EL84 fireworks
Moderators: zaphod_phil, Daviedawg, Graydon, CurtissRobin, colossal
-
- Unrated
- Posts: 7
- Joined: Sat 05/21/22 5:24 pm
EL84 fireworks
Hi there, new to this forum but have been perusing this site forever. I'll cut to the chase, I have an 18watt that I built about 10 years ago, not used much but was a very successful build. Great tone etc etc. Well I took it out of storage the other day and found it had a broken el84. I swapped the pair out for some old Sylvania 6bq5/el84 I had lying around, powered the amp up, and after about 5 sec one of the el84 sparks profusely internally.
Can someone guide me through diagnosing and testing the voltages etc to make sure it's not the amp circuit but in fact just dodgy tubes? I've ordered new el84s but want to be sure the amp isn't going to kill them.
Edit.. I have tested the voltages after the main caps and all seem to line up with diagrams I have. I just want to be sure I haven't missed anything.
Can someone guide me through diagnosing and testing the voltages etc to make sure it's not the amp circuit but in fact just dodgy tubes? I've ordered new el84s but want to be sure the amp isn't going to kill them.
Edit.. I have tested the voltages after the main caps and all seem to line up with diagrams I have. I just want to be sure I haven't missed anything.
0 x
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
Sounds like bad tube, especially if the voltages look good. The easiest way to confirm is to swap the tubes around, and you'll see the sparks follow the tube. That's assuming the tube has any life left. Sometimes a tube sparks and that's the end of the story.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
-
- Unrated
- Posts: 7
- Joined: Sat 05/21/22 5:24 pm
Re: EL84 fireworks
Thanks, I had 5 different tubes I tried but they were all same age and type out of an old Hammond organ. Maybe they were all toast. I'll try my new tubes when they arrive. (I bought 2 pairs just in case haha)
0 x
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
If they all sparked, that's suspicious. Try the tube swapping idea, see if the sparks are only in one socket, or if they follow the tubes in question.mentalmuso wrote: ↑Sun 05/22/22 10:20 amThanks, I had 5 different tubes I tried but they were all same age and type out of an old Hammond organ. Maybe they were all toast. I'll try my new tubes when they arrive. (I bought 2 pairs just in case haha)
0 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
-
- Unrated
- Posts: 7
- Joined: Sat 05/21/22 5:24 pm
Re: EL84 fireworks
Initially, they were all in one socket, but the very last one I tried was in the other socket. So yeah I dunno. I think it's best to just be ready to sacrifice new tubes if it comes to that.JMPGuitars wrote: ↑Sun 05/22/22 10:37 amIf they all sparked, that's suspicious. Try the tube swapping idea, see if the sparks are only in one socket, or if they follow the tubes in question.mentalmuso wrote: ↑Sun 05/22/22 10:20 amThanks, I had 5 different tubes I tried but they were all same age and type out of an old Hammond organ. Maybe they were all toast. I'll try my new tubes when they arrive. (I bought 2 pairs just in case haha)
Can I run the amp on only one power tube in a push pull scenario? Just to test? I know I have one good JJ tube.
0 x
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
No, put both tubes in. JJ tubes are trash when it comes to reliability, but if it's an older JJ, it might be okay. All you need to do is fire up the amp and see if only 1 tube sparks. If it's only 1 tube, then swap the two power tubes around and see what happens.mentalmuso wrote: ↑Sun 05/22/22 12:23 pmInitially, they were all in one socket, but the very last one I tried was in the other socket. So yeah I dunno. I think it's best to just be ready to sacrifice new tubes if it comes to that.
Can I run the amp on only one power tube in a push pull scenario? Just to test? I know I have one good JJ tube.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
-
- Unrated
- Posts: 7
- Joined: Sat 05/21/22 5:24 pm
Re: EL84 fireworks
What do you recommend for midrange el84? Brand I meanJMPGuitars wrote: ↑Sun 05/22/22 2:06 pmNo, put both tubes in. JJ tubes are trash when it comes to reliability, but if it's an older JJ, it might be okay. All you need to do is fire up the amp and see if only 1 tube sparks. If it's only 1 tube, then swap the two power tubes around and see what happens.mentalmuso wrote: ↑Sun 05/22/22 12:23 pmInitially, they were all in one socket, but the very last one I tried was in the other socket. So yeah I dunno. I think it's best to just be ready to sacrifice new tubes if it comes to that.
Can I run the amp on only one power tube in a push pull scenario? Just to test? I know I have one good JJ tube.
