Random Static issue on clean channel

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bandit2013

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This issue creeps up once in a while. I notice it more on the clean channel. Random static sound though the speakers. This may be caused by loading on the AC line or transients caused by the central heating and cooling system. This issue was more of a concern in one room I was using for general use. However, the issue was not associated with that one room as I moved the amp to a different location. Now the random static issue has lessened in occurrence but is still present even with the central heating and cooling system turned off. I have not unplugged the refrigerator yet as that may be another cause (that one uses an ECM motor on the compressor which in fact may be a brushless DC motor as I can tell the compressor is running at a variable speed). The dishwasher on the other hand is hard to avoid eliminating the line noise from that.... not the cause of the static problem.

I will order some new Mesa 12AX7 tubes to replace the ones in the amp as what I have now in my box of preamp tubes have been used at least once in the Roadster or Mark V. They are still good but would rather rule out preamp tubes with new ones. I also have a new set of Mesa power tubes 6L6 STR440 in a close color code to the one's that came with the amp. Perhaps I should try those too. If I cannot eliminate the static creep or random static issue with new preamp tubes or power tubes. I will give Mesa customer service a call on the issue.

Odd thing, I had both Roadster and JP-2C on the same ac line power up and active. I was using an isolated signal splitter to run both amps. Static is present though the JP-2C but not the Roadster.... the obvious is that both amps are not identical in design so that could be one thing. First I will see what new tubes will do if that does not resolve the problem I may be sending another amp to Mesa for service...... To note I have not even seen the innards of this amp so my warranty should still be intact. I will wait for the TC-50 to return before I send in the JP-2C.
 
It will be one of those issues that comes and goes. Played through it at lunch with the AC running and it did not happen. Still has the same tubes. I have to stock up on some new tubes anyway so may as well get them. May get another quad of 6L6GC tubes and ask for them to be the same. Last set I got were blues and green. May be okay to use in the amp as it is not required that both pairs be identical. Those are close enough anyway. Not like this is a bass amp with the KT88.... I doubt I have yet to break the amp it as the TC-50 arrived not long after getting the JP. I cannot say I like one better than the other, just depends on what I want to play.
 
I have one plan if the static becomes persistent and I cannot isolate or confirm AC line transients if tube replacement does not cure the issue would be to take the amp and cabinet to work and run it though a programmable AC power supply set to 110VAC at 60Hz. We have several of them as we have several products that we have designed and manufacture for use in Europe or Asia as well as test and evaluation of some other products that are sensitive to variations in the AC line voltage and frequency (brushless DC motors are one of the primary products) and many others. It would be easier to take the amp and 412 cabinet to work than to attempt to move the programmable AC power supply as they are extremely heavy (more than 300lbs). Those are a valuable tool for isolating the line transients as well as ideal performance since one lab is running from a Delta 3 phase transformer and the other lab is running off of a Y 3 phase transformer. At least that would keep the power consistent at the programmed voltage and frequency. If static continues under that condition it would point to either power tubes or preamp as the line transients would be non existent. I do not think this to be necessary. I will have to order more preamp tubes as the new ones I had in storage are already in the JP-2C. The remaining preamp tubes are just spares that have been pulled from amps so most may not be ideal. New power tubes may be required but I do have a quad of new Mesa 6l6 tubes but the two pairs are of different color code. (blue and green if I recall correctly). I did run them in the amp for a short time when the came in however I thought the grays sounded better but that just may be psychological and not actual. Sometimes I hear the static and sometimes I don't. When it does creep in it is not the typical popcorn noise you hear with a preamp tube boiling off the cathode coating (that is what it sounds like if it were a heated pan of tomato sauce bubbling up once in a while but at a consistent interval). The static issue is more like a machine gun burst that may last half a second to 2 seconds. Due to the intensity of the noise level it could be the power tubes. I do not have enough hours on the tubes to be a concern but I am sure I passed the six month period of ownership on the amp. No big deal on that.... but this amp has not seen any tubes other than Mesa and has not had the chassis removed from the shell. It should still be covered under Mesa warranty. More than likely a tube issue but still could be an AC transient that has nothing to do with the amp. This brings up a concern that can be corrected assuming the consumer power conditioners are of any use (clamping of voltage spikes makes them worth while) , not at the same caliber of the industrial AC power sources I have at work. Will have to take a look at them and figure out what would work for my application.
 
