Rocket rectifier reliability...

[eddie25]

Now that I am making a few of these for friends and musicians, I'm slightly worried about the reliability of the rectifiers. After searching on the subject a bit I've only learned that Ken just used really good tubes, which I don't have. I've made a some with 80uf and some with 94uf at the first node (sprauge vs. f&t values).

So has anyone been running theirs for years with low cost GZ34/5AR4, with no problems?

I'm thinking about trying to decouple the first two caps of my next build with maybe a 10R 5w resistor or something and see how that sounds. Has anyone tried something like that?

Thanks

[azatplayer]

I think the consensus is, because the first cap is filled before the standby switch is on, then its not an abrupt start to the entire supply, therefor reasonably safe for the rec. Of course the requirement for a good rec is still there. I ran a JJ in mine for over a year. I dont think it would hurt the amp much to drop that node to say 60uf tho. Pair of 30's in parallel would be great i reckon.

[eddie25]

Ok cool. The problem is that any quality GZ34's I've found are out of my price range so I'm looking at JJ and Sovtek. Mostly what I've read is that people are surprised that he did this high of filtering, but I thought I remember reading something like you said, so I needed to ease my mind a bit. Guess I'll have to do the ol' wait and see, though my original one has been running good for about 6 months or more.

[M Fowler]

I am an exception probably as I only use current production tubes and have a few old tubes scrounged but not many.

I do gig regularly and have over three years on my Stangray GZ34, 2 years on Rocket, Spitfire, and other amp's rectifier tubes.

I also put many hours each week on my other builds. The new production tubes are holding up so far. JJ, EH, and Sovtek. Not sure on all the brands.

Mark

[rawnster]

I'm going on a about 18 months with my rocket build using the same rectifier tube, and old Mullard GZ34.

[eddie25]

Well that's all good to know. Just a little concerned about the first filter node being way over spec for the GZ34 (should have clarified that in my first post). I've made a couple amps for serious gigging players and want them to be reliable, but this eazes my mind.

[passfan]

They'll let you know when you push it too far. They look like a tiny fireworks show going on inside the tube. I destroyed a couple of Russian 5V4G rec. tubes before I realized you couldn't put as many uf's as you wanted. The amp sounded really tight for a little while and then one day when I turned her on they erupted. They both test below the threshold now so I tossed them in my "oops" bin that I keep around to remind me.

[RJ Guitars]

I studied this for a while and found the best reports on current production tubes were the Sovtek GZ-34.

It's not entirely clear why Ken Fischer chose to use a rectifier tube but he did say he wanted to make the ultimate sounding AC-30 and he stayed pretty close to that schematic and parts lineup. He also mentions in the Trainwreck pages that the GZ-34 sounds and acts most like a solid state rectifier.

I have some of these rectifier replacement solid state modules and I've tried them in more than one Rocket amp. I found them to be mostly transparent for this build. The differences were pretty subtle...YMMV

I have used a Sovtek GZ-34 for a couple years now in may main Rocket build that I play through personally. It seems quite healthy and happy.

rj