New Tubes, Funny Behavior
Posted: January 23rd, 2017, 6:50 pm
Hi All
I have a EL34 type tube amp.
A couple years ago I started rolling tubes, and I found some pretty nice Psvane UK reproductions that I liked. They have been in service for this whole time, and I have had zero issues with them.
I found some listings on Ebay however for a new (even more premium) Psvane EL34PH Phillips Holland Reproduction, so I bought a quad. (preamp and predriver tubes are still 6sn7 Psvane UK reproductions I bought around the same time as the UK output tubes).
When I got the box of four tubes, I was excited because everything looked really premium. Pretty quickly however, I located two tubes that had some minor cosmetic flaws. One was a little bit of glue squeezing out between the base and the glass on one tube, that I didn't find any evidence of on the other three. Another was that the painted Psvane label on one tube, when it was located in the mount, didn't face straight ahead. And the last was that the shape of the glass on one tube was slightly differently shaped than then glass on the other three.
I know! I'm knit-Picking almost stupid, irrelevant details, but I didn't find any of those imperfections in the four Psvane UK tubes I bought a couple years ago!
I wouldn't have thought too much about it because the tubes sound brilliant, but today (day 3 of the tubes being in service), I turned on my cold amplifier, and there was a spark in one of the tubes. A slightly loud "pop" coming through my speakers accompanied it, and afterwards I found the offending tube had a little bit of brown residue on the inside of the glass near the top of the tube that I have seen on tubes before after prolonged use, but was not present on the other three.
Apparently there was no damage, because the amplifier still works perfectly fine, but I don't want to take too many chances with this happening again.
I don't suspect there is anything wrong with the amplifier, because I have swapped in several differnet complements of tubes, and it has never done that before.
If it does happen again I'm going to swap the UK tubes back in.
Does anybody have any Ideas what might be happening?
Did I get faulty tubes?
Maybe I bought seconds of something some sort of un-official Psvane seller?
I set the bias current to the figure the literature with the tubes indicated. Would there be anything funny happening here?
I like the Phillips Holland better than the old UK tubes, so if I can resolve the problems, that's the tube I want to use.
If I have to buy new ones I will, but I would like to have some comprehension of why I'm suddenly having this problem with the tube I bought.
Thanks,
Any advice would be welcomed!
Chris
I have a EL34 type tube amp.
A couple years ago I started rolling tubes, and I found some pretty nice Psvane UK reproductions that I liked. They have been in service for this whole time, and I have had zero issues with them.
I found some listings on Ebay however for a new (even more premium) Psvane EL34PH Phillips Holland Reproduction, so I bought a quad. (preamp and predriver tubes are still 6sn7 Psvane UK reproductions I bought around the same time as the UK output tubes).
When I got the box of four tubes, I was excited because everything looked really premium. Pretty quickly however, I located two tubes that had some minor cosmetic flaws. One was a little bit of glue squeezing out between the base and the glass on one tube, that I didn't find any evidence of on the other three. Another was that the painted Psvane label on one tube, when it was located in the mount, didn't face straight ahead. And the last was that the shape of the glass on one tube was slightly differently shaped than then glass on the other three.
I know! I'm knit-Picking almost stupid, irrelevant details, but I didn't find any of those imperfections in the four Psvane UK tubes I bought a couple years ago!
I wouldn't have thought too much about it because the tubes sound brilliant, but today (day 3 of the tubes being in service), I turned on my cold amplifier, and there was a spark in one of the tubes. A slightly loud "pop" coming through my speakers accompanied it, and afterwards I found the offending tube had a little bit of brown residue on the inside of the glass near the top of the tube that I have seen on tubes before after prolonged use, but was not present on the other three.
Apparently there was no damage, because the amplifier still works perfectly fine, but I don't want to take too many chances with this happening again.
I don't suspect there is anything wrong with the amplifier, because I have swapped in several differnet complements of tubes, and it has never done that before.
If it does happen again I'm going to swap the UK tubes back in.
Does anybody have any Ideas what might be happening?
Did I get faulty tubes?
Maybe I bought seconds of something some sort of un-official Psvane seller?
I set the bias current to the figure the literature with the tubes indicated. Would there be anything funny happening here?
I like the Phillips Holland better than the old UK tubes, so if I can resolve the problems, that's the tube I want to use.
If I have to buy new ones I will, but I would like to have some comprehension of why I'm suddenly having this problem with the tube I bought.
Thanks,
Any advice would be welcomed!
Chris