My amp took a poop last night! Help!

[Lord Toneking]

Played a private party last night. I was using my Splawn and everything was fine until a breaker blew and shut us all down. Once power was restored I turned my amp back on and we continued to play.

Just 2 songs in after the power outage I noticed I was losing volume. I turned up and I knew right away that there was a serious issue. I had my amp turned up to 10:00 which on any other day would have blown the tent we were playing under across the street and over the neighbors house! It's a LOUD amp!

I noticed then it was sounding all crackley and breaking up. All the tubes were glowing perfectly but I shut it down. In my mad dash to get to the party on time I not only forgot my backup head but I also forgot my spare power tubes I did have some pre tubes and swapped those with no results. I switched to half power and used only two power tubes but that didnt work either

You guys think it's a tube problem? The only other time I had an issue I could see a tube red plating. The tubes are about a year and a half old with quite a few hours on them...but I'm biased pretty cold (27ma-29ma)

 

[Vrad]

Have you tried it since then? Wondering if it had to do with the power where ever you were playing?

 

[Shawn Lutz]

sounds like power tubes or tranny to me.

 

[nevusofota]

Sounds like a preamp tube to me. Did you change them all? Thats the first thing I would do.

I had an outdoor gig last summer with my 5150III. The exact same thing happened to the power at the event. A few songs later my volume was getting lower and became distorted (in a bad way). Things got progressively worse. Wound up being a bad preamp tube. I since purchased a Furman power regulator and it hasn't happened since.

 

[Lord Toneking]

Have you tried it since then? Wondering if it had to do with the power where ever you were playing?

No, it's just sitting in my living room. Everyone else kept playing and there was another band with no issues

I'll fire it up here in a few and see what happens. I do have a quad of old Mullards that I can toss in there but they have some hours on them...and I dont have any way to bias today

 

[Lord Toneking]

Sounds like a preamp tube to me. Did you change them all? Thats the first thing I would do.

I had an outdoor gig last summer with my 5150III. The exact same thing happened to the power at the event. A few songs later my volume was getting lower and became distorted (in a bad way). Things got progressively worse. Wound up being a bad preamp tube. I since purchased a Furman power regulator and it hasn't happened since.

Not all at once but just one (at a time). I will try this first I hope that's it

 

[glip22]

Usually a breaker blowing will not cause any voltage spikes which can definitely cause a problem if your fuses do not do their jobs. As posted swap all of your tubes out. I would start with the PI tube as that will definitely cause a volume loss if one triode fails. Check your power tubes bias first.

 

[Vrad]

Have you tried it since then? Wondering if it had to do with the power where ever you were playing?

No, it's just sitting in my living room. Everyone else kept playing and there was another band with no issues

I'll fire it up here in a few and see what happens. I do have a quad of old Mullards that I can toss in there but they have some hours on them...and I dont have any way to bias today

I bet it's tube-related. Try a different set of tubes. Check the fuses (although it turns on, so it's probably not that).

 

[Ventura]

Usually a breaker blowing will not cause any voltage spikes which can definitely cause a problem if your fuses do not do their jobs. As posted swap all of your tubes out. I would start with the PI tube as that will definitely cause a volume loss if one triode fails. Check your power tubes bias first.

This. Re-glass, done.

Mo

 

[Lord Toneking]

found the culprit. PI tube was bad

Last night i just grabbed one pre tube out of my gig bag and here that tube was bad as well. I had 3 spares and I grabbed the bad one, go figure

thanks guys! I'm a happy camper...I get to use my Splawn for tonights party instead of the mighty HT-5

 

[steve_k]

Gary won tonight's door prize.....

 

[glip22]

Gary won tonight's door prize.....

And that will be what... Really how many times have you been jamming and poof there goes allot of volume. Sometimes with crackling. First thing me does is swap the PI and has always been the culprit. Well not always. I can tell when it is probably the PI. Now, a cooked OT. Thats a different sound. My last one sounded like a jet engine. Same sound as when you reverse your OT primaries going to the PT sockets. That'll wake you up.

 

[squank]

found the culprit. PI tube was bad

Last night i just grabbed one pre tube out of my gig bag and here that tube was bad as well. I had 3 spares and I grabbed the bad one, go figure

thanks guys! I'm a happy camper...I get to use my Splawn for tonights party instead of the mighty HT-5

Man, this has been the issue with diagnosing so many amp problems. The 'good' tube you use to see if it's a tube problem turns out to be a bad tube. It's tough to remember, but I try to remember the rule of 3s - try 3 different 'good' tubes in each spot before you declare that it's not the problem.

Glad you got it figured out!

 

[FIREBALL]

it could have made the secondary fuse blow which we make it seem like a tube....but not the main fuse