Back to the RCA 6DE7 discussion...
Originally Posted by Orcin
I got another set of RCA's. I bought them off eBay as "NOS". When I got them... well, it was like a box of chocolates as Forrest Gump's mother would say. They are the tubes that are shown in the picture two posts above this one.
The boxes are like new, and are date stamped 09/60. The tubes sound great in my amp, and I was pretty happy until I did a closer inspection. One of the tubes has the RCA logo and has the two plates with the shield. The other tube has no brand logo (completely rubbed off) and has the cross-style second plate with several perforations and no shield.
The tube with no brand logo is stamped 6DE7, but it does not say "U.S.A." above it like the RCA does and the size of the "6DE7" is slighter larger than the same printing on the RCA. The tube with no logo does not have the black box at the top of one of the plates like the RCA does, instead it is finished with a smaller thin black square like my Sylvania.
Is it possible that the tube without the shield is RCA also? Did they make both styles? This goes back to atbglenn's point that I quoted above. The construction looks like my Sylvania tubes, but maybe they are some other brand or RCA's made for someone else.
RCA or not, should I be happy to pair these tubes together if they sound good together? I don't see how it could harm the amp, and the sound is the ultimate grade card.
I tried these tubes against my Sylvania 6DE7's, 1970 RCA 6DE7's, and Sylvania fat bottle 6EW7's in a "power tube shootout" last night. The mystery tubes were a clear winner. They have better bass and clarity than any of the other tubes, without losing any of the soundstage that the 6EW7's demonstrate. This says a few things:
1. The state of my power tube collection is sad.
2. Sylvania tubes are weak on bass?
3. Jam is right when he says the older tubes are better.
I still prefer to have two tubes with the same cosmetics (and branding!). I'm still looking for those NOS 1950's RCA 6DE7's... they must be out there. It's nice to have something to chase.