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Post by Deleted on Jul 6, 2017 6:47:46 GMT -7
Blondie developed an intermittent buzz/hum last night in band practice--suspect a preamp tube. Will investigate today, probably not a big deal--but definitely re-emphasizes the need for a keeping a good backup amp on hand when gigging.
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Post by scottunzicker on Jul 6, 2017 7:57:30 GMT -7
Blondie developed an intermittent buzz/hum last night in band practice--suspect a preamp tube. Will investigate today, probably not a big deal--but definitely re-emphasizes the need for a keeping a good backup amp on hand when gigging. Or at least a known good set of back up tubes. I have an old, hard-sided sunglasses case that holds 2x 12AX7s and 2x 12AT7s perfectly, and I have a backup set of 6V6s taped up in their boxes in case a power tube goes sideways on me (which actually happened a while back). Also, I keep 3-4 fuses in a little case, as well. Good luck!
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Post by Deleted on Jul 6, 2017 8:14:22 GMT -7
I do the same, but it's a lot easier to switch amps mid-set than troubleshoot hot preamp tubes.
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Post by simpleton on Jul 6, 2017 8:37:31 GMT -7
I do the same, but it's a lot easier to switch amps mid-set than troubleshoot hot preamp tubes. That IS next level. I just kept spare tubes and fuses in the compartment of my guitar case. But I never needed them.
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Post by Deleted on Jul 6, 2017 15:27:40 GMT -7
Apparently as simple as swapping out V1. Left the amp turned on for a couple of hours and it's quiet as a Quaker meeting. Also had the pleasure of playing straight in with the amp semi-cranked for the first time in awhile--usually I'm running it clean with a dirt pedal and a skosh of delay--boy, does it give up the goods. What a primo amp this critter is.
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Post by Deleted on Jul 11, 2017 17:18:44 GMT -7
Well, balls. Noise (loud buzzing hum) re-appeared at practice just now--pretty sure it's not a power issue or environmental. Starts up when amp is cooking; not evident when tubes are cool, so implies a tube issue, I guess. Argh. Will futz around with it some more, maybe take it into local repair dude to sort out if that doesn't work.
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Post by premiumplus (Dave) on Jul 11, 2017 19:41:08 GMT -7
Check out Doc's tube amp troubleshooting steps on his website. Also, after it's warm and humming take a pencil or a chopstick and lightly tap each tube starting with the little preamp tubes on the right as you're looking at the back of the amp. Oftentimes this will change the nature of the noise when you tap the faulty tube. Have a guitar plugged in and the amp turned low when you're doing it. It sure sounds like a tube issue. Good luck Jon, you can do it.
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Post by Deleted on Jul 12, 2017 7:34:28 GMT -7
Thanks. Yeah--it's just a time suck and involves lugging gear back and forth, but will attempt to DIY trouble-shoot before throwing in the towel. I've got a full set of replacement tubes on hand, so that's not an issue. I'm just slightly spooked due to the problem that developed in my other Lux, which required a trip (for the amp, not me) to Cleveland. It's not the same noise, though.
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Post by MacStevenXIII on Jul 12, 2017 12:53:00 GMT -7
The V3 tube in my Z-Lux went microphonic on my last week
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Post by nicholas on Jul 13, 2017 15:25:34 GMT -7
That blows. Hope you get it sorted.
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Post by Deleted on Jul 13, 2017 19:10:59 GMT -7
Thanks, Nicholas. It's part of the reason I have two of them. Will try to dig into it tomorrow—have to fetch it from our practice space, lug it home, open it up and see if I can get it buzzing. It's the intermittent stuff that's tough to sort out--for me, at least.
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Post by Deleted on Jul 18, 2017 20:15:35 GMT -7
So this is interesting. I took Z-Lux #1 down to our practice space and ran it at practice tonight, same pedalboard, same setup--and it start to buzz/hum, too. So now I'm thinking it's environmental, right? Not a tube issue at all. So I plugged into a different outlet across the room, hoping I'd be on a different circuit--still made the noise. Tried plugging straight into the wall, bypassing my voltage regulator--ditto. We even turned off the central AC unit, thinking that it might be creating the problem when it cycled on--didn't help. So now I'm wondering if it might not be coming from some other part of my rig--pedalboard seems the most likely suspect. I've never heard of such a thing, though. Other possibilities: evil spirits, sunspots, Russian hackers--who knows?
