Got the '65 Princeton out of the closet - tube question

Tom Huff

Tom Huff

New member
I noticed that it just didn't sound right. It got noisy really quickly and had a lot of crackling and hiss.

I turned it off and examined the tubes. The 6V6 pair were old Whirlwind branded black tubes that I put in there years ago. The 12AX7 tubes were one old Mesa SPAX7-A and a British Mullard. I pulled the Mesa and left the Mullard in there just because.

Then came the 5U4GB. It is an old RCA. At first I was happy to see it but upon examining it I noticed that it has what appears to be 2 tiny cracks or deep scratches inside the bottle. That leads me to believe this tube has limited life for sure.

So... I yanked out the Whirlwind branded power tubes and replaced them with a new matched pair of EH 6V6GT and the Mesa pre with a new EH 12AX7 gold I had in the closet.

I didn't have a replacement 5U4GB so I went on line and ordered a SED Winged C 5U4-G and a EH 5U4GB. I figured I'd swap them to see if I can hear the difference in the behavior of the amp with each.

My question is this, the Winged C is labeled 5U4-G and not GB. Is this going to be an issue with the DC voltage as compared to a 5U4GB tube?

Also, have you guys ever seen a crack or scratch inside the bottle like I described? This is a first for me. Maybe I just caught it before the crack broke through?
 
Re: Got the '65 Princeton out of the closet - tube question

Someone can correct me on this,but I think "G" just means Glass and "GB" Glass Bottle..Either way you should be fine if you use a true 5U4 spec rectifier tube...The tube converts your 120 volt wall current into dc voltages that your amp needs..
 
Re: Got the '65 Princeton out of the closet - tube question

The 5U4G should be totally interchangeable with the 5U4GB. I have never seen a tube with cracks inside the glass, but I would be hesitant to use it. If you don't like the 5U you ordered, here is a link to get an ANOS RCA to replace it for $15. A brand new NOS RCA will run you $48. The RCA's are considered by some to be the best of the best in 5U4GB'. You can also replace the original GE with NOS for $24. Very reasonably priced tubes.

http://www.kcanostubes.com/catalog/16
 
Re: Got the '65 Princeton out of the closet - tube question

Thanks Guys. Jeff, I'll go check out that site. I've never been to it before. I usually use thetubestore or boiaudio.
 
Re: Got the '65 Princeton out of the closet - tube question

I hope you find something you like that make the amp sound fantastic Tom.
 
Re: Got the '65 Princeton out of the closet - tube question

It is such a nice sounding amp. I forgot how much I loved it. I've been playing my giant rigs and my 4 watt Matamp for so long it was a breath of fresh air once I plugged this baby in.

Thanks Jeff. I will most likely put in those two new issue 5U4s that I bought then in a month or two get another NOS RCA for it.
 
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