EH Gold 300B crackle

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Michael L
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#1 EH Gold 300B crackle

Post by Michael L »

I've noticed that when I turn on my Border Patrol SE300B amp
(heaters+signal HT +neg 90V bias) I get some brief bursts of crackling from one of the o/p valves. The other valve is quiet and crackle moves with the valve when swap the two over.
So far I haven't heard any crackle after the HT (to o/p stage) has been switched on more than a minute or so.
I bought the valves new less than six months ago.
Is the valve on it's way out? Could I ask the valve supplier for a replacement?
Everything sounds very good when I'm playing music.
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Paul Barker
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#2

Post by Paul Barker »

I don't know the circuit diagram but if it has 6sn7's and they are Chinese or Russian you have your answer.
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Nick
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#3 Re: EH Gold 300B crackle

Post by Nick »

Avinunca1 wrote:I've noticed that when I turn on my Border Patrol SE300B amp
(heaters+signal HT +neg 90V bias) I get some brief bursts of crackling from one of the o/p valves. The other valve is quiet and crackle moves with the valve when swap the two over.
So far I haven't heard any crackle after the HT (to o/p stage) has been switched on more than a minute or so.
I bought the valves new less than six months ago.
Is the valve on it's way out? Could I ask the valve supplier for a replacement?
Everything sounds very good when I'm playing music.
I dont think there is any reason why you should not ask, sounds like its the valve, and new valves should not do it. Was it from a "official" EH supplier?
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Michael L
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#4 Re: EH Gold 300B crackle

Post by Michael L »

Nick wrote:
Avinunca1 wrote:I've noticed that when I turn on my Border Patrol SE300B amp
(heaters+signal HT +neg 90V bias) I get some brief bursts of crackling from one of the o/p valves. The other valve is quiet and crackle moves with the valve when swap the two over.
So far I haven't heard any crackle after the HT (to o/p stage) has been switched on more than a minute or so.
I bought the valves new less than six months ago.
Is the valve on it's way out? Could I ask the valve supplier for a replacement?
Everything sounds very good when I'm playing music.
I dont think there is any reason why you should not ask, sounds like its the valve, and new valves should not do it. Was it from a "official" EH supplier?
I bought them here -http://www.hotroxuk.com/electro-harmoni ... -grid.html I will contact them and update this thread. Thanks Nick
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Nick
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#5

Post by Nick »

Ok, well, if its Hotrox I can't see there being any problem. I use them a lot. Let us know how you get on.
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#6

Post by jack »

Nick wrote:Ok, well, if its Hotrox I can't see there being any problem. I use them a lot. Let us know how you get on.
Indeed.

I was reading that page above when I noticed that they sell "Matched Single" valves :)

Also, the comment below was a bit strange: "The Gold plated grids offer more stability than the standard Nickle plated type enhancing better tonal quality due to reduced grid current".

The standard grids are solid nickel or molybdenum (typically nickel in 300Bs), not plated and why would the grid current be reduced? And why would that improve tonal quality?

Just a'wonderin...
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Michael L
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#7

Post by Michael L »

It's a mystery. Also puzzling to me that I can get this crackling or for that matter any output to the speaker when the o/p stage B+ is still switched off. I normally switch this on after the heaters have
been on a minute or so.
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#8

Post by Nick »

Well, I assume the gold alters the contact potential, and possibly any out gassing from the grid (don't know about the latter).

The matched single (I assume) is because if you previously (for example) get a quad and one fails, send them their previous matching data and they will find another single to match the set.
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#9

Post by jack »

Nick wrote:Well, I assume the gold alters the contact potential, and possibly any out gassing from the grid (don't know about the latter).
Not seen out-gassing from grids mentioned anywhere in the literature...

Nickel has a work function of 5.01eV and gold of 5.1eV - a difference of 2% - whilst contact potential is related to the difference in the work function value of the two metals in contact, looking at the maths any effect would be tiny, especially as emission from the grid is controlled by the surface work function which is either gold, nickel for the grid itself or copper for the grid supports - secondary emission effect are also very small for the grid (by design). I'm not even sure why contact potential comes into this at all... Reading around, gold grids seems to have dubious value, as the gold can sputter unless the grid current is carefully limited and is in itself a failure mode.

Eimac use gold plated grids in high-temperature transmitting tubes with oxide-coated cathodes as this reduces primary & secondary emission from the grid - again, they don't state by how much (http://www.cpii.com/docs/related/22/C&F2Web.pdf) - anyway, 300Bs use a thoriated tungsten cathode, not an oxide coated one as thoriated cathodes don't "strip" as fast in higher voltage tubes - oxide cathodes in that environment last up to about 2,000 hours - thoriated ones routinely last between 5,000 - 10,000 hours.

So, if the grid current is decreased, I wonder how large the effect is of gold plating (if anything, the maths shows it to be tiny), and what effect would that have on the tube "tone"? But, hey, gold looks cool :)
Nick wrote:The matched single (I assume) is because if you previously (for example) get a quad and one fails, send them their previous matching data and they will find another single to match the set.
That make sense - hadn't thought of that - guess you return a good tube to have one matched to...
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Nick
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#10

Post by Nick »

If you have the previous boxes from HR, then they will have the numbers on. But I am sure they will match to a existing one as well.
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#11

Post by Michael L »

Nick wrote:If you have the previous boxes from HR, then they will have the numbers on. But I am sure they will match to a existing one as well.
I do have the boxes with the figures Nick. Do you know what valve condition can cause this problem?
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#12

Post by Nick »

Avinunca1 wrote:
Nick wrote:If you have the previous boxes from HR, then they will have the numbers on. But I am sure they will match to a existing one as well.
I do have the boxes with the figures Nick. Do you know what valve condition can cause this problem?
I would only be guessing.
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#13

Post by Greg »

nickds1 wrote:Not seen out-gassing from grids mentioned anywhere in the literature...

Nickel has a work function of 5.01eV and gold of 5.1eV - a difference of 2% - whilst contact potential is related to the difference in the work function value of the two metals in contact, looking at the maths any effect would be tiny, especially as emission from the grid is controlled by the surface work function which is either gold, nickel for the grid itself or copper for the grid supports - secondary emission effect are also very small for the grid (by design). I'm not even sure why contact potential comes into this at all... Reading around, gold grids seems to have dubious value, as the gold can sputter unless the grid current is carefully limited and is in itself a failure mode.

Eimac use gold plated grids in high-temperature transmitting tubes with oxide-coated cathodes as this reduces primary & secondary emission from the grid - again, they don't state by how much (http://www.cpii.com/docs/related/22/C&F2Web.pdf) - anyway, 300Bs use a thoriated tungsten cathode, not an oxide coated one as thoriated cathodes don't "strip" as fast in higher voltage tubes - oxide cathodes in that environment last up to about 2,000 hours - thoriated ones routinely last between 5,000 - 10,000 hours.

So, if the grid current is decreased, I wonder how large the effect is of gold plating (if anything, the maths shows it to be tiny), and what effect would that have on the tube "tone"? But, hey, gold looks cool :)
I don't understand the science as you do but I can offer a subjective observation. I have trialled basic EH 300B's and compared with the Gold Grid versions. The goldgrids are far more transparent and revealing. The standard version is dull sounding in comparison. I know that proves nothing because we don't know if the addition of gold is the only difference between them although visually they look identical except the latest gold version (received a new quad two days ago) now includes gold plated pins and a thicker glass envelope.
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#14

Post by Michael L »

I emailed HotRox who I bought the valves off six months ago. There was no reply at all so I called them today. My initial joy at being offered a replacement was soon dampened when I was told the guarantee is a mere 90 days.
What are my consumer rights? This seems unreasonable to me.
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#15

Post by Ali Tait »

That seems par for the course for valve sellers unfortunately.
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