Tube info very old coin base

heiney9

Anyone have any general input about older, rare coin based tubes? I have run across a pretty good deal on very early 12AT7 coin base tubes. These are some of the earliest 12A*7 type tubes to be manufactured.

Here is a pic of a coin base see how the bottom is completely flat



Here's a normal base tube



Just wondering if there are any inherent problems with these very early production coin base type tubes. I know some of the early Telefunkens with the 45* getter have some noise issues, etc.

Thanks

H9

heiney9

Late 40's to early 50's for the coin base. The ECC81 was the first double triode with noval socket introduced by Valvo in 1951. So maybe 1951.

Research states the coin base is ultra rare and extraordinary. Not sure if that translates to superior sound or not. One site groups it with the blue label gold pin Valvo 6201 which is thought by many to be one of the two best 12AT7's ever produced. The other being the Telefunken ECC801S, I have both the 6201 Gold Pin and Tele ECC801S and they are superb tubes

H9

heiney9

The pair I'm looking at were made in 1952 according to the tube code.

heiney9

Keiko wrote: »

And quite pricey from what I've seen. Maybe I'll get lucky and find some within my budget one day. Of course there's always the PLaSMa CeNTeR.

Yeah, if you look like I did you can find a good deal.

I paid about $60 for each pair which are used, but test strong. They both last forever 10,000+ hours and the triodes are well matched from the factory to begin with.

I looked on Ebay every day for about 6-7 mos. to find those kinds of deals and missed many others by being outbid.

NOS- forget about it!!! You'll be into $300-400 range for true NOS with boxes, etc of either one

H9

organ

Try doing a search in audioasylum's tube forum. There's a lot of info on old/rare tubes there.

Very interesting tube. I've never even heard about the coin base until you posted this.

mhardy6647

nor have I (and I fell off the turnip truck a long time ago).

heiney9

http://www.hifiaudio.cn/en/article.jsp?id=15

Scroll down to Valvo tubes; middle tube in the first row vertically

http://www.tube-classics.de/TC/Tubes/Valvo%20ECC81/ECC81.htm

1st tube listed in the above link.

That's how I know, otherwise I wouldn't have been aware either. I just decoded the code to get the year and month of production July 1952 and it looks like Valvo produced the first ECC81 noval tube in 1951.

H9