Random Flash On One Of My New Tubes????

[Nostalgic Distortion]

So I just replaced the tubes on my Tiny Terror. After installation of 2 Ruby EL84"s & a couple of Gold pin 12AX7"s I turned it on & there was a flash on my right power tube, it kinda looked like a Tesla coil & then it seemed to be fine? I turned it on & off a few times and it looked like it was a one time thing but it just happened again so whatever is going on only seems to happen when the valves are cooled? I played it & it sounds good, actually a great improvement over what it was but it reminds me of a light bulb that's about to pop & die so I'm a little concerned. Anyone else ever see something like this???

 

[beaubrummels]

Re: Random Flash On One Of My New Tubes????

I've only seen it with my Mullard 10M 12AX7A, which for that particular tube manufacture/model, it's normal on startup.

But for an EL84, that doesn't sound normal. I don't recall seeing that with any of my EL84 based amps anyway. Don't know if it could be normal for a particular brand/manufacture.

 

[Nostalgic Distortion]

Re: Random Flash On One Of My New Tubes????

I found some information about this issue on another forum, even a video of it happening so I know he & I were having the same issue. Most people said it should be fine as long as it goes away fast and isn't making any noises? If it makes a pop then it a arc & the tube is dying? I'd still love to hear from someone who has dealt with this first hand to be sure... Perhaps I can get a video of it happening up? It's just a quick flash then everything is normal, I hope they are good because they sound great! I think I remember someone saying something about the heaters but I'm a little concerned about it harming my amplifier?

 

[beaubrummels]

Re: Random Flash On One Of My New Tubes????

Sanity check: your amp has a standby and you power on, let it heat up, then flip the standby and this happens? Or does your amp not have a standby and on power up this happens?

 

[Nostalgic Distortion]

Re: Random Flash On One Of My New Tubes????

The amp has a standby switch but it's happening when I turn on the power, it lasts for about half of a second & then it's fine? When I hit the standby switch it sounds & works great! Also if I hit the power switch when the tubes are still warm it doesn't happen, only when they are completely cooled...

 

[Vasshu the humanoid typhoon]

Re: Random Flash On One Of My New Tubes????

Well the tube is about to die...
We had in one of the shops Vox heads with EL-34's.....total lightning inside the tube!
We changed them!

 

[Nostalgic Distortion]

Re: Random Flash On One Of My New Tubes????

I've got a new set on the way, should be here tomorrow....

 

[JeffB]

Re: Random Flash On One Of My New Tubes????

Yeah. Just a matter of time. Had that issue twice. First time it was a valvetech or whatever..chinese...finally blew and took a fuse out with it. Had it happen again with a jj and it blew instantly but left the fuse intact.

 

[Nostalgic Distortion]

Re: Random Flash On One Of My New Tubes????

Not to beat a dead horse but I talked to the guy that I got the tubes from & he said that this bright flash is nothing to worry about. He said he's got the same issue with one of the valves in his amplifier & its been going on for 2years now with no problems? Oh, his are 6V6's, not EL84's but still new stock power tubes?

He also sent me a video of his Tweaker 15 & sure enough he has the exact same thing going on with it! Right tube flashes @ first & then seems to be fine 1/2 a second later & makes absolutely no noises it shouldn't? I really love the way theses sound & would love to put them back in as long as its safe to do so. I just bought & dropped in some Mesa valves but they don't sound right, too stiff and hard. I do have a little more headroom now but not in a good way, what should I do???

 

[GoldenVulture]

Re: Random Flash On One Of My New Tubes????

Probably re-bias the tubes if you haven't.

 

[Rex_Rocker]

Re: Random Flash On One Of My New Tubes????

Probably a faulty tube. I had a JJ 6V6S do that to me on my Randall, but it was doing all sorts of crackling and popping as well when the amp was on. I replaced it, and it's fine.

Yeah, maybe the Mesa EL84's aren't your thing. They're Sovteks, AFAIK. I believe the stock tubes in the TT were JJ's?

Probably re-bias the tubes if you haven't.

The Tiny Terror is cathode-biased. The amp biases itself.

 

[beaubrummels]

Re: Random Flash On One Of My New Tubes????

The Tiny Terror is cathode-biased. The amp biases itself.

I wonder if that's part of it. My understanding is cathode bias puts the tubes in a safe zone, but not their ideal operating level for sound.

 

[Nostalgic Distortion]

Re: Random Flash On One Of My New Tubes????

Since I re-tubed I've tried a set of Mullard's, T.A.D.'s, the Grove Tubes, & the Mesa's! The Mullard's were alright I guess but still there was just something not right about them, the TAD's & Mesa tubes were just way too hard for this amp & sounded awful, and the Grove Tubes were pretty much perfect in tone but I've got this heater issue? I ordered some J.J.'s today, maybe there's a reason they use them stock (aside from the fact that they are cheap)?

It's a good thing I've got three amps that run off a pair of EL84's in the power section because I'm going to have a lot of spares after this!!! Hopefully the J.J.'s will be the solution, I'm going to try some different preamp tubes as well, I've got Gold Pin E-H 12AX7's in it now and I normally love the way they sound but I've also had this problem before. The answer ended up being some no-name super soft Chinese valves I ripped out of another amp because they weren't right for my It but worked great in my AC-Twin & AC-30???

I'm hoping after I get X-mas out of the way & my credit card bills taken care of to get the parts for the Holy Terror Mod. Replacing the transformers & doing the mod is something I can probably do myself as its supposed to be a pretty easy but I think I'll send it out to have the work done and have it serviced at the same time??? Sending this out for work isn't such a big deal because of the size and weight, if one of my AC's goes down its probably going to cost me more for shipping than parts and service!!! 70+ lbs unpacked makes for a pricy trip, now that my AC-30 is loaded with Blues its probably closer to 95lbs???

 

[Rex_Rocker]

Re: Random Flash On One Of My New Tubes????

I wonder if that's part of it. My understanding is cathode bias puts the tubes in a safe zone, but not their ideal operating level for sound.

Well, the amp was designed to run with cathode biased tubes. That's how they voiced it. Cathode bias runs tubes pretty hot, actually.

I think you may be thinking of non-adjustable fixed bias like Mesas or 5150's where they set them so that they run the power tubes safely cold, and it cannot be adjusted without actually modding the amp.

Since I re-tubed I've tried a set of Mullard's, T.A.D.'s, the Grove Tubes, & the Mesa's! The Mullard's were alright I guess but still there was just something not right about them, the TAD's & Mesa tubes were just way too hard for this amp & sounded awful, and the Grove Tubes were pretty much perfect in tone but I've got this heater issue? I ordered some J.J.'s today, maybe there's a reason they use them stock (aside from the fact that they are cheap)?

It's a good thing I've got three amps that run off a pair of EL84's in the power section because I'm going to have a lot of spares after this!!! Hopefully the J.J.'s will be the solution, I'm going to try some different preamp tubes as well, I've got Gold Pin E-H 12AX7's in it now and I normally love the way they sound but I've also had this problem before. The answer ended up being some no-name super soft Chinese valves I ripped out of another amp because they weren't right for my It but worked great in my AC-Twin & AC-30???

AFAIK, TT's have also come with Rubys and EHX's stock, but the latest ones have come with JJ's. I guess they just put whatever it's cheap for them to get, reliable, and doesn't sound too bad.

After going through 4 brands sets of power tubes for my Krank (Tung Sol 5881, Tung Sol 6L6GCSTR, JJ 6V6S, and Sovtek 5881/6L6WGC), I came to the conclusion that I liked the cheapo Sovteks that everybody hates the best in that amp. Some amps are more flexible when it comes to tube experimentation, but sometimes cheapy stock tubes sound good in certain amps because that's what they used when designing the amp in the first place.

Oh, and the Chinese 12AX7's are by far my favorite for anything that involves distortion. My Krank, Randall, and Peavey all love the Ruby 12AX7AC5's which are just re-branded Shuguang 9th Gens.

 

[Nostalgic Distortion]

Re: Random Flash On One Of My New Tubes????

I agree with you on the preamp valves, in this amp & my AC's absolutely nothing sounds better than cheap Chinese tubes! I got my J.J.'s today so I'll try them out in the morning and then try out some different 12AX7's to see what works best. My buddy put a 12AT7 in V1 of his & it sounds amazing but he's had the Holy Terror mod done? That's the way I'm leaning too, (sounds great and looks even better with them orange transformers & the multi choke in it) but its probably not going to happen until after the new year?

I hate Christmas so much!!!! When I was 10 I got a $20 J.I. Joe toy & that was like a really big deal? This year my 10 year old son wants $600 cell phone for his "big gift" & a few games too, for $600 it should come with @ least 3 beer flavored nipples and a case made out of Giant Panda leather!!!! This isn't one of those back in my day stories either, I'm only 34????