random LOUD buzzing through 68 deluxe reverb

[jorbjorb]

I was playing through the amp this morning at low bedroom volumes (1-2) and my amp started to buzz LOUD enough to shake my entire house. No guitar sounds can be heard during this buzz. I had to turn the amp off right away. After I disconnected my guitar pedals and plugged straight in it worked fine again. This has happened about three other times within the last two months but only when I'm using the following scenario.

1. Pedals are plugged into the same outlet as the amplifier.
2. Using telecaster with maybe bad grounding? I installed new pickups myself on it.

When I plug my pedals into a different outlet in the room it seems to fix the problem? I don't know if this is the real issue though as I've been plugging the pedals and amp into the same outlet for about 3 years now. I never played the telecaster much before this started happening.

I'm currently playing into it with my jazz master and no pedals and it's working just fine....

It almost sounds like it's an internal problem with the amp but it is puzzling me why it is random... Anyone have this issue before?

I would like to prevent this from happening again because it scares the sh*t out of everyone that I live with.

 

[Lowerleftcoast]

I'll take a guess.
I think it is runaway oscillation. The pedals may add some gain to help get the oscillation started.
Tube going bad. Possibly a cap.

Tap on tubes at volume to see if you can create the buzz.

Clean all the tube pins and sockets to see if it helps. Clean all jacks as well.

 

[Lowerleftcoast]

Take out tube V3. It is the reverb tube. See if you can recreate the buzz with V3 removed.
Try the same by removing V5. The vibrato tube.

 

[Lowerleftcoast]

Tell more about the amp. How often is it played. When was it last serviced. Do you have different tubes to try?

 

[Dacious]

It sounds to me like a dud lead, or bad input jack. Possibly the ground on the lead

 

[JDB2]

In my experience, intermittent noise like that is usually a bad or loose tube. So tubes should always be checked in the first round of trouble shooting.

Clean all the tube pins and sockets to see if it helps. Clean all jacks as well.

+1

I once had an amp arrive after shipping cross-country and upon clicking off standby it would do nothing but buzz, a buzz just as you describe. I found the buzz would come and go when I wobbled one of the power tubes with my finger (before it was too hot to touch). So I pulled the power tubes, sprayed some deoxit on the pins, and carefully reseated them. No more buzz.

 

[stantheman]

I had this problem thirty years ago with my 1968 Deluxe Reverb too. In my case one of the tube sockets had a hairline crack - and when it warmed up...well.

 

[jorbjorb]

Tell more about the amp. How often is it played. When was it last serviced. Do you have different tubes to try?

Bought in 2016 and I probably only play it twice a week. Never serviced. No tubes to try. I will start by checking out the tubes tomorrow though.

 

[Milspec]

Try tapping/slapping on top of the amp while it is powered up and see if that duplicates the problem. Seen that problem on Peavy Delta Blues amps....a runaway oscillation is correct.

 

[schmee]

Sounds like a cord or jack issue to me.

 

[jorbjorb]

Try tapping/slapping on top of the amp while it is powered up and see if that duplicates the problem. Seen that problem on Peavy Delta Blues amps....a runaway oscillation is correct.

Ya I smacked the amp and nothing happened.

Sounds like a cord or jack issue to me.

I'm leaning towards this as the issue here. Played again this morning with one of my cords plugged straight into the amplifier with no issues. I'm going to try ordering some new cables and replace the pedal board patch cables with something of higher quality. Hopefully no more issues after that.

Thanks again everyone for your help.

 

[Milspec]

Ya I smacked the amp and nothing happened.


I'm leaning towards this as the issue here. Played again this morning with one of my cords plugged straight into the amplifier with no issues. I'm going to try ordering some new cables and replace the pedal board patch cables with something of higher quality. Hopefully no more issues after that.

Thanks again everyone for your help.

Sounds like you find the problem. If the hard tap didn't duplicate it, it was not likely to be in the circuit nor the tubes....cable makes sense.

 

[schmee]

Ya I smacked the amp and nothing happened.


I'm leaning towards this as the issue here. Played again this morning with one of my cords plugged straight into the amplifier with no issues. I'm going to try ordering some new cables and replace the pedal board patch cables with something of higher quality. Hopefully no more issues after that.

Thanks again everyone for your help.

I had an import cord once that kept giving me trouble. I could see nothing wrong with it. Eventually I discovered that the shank on the jacks was metric 6mm/undersize.... not 1/4". Not sure if it wasn't grounding well or if the looseness made the ball tip not contact well.

 

[JDB2]

From the description of the buzz in the OP it was very loud - house shaking loud - even though he wasn’t playing the guitar loudly. I infer the buzz was loud even though the amp volume was not. If so, the buzz can’t be coming from a bad jack or cable. I have had the exact syndrome from a poorly seated power tube. And a very similar problem from a power tube that was failing.

 

[jorbjorb]

From the description of the buzz in the OP it was very loud - house shaking loud - even though he wasn’t playing the guitar loudly. I infer the buzz was loud even though the amp volume was not. If so, the buzz can’t be coming from a bad jack or cable. I have had the exact syndrome from a poorly seated power tube. And a very similar problem from a power tube that was failing.

Thanks for the response. I'll look into this.

 

[jorbjorb]

Update:
The random buzzing ended up being a permanent one. Turns out it was a failing 12ax7 tube that eventually fully failed.

Cost of tube + diagnosis: $200 CAD

Lesson of the day: check your tubes

 

[Burning Fingers]

Update:
The random buzzing ended up being a permanent one. Turns out it was a failing 12ax7 tube that eventually fully failed.

Cost of tube + diagnosis: $200 CAD

Lesson of the day: check your tubes

Another lesson for the day...find another tech.

$200 for a 12ax7 plus diagnosis time = OUCH ...what $30 for the tube and $170 for time? ... the first thing to check with noise problems is the tubes ... a 10 minute job ...even allowing for a minimum charge of 30 minutes time the tech charged $340 an hour.

 

[Jasonpatrick]

FIRST THING YOU ALWAYS CHECK IS TUBES…. ALWAYS ALWAYS ALWAYS…
And find a new amp guy, that’s a damn ridiculous bench rate.

 

[jorbjorb]

Another lesson for the day...find another tech.

$200 for a 12ax7 plus diagnosis time = OUCH ...what $30 for the tube and $170 for time? ... the first thing to check with noise problems is the tubes ... a 10 minute job ...even allowing for a minimum charge of 30 minutes time the tech charged $340 an hour.

This was the breakdown. Note the that the value is in CAD. So around $150 USD. If I bought the tube + shipping it probably would have cost me around $ 55 CAD.

 

[Burning Fingers]

Wow .. I thought paying $30 Aud inc postage ($27.80 Cad ) for a 12ax7 in Australia was bad, but you are paying well over that in Canada !