Triple Rectifier help (tube newbie)

[illbeinyourband]

Hi,

I am experiencing some weird issues with my Triple Rectifier. This being my first tube amp (just got it about a year ago, but have only been playing it heavily the last 6 months), and my first "problem" with the amp, I'm pretty lost and this seemed like a good place to get some pointers.

So I had the amp on standby last night for a few hours, and ended up deciding not to play. I go to turn it off, and I notice a smell, kind of like a faint burning smell (and different from how it normally smells while running). I looked at the tubes, and some of them were glowing extra orange. I turned it off.

Some friends came by shortly after, and I decided to start it up again, but when I turned it on, it made a loud popping noise. But it played fine (I was playing at low volume). The next time I started it up, there were no popping noises but after a few minutes of playing, the amp made a brief, weird sound (hard to describe... like a "whooo" sound, kind of low pitched, but at a much louder volume than the amp was putting out). Again, after this, playing was fine and it hasn't happened since.

I'm just wondering if these are symptoms typical of dying tubes, and if I should just replace them, or if these could be signs of something worse.

Thanks!

Bryan

 

[domct203]

Do you have your speaker impedence correct?

What power tubes are in the amp? Are they Mesa Tubes?

When you say "I looked at the tubes, and some of them were glowing extra orange", do you mean the grey metal plates were orange-red in spots, or that the tube just seemed "brighter" looking?

If the amp was in standby, there is no high voltage going to the powertubes, only the heaters are on.

Did you buy the amp new, or is it used? If its used, with the same tubes it came with, it's time for new power tubes. You have no idea how long those tubes have been in there.

When a power tube fails, it could take out other components in the amp with it. DO NOT keep playing the amp it it shows signs of Tube Red-Plating, where the grey plates in the tubes start to go red/orange in color, or if there are strange loud noises.

If the amp is less than 5 years old, you should call Mesa and see if the warrenty is still valid. This will cover internal parts in the amp, but for tubes you are on your own.

Dom

 

[illbeinyourband]

Thanks for the quick response.

Yes, speaker impedance is correct, the 8 ohm output to an 8 ohm 4x12.

The amp was purchased new, and it still has all the Mesa tubes in it. The only tubes I noticed a difference in were the preamp tubes. In the leftmost (while facing the back) few tubes, there was a searing orange glow straight down the middle of the tube, from top to bottom, very strong. So I guess that sounds like what you're describing.

A power tube went out a few months back. I talked to the guy at the shop I bought the amp at, and he said that I could still play through the amp, but the power would be reduced. Is that not correct?

So it sounds like I need to replace the power tubes?

 

[illbeinyourband]

I'm sorry, the glow was in the 6L6's :?

 

[illbeinyourband]

And it was a rectifier tube that went out and I was told I could play the amp without. I'm really embarrassed, and sorry for getting these details wrong.

 

[domct203]

Thanks for the quick response.

Yes, speaker impedance is correct, the 8 ohm output to an 8 ohm 4x12.

The amp was purchased new, and it still has all the Mesa tubes in it. The only tubes I noticed a difference in were the preamp tubes. In the leftmost (while facing the back) few tubes, there was a searing orange glow straight down the middle of the tube, from top to bottom, very strong. So I guess that sounds like what you're describing.

A power tube went out a few months back. I talked to the guy at the shop I bought the amp at, and he said that I could still play through the amp, but the power would be reduced. Is that not correct?

So it sounds like I need to replace the power tubes?

Hmm- I'm a little confused, you say that the only tubes you noticed a difference in was the preamp tubes, and there was a glow down the middle of the left few tubes?

Let's make sure you understand the amp.

Preamp tubes
These are the smallest tubes in the amp, usually under small metal covers. In the Triple Recto there are 5 of them, all are 12AX7. These tubes will shape your tone, provide overdrive, bring you guitar level up to feed the power section, buffer your FX Loop (if used) and balance the operation of the power section.

Rectifier Tubes
These are the tubes that (when chosen with the SS/Vacuum Tube switch) will convert the AC voltage from your home, to the DC voltage that your amp needs. In the Triple Recto there are 3 of them, all are 5U4GB.
One Rectifier tube is needed per pair of Power Tubes.

Power (output) Tubes
These are the tubes that provide the 150 Watts of output power. In the Triple Recto there are 6 of them, and from the factory all are 6L6GC. These are utilized in pairs (Class AB), and need to be matched. In the Triple Recto the pairs are arranged as (A)(B)(C)(C)(B)(A).

Now, if you blow a rectifier tube, yes you can run the amp without it. If you use the Vacuum Tube Rectification setting like this, the 2 Rectifier tubes will not be able to supply enough voltage levels to the 3 pairs of power tubes, output power will drop, and the amp will most likely be over compressed sounding, lacking any punch or authority and the difference should be very noticable due to the power tranny's sag, or lack of ability to keep up with voltage demands. If you run the amp in Silicon Diode mode, the Rectifier tubes are not being used, instead a SS Diode curcuit is used and full power is being utilized, with just about no power tranny sag.

If it is the 6L6CG power tubes that are glowing bright red/orange on the plates STOP using the amp and replace the power tubes.

BTW- check the rating on the mains fuse. It should be a 4amp Slo-Blo. If there is anything else in there replace it immediatly. That fuse is there to protect your amp in situations like this. IMHO im suprised it didn't blow already.

Dom

 

[domct203]

I'm sorry, the glow was in the 6L6's :?

Opps, Missed that post.

Still, check that fuse.

Dom