Oh no my tube!

[Bloodstone]

One of my 5U4GB tubes in my triple rectifer cracked today and I don't have a replacement nor can I get one locally without ordering it and that will take days! The rest of the tubes are 6L6GC's so my question is can I play my amp without that tube in there (I haven't attempted to yet out of fear) or can I temporarily replace it with a 6L6? And what are the 5U4GB tubes for anyway?

 

[kylek]

NO NO NO NO NO NO NO

they do COMPLETELY DIFFERENT THINGS.

6l6 = powertube = amplify yoru sound and supply power to the speakers. 5u4 = rectifier tube, it converts AC current to DC current.

DO NOT REPLACE IT WITH A 6L6.

you can take out two of the 6L6's though and run it at 100 watts. I am not sure if it is the far left and far right, or the two middle ones, I believe it would be the 2 middlemost 6l6's check your manual.

 

[Bloodstone]

OK see this is what I call the learnign process. I ask rediculous questions and get definitive answers lol.

So I have 3 of these 5U4GB's and the first on on the left busted. Now my manual will tell me how to pull some 6L6's out and make it 100w and playable again? What would happen if I played it with just that one tube taken out? Just curious, but it sounds like my best bet is to suck it up and just turn it off until I can get a new tube and some spares.

 

[ibanez4life SZ!]

^That probably would be the best idea.

Also, if you use the Silicon Diode rectifier, you should be able to play it without a problem. When in silicon diode mode, you don't use the rectifier tubes.

 

[Dale B.]

Pull all of the Rectifier tubes out of the amp and swap it over to Silicon Diodes.

I wouldn't pull two power tubes because the Impendence will be off.

 

[musicbox]

Pull all of the Rectifier tubes out of the amp and swap it over to Silicon Diodes.

I wouldn't pull two power tubes because the Impendence will be off.

agreed.

do this, and you should be fine!

 

[tele_jas]

Unlike the Dual Recto, you can't run the Triple safely at anything but 150wts. Just pull the rectifier tubes out until you get the replacment and run in the solid state rectifier mode, you'll be fine.

 

[Dale B.]

Unlike the Dual Recto, you can't run the Triple safely at anything but 150wts. Just pull the rectifier tubes out until you get the replacment and run in the solid state rectifier mode, you'll be fine.

You can run it safely, but there will be weird mismatches.

Pull a pair - Amp is now 10.667 ohms out of the 16 ohm Impendence Jack. Weird mismatch. The 8 ohm jack is now at like 5.333 ohms and you can run an 8 ohm load, but it's still a weird mismatch. 4 ohm Jack is now 2.66 ohms and a 4 ohm load is safe, yet a weird mismatch.

Pull a quad and you drop everything down by 2/3.

I haven't ever tried it. Some amps tend to hum very badly when running weird mismatches like that.

 

[tele_jas]

Unlike the Dual Recto, you can't run the Triple safely at anything but 150wts. Just pull the rectifier tubes out until you get the replacment and run in the solid state rectifier mode, you'll be fine.

You can run it safely, but there will be weird mismatches.

Pull a pair - Amp is now 10.667 ohms out of the 16 ohm Impendence Jack. Weird mismatch. The 8 ohm jack is now at like 5.333 ohms and you can run an 8 ohm load, but it's still a weird mismatch. 4 ohm Jack is now 2.66 ohms and a 4 ohm load is safe, yet a weird mismatch.

Pull a quad and you drop everything down by 2/3.

I haven't ever tried it. Some amps tend to hum very badly when running weird mismatches like that.

I was just going by what Michael at Mesa Boogie told me when I asked him about pulling tubes in my triple recto. He said you could probably do it to record a song part, but he couldn't recommend me running with pulled tubes for any longer because he said I'd probably harm the amp.... He said I may be lucky and it may run like that for a little while or it may not make it through one show. I figured he knew more than I did so I never tried it :wink:

 

[Dale B.]

Unlike the Dual Recto, you can't run the Triple safely at anything but 150wts. Just pull the rectifier tubes out until you get the replacment and run in the solid state rectifier mode, you'll be fine.

You can run it safely, but there will be weird mismatches.

Pull a pair - Amp is now 10.667 ohms out of the 16 ohm Impendence Jack. Weird mismatch. The 8 ohm jack is now at like 5.333 ohms and you can run an 8 ohm load, but it's still a weird mismatch. 4 ohm Jack is now 2.66 ohms and a 4 ohm load is safe, yet a weird mismatch.

Pull a quad and you drop everything down by 2/3.

I haven't ever tried it. Some amps tend to hum very badly when running weird mismatches like that.

I was just going by what Michael at Mesa Boogie told me when I asked him about pulling tubes in my triple recto. He said you could probably do it to record a song part, but he couldn't recommend me running with pulled tubes for any longer because he said I'd probably harm the amp.... He said I may be lucky and it may run like that for a little while or it may not make it through one show. I figured he knew more than I did so I never tried it :wink:

Nah, the Output Transformer isn't seeing as much current as it would when it's operating during normal loads.

