Tube Experts, Are these RCA Black Plates?

[bob06]

I just bought this amp but don't have it in my procession yet. It has RCA 6L6 tubes in it. I was wondering if these where Black Plates.:scratch2:

 

[buglegirl]

Hiya,

No ... The 5U4GB is black plate though ... note the difference in contrast.

Frannie

 

[Dukiedook]

Huh, when one guy on here a while ago had pics of Tung Sols that looked grey to me people insisted they were black plates. They looked grey to me like those RCAs do.

 

[buglegirl]

Huh, when one guy on here a while ago had pics of Tung Sols that looked grey to me people insisted they were black plates. They looked grey to me like those RCAs do.

So you are doing a "huh" to actual Gray plate tubes by your own admission because I say they are not Black.

Look around ... you will see actual Black Plate RCA 6L6GC's that look surprise ... Black not Gray

Ok ...

EDIT:: After reading what you wrote I guess you are siding with my observation ...

Frannie

 

[buglegirl]

Hiya,

Maybe they are talking about the Queens English "Grey" vs our USA "Gray" ... heck who knows ...

But Black is Black and only people wanting extra money or who are clueless call a Grey/Gray Plate Black.

Frannie

 

[Tom Bavis]

They look like 6L6GCs from here - should last a long time in an amp designed for 6L6GBs. (and I'd be happy to trade black plate 6L6GBs for 'em...)

 

[bob06]

Hiya,

No ... The 5U4GB is black plate though ... note the difference in contrast.

Frannie

Now that I look closer I can see the difference between both. Thanks.

 

[bob06]

So even thou there not blacks plates I will take it they are still good tubes to have. Thanks Guy's. :thmbsp:

 

[frankxbe]

So
Look around ... you will see actual Black Plate RCA 6L6GC's that look surprise ... Black not Gray

observation ...

Frannie

OP , like these NOS real deal black plates ....not the grey ones that were likely re labled GE's they all made tubes for each other back then depending on demands

U could just drop some 6L6 GT they are same same see below ( *usually matched pairs or quads ofc )but in a pinch work otherwise . 0 ******

That being said ....... AFAIK the 6L6GC is the high current standard for Guitar amps .but data sheet are same same and 6L6 GT were common high powered 6L6 back in the day GE made a ton of them for RCA IIRC also that usually what U got re labled from RCA 4 6L6 GT replacements .

6L6 GC

Class Va Vg2 Vg1 Ia Ig2 Rk Zout Pout THD Notes
Line output 700 350 70.0 6.0 100
Line output 60 250 0.0 180.0 18.0
A P/P 360 270 50.0 9.5 250 shared 9,000 24.0 4.0
A P/P (triode) 325 42.0 375 shared 8,000 6.0 0.6
AB2 P/P 360 270 -22.5 69.0 8.0 6,600 26.5 1.8
AB2 P/P 360 270 -22.5 69.0 8.0 6,600 26.5 1.8
AB1 P/P 450 400 -37.0 116 - 210 5.6 - 22.0 5,600 55.0 1.8
RF, C (CW) 750 250 -45 100 6 50
RF, C (AM) 600 275 -90 100 6.5 42.5
RF, AB1 750 300 -35 15-70 3-8 72
RF, B 750 0 15-240 120 Input on g2, g1 connected to g2 via 20k ohms
=====================================================================
6L6 GT

Class Va Vg2 Vg1 Ia Ig2 Rk Zout Pout THD Notes
Line output 700 350 70.0 6.0 100
Line output 60 250 0.0 180.0 18.0
A P/P 360 270 50.0 9.5 250 shared 9,000 24.0 4.0
A P/P (triode) 325 42.0 375 shared 8,000 6.0 0.6
AB2 P/P 360 270 -22.5 69.0 8.0 6,600 26.5 1.8
AB2 P/P 360 270 -22.5 69.0 8.0 6,600 26.5 1.8
AB1 P/P 450 400 -37.0 116 - 210 5.6 - 22.0 5,600 55.0 1.8
RF, C (CW) 750 250 -45 100 6 50
RF, C (AM) 600 275 -90 100 6.5 42.5
RF, AB1 750 300 -35 15-70 3-8 72
RF, B 750 0 15-240 120 Input on g2, g1 connected to g2 via 20k ohms

 

[PakProtector]

Just keep in mind the issues NASA had making sure the pictures the Mars rover sent back were as would seen in person. The best comparison would be a side-by-side with a known sample of the RCA BP...I have seen some rectifiers look deep, inky black next to a real RCA BP...
cheers,
Douglas

 

[Dukiedook]

So you are doing a "huh" to actual Gray plate tubes by your own admission because I say they are not Black.