I had a very similar occurence myself the other day, it was the first time I had run something into the FX loop and switched the clean channel on at start up. It lasted for just a brief second. I tried to duplicate it two times since and nothing. I have very clean consistent power at my home and have never had this issue with this amp or any other. If you discover anything on this please post an update as I am curious if it's an actual issue or just a one time thing.

Mark
 
As it seems now that I am waiting for it to happen again, it is not happening, even with the central air cycling. I have not changed any tubes yet either. By the sound of it I am convinced it is AC line related. I did call Customer Service on the issue. They believe it may be a power tube. That it could be. I have not changed the power tubes since I got the amp but have not put as many hours on the tubes as I have with the TC-50. The more I think of it and how unpredictable the symptom has become it may actually be a power tube. I could see if I can excite the condition by tapping on them.
 
A watched kettle never boils hey! Don't you just love those intermittent problems. My Mark V tuned itself into some European old analog radio station the other week, really loud too so that you could almost hear it even when playing on ch1. Only did it for an hour and hasn't happened since. Was quite funny listening to some language I can't understand running on about what must have been pink floyd as that's what they where playing. Back on point I would guess power tube, might just be one of those quirks of old technology though, it is magic that happens in those little glass bottles after all!
 
For radio reception, all you need is a diode and a tuned LRC circuit and if a broadcast is not playing to the FCC rules you may find yourself listening to something unexpected. You guitar is also a good antenna for some low frequency AM stations. The Mark IV was awesome for radio reception in a particular room. The question is, was it though the air waves or was it thought he power line? The filament transformer does a great job at amplifying low level signals on the AC circuit. Reason I do not play though my amps when the dishwasher is running since the motor noise from the dish washer bleeds into most audio circuits except with the TV or home theater. Transient filters usually help eliminate the effects of AC line noise.

I will be trying out the ribbon mic today with the JP-2C. Thinking of getting a recording of this amp with something better than what I have been using as my condenser mic's just seem too harsh and the dynamics just do not cut the mustard. Cloudlifter or mic activator should work with the dynamics but is more necessary for the ribbon mic. The manufacturer of the Cloudlifter (designed for the Cloud ribbon mic) is also great for the EV RE320 (I have one so will have to try it with the ribbon mic as I got the dual channel cloudlifter). In short (is that possible?) the JP-2C will present its static issue when I am recording. It dawned on me there was one appliance I have not ruled out yet.... the electric water heater and I believe that one uses PID control with an power puck relay (solid state) as it turns on without any mechanical noise. Considering the random noise and its duration that may be the culprit. Also it generally stays in energy saving mode but may heat the water periodically as I think the issue may be related to environmental conditions. Seems more apparent at night than during the day and it has been getting cooler at night lately.

Also the randomness of the event is not predictable.... so it is a 50/50 chance it is external or tube related. And if it is tube related, it does hold to the nature of the beast since tubes cannot be manufactured in bulk and remain consistent like transistors or monolithic amplifiers.
 
Yeah always makes me chuckle when a bit of radio Luxembourg comes through an amp. Very rarely happens with the Mark V though. Used to happen all the time in my old house garage where i used to live with both a Peavey Bandit and a Marshall Valvestate. Most likely caused this time by the 30m extension lead I had used to get power to my new garage. Only pulled a proper mains supply cable through this week and I'm yet to get the fuse board fitted and hooked up so that will probably cure this particular problem.

Look forward to hearing the new mics you have, both with the JP-2C and the Mark V. Also look forwand to hearing if you get your noise issue narrowed down to a particular cause. Love a good puzzle me!
 
