Recent content by MDR30

https://sv.wikipedia.org/wiki/Svenska_Elektronr%C3%B6r_AB

12AT7.

Mullard (1963), Telefunken (1968), Siemens (1969). Shield between the anodes per the construction of ECC85. Draws 435 mA heater current compared to 300 mA of the ECC81.

The ECC85 (1954) has an amplification factor of 57, and can be seen as a more modern version of ECC81. I have used it in several of my amps with excellent results. Top brands like Telefunken, Siemens etc can be had fairly cheap.

One possible explanation could be a burnt resistor in the PSU. They often turn brown/black so should be easy to see if you open the amp.

A pair of the very rare Sony MDR-CD999 with "amorphous diamond diaphragms". The headphone plays very nicely. As can be seen on the photos the left side yoke has been broken, but is repaired. Pads are worn but a set of new pads (not original) are included.

Sorry, there is no code "under" the tube designation, only below: I7B, September 1957, Brookville, PA. As for my original inquiry, it seems still to be somewhat of an enigma: the code BNC on the Silvertone 6SN7GTB. I can't remember if Sylvania used this three letter code on their other...

Not only for the X9000, but this work will test your headphones to the limit: (cd/high res better) I'd also recommend Stravinsky's Firebird with Chailly/Concertgebouw (Decca), and for dare-devils only: Varèse's Ameriques with Boulez/NYPO (Sony Classical). Lighter fare: Mozart Symphony No. 25...

https://vacuumtubearchive.com/volume-21-number-6/ Page 86, the article "Deciphering Sylvania Date Codes 1943-1988".

Made a mistake in my previous post. The Philco/Sylvania 6SN7GTB code should be I7B (which Doug2507 correctly stated). First letter month, second digit year, third letter factory. So: September 1957, Brookville, PA.

No number. I have a virtually identical tube (marked Philco!), they are a perfectly matched pair, which has the code "17B" on the top. I think that one is from 1957.

Got this Sears/Silvertone 6SN7GTB manufactured by Sylvania. Would be interesting to know which year it was made but I haven't been able to decipher "BNC". Any ideas?

What is "Dellay"?

GEC6080 with a Valvo (Philips print) ECC81 from 1954, red tip. Sounds great. Chatham 6AS7G and Siemens frame grid E283CC. Nice.

Sylvania 6080 is a workhorse, strong and reliable. First alternative I got for my OTL amp. But was it a 6080? Not sure. Seems to be a mixup opportunity here. "Same internal structure as... with a different bottle".