Tube Dampers For EL84's

[Jason Carter]

I was wondering if anybody has ever used a tube damper on an EL84 power tube before. I saw some advertised that can withstand 400 Degree Temperatures. How hot do you think an EL84 tube is running in an AC30?

[Blue Strat]

Hopefully no hotter than 400F! That would be "SumOkin!". :D

[Jason Carter]

Mike,

I guess this is one of those "Here's Your Sign Post" :D.

[stratman_el84]

I believe the maximum bulb temperature was rated at 250C/482F, typical was 180C-200C/356F-392F for the 6BQ5. Still quite toasty.

Cheers!

Strat

[Jason Carter]

I believe the maximum bulb temperature was rated at 250C/482F, typical was 180C-200C/356F-392F for the 6BQ5. Still quite toasty.

Cheers!

Strat

Stratman_el84 thanks for the technical info!

[kidmandude]

Sorry if I dont know the lingo.

Are you referenceing what keeps the tube seated? The spring halo that goes over the tube to keep it from ratteling or falling out? If So yes I have them in my amp..

[Jason Carter]

Sorry if I dont know the lingo.

Are you referenceing what keeps the tube seated? The spring halo that goes over the tube to keep it from ratteling or falling out? If So yes I have them in my amp..

Kidmandude,

I have an EL84 tube that has a slight ring to it when I hit certain notes. I was hoping to try some of these to see if it would help.

http://cgi.ebay.com/8-TUBE-AMP-PREAMP-DAMPERS-12AX7-12AU7-ECC83-EL84-6922_W0QQitemZ320264432560QQihZ011QQcategoryZ64629 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[kidmandude]

Kidmandude,

I have an EL84 tube that has a slight ring to it when I hit certain notes. I was hoping to try some of these to see if it would help.

http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=[CacheBuster]&adtype=1&size=1x1&type=4&campid=5335828753&toolid=10001&mpre=http%3A%2F%2Fcgi.ebay.com%2F8-TUBE-AMP-PREAMP-DAMPERS-12AX7-12AU7-ECC83-EL84-6922_W0QQitemZ320264432560QQihZ011QQcategoryZ64629 QQssPageNameZWDVWQQrdZ1QQcmdZViewItemhttp://cgi.ebay.com/8-TUBE-AMP-PREAMP-DAMPERS-12AX7-12AU7-ECC83-EL84-6922_W0QQitemZ320264432560QQihZ011QQcategoryZ64629 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem (http://rover.ebay.com/rover/1/711-53200-19255-0/1?type=3&campid=5335828753&toolid=10001&mpre=http%3A%2F%2Fcgi.ebay.com%2F8-TUBE-AMP-PREAMP-DAMPERS-12AX7-12AU7-ECC83-EL84-6922_W0QQitemZ320264432560QQihZ011QQcategoryZ64629 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem)

Whoa Jason,

I use an EL84 amp too. And these i did not know of? Wow let me know if these make a difference if you get them? I can't see how they would make a big difference. Has anyone tried these before we would like to hear from you.

Jason make sure your tube didnt go microphonic. Tap on it to see if its no good?

[stratman_el84]

Kidmandude,

I have an EL84 tube that has a slight ring to it when I hit certain notes. I was hoping to try some of these to see if it would help.

http://rover.ebay.com/ar/1/711-53200-19255-0/1?mpt=%5BCacheBuster%5D&adtype=1&size=1x1&type=4&campid=5335828753&toolid=10001&mpre=http%3A%2F%2Fcgi.ebay.com%2F8-TUBE-AMP-PREAMP-DAMPERS-12AX7-12AU7-ECC83-EL84-6922_W0QQitemZ320264432560QQihZ011QQcategoryZ64629 QQssPageNameZWDVWQQrdZ1QQcmdZViewItemhttp://cgi.ebay.com/8-TUBE-AMP-PREAMP-DAMPERS-12AX7-12AU7-ECC83-EL84-6922_W0QQitemZ320264432560QQihZ011QQcategoryZ64629 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem (http://rover.ebay.com/rover/1/711-53200-19255-0/1?type=3&campid=5335828753&toolid=10001&mpre=http%3A%2F%2Fcgi.ebay.com%2F8-TUBE-AMP-PREAMP-DAMPERS-12AX7-12AU7-ECC83-EL84-6922_W0QQitemZ320264432560QQihZ011QQcategoryZ64629 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem)

I'd advise getting new tubes. They shouldn't be that microphonic. If the amp is a head and doesn't have soft-rubber type feet, you could sit it on a piece of foam if you need it to sit on the speaker cab to minimize vibration transfer. If the amp is a combo style, there's not much you can do besides getting new tubes.

I'm averse to the idea of hanging things on power tube bulbs which might affect heat transfer, as even heat transfer over the surface of the bulb at a specific range of convective dissipation rates were a part of the design and could lead to internal mechanical warpage, and there's also the possibility of inadvertantly creating a hot-spot on the bulb, or uneven temperatures over the surface which will cause uneven heat expansion, causing mechanical stress to the bulb itself.

If this is an amp that you built, you might consider adding shock-mounting for the sockets in combo designs to prevent future problems. Weber has shock-mounting kits available for 9 pin sockets. It may also be possible to add shock-mounting kits to a production amp depending on the design, your skills, and the amount of work you're willing to do (or pay someone else to do).

Cheers!

Strat

[Mike9]

The dampers the OP is talking about are high mass and are use to absorb vibration and not heat - I have experienced no adverse affects from using these.

[mcdes]

its only my experince, short as it was, but i tried tube dampers and after trying on a few of my valves, i found that the sound was kinda flat slightly and dulled it a bit, so i took them off and the extra sparkle came back.

just from when i tested on mine, tried the ef86, 12ax7 and the el 84's.

[DGDGBD]

I wonder which spec washer/gasket from home depot these are?

[stratman_el84]

The dampers the OP is talking about are high mass and are use to absorb vibration and not heat - I have experienced no adverse affects from using these.

Yes, I understand what they are and how they're used, I just disagree with the whole idea in general. Tubes transfer heat away from themselves with a combination of convection and radiant cooling. Anytime you put anything in contact with the glass envelope of the tube (or even in very close proximity) you affect the heat transfer characteristics of the tube.

You may not have been aware of any adverse effects, but that doesn't mean there weren't any. Most likely the adverse effects wouldn't result in a catastrophic failure, but show up as reduced service life.

My electronics teacher in high school was a former RCA engineer who had been involved with tube design among other things. The ebay seller of those dampeners states:

"When vacuum tube engineers design these tubes, vibration and microphonics are not factored into the equation. "

which is completely false according to everything I've been taught about tube design. Those were two of the major design problems that were addressed, especially as tubes were used in commercial, broadcast, and military/aerospace applications.

IMO sticking a couple of silicone gaskets around the tube envelope isn't the way to address the problem. The proper way is to use tubes that have been tested and selected for low microphonic characteristics and to mechanically isolate the socket and tube from conducted vibration.

Cheers!

Strat

[bgood]

I've used this with good noise reduction results on my Rivera R55 - EL34s/12AX7s. They helped quiet some tube noise that seemed to happen regardless of what I put in there. For a while they'd be Ok then they'd start rattling - seemed mostly in the pre amp tubes.

I haven't had any ill effects that I notice. I can see the point about the rings impacting the heat dissipation. I'm sure it changes the way the heat comes off the tube - to what extreme - who knows.

[stratman_el84]

I've used this with good noise reduction results on my Rivera R55 - EL34s/12AX7s. They helped quiet some tube noise that seemed to happen regardless of what I put in there. For a while they'd be Ok then they'd start rattling - seemed mostly in the pre amp tubes.

I haven't had any ill effects that I notice. I can see the point about the rings impacting the heat dissipation. I'm sure it changes the way the heat comes off the tube - to what extreme - who knows.

I don't think the effects on preamp tube heat dissipation characteristics would be too critical, as most preamp tubes aren't dissipating a lot to begin with. It's mostly power tubes that I would be really concerned about using these with.

Again though, I still think the better/proper solution is to first select tubes for lowest microphonics and second to mechanically isolate the entire chassis and/or the tube sockets from vibration as much as is practical.

There are many amp designers/builders that refuse to build combo-style amps precisely because of the vibration problems associated with having the amp chassis in the same cabinet as the speaker.

Cheers!

Strat

[Jason Carter]

I received my tube dampers today. I need to better clarify the issue I was looking to resolve. The noise from the EL84 is not coming through the speaker. It is a ring/rattle coming from behing the amp. If you were playing in a club at stage volume the ring/rattle would not be noticable. Playing at the house the ring/rattle is very noticable. My OCD kicks in and the noise is too distracting while I play. So....in come the tube dampers linked in the OP. I put one on the tube that is making the noise, fired the amp up and played for about an hour tonight. Problem solved, the ring/destraction is gone. They seem to work and I did not have to buy a new set of tubes to fix my problem. I think everyone has made some valid points concerning the use of tube dampers on power tubes in this thread.

[Groovey Records]

I'll swear by these- I use them on my EF86 in my Supreme 16

take another peek under your hood you may need to check your oil

EF86 probably the culpret

http://herbiesaudiolab.home.att.net/halo.htm

[UMT]

I've been following these threads regarding tube dampers and shields. I just retubed my DSL401 with JJ Power Tubes and ended up with a combination of JJ/Mullard/Stock Marshall tubes in the pre-amp section.

The DSL401 only has a tube shield on the V1 pre-amp tube. I tried it with it on and with it off and could not tell any difference.

My amp is quiet, doesn't make any sort of noise and I don't have any microphonic problems. Is there any reason to put tube dampers on? (Which by the way, high temp rings can be purchased from ORing suppliers CHEAP online)

I'm thinking: 'Why bother?'

Thoughts?

Thanks,
U..........