# 70's VibroChamp - Rectifier



## ed2000 (Feb 16, 2007)

I was about to fire up this little beauty after 10 years of rest. It's 5Y3 tube is missing. I have a 5U4G and 5AR4 tube. Which can I install without harming the circuit?


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## Lincoln (Jun 2, 2008)

I'm not a tech, but I believe you can use can use either one of those tubes. They are both capable of passing higher current than the 5Y3 but that shouldn't matter. 

Wait for the Pro's to show up to be sure.


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## WCGill (Mar 27, 2009)

Possibly the 5AR4, much higher voltage to the tubes, it'll sound different for sure. If the filter caps are marginal after that long being idle, they may not like the extra voltage. On the other hand the slow voltage ramp-up of the 5AR4 is easier on them. 5U4G isn't a good choice because it draws 50% more heater current than the 5Y3, putting stress on the power transformer.


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## jb welder (Sep 14, 2010)

Sometimes people install diodes inside and leave the socket empty. You didn't say whether you used it 10yrs ago or got it from someone, so in case you don't know, try it without a rectifier.


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## ed2000 (Feb 16, 2007)

I've owned the amp for close to 20 years but stopped playing it because something was "off" with the tone and never followed up on it. It had the full compliment of tubes.

I'll install the 5AR4 and hope for the best.


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## traynor (Sep 14, 2012)

*DON'T * put anything other than a 5Y3, and avoid the new ones they don't all drop the voltage like a vintage one.


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## Guitar101 (Jan 19, 2011)

ed2000 said:


> I've owned the amp for close to 20 years but stopped playing it because something was "off" with the tone and never followed up on it. It had the full compliment of tubes.
> 
> I'll install the 5AR4 and hope for the best.


A used 5Y3GT just came up on Kijiji. I have no idea what the GT stands for or if it would work for you. Location is Toronto.

_RCA 5Y3GT Rectifier Tube - used 
Printed factory code on the base: 57 - 09 
Made in the USA _


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## nonreverb (Sep 19, 2006)

5AR4 will work but as stated, B+ will be significantly higher. Unless the circuit has been serviced with new caps, I wouldn't try it. The "GT" stands for glass tube. 57-09 is the 9th week of 1957 production. Looks to be untested so it can be a bit of a crap shoot.


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## Gizmo (Aug 7, 2008)

This old thread might be of some help.

http://www.guitarscanada.com/index.php?threads/vibrochamp-hi-b.54944/


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## ed2000 (Feb 16, 2007)

Tremelo Question...
I don't recall if the knobs being turned activates trem or is a footswitch needed?
It's not working via knobs. Tubes are in place and lit.
Come to think of it I haven't powered it up in 15 years.


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## ampaholic (Sep 19, 2006)

No foot-switch needed.


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