In my last post I talked about my growing awe for the Duelund Silver CAST 6.8uF capacitors, and my first reaction after a quick listen to the NOS RCA 6LCGC Black Plates (below right) that my buddy Leo brought over and the GE 6L6GC Grey Plates (below left) that came in my McIntosh MC30 mono amplifiers that I bought from Yves Beauvais at Vintage Vacuum Audio.

Both of these 6L6GC variations are extremely good, so keep that in mind that when I'm sharing my thoughts on these two fine vacuum tubes - there's no loser. It is rather more like comparing two fine bourbons, say Pappy Van Winkle’s Family Reserve 23yr and 20yr, which you'd consider yourself very lucky if you had access to either one, which is the same way I feel about these two fine examples from the 6L6GC Hall of Fame.

Price-wise there is a big difference between the RCA & GE, with the RCA 6L6GC Black Plates going for about $120 each when you can find them, and the GE 6L6GC Grey Plates going for about $75 each. That's expensive, but not as expensive as the best 300B tubes, for example.

Right now there's lots of good new stock vacuum 6L6GC tubes being made out there (that's a really good thing), although I don't think any of them that I have heard match these two vintage 6L6GCs.

The new production Tung Sol 6L6G (below) - which you can run as a 6L6GC - is definitely the prettiest of the new tubes with its ST bottle shape, and it sounds great too, just not as great as the NOS RCA & GE. I'll keep listening to new stock tubes as I get access and let you know my thoughts.

If you look closely at the photos, you'll notice there's quite a difference in the internal structure between the RCA and the GE.

While it is a little hard to tell in the photos, the GE Grey Plates are quite a bit lighter in color plate-wise than the RCA Black Plates. Under a light the Grey Plates are about the color of magnesium where the Black Plates are closer to the color of cast iron - a lighter grey vs. a charcoal grey.

The most obvious difference between the internals is that the GE has two getters and the RCA has one getter.

I also noticed that the bulb size between the RCAs was quite different. There's seems to be one RCA version that has a larger bulb (the one on the far right above & below), and one that has a more compact bulb size (the one to its left above & below). The RCA Black Plates that came in my MC240 are all the big bulb variety. The RCA internal structures look the same.

Hopefully the tube experts reading this will comment more about the technical differences between these tubes, which I don't know all that much about. But enough about that, the intertwined question is "What do they sound like and how well do the play music?"

As I mentioned earlier, McIntosh branded RCA 6L6GC black plates are what vintage specialist Tom Manley of McIntosh Home Audio put in the mint McIntosh MC240 I bought from him, and they have been a clear favorite for me in my MC240, but I haven't yet tried the GEs in it yet.

Now that I've got a little more time on Leo's NOS RCA 6L6GC black plates, I thought I'd put on the new  The Soul of Ben Webster 45RPM album from Analogue Productions that just came in the mail, and give it a listen.

On the musical side, the RCA black plates really make tempo, melodies, and rhythm come alive, which makes them exciting & engaging to listen to music with. The horns sound brasher and have more edge on the RCAs than with the GEs. The imaging, sense of space, soundstaging, and layering back into the depths of the soundstage with the RCAs is superb. The RCAs are tighter and punchier in the low frequencies, giving bass lines real propulsive power.

The GE 6L6GC Grey Plates are smoother and more laid back sounding, which I like a lot. Horns are tamed a little, with less brashness & edge compared to the RCAs. The GEs are not quite as transparent as the RCAs, but still by any measure they are nicely transparent, with superb imaging & soundstaging, but perhaps not quite as an obvious sense of layering back into the depths of the soundstage as the RCAs possess. The GEs don't have quite the same prowess as the RCAs when it comes to tempo, melody lines, and rhythm, but do best the RCAs in terms of timbre and tone color.

The verdict: I like the GE 6L6GC Grey Plates the best in my MC30s. They have a smoothness and richness that makes them easy on the ears, and as a side benefit they're almost half the price of the RCA 6L6GC Black Plates. You might come to the opposite conclusion, and favor the RCAs for their superior low frequency performance, and snappy renditions of tempo, melody, and rhythm. All I can say is I'm glad I've got a set of both.

In the future I'll report on the GE 6L6GC Grey Plates in the MC240 amp and see how they compare to the RCA 6L6GC Black Plates in that context.

As always, thanks for stopping by!