Look around ... you will see actual Black Plate RCA 6L6GC's that look surprise ... Black not Gray

Ok ...

EDIT:: After reading what you wrote I guess you are siding with my observation ...

Frannie

Yep. People kept telling this guy his Tung Sol 6550s were black plates when unless his camera was jacked they appeared to be gray to me. Hehe, the pommies on my motorcycle site have me spelling gray wrong.

http://www.audiokarma.org/forums/showthread.php?t=647155&highlight=6550

 

[byoungman1]

At the risk of being contrary, the tubes in the OP's photo do appear to be black plate 6L6GC's. The plates of the 60's era RCA 6L6GC's often appear more of a charcoal color, relative to the "shiny" black plates produced by others. Took a picture of some RCA 6L6GC black/charcoal plate tubes I have here to show the "illusion"/difference.

 

[bob06]

I should have the amp next week so I will take a close up picture and the mystery will be solved. I read some where that the black plates are better?

 

[bob06]

At the risk of being contrary, the tubes in the OP's photo do appear to be black plate 6L6GC's. The plates of the 60's era RCA 6L6GC's often appear more of a charcoal color, relative to the "shiny" black plates produced by others. Took a picture of some RCA 6L6GC black/charcoal plate tubes I have here to show the "illusion"/difference.

The ones in the amp do look like that. :thmbsp:

 

[frankxbe]

At the risk of being contrary, the tubes in the OP's photo do appear to be black plate 6L6GC's. The plates of the 60's era RCA 6L6GC's often appear more of a charcoal color, relative to the "shiny" black plates produced by others. Took a picture of some RCA 6L6GC black/charcoal plate tubes I have here to show the "illusion"/difference.

I would buy that.... those are more black than grey whereas the grey ones * I recall* were more grey than black :scratch2:

 

[Sam Cogley]

I think those might be black plates that are simply getting more light on them than the 5U4GB next to them. They're nowhere near as light-colored as grey-plate tubes, and RCA, to my knowledge, never made anything but a black-plate 6L6GC. They could be re-labled GEs, but they look more like RCA construction to me. Better pics, including the etching on the glass, are necessary.

 

[buglegirl]

Hiya,

So you guys are saying that its a subjective thing as in darker shades of Gray always equals Black. I understand now.

If you want them to be Black Plate enough anything will look Black after a while.

I get what this is about from a Audiophile point of view.

Placebo effect anyone ???

Frannie

 

[buglegirl]

Hiya,

After thinking a bit more about this I have come to the conclusion that more important than what something looks like its about how a tube performs that is key.

RCA 6L6GC's are excellent tubes and while some plates may or may not be true Black perhaps they are all considered Black for the purposes of tube merit.

As far as Black vs Gray plates. Heck its your ears that matter. The tube sounds better may be more about the construction over plate color or maybe its plate color if that makes one happy.

This is about being happy with the sound in the end no matter what color or shade something is ... right ???

Frannie

 

[Sam Cogley]

Hiya,

After thinking a bit more about this I have come to the conclusion that more important than what something looks like its about how a tube performs that is key.

RCA 6L6GC's are excellent tubes and while some plates may or may not be true Black perhaps they are all considered Black for the purposes of tube merit.

As far as Black vs Gray plates. Heck its your ears that matter. The tube sounds better may be more about the construction over plate color or maybe its plate color if that makes one happy.

This is about being happy with the sound in the end no matter what color or shade something is ... right ???

Frannie

Every RCA 6L6GC I've seen has that dark color to them. Grey plates are much lighter, like the GE 6L6GCs (which I prefer for hi-fi anyway).

 

[zandru]

Yes! they most certainly are Black Plate.. (Case Closed)