The only thing that you're really worried about on a Dual Rectifier when you pull tubes and compensate for the Impendence differential is the power tubes. If you don't make that change, the load the power tubes will be seeing is much greater. The Rectos are typically biased fairly cold, but it's always a good thing to check to be on the safe side. A lot of Mesa owners and a lot of people who own tube amps don't understand the concept or know the first thing about biasing an amplifier.

The only bad thing that could happen is if your power tubes are running too hot, you could blow screen grid resistors and your Mains Fuse when the tubes short. That's the main thing, but you can run into arcing and other things that I'm too tired to think about at the moment.

Anyway, like I mentioned before, it may not be too big of a deal because the cathode current is so low. Also, each mode on the Variac switch (Bold/Spongy) and each rectification option will have different plate voltages. In some settings, there may be enough room to compensate for the higher cathode current draws. The Dual Rectos usually don't see anymore than 100 mA global at Idle Current in the Bold/Silicon Diode position with Mesa Tubes in them. The Triple Rectos don't usually see anymore than 150 mA global in that same position with Mesa Tubes. It definitely can vary depending on the power tubes and the current coming in from the wall.

If you're not exceeding those figures by a great margin, you're OK. When you pull tubes, your OT is on vacation.

That's just something to think about. Like I said earlier, I would just pull all the rectifier tubes, swap her over to Silicon Diodes and let her rip.

Dale

 

[Bloodstone]

Ok now I am not in a good mood at all. :evil: :evil: :evil:

I pulled all 3 of my rectifier tubes (5U4GB) ans switched to my Slicon Diodes. Within 30 seconds of playing I blow a fuse, a puff of smoke comes out of my top grill, and I smell burnt ****. I replace the fuse, turn the power to ON with standby switch in standby mode. Power light comes on, I switch standby switch to ON and I hear a loud POP and my lights dim in my room, I switch the standby switch back to standby to prevent fuse from blowing.

So now I have a Triple rec with one known busted 5U4GB, which I caused it to go bad, and now I took you guy's advice and now my amp is shot to **** and I'm going to have to take it to a repair specialist and have him work on it and who knows how much thats gonna run me. What a great night. Anyone got anymore suggestions I could do since the amp is already shot I don't know how much more damage we can do to it.

 

[Bloodstone]

Ok I pulled out all my tubes and found one that smelt burnt, it was a 6L6. I replaced the tube and turned it on. I have sound now but amp is making strange noises and when i tap on any tube or eventhe amp itself it makes a buzzing crackling static noise.

I have all the 5U4GB's pulled and the toggle switch set to silicone diodes. My power is set to Spongy also. Any clue what this could be or do I need to take it in to a shop.

P.S. sorry if i came off rough on the last post, i really do appreciate your help but whem my baby isn't working right I get upset

 

[Bloodstone]

Ok I pulled another 6L6 (actually the one I just replaced, it was an older spare) and it stopped making the noises. I replaced it with another spare and now it is not making noises but after a few minutes the tubes are extremely hot to the touch. Is this normal or should I be concerned.

It sucks that the tube that originally burnt out was a brand new tube only 3 weeks old. I hope its not something inside the amp causing this. If the 5U4GB went bad and started popping fuses could it also have blown the 6L6 beside it?

PS
All the tubes are coded RED but the first 4 are numbered 05 the 5th one is a 10 and the 6th one is a 05. Will this cause problems now?

Oh the horror....

 

[Humbility]

sometimes tubes blow after only a short while. I bought a single recto and one of the 6l6'd blew in less than 3 days. Who KNOWS how long it had been at the store, but still. So anything is possible man.
Hum

 

[Dale B.]

So now I have a Triple rec with one known busted 5U4GB, which I caused it to go bad, and now I took you guy's advice and now my amp is shot to sh!t and I'm going to have to take it to a repair specialist and have him work on it and who knows how much thats gonna run me. What a great night. Anyone got anymore suggestions I could do since the amp is already shot I don't know how much more damage we can do to it.

Pulling all the rectifier tubes and swapping the amp over to the silicon diode rectifier option wouldn't have caused this to happen to the power tubes. It looks like you have had a power tube short.

If you have seen smoke, you need to take it to a tech as soon as possible. You could have had a power tube arc and that leaves tracing on the power tubes sockets. If it can be, the power tube socket needs to be cleaned or it needs to be replaced. That is if that has actually happened.

The static noises or other weird noises are more than likely coming from the power tubes.

Like I mentioned earlier, you need to go have it looked at.

 

[ibanez4life SZ!]

It looks like hte original problem might have been a power tube also.....I think it may be time for a complete retube, just for the safety of your amp.

 

[Bloodstone]

If you had to do a complete retube of a triple rect what would you put in it for a tone thats thick and heavy i.e. metallica godsmack, tool, etc..

And would you do the preamp tubes also and if so what kind too.