack of the speaker just laying on the floor.
Since my amp is quiet without the guitar pluged in does this mean the amp is fine???? That would be GREAT news!!!

It very well could just be a bad cable or jack. It's always best to start by eliminating the simple stuff first.