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Post by cacibi on Jul 12, 2006 18:15:48 GMT -7
Okay - so got the amp home and it has a noticeable whine - which I'm assuming is coming from the reverb.....also has some fan noise - which doesn't bother me as much.
The whine in the reverb gets worse if it is full off, or full on and mellows out, but is still there, when the reverb knob is at 12' o'clock straight up.
Let's get the troubleshooting started!
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Post by billyguitar on Jul 12, 2006 18:29:55 GMT -7
I'm assuming the guitar is unplugged?
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Post by cacibi on Jul 12, 2006 18:34:09 GMT -7
I'm assuming the guitar is unplugged? I don't know what you mean.....the guitar is plugged into the amp. Also, the amount of whine seems to be affected by both volume controls - master has the most effect. There a lot of noise as I turn up the Cut knob.
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Post by billyguitar on Jul 12, 2006 18:35:43 GMT -7
I was wondering if the whine went away when there is no guitar cable plugged in. You might want to try wiggling the cables where they plug into the amp and into the reverb. Just give them a few twists and see if maybe it is a weak connection.
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Post by cacibi on Jul 12, 2006 18:46:04 GMT -7
I see - sorry, didn't see what you were getting at.
I'll see if it happens without the guitar cable plugged in. Checked the reverb tank connections and they seem fine. Any tubes in particular that I should try swapping out? Should I try disconnecting power from the fan? I'm wondering if vibration from the fan might be a factor.
Also - The tube chart on the amp indicates 4 - 12AX7's and 1 - 12AT7, but the tube info on the Dr. Z site for replacement tubes lists two 12AT7's:
-GT12AX7S, 1-GT12AX7S, 1- GT12AT7C, 1-GT12AX7R1, 1-GT 12AT7 NOS, 1-Quad GT EL-84-S, 1- 5AR4
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Post by cacibi on Jul 12, 2006 19:15:15 GMT -7
So far I've tried replacing V3, V4 & V5 and unplugging the fan. So far no resolution, although the whine has gotten a little tamer. Now it's mainly noise from the Master volume and cut knob that is the issue. The whine DOES NOT occur when the instrument cable is unplugged from the input of the amp.
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Post by cacibi on Jul 12, 2006 19:59:30 GMT -7
Okay - after messing around a bit more, it seems the problem is related to the Cut knob. With the Cut rolled all the way back, I get no noise or whine - also, obviously, no treble.
Update: it seems like a combination of the cut knob, master volume and reverb - the cut knob can activate it at around 9:00, then the Master volume and reverb can aggravate the problem when rolled on. Could it be microphonic power tubes?
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Post by billyguitar on Jul 13, 2006 6:42:26 GMT -7
If you don't get the noise when there is no cable plugged in then I don't think it's tubes. I suspect it may be an effect pedal's power supply. The sound you describe sounds like the sound I hear some pedals make when they don't like a One-Spot power supply. Try plugging directly in a humbucker guitar, no effects and no tuner. If it's still there try switching cords. It could also be something else altogether, like a digital watch or cell phone or perhaps a motor running in the house on the same circuit like a refrigerator or an aquarium pump.
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Post by cacibi on Jul 13, 2006 6:57:53 GMT -7
Well - I have been getting more than the usual amount of 'cell phone stutter' so - I'll try shutting down some wireless gizmos, and removing what I can from the circuit.
As for the pedalboard and cord - I've never had any grounding or other issues with this rig through my other amps. I'd be surprised if the problem was there. I tried going direct with my tele on a few cords and that didn't help - but I'll try a humbucker guitar for kicks.
The reason I though it might be power tubes was the way it seemed to get worse when I turned up the master volume, but then again - when you turn up the volume, you turn up everything I guess, noise and all.
I'm also wondering if I can get by safely without using the cabinet mounted fan, at least for recording - cause it would definitely be audible through a mic. I would even be tempted to use a smaller fan farther from the amp to circulate air live. Mine almost seems like it's unbalanced, it has kind of a cyclical grind to it.
