Metal RCA 6V6's in a 5E3

springhead

Friend of mine gave me a NOS pair of them.  They measure about the same as the new Tung Sol 6V6's I had in previously.  Idling at about 12W.  They sound very good, maybe a bit more attack on notes.  They smell different!  Hot metal I guess, and maybe a bit of 60+ year old paint burning in.

Anyone else tried them?

ryanverbena

I always thought this was a huge no-no?

No real justification, just remember being strongly advised against it once. 

ICBM

ryanverbena said:

I always thought this was a huge no-no?

No real justification, just remember being strongly advised against it once. 

Probably just about OK in a 5E3 Deluxe - the HT and screen voltages are quite low, although still above the valve ratings. Definitely a bad idea in a Princeton Reverb or Deluxe Reverb, or even a BF/SF Champ, they will probably fail immediately.

springhead

From data sheets I found the spec was the same. I always had it in my head that the metal versions were lower rated though. The anodes are sitting at about 360V with around 18V on the cathodes. So 340 ish across the valve.  Have you seen data sheets that suggests that’s pushing them?

I run that amp with power scaling which works very well in a 5E3 so most of the time they’ll just be ticking over. 

ICBM

springhead said:

From data sheets I found the spec was the same. I always had it in my head that the metal versions were lower rated though. The anodes are sitting at about 360V with around 18V on the cathodes. So 340 ish across the valve.  Have you seen data sheets that suggests that’s pushing them?

The datasheets do suggest that, but more importantly the practical experience of a large number of builders and techs is that the metal ones don't survive at Deluxe Reverb-type voltages but 6V6GTAs do.

springhead

What does a deluxe reverb run them at , 400+ ?they do sound rather good and as with my power scaling they’ll be probably under 200 most of the time apart from any outdoor festivals hopefully all is well.  

ICBM

springhead said:

What does a deluxe reverb run them at , 400+ ?

Yes, typically around 420V.

RiftAmps

The metal screen is connected to pin1 which is usually the parking point for the grid-stopper on modern 5E3 builds. I would just confirm socket wiring before continuing.

springhead

RiftAmps said:

The metal screen is connected to pin1 which is usually the parking point for the grid-stopper on modern 5E3 builds. I would just confirm socket wiring before continuing.

Good catch. I built the amp but can’t remember if I used pin 1. I’ll open up and check. Thanks!