[Oskari]

Quote:

Am I correct in that there were four major manufacturers: Toshiba, Matsushiita/National (Panasonic today), NEC and Hitachi?

 
Apparently those plus TEN (Kobe Kogyo, later part of Fujitsu) were the big names in receiving tubes postwar.
 
Quote:

Did Phillips supply tooling for all four?

 
As far as I understand, Matsush¡ta was not an established tube manufacturer and bought Philips technology to get in the game. The others may have been established manufacturers or had other partners. Hitachi, for example, co-operated with Raytheon (Hit-Ray brand!), and Toshiba was totally in bed with GE and NEC with Western Electric prewar.

 

[mordy]

Found a few bits and pieces trolling the Internet:
 
"Old Japanese tubes like Matsushiita, Awai, and examples made on the old Mullard tooling are some of the best values in tube HiFi IMO. "
 
"The link between Matsushiita and Philips was that they entered into a joint "technical cooperation" agreement starting 1952-53. In essence, Philips offered premier technical guidance in exchange for access of acknowledged managerial/corporate acumen of Mr. Konosuke Matsushiita, and I think there were financial compensations too. Unlike Mullard, Matsushiita was never owned or controlled by Philips, but starting 1953 much of their engineering, design, technical production including tubes was heavily influenced/donated by Philips and by mid-late '50s it certainly showed in their tubes, both literally and figuratively, across a spectrum of details. Matsushiitas tended to evolve along similar lines as W. Euro Philips versions "
 
Note: An added i has been added to the Matsu****a name to avoid censorship lol
 
PS: Awai brand?
 

 

[Oskari]

Quote:

PS: Awai brand?

 
Nothing. Error? Off-brand?

 

[Edgard Varese]

Quote:

There was a mention that it was hard to find the 6DT6 tubes. Here is a link to a seller I have dealt with several times. The prices are very reasonable, and this seller is very cooperative and honest.
 
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330994068719
 

Thanks Mordy, I have sent a message to the seller to ask whether he has a pair of RCA tubes...

 

[gibosi]

Quote:

 
See http://www.geocities.jp/antique_radio_exhibition/ as well.
 

1. http://www.geocities.jp/antique_radio_exhibition/tubes_mt1.html
2. http://www.geocities.jp/antique_radio_exhibition/tubes_mt2.html

 
After looking more closely at all these pictures, I now don't think my 6AV6 were manufactured by BESTO. As the pictures are not the best, it's really very hard to say with any certainty, but the tube it seems to match most closely is the second tube from the right:
 
http://www.geocities.jp/antique_radio_exhibition/tubes/6av6.jpg
 
The shape of the glass envelope, the mica, the tall getter support rod, the metal structure situated on the top mica look right. Unfortunately, we cannot see the getter or the top of the diode plates, but from what we can see, it matches up well....
 
The text indicates that this tube is manufactured by 日本ビクター株式会社 which translates to the Victor Company of Japan. We now know this company as JVC. Pre-WWII, RCA-Victor was the majority stock holder. After WWII, Matsushta (Panasonic) became the majority stockholder. (Since the "i" is not vocalized, writing "shta" facilitates the correct pronunciation and doesn't trip the forum censor. win-win) Anyway, these don't look anything like any RCA I have ever seen, and they don't look like the few pictures of Matsushta 6AV6 I have seen. So until I learn different, these are JVC 6AV6. This is my story and I'm sticking with it! lol

 

[gibosi]

Quote:

EF92s were semi-remote, but linear over the range we use(d) them, so OK. Remote cut-off tubes just won't be ideal on the standard LD amps. On the I+, it could be OK though, and I think gibosi had successfully tested a remote cut-off 6BA6 on his amp (you had, right? I forget...).

 
Yes indeed, I tested several pairs of 6BA6 in my LD1+, including a pair manufactured in 1947, and they sounds fine... maybe not great, but at least average.
 