First run though with the mic and cloudlifter. At best this is a learning curve that needs more attention than I am willing do put in but I do like to listen to my own music so probably worth the effort. I started with the Roadster first and opted to use the Rivera attenuator with the OS Recto 412 loaded with EVM12L black label speakers. I used the SE Voodoo VR1 and a EV RE320 with the dual channel cloudlifer. I never knew the RE320 could sound so good. It never satisfied me before without the mic activator. Almost rivaled the ribbon mic. For some odd reason I still decided to throw a match pair of condenser mics arranged in the typical 90degree offset and panned hard left and hard right. I used the recorder as the input for the Rivera signal out set to EV pattern. I could have omitted this as it did not really contribute the full sound. If you use the patterns it simulates an SM57, better to dial in your own as I have done that many times with better results. Anyway it was set to a low level and I put it out of phase as that helped to reduce the room effect since the drum set is adjacent to the speaker cab. A full drum set adds reverb to the room and could swamp the recording. I could have used a isolation material but opted to see what the figure 8 pattern would do first. I did not want a sterile recording.... I could go on and on.... blah blah blah... in light of Alex Lifeson's speech for the hall of fame. I may post the recording but will do it over with a different placement of the mics. I had them about 5 feet from the cab and so far that sounded good. Ribbon mics do not have the same proximity effect as do dynamic mics so I will try it closer to the cab and may try a different cab combination like the horizontal 212 and the vertical 212 as that provides more depth to the sound than the 412. Why not post the recording, I will do it once I load it up to soundcloud.

Back to the point of the thread...... static at random....... while dialing in the recording of the JP-2C I did not get the static, but once I started to play, bingo it was there in abundance. At that point I had two options, one was to pull all of the circuits on the power panel of the home and the other was to change tubes. I opted for the ladder as I had a new quad of green Mesa 6L6GC STR440 waiting to be used. I already cycled through preamp tubes and could not isolate the occurrence of the problem. Of course the next course of action is to start pulling preamp tubes to see if it is preamp vs power supply. New tubes did not cure or curb the issue. Static was still present. Opted for option 1 and turned off all of the 220VAC breakers first. Static was still present but subsided and did not return during the recording session. Why only the JP-2C is affected and not the other amps? Perhaps that huge power transformer has something to do with contributing to the problem especially as I believe it may still be AC line transients as that has not been fully ruled out. I have run several amps at the same time with the JP-2C on the same circuit, only amp that spits out the static is the JP-2C. Next step is to take it into work and run it with the AC power source to rule out AC line transients.

I would say the static issue sounds similar to this person's Mark V..... there is a video attached in the top thread. Not as severe but very much the same magnitude of static.
http://forum.grailtone.com/viewtopic.php?f=33&t=73792
 
Since I had to order new preamp tubes, Actually got enough for two amps, may as well get another quad of 6L6 tubes. Also decided to add something to my gear that I do not have. Furman Power conditioner. Why not? I get more ground noise with the Mark V than any other amp so at least that would reduce or eliminate that problem. Too bad the static issue is not simple....like a guitar cord or jack. I get the static with nothing plugged into the amp.

May just pull all the preamp tubes except for the PI and see if it still happens. Since the static is random in occurrence it is difficult to narrow down as noise associated with tubes can be random. Does not seem to matter if the amp is hot or just turned on so I doubt it is thermally related but could be. I have reason to believe it is on the front end so V1 would be the first candidate to remove once the static starts up or becomes less random as this has crept up a few times. Issue is not isolated to just the clean channel but is more noticeable when using the clean channel and does not seem to be associated with the tone, gain or volume controls.

If the issue cannot be resolved with multiple tube swaps, I have gone through the entire box of mesa preamp tubes, and all of the Mesa 6L6 tubes to no avail, I doubt 12 more preamp tubes and a new quad of 6L6 will cure the issue as it has all new tubes in it now. More reason to believe it is external and not internal but only one way to find out.... take the amp into work and power it up with the programmable AC power source (that will definitely rule out static as a result of AC line transients which is what I believe the issue to be).
 
I tried the Furman PST-8 power strip with the JP-2C for a few hours and two sessions. First run was with the replacement Mesa 6L6 tubes (green) and the questionable 12AX7 tubes I had available. Not a instance of static. I had everything running on the AC electrical panel, no breakers switched off. I played for a while until the Central heating/cooling system cycled a few times, nothing... I let the tubes cool down so I could install the original 6L6 tubes (gray). Same thing, no static noise. So far all is good so at least I was able to narrow down to AC line transients at the moment. Will have to see what happens when I move the amp to another room where noise is more prone to occur since the amp sounds better in that room for some reason. I highly doubt it is the amp causing the issue but more so the AC line source. At least I can put this issue to bed. Needed a reliable power source anyways as I was getting pops in the recording gear once in a while associated with the Central heating /cooling system. Water heater is also another source of electrical line noise. The acid test would be to run the dish washer as that appliance creates motor noise transients that I can hear in the speakers. It that goes away with the Furman power strip I will be a very happy camper.
 

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