budlovesaly said:
With the loop engaged or disengaged, if you turn down the volume in the channel you are in, no matter if it's high gain or low gain, and, if you turn down the gain, do your amps make a loud hum/noise that is audible through your speakers? If so, does it still make this hum/noise when you disconnect the instrument cable from your guitar?
Not to be cute but the noise gremlins are very hard to determine at times. Here are my experiences based upon 3 mesas, a Mitchell, an Acoustic, a Fender, and [just so no one else does] a partridge in a pear tree. :lol:
O.K. I know this is serious so here goes [every one of the following got the tube sockets retentioned and best 12AX7s (or 12AT7s for the non Mesa amps where applicable) I could find for the reverb units in all since that seems to be a strong hum and breakup problem for me].
1) Mitchell Pro 100 [circa 1970s] = lots of noise as I raise the gain no appreciable hum unless my reverb tank is too close in proximity to another amp or power unit of some type. Then the caps start going south and hum starts to go on the rise. Re-cap, new tubes, a few resistors replaced and quiet as a church mouse unless I run my compressor and break during high gain setting solos. Fixed and given to a kid at church who is quite the good guitarist at 15 still needing to learn about how to get tone from a real amp which requires ones ears to find the settings and not a preset one push models all amp.
2) Acoustic 165 [circa 1970s] = no hum even with the reverb tank in close proximity to other power units or amps. Even when the caps started to go and a power tube red plated there was no hum. Fixed and working well.
3) Fender 75 [circa 1980??] = V1 preamp tube cracked hum - hum - hum. Use the high gain channel via switch slight hum based upon volume rise not volume reduction.
4) .50 Caliber 6BQ5 [circa 1986?] = First Boogie and substantial hum even in standby through speakers. Took it to my local tech (Tube Sonics Amps in Sacramento, CA) and discovered the tubes where shot, it needed a cap job, the PCB was as brown as it gets around the power tube section, the OT was not just going south but mislocated somehow and the wires needed some rerouting and a few extra twists along with replacing several tube sockets as well as resoldering the connection on others. New Mercury OT as well as new Mercury Reverb Tranny plus new tubes (three quads of 6QB5 tubes until I finally put a sleeve bearing fan at about a 30 degree angle across the speaker and away from the side mounted reverb tank due to much hum coming through the speakers in on position) and an extreme amount of resistors and I think 1 or 2 diodes.
Also, resolder the input jack lead and test all grounding points plus use new lock washers on the pots for the grip behind the faceplate! After getting a TAD balanced 7025-S in the PI
[noted that when I pulled the PI all hum when away] there is very little hum unless I want to make ears bleed with the volume this little box emits and in which case the law of high gain amps and finding the perfect tube set while recognizing that the more I push a high gain amp the sooner I better be replacing my power tubes and (less frequently but sooner then not) my preamp tubes [and the law of grid resistors as well]. Also resoldered the little wire which can connect to the shock mount screws on this cab. One last note on the .50 is that I stopped using the effects loop due to it being real hard on my power tubes as well even though I was only using a Boss EQ pedal with either a battery or a power supply. Seems that Mesa's reference to testing any piece of equipment through the effects loop prior to purchase of said equipment to determine how their amps' effect loops are affected is real important.
5) Mark III [circa 1985] = Complete cap job, solder all tube sockets, replace a bunch of resistors, clean, locate the "snap-crackle-pop" loose resistor on V6, new sleeve bearing fan, new Classic EV 12 200W [peak] speaker, replace all tubes with Mesa Yellow Rated power tubes (6L6 and EL34 simulclass) plus a balanced TAD 7025-S in the PI & Mesa SPAX7s in the other preamp spots, refinish the Imbuya cabinet using just the Perifin oil and a finishing paste and no hum unless .. refer to high gain remarls in #4.
6) Heartbreaker Version B [circa 2000?]= Winged C 6L6, running in Tube Rectifier mode with TAD 7025-S and a balanced TAD 7025-S in the PI with two Gold JJ 12AX7 tubes (one in V6 for reverb and one in V2 due to senior moment on counting) and holy bat :shock: - Here is a ten year or so old amp which is quiet up to the "refer to my high gain remarks in #4" and actually can get a little more gain then I even think I need to make ears bleed with little hum until 50% [a speculative figure due to number of volume and master pots there are].
The thing about the input jack wire resolder was the this seems to be a cause of much grief when determining hum related problems as there are so many other factors once the amp is played/jarred in transit/ used repeatedly at high volumes, etc. But I thought it may be important overall to give all the variables I have ran into. I am sure and I have read there are many many more.
Respectfully,
Dennis