0 x
- Unit_1
- Newbie
- Posts: 32
- Joined: Sun 11/09/14 6:35 pm
Re: EL84 fireworks
When you say sparks, do you mean it just flashes at power-up? Or are there prolonged sparks until power is off? Hammond used a lot of mullard tubes (among others) and the brief flash at startup is normal for mullards, although not all exhibit this flashing....
I have several on my JTM50 build that flash at startup and sound ***great***
They test as new on my Sencore TC162 solid state tube tester.
I have several on my JTM50 build that flash at startup and sound ***great***
They test as new on my Sencore TC162 solid state tube tester.
0 x
The ability to play/make music is a gift that not everyone gets. Those of us who have it should use it.
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: EL84 fireworks
I use old Russian 6p14p or NOS Sovteks. They're priced very decent and are very sturdy. They sound great too IMHO.
https://youtu.be/DJde9deFb0M
https://youtu.be/DJde9deFb0M
1 x
"THIS should be played at high volume..preferably in a residential area"
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
I like new production Mullard or TungSol, but they're not really available right now.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
Even those have gone up in price significantly with the war.Bieworm wrote: ↑Sun 05/22/22 10:37 pmI use old Russian 6p14p or NOS Sovteks. They're priced very decent and are very sturdy. They sound great too IMHO.
https://youtu.be/DJde9deFb0M
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: EL84 fireworks
It's a sad thing. I bought a batch from a supplier in Ukrain though. 3 weeks after the order they arrived. I paid like 3 or 4 € a piece for NOS Reflector 6p14p tubesJMPGuitars wrote: ↑Mon 05/23/22 6:15 amEven those have gone up in price significantly with the war.Bieworm wrote: ↑Sun 05/22/22 10:37 pmI use old Russian 6p14p or NOS Sovteks. They're priced very decent and are very sturdy. They sound great too IMHO.
https://youtu.be/DJde9deFb0M
And my new builds all sport Voskhod 6N2P preamp tubes. They are excellent!!! Non interchangeable with 12AX7 though.. but I don't care.
BTW, that new reverb unit I built is awesome!!! no hum this time..
You do not have the required permissions to view the files attached to this post.
1 x
"THIS should be played at high volume..preferably in a residential area"
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
I ordered some "used, working" 6p14p tubes for just a little less than that 3 weeks ago, still waiting though.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: EL84 fireworks
lol.. on the gambling tour too I guess.. Out of the 12 I bought from Ukrain one was bad.. that's a good thing I think. The war forces us to get creative, but drags us out of our lazy chair and do something different from what we're used to. Maybe we end up having better alternatives, who knows?JMPGuitars wrote: ↑Mon 05/23/22 7:05 amI ordered some "used, working" 6p14p tubes for just a little less than that 3 weeks ago, still waiting though.
0 x
"THIS should be played at high volume..preferably in a residential area"
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
I bought them to run through my tester, not for my amps. I figure if I get at least one decent pair out of the 8 I ordered, that's a bonus.Bieworm wrote: ↑Mon 05/23/22 7:10 amlol.. on the gambling tour too I guess.. Out of the 12 I bought from Ukrain one was bad.. that's a good thing I think. The war forces us to get creative, but drags us out of our lazy chair and do something different from what we're used to. Maybe we end up having better alternatives, who knows?
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
-
- Unrated
- Posts: 7
- Joined: Sat 05/21/22 5:24 pm
Re: EL84 fireworks
It was a lot of snap and popping in the speaker accompanied by blue flashing with trailing sparks inside. It was great.Unit_1 wrote: ↑Sun 05/22/22 10:33 pmWhen you say sparks, do you mean it just flashes at power-up? Or are there prolonged sparks until power is off? Hammond used a lot of mullard tubes (among others) and the brief flash at startup is normal for mullards, although not all exhibit this flashing....
I have several on my JTM50 build that flash at startup and sound ***great***
They test as new on my Sencore TC162 solid state tube tester.
2 x
-
- Unrated
- Posts: 7
- Joined: Sat 05/21/22 5:24 pm
Re: EL84 fireworks
Just to let you all know, new JJ tubes went in and seem to be working fine. Thanks for all the help
0 x
- JMPGuitars
- Super Duper Admin
- Posts: 3968
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: EL84 fireworks
Oh, that is fun! I had somebody bring me an amp with a similar tube. Instead of blue, it was purple, and it did eventually spark and die. I recorded it before it died: https://www.instagram.com/p/CdJVToTAdyZ/mentalmuso wrote: ↑Thu 05/26/22 8:09 amIt was a lot of snap and popping in the speaker accompanied by blue flashing with trailing sparks inside. It was great.
1 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale