[moodyrn]

I just received a pair of GE 5751 black plates I got off ebay. One tube is significantly brighter than the other one. Does that mean something is wrong. They both sound fine, but I don't know if something is wrong with one of the tubes or not.

 

[Redcarmoose]

I am very happy some one asked this some tube tops have a way brighter glow but the sound is perfect? What is the deal? You would think the glow would be the same?

 

[wallace]

I have three pairs of valves for my LD1+ ,and only one pair glow equally bright.
Can't hear any SQ difference with any of them. Bound to be cosmetic differences,they were hand made by humans in those days..,and i guess they still are..

 

[moodyrn]

Well I contacted the seller and he has agreed to take them back. So I guess all is well.

 

[Pricklely Peete]

If there are no SQ,noise,channel imbalance issues then they should be OK to use. Rarely are tubes of equal brightness but it does warrant some attention when one is much brighter than the other. Might be worth sending them to a member with a tube tester (or locally if possible) and get them checked out. If they are good you save the return cost to the vendor and you get keep those excellent 5751s

Peete.

 

[moodyrn]

There is a little hissing sound from the bright tube from time to time. The seller insists that they have been checked on two different tube testers and they both are supposedly matched(45/44 and 44/44). But the occasional hissing sound from the bright tube is a little alarming to me. I have two sets of 12ax7s(one stock chinese tubes), and the tubes in both sets have equal brightness. All of them are about the brightness of the less bright tube. But both tubes do sound the same though.

 

[Oskari]

Has the brighter one more of the heaters visible outside of the cathode sleeves? That could explain the difference and would be just cosmetic.

 

[moodyrn]

No, it doesn't appear to have.

 

[moodyrn]

These are definitely going back now. The bright tube is now emitting a constant hiss/static type noise. It started out as an occasional type hiss, now it's constant and louder. Thanks all for your input.

 

[MrGreen]

Have you had problems with the amp before?
This type of thing can happen when voltage/current going to each tube is different.

 

[moodyrn]

Well I had posted eariler that I have two other sets of tubes and they both work fine. So the problem is not the amp.

 

[OutdoorXplorer]

How bout switching the tubes and does the hissing still present?

 

[moodyrn]

Yes, it follows the tube.

 

[928GTS]

Sounds like the tube,if it didn't follow the tube then I would have thought your amp was running more filament on one tube versus the other.

 

[Redcarmoose]

3rd one over