Mesa Lonestar hum(generally about hum)

[Stretto]

My lonestar hum is significant and virtually impossible to play with gain. The hum is from the guitar but seems to be picked up from the amp as the closer it is to the amp the more significant it is. The hum is effected by the guitar volume and I have seen the hum on an oscilloscope comming off the input jack when the guitar is plugged in.

So I'm positive the guitar is picking up the hum but I'm unsure why it is doing so. The pickups are humbuckers of course and the guitar along with the amp are grounded to earth properly since I have a separate earth ground added because my outlets are not grounded(else I get noise if I don't touch the strings).

I get the same noise regardless of any other electrical devices on or off or if moved to another room. The angle of the guitar to the amp also matters.

My best best is that the amp is radiating the 60hz noise and the guitar is picking it up. But why would this be happening? I do realize that some noise will be emitted but this is not normal. The notes are a bit modulated with the 60hz making them sound bad.

I'm not sure if it's a design problem with the amp or something is defective. I have replaced the tubes and the input tube(V1) burned up or was defective as it started oscillating when every I would play very hard(just give give this farting sound when I would pick a note and sometimes would not stop).

Anyone have a diagnosis?

Here is an audio of it. At first I change angles relative to the amp so you can see how it effects it. At some points it gets pretty quite. Then I play with drive and gain about 2 while master is at 12. Reverb and fx loop are off. I then switch to a higher gain with drive at 3, gain at 4, and master at 1. (note I mean in o'clock. 5 is about max)

Notice how the notes distortion sounds more like clipping or noise. I switch angles to clean them up at some points and then as I'm playing I change angles to get the noise(at about 1:05 I play high E and move the guitar angle and you hear how the note starts distorting funky). This definitely does not sound right as I've played on a rectoverb that sings and has virtually no noise with humbuckers. The distortion is smooth and liquid and doesn't sound like some some ditigal POS fuzz box.

I can be 5ft away from the amp and it still does almost exactly the same except about 1db lower.

http://download72.mediafire.com/xkjj...wzmz/noise.mp4

[txstrat]

I'd have a closer look at the cables (go straight into the amp - no effects etc.) and the jacks (input of amp, output of guitar).
See if a solder joint became loose. This worked out fine for me when I had a amp doing the same.
And BTW welcome to the forum.

[Stretto]

As far as I can tell everything looks fine. There are no obvious defective(burnt) components and all the connectors and connections look fine. It is not an issue with the power amp because I can put in a signal into it without any distortion/noise(i.e., I'm bypassing everything before the fx and no hum). I do this by running a mic into a mixer and the out from that into the return.

So its either something wrong with the input/preamp/reverb sections, guitar, or just a very noisy amp.

I wonder if there is a way to check the shielding besides visually?

[Gtr_tech]

Maybe the chassis gnd you're adding is not good enough. Have you tried it on known good power (ie somewhere else) and had the same result?

[tedmich]

good advice, always swap out the cheaper variables (guitar, cable, location in that order) then check grounds on amp, amp cord, wire routing, bad tube noise.

go $->$$$

[Stretto]

I live in an old house. The ground I'm using is from rebar I drove in the ground. The outlets do not seem to have proper safety ground because I would get noise when I didn't touch the guitar strings. When I grounded the amp using the rebar it removed that problem which leads me to believe it is good enough. i.e., it did ground it enough to remove the noise from not touching the guitar. I would expect at least some reduction in the hum from the amp.

Though, when I first got the amp(used) I do not remember it having all that hum. I changed tubes because they sounded bad and even after that I do not remember them having that much hum(of course it had some but just normal hum). After the input tube went bad is about when it started having the problems. I'm not exact on the timings though and I could be completely confused. But I haven't even played my amp much in last 2 weeks because of the hum yet when I first got it I would play it every day.

I'm just not sure where to begin to diagnose the problem. I guess I can try a few more things to see. I'm going to call mesa sometime today hopefully and see if they can help.

[Gtr_tech]

A certain amt of hum is normal when you are not touching the strings.....thats just how high Z p-ups work. Still sounds to me like the chassis gnd is not doing the job. But haul the whole setup somewhere that has correctly wired AC mains supply and see what happens. If you get the same result look to the other variables.

Keep in mind that alot of Mesas use a DC heater supply for some of the front end. I've seen gnd reference resistors in them go supernova and cause noise/voltage problems due to the heater supply being too high/unbalanced. So you won't see a 6.3VAC supply to the first gain stages, it'll be a +/-3VDC supply.

Ok, here's the schematic:
http://www.schematicheaven.com/boogi...e_lonestar.pdf

They don't use the split supply in this one, its a 7812 regulated 12VDC supply. It only is used on V1 and V2. You'd need to check the supply voltage and see where its at. The 2 10,000u caps and the diode gnd reference need to be verified as well. If this is over your head, have a tech check it out. It will cost you more if you go in there and fuss with it and cause more damage than there was to begin with.

[Stretto]

I've taken the out of my computer and plugged in to the amp along with trying a bass guitar. There is virtually no hum(although there is a little bit of static and poping(microphonics I guess)).

This leads me to believe it is the guitar. I've taken a pickup I had and tried it but also get a lot of noise. Maybe the pickups are just extremely hot or I have them hooked up wrong. I'm going to try a friends guitar and see if I have a similar problem.