The LD1+ uses tubes as buffers, not as drivers to provide voltage gain before a power tube. In fact, tubes in the 1+ provide something less than unity gain. Believe or not, you could cut all the tube circuitry out of this amp, replace it with a straight wire, and it would work fine. (Yes, it has been done! lol )

 

[Iron58p]

Using the cutter posted some days ago by Gibosi, is safe to put the cutting wheel against the glass ?
 
Or is better stay a little bit far ( for example 1 millimeter ) from it ? It's first time that i will do...

 

[gibosi]

Quote:

Using the cutter posted some days ago by Gibosi, is safe to put the cutting wheel against the glass ?
 
Or is better stay a little bit far ( for example 1 millimeter ) from it ? It's first time that i will do...

 
It is best to cut the pins as close to the glass as you can. It is safe. And you will discover that the pins are fairly soft and cut easily.

 

[Jesterphile]

Not incredibly impressed with my Little Dots build, I understand its a cheap amp made in China, but the transformer wasn't even screwed down and was banging around in its housing...
 
 
The amp sounds good though

 

[MIKELAP]

Quote:

Not incredibly impressed with my Little Dots build, I understand its a cheap amp made in China, but the transformer wasn't even screwed down and was banging around in its housing...
 
 
The amp sounds good though

A guy received is Burson Conductor and out of the box it wasnt working  good i understand or not at all turns a connection for the stepped attenuator wasnt even plugged in so these days you never know its like multiple recalls for cars its almost normal these days.

 

[MIKELAP]

Quote:

 
It is best to cut the pins as close to the glass as you can. It is safe. And you will discover that the pins are fairly soft and cut easily.

 
Quote:

Using the cutter posted some days ago by Gibosi, is safe to put the cutting wheel against the glass ?
 
Or is better stay a little bit far ( for example 1 millimeter ) from it ? It's first time that i will do...

 
 
Quote:

 
It is best to cut the pins as close to the glass as you can. It is safe. And you will discover that the pins are fairly soft and cut easily.

Personnally  i was tempted to use a cutting wheel also but like gibosi said there easy to cut with cutters and what remains about 2 millimeters  i file down with a small file being careful not to touch the other pins close by and after put electrical tape over the 2 pins you just filed down .

 

[Audiofanboy]

Quote:

 
 
 
Personnally  i was tempted to use a cutting wheel also but like gibosi said there easy to cut with cutters and what remains about 2 millimeters  i file down with a small file being careful not to touch the other pins close by and after put electrical tape over the 2 pins you just filed down .

 
I've done it the same way since the second pair of tubes I chopped up (on the first tube, pins snapped off clean and neatly, but on the second I tried it on, the tube imploded, so now I use cutters...).
 
I would tend to encourage using some kind of protection on the chopped off pins -like electrical or thick duct tape- just on the off chance that something gets connected somewhere it wasn't supposed to. It just seems silly to mangle your amp for a silly one-shot mistake...

 

[jaywillin]

does anyone know of or can you recommend a good reference book on tubes , starter guide, history etc ???

 

[duncan1]

For accuracy and presenting the true engineering also  specs. of tubes try to obtain  RCA tube manuals-Mullard  tube manuals-Osram-  Phillips-Mazda Also The Radio Tube-Vade-Mecum-1950s onward  especially- Radio Valve[tube] Data-- [ Wireless World-AKA-Electronics World.] Characteristics of 7000 tubes/6/7/8editions. While specs of tubes can be downloaded from the Web. It is much better to buy an old engineering manual as it  contains things like -inter-electrode capacitance-output at a set plate current/grid bias. etc and equivalents which is a lot easier to look through than keeping it on your PC. 

 

[gibosi]

Quote:

does anyone know of or can you recommend a good reference book on tubes , starter guide, history etc ???

 
Haven't really looked for any books, so if you find something, please let us know.
 
In the meantime, these might be helpful:
 
How Vacuum Tubes Work
by Eric Barbour
 
http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm
 
Pentodes connected as Triodes
by Tom Schlangen
 
http://www.kaponk.com/~yanyong/ETF06TS.pdf