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Post by BritInvasion on Jul 19, 2017 4:03:10 GMT -7
Are you running wireless by any chance? I've seen strange stuff due to cellular towers injecting noise.
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Post by Maddog on Jul 19, 2017 5:13:28 GMT -7
Do your amps make that same noise when they're away from your practice space, Jon? Like at home?
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Post by benttop (Steve) on Jul 19, 2017 6:43:42 GMT -7
So this is interesting. I took Z-Lux #1 down to our practice space and ran it at practice tonight, same pedalboard, same setup--and it start to buzz/hum, too. So now I'm thinking it's environmental, right? Not a tube issue at all. So I plugged into a different outlet across the room, hoping I'd be on a different circuit--still made the noise. Tried plugging straight into the wall, bypassing my voltage regulator--ditto. We even turned off the central AC unit, thinking that it might be creating the problem when it cycled on--didn't help. So now I'm wondering if it might not be coming from some other part of my rig-- pedalboard seems the most likely suspect. I've never heard of such a thing, though. Other possibilities: evil spirits, sunspots, Russian hackers--who knows? Rule number 1 when troubleshooting noise issues - plug straight in. Pedalboards are the most likely cause of a bazillion different issues. Think about how many cable connections you have there - it only takes one flaky connection to drive your whole system wild. I had a particularly troublesome problem that I isolated to my pedal board, but I just couldn't find the culprit, so I started removing boxes and cables one by one, until the problem dropped out, and sure enough, I found an intermittent jumper cable there.
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Post by Deleted on Jul 19, 2017 6:47:52 GMT -7
Are you running wireless by any chance? I've seen strange stuff due to cellular towers injecting noise. Nope--no wireless, and all cell phones turned off.
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Post by Deleted on Jul 19, 2017 6:48:45 GMT -7
Do your amps make that same noise when they're away from your practice space, Jon? Like at home? I wasn't able to reproduce it at home--but I was also using a different pedalboard at home.
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Post by Deleted on Jul 19, 2017 6:55:43 GMT -7
So this is interesting. I took Z-Lux #1 down to our practice space and ran it at practice tonight, same pedalboard, same setup--and it start to buzz/hum, too. So now I'm thinking it's environmental, right? Not a tube issue at all. So I plugged into a different outlet across the room, hoping I'd be on a different circuit--still made the noise. Tried plugging straight into the wall, bypassing my voltage regulator--ditto. We even turned off the central AC unit, thinking that it might be creating the problem when it cycled on--didn't help. So now I'm wondering if it might not be coming from some other part of my rig-- pedalboard seems the most likely suspect. I've never heard of such a thing, though. Other possibilities: evil spirits, sunspots, Russian hackers--who knows? Rule number 1 when troubleshooting noise issues - plug straight in. Pedalboards are the most likely cause of a bazillion different issues. Think about how many cable connections you have there - it only takes one flaky connection to drive your whole system wild. I had a particularly troublesome problem that I isolated to my pedal board, but I just couldn't find the culprit, so I started removing boxes and cables one by one, until the problem dropped out, and sure enough, I found an intermittent jumper cable there. I've had loss of signal due to bad cabling in a pedalboard, but not buzzing leading to loud hum. That's the issue--amp starts to buzz, like single coils under a rheostated ceiling fan (I'm playing a Lester, though), then after a bit it produces a loud and very unpleasant hum. Turn the amp off, then back on, and the noise goes away for awhile, which is why I thought it was a tube issue (also, most issues are tube issues). It may be coming out of a specific pedal, the one I mostly use in practice, but I've never had a pedal do anything like this, so who knows. I'll see if I can reproduce the issue at home, and then it's a matter of going through, as you say, one component at a time.
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Post by doctorice on Jul 19, 2017 7:41:59 GMT -7
Jon, you need to put Det. Coffin on the case
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Post by Deleted on Jul 19, 2017 8:28:33 GMT -7
Jon, you need to put Det. Coffin on the case Frank would be baffled. Maybe Rudy knows a guy who knows a guy.
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Post by Maddog on Jul 19, 2017 9:03:44 GMT -7
Jon, you need to put Det. Coffin on the case Frank would be baffled. Maybe Rudy knows a guy who knows a guy. I've got to start reading more....
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Post by greenblues58 on Jul 19, 2017 9:07:46 GMT -7
Just a thought as l have had reverb noise issues with various amps before and it turned out the whole system cable and pedal included where acting as an antennae. I had it particularly shortly after my Vibrolux was rebuilt with new caps etc and had previously been silent after its rebuild. The noise and hum etc would fluctuate and get louder but if l switched the reverb off at the footswitch or removed the footswitch it would go. On talking it through with my amp tech he asked if l had moved the amp into a different position in the room when l had actually put it in a different room so he advised moving the amp into a different position and lo and behold just picking the amp up 6 " of the floor and rotating the amp through 360 degrees there was a couple of silent spots and a couple of extremely noisy spots and everything in between. All my tube driven reverb amps do it in that particular spot including the Z lux ,l owned very briefly , my deluxe reverb and recently acquired Victory deluxe .
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Post by Deleted on Jul 19, 2017 9:22:29 GMT -7
I've had RF interference issues with reverb amps before, but this seems different. Also, I did not have the footswitch connected, if that makes any difference. Plus, it's really weird that it would crop up suddenly in the same space we've practiced in for the last 18 months or so, unless some neighbor's acquired a huge CB or ham radio setup, maybe.
I've got Lux #1 and pedalboard-in-question plugged in and fired up in my guitar room. So far I'm not hearing anything untoward. It seems to take awhile for things to get going, though--we'll see.
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Post by Deleted on Jul 19, 2017 11:36:53 GMT -7
Okay, it's been plugged in and turned on for over two hours at band volume, with the usual pedal array also running, and aside from a normal amount of hiss given the gain I've got running into the front end, it hasn't reproduced the noise. Which is baffling. Maybe it really is RF interference of some really horrible kind, local to our practice space.
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Post by Deleted on Jul 19, 2017 13:38:33 GMT -7
Running for four hours, no sign of the problem. Played through it just now and it sounds great--no buzz, hum, or any other damn thing. So I'm back to square two in thinking that it's an environmental issue, probably RF interference from some powerful source near our practice space, coming through the reverb circuit. So now my question is, what's the best/safest way to disconnect the reverb circuit? Just unplug the tank? Pull the send/receive tubes? Both?
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Post by premiumplus (Dave) on Jul 19, 2017 14:47:34 GMT -7
If you pull the reverb driver tube you'll lose all sound. I'm pretty sure you can remove the reverb recovery tube without signal loss, but this is from memory. You could try disconnecting the tank, but first you also might try using the footswitch. It shunts the reverb signal to ground. It may or may not be different than turning the reverb control to zero, but it's an easy experiment. I'd do that first and then pull the reverb cables from the plugs on the bottom of the amp chassis.
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Post by Deleted on Jul 19, 2017 15:14:34 GMT -7
Sounds reasonable--thanks!
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Post by j4gitr (John) on Jul 19, 2017 16:18:12 GMT -7
Maybe a pedal on the board is receiving RF interference. Try rehearsal without the pedalboard if you haven't already. I think I would try that before disconnecting the reverb. I know our church has some hearing aid compatibly system that is running under the carpet or somewhere like that. Every now and then I will receive a slight ?? cycle hum. Nothing that interferes with my playing or even loud enough for the congregation to hear but its perceptible to me. These little gremlins are sly devils. Good luck with the hunt.
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Post by Deleted on Jul 19, 2017 17:09:17 GMT -7
Also reasonable advice.
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Post by DRZ on Jul 20, 2017 1:44:04 GMT -7
Jon I have been following your thread. I must say I do not advocate removing or disconnecting any part of your Z Lux in an attempt to solve this issue. I have found in my 30 years at this, that even the best and most careful attempts to troubleshoot a problem this way can cause additional problems.
So try this simple method to eliminate your environmental problem, I'm assuming this to be a RF issue as I don't believe you have an amp problem. Also all DR.Z reverb amps have an RF trap circuit installed to help eliminate just this issue. But with us now being bombarded with WiFi, Cell phone, Radio, TV and many other types of in air frequency assault, a simple snubbing cap cannot possible handle the bandwidth in todays air ways. So try this: once your amp starts buzzing grab the handle pick it up and slowly spin the amp CW and CCW. This will be like turning the tuning knob on your radio and can detune the troublesome frequency. It may not stop it completely depending on its strength , but it will demonstrate to you the source of your problem. Understand if the RF is present in your wall wiring then this will have no effect, as the problem is entering your amp through the power cord.
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