[gibosi]

There appear to be two versions of the Brimar 5R4GY/CV717.
 

 
The one of the left is older, October, 1956, whereas, the one of the right is newer, probably from the 1960's or later, judging by the halo getters. To my old ears, they sound substantially the same. Has anyone else compared these?

 

[leftside]

Does the one on the right have the double mica with ceramic spacers? I've heard good things about that tube and picked up a couple recently (haven't arrived yet). One branded Ultron and the other branded Haltron. Both with the double halo getters. I'm thinking they could actually be made by Brimar. I'll let you know what they sound like when they arrive.

 

[gibosi]

Yes, it is the one with the double mica and ceramic spacers. And I am quite sure that both of these 5R4GY were manufactured by Brimar, but at different times. And again, to my ears they sound substantially the same. But my ears are old and not all that good, so I wonder if others also find them to sound about the same...

 

[abvolt]

I have the same one on the left which sounds awesome sure would like to get my hands on the double mica tube guess I'll have to start looking for one..enjoy

 

[auricgoldfinger]

If anyone is interested, I have a GEC U52 brown base and a Marconi U52 black base for sale.  The GEC was originally owned by @Dubstep Girl and is an excellent tube.  When I bought the Marconi, it had never been used.  It comes with the original box.  I have <10 hours on it.  The Marconi is considered by many experts to be the best of the U52 family.
 
PM me if you are a serious buyer.  Thanks.

 

[gibosi]

To the best of my knowledge, all U52 were manufactured in Hammersmