Paging Heiney9

snow

Hey Brock I have a couple of questions for you. Do you own or have you ever heard the CBS 7318 tubes before? I have some and I think they might be prototypes "Engineering Examples" because they have an odd designation after the 7318/SA2312

Here are a couple of pics.






Regards Snow

heiney9

I think what info you have in your Ebay ad is correct. Not sure about the prototype thing, but they are industrial tubes, 12AU7 equivalent, and not often seen for sale. Never heard them but I would make an educated guess they are similar in purpose as the CBS 7728 (12AT7 equivalent) that was used for radio broadcasting equipment. Very rugged and precision manufactured from the factory. Those are rare as well. I had a quad at one time of 7728's.

H9

snow

Thanks Brock for the extra info and your opinion. I have no solid evidence to support my theory on whether or not the SA312 desigination is a prototype code other then I have not seen it before, all the 7318 tubes I have seen had just the 7318 and nothing else and they have all been Red in color too.



Regards Snow

heiney9

It could very well be or they are a part number for a particular vendor that they supplied those for. It's as good a guess and any and they very well could be engineering examples. Although it looks as if they are packed for retail use.

I've come across few "engineering samples" in the past and they are not usually packaged like that and they usually have "test" data sheets with them. But anything is possible.

Also I have seen other CBS tubes from that era with the light (baby) blue printing labels that weren't engineering samples.

I am intrigued, but not really having any idea how they sound, too rich for me to take a chance on since I need quads these days.

GLWS.

H9

heiney9

Another idea I just thought of, they could be CBS's version of Amperex Holland made 7316. Heerlen Holland made long and short plate versions of the 7316 which is a ruggedized, precision matched tube used in computers of the day. They needed ot be rugged and long lasting since computers were constantly running, much like broadcast radio equipment of the day.

Any idea when these were manufactured? CBS stopped producing their own tubes pretty early on. But, perhaps they made some special types for specific applications like the 7728 for radio broadcast (as I mentioned before). The 7728's were black plates w/gold pins.

H9

pitdogg2

seems like you are doing good on that auction congrats. may it triple for you:)
interesting read here guys

snow

Thanks Pittdog. Brock you could well be right they could be numbers for a batch for a dealer. From what I have read the consensus seems to be these sound better then the Amperex 7316 tubes but are indeed an industrial tube. These were made in April 1961 not sure when they started and stopped.



Regards Snow

heiney9

I'd be in the bidding if I had heard them before and knew I liked them. For me, at this cost, never having heard them dissuades me from spending big $$$ and taking a chance. Granted I could recoup my $$$, most likely.

I personally don't think the 7316's sound any better than a standard ECC82 Holland tube and those just round out my top 10.

Anyway, a great rare find and I wish you well on the sale. Maybe some day if I run across a quad at what I think (I'm cheap) is a good price I might try them. Right now I have so many combo's to try, I'm not sure I have that much time left on this Earth to explore them all.

H9

snow

heiney9 wrote: »

Also I have seen other CBS tubes from that era with the light (baby) blue printing labels that weren't engineering samples.

Hi Brock I know the CBS 7730 12AU7 tubes had a light blue print but I think it was lighter then these not 100% sure though here is a couple of pics to compare. It appears the 7318 tube was started in late 1958 so these being made in 1961 would rule them out as proto types. Perhaps the SA stands for special application?





Regards Snow

dkg999

I have some CBS Hytron tubes that sound really nice. I would have to go dig through the box, however I believe they are 12au7's.

heiney9

Real CBS Hytrons are nice. Lots of tubes labeled CBS, but the fact is CBS only produced their own tubes for a very short time the rest are rebranded.

The CBS JHY-5814, bp, sq getter is a superb sounding tube.

H9

P.s. More accurate is that Hytron only produced tubes for a short time, CBS eventually bought Hytron thus the CBS Hytron label. I have an early 50's Hytron 12AX7 bp, looking for a mate. Super hard to find.