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Mike
Junior Member
Posts: 52
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Post by Mike on Jul 13, 2006 8:35:29 GMT -7
Sounds like the guitar cable to me. Those will get microphonic too. Most of the time if you unplug from the amp and the problem goes away then the amp is ok. Definately try a different cord and guitar, you have nothing to lose trying them.
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Post by billyguitar on Jul 13, 2006 9:07:40 GMT -7
If it's any tube at all it would be a preamp tube. power tubes just amplify what comes to them. Sometimes they may rattle but whine would be unlikely. To test the preamp tubes get any 12AX7 that you know is fine, pull one out of another amp, preferably the tube farthest away from the power tubes. Then replace your tubes one at a time and see what you get.
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Post by cacibi on Jul 13, 2006 10:14:38 GMT -7
Well - here's what I've pretty much eliminated - it's not any of the following:
cords/cables pedalboard Other appliances/electronics on the circuit instrument
I'm going to pick up some power tubes and preamp tubes to swap out today, just for fun (I'll have a backup set for emergencies even if that's not the culprit) - but have not ruled out wireless interference as - now that I think about it - there is a cell tower on top of my apartment building. I'll have to power it up at another location to eliminate that suspect.
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Post by billyguitar on Jul 13, 2006 10:35:46 GMT -7
You're doing all you can. Like any problem, try the easy stuff first.
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Post by cacibi on Jul 13, 2006 12:38:11 GMT -7
Okay - all tubes have been replaced except the rectifier. Can't purchase one locally, so have one on the way via the internet machine.
In the meantime, going to try to contact the shop for more help.
Thanks all for your replies and suggestions.
I have to say, except for the noise - it sounds great!
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Post by billyguitar on Jul 13, 2006 13:38:55 GMT -7
I'll still bet it's a line power problem.
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Post by cacibi on Jul 13, 2006 17:54:31 GMT -7
Well I'll be damned. I think you may be right. I was just monitoring my Maz 18 through headphones and I hear it on that one too - same exact thing. It's got to be either power or interference from the cell tower upstairs. I feel better that it's not something gone wrong in a used piece of gear. Whew - was a bit worried I got one that had been abused.
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Post by billyguitar on Jul 13, 2006 19:34:46 GMT -7
Sounds like the answer. No guarantee but you might try a real good power conditioner. If it doesn't work you could easily return it. Check out the return policy wherever you buy one, if you do.
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Post by cacibi on Jul 14, 2006 7:10:07 GMT -7
I'm running everything on a Furman now. The voltage is a little hot (125), but I hate to think I need to get a voltage regulator to run these without the noise. That's a pretty big investment.
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Post by billyguitar on Jul 14, 2006 8:36:56 GMT -7
I have a Furman regulator and that introduces a whole 'nuther set of problems. The 4% higher than ideal voltage shouldn't be the cause. I think it's just something you'll have to live with. Sorry.
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Post by cacibi on Jul 17, 2006 8:54:53 GMT -7
Well - the good news is that I had a chance to gig it this weekend and the whine was gone, noise is still there. It's definitely a liveable amount with respect to the volumes at which it occurs. Thanks for your replies.
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Post by squeallydan on Jul 21, 2006 7:25:23 GMT -7
I just changed out all my tubes on my Maz and it is real quiet. IT was making a wierd noise but the noise was there even if the guitar was not plugged in. I guess it was a totally different thing than what your describing, but what would it hurt to change out all the tubes. It'll cost some money but if its a used amp it might be a good idea.
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Post by cacibi on Aug 3, 2006 7:29:11 GMT -7
Well - after messing around with a bunch of factors I've decided that the problem was a combination of factors, including the Maz probably being more sensitive to single coil hum than other amps I have played, not unexpected as it is higher gain than the fender-ish amps I am used to. It is definitely a liveable amount of line noise for the volume and tone I'm getting - so I am not at all regretting my purchase. Both my 18 2x10 and my 38 2x12 sound amazing and I couldn't be happier. Thanks to everyone for their help troubleshooting.
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