[gibosi]

  Please let us know.  I got Lorenz and Siemens, but stayed away from Telefunken because they are supposedly the same.

 
As best as I can tell, all the shiny black C3g with white paint were manufactured in the 1970's by Siemens, regardless of the label -- Telefunken, Valvo or Lorenz. But prior to that time, in 1950's and '60's, Telefunken, Siemens and Lorenz all manufactured this tube in their own factories.
 
So. If a tube labeled as Telefunken is not as shiny as the '70's production and carries a Telefunken date code, it was manufactured by Telefunken. And while I cannot say at this time how it sounds, in my experience, tubes manufactured in different factories by different companies always sound different.

 

[whirlwind]

  I hope this will be an interesting respite from the problems some folks are having....
 
Received a pair of Telefunken C3g today and I am quite sure that these were actually manufactured by Telefunken. Upon close inspection, they do not look like rebranded Siemens to my eyes. What initially caught my eye was the Telefunken date code, "wr" (September, 1966).
 
Telefunken tubes link
 
I feel quite certain that as a general rule Telefunken did not put their date code on tubes procured elsewhere and relabeled. So my advice is look for this date code. If there is no date code, they are not most likely not genuine Telefunken.
 

 

 
So in terms of construction differences, how do they compare to the Siemens? First, while the cans are not flat-black and embossed like 1960's Siemens and Lorenz, they are not as shiny as the 1970's Siemens.
 
Compared to 1970's Siemens

 
Compared to 1960's Siemens

 
Since these tubes are enclosed in metal cans, the best and only place we can look for construction differences is the base. Note especially the area surrounding the base of the guide pin. The 1970's Siemens have a prominent escutcheon at the base, while the 1960's Siemens have no escutcheon. That area is almost perfectly flat with only a faint circle surrounding the guide pin. On the other hand, the 1960's Telefunkens have what looks like rays emanating out from the base of the guide pin.
 
Further, upon close inspection, there are also noticeable differences at the outer edges of the base where the metal cans are attached to the base.
 
1970's Siemens with prominent escutcheon

 
1960's Siemens with only a faint circle surrounding the guide pin

 
1960's Telefunken with emanating rays

 
Hope this is interesting and useful to those who roll C3g.
 
Cheers

It sure is helpful  

....thanks for the great pics...looking forward to your impressions.
 
The C3g driver tubes make all of my power tubes sound good 

 

[Xcalibur255]

Update:  amp appears to be operating normally with a different set of rectifers.  The ones that went cherry red were G's so I've put in another pair of G's to see if it happens again.  If it does then I'll just switch to using GA's permanently, which is a shame because I seem to have better luck finding tubes that aren't noisy with the G tubes.
 
That pair of Sylvanias that went crazy last night were the very first pair of 6BY5 I've ever found that were QUIET.  So of course something else had to go wrong instead. 
 
I really want to understand why that happened.  Why those tubes and not any of the others?  They're all the same and don't see how those particular tubes could draw more power and overheat themselves like that.

 

[TonyNewman]

  Update:  amp appears to be operating normally with a different set of rectifers.  ...

 
Glad your amp is working OK. A fried amp is no fun at all.

 

[2359glenn]

  Update:  amp appears to be operating normally with a different set of rectifers.  The ones that went cherry red were G's so I've put in another pair of G's to see if it happens again.  If it does then I'll just switch to using GA's permanently, which is a shame because I seem to have better luck finding tubes that aren't noisy with the G tubes.
 
That pair of Sylvanias that went crazy last night were the very first pair of 6BY5 I've ever found that were QUIET.  So of course something else had to go wrong instead. 
 
I really want to understand why that happened.  Why those tubes and not any of the others?  They're all the same and don't see how those particular tubes could draw more power and overheat themselves like that.

I will make you SS rectifiers as soon as I get tube bases. No more noise.
Due to the problems with rectifiers I am thinking of using SS in future amps. Plus easy to use them.

 

[TonyNewman]

 
...
Due to the problems with rectifiers I am thinking of using SS in future amps. ...

 
100% support this move. I like the glow of the PY500s, but do they add much to the SQ of the amp? Having seen what can happen when they fail I would be only too pleased to be without them and have SS rectification.

 

[2359glenn]

 

  Update:  amp appears to be operating normally with a different set of rectifers.  The ones that went cherry red were G's so I've put in another pair of G's to see if it happens again.  If it does then I'll just switch to using GA's permanently, which is a shame because I seem to have better luck finding tubes that aren't noisy with the G tubes.
 
That pair of Sylvanias that went crazy last night were the very first pair of 6BY5 I've ever found that were QUIET.  So of course something else had to go wrong instead. 
 
I really want to understand why that happened.  Why those tubes and not any of the others?  They're all the same and don't see how those particular tubes could draw more power and overheat themselves like that.

I will make you SS rectifiers as soon as I get tube bases. No more noise.
Due to the problems with rectifiers I am thinking of using SS in future amps. Plus easy to use them.

Ether one of them became gassy and started to conduct AC or one of them got a cathode to plate short.

 

[Xcalibur255]

A question that come to mind about using SS diodes..........  Are they harder on the power tubes because they turn on instantly (no soft start)?
 
I'm very curious to find out if they sound any different than a tube diode does.  I imagine the switching noise they generate isn't exactly the same.  As long as it doesn't sound hard/etched/glassy/glary it should be good.

 

[2359glenn]

  A question that come to mind about using SS diodes..........  Are they harder on the power tubes because they turn on instantly (no soft start)?
 
I'm very curious to find out if they sound any different than a tube diode does.  I imagine the switching noise they generate isn't exactly the same.  As long as it doesn't sound hard/etched/glassy/glary it should be good.

They will give you a higher B+ voltage to your tubes. Might sound better.
They are HEXFRED high speed soft recovery so they don't make much noise.

 

[JazzVinyl]

They will give you a higher B+ voltage to your tubes. Might sound better.
They are HEXFRED high speed soft recovery so they don't make much noise.

I like the SS rectifier option. Very nice.

 

[Khragon]

Just received my Glenn 300B amp!  Wow, great build, pictures don't do it justice, this thing is solid!
 
Upon listen, first thing I noticed is the expanded sound stage.  I'm not good at describing sound, but pairing with the Master 11 R2R DAC it sounded very good, very detail, yet non fatiguing.
 
Will give more impression, but now onto the pics:
 
 
The famous floatie tubes packaging, I got my toys and my kids got some too... just perfect:

 

 

 

 
 

 

 

 

 
Now got to take the family out to dinner.. can't wait to get back and give this a proper listen.
 
Thanks for a great amp Glenn!

 

[JazzVinyl]

How beautiful....!!!

Congrats!

 

[Khragon]

Here's a night shot
 

 

[TonyNewman]

  Here's a night shot
 

 
Nice.
 
Are those ER300Bs the "new. improved" version? How do you like the sound signature?

 

[Khragon]

Yeah they're ER300B, I got them as RMA from my first pair back in January, so they are supposedly the new base/design.  I really like the smoothness of these back when I have the WA5, and now with Glenn 300B, comparing from memory about a year ago, I get alot more details and clarity compared to the WA5 while still getting that mid range smoothness.  I can hear this fairly easily while comparing to my M11 SS amp.  Still burning these in, so that's my preliminary observation.  I have WE300B reissue as well as SERP, so will be rolling them in over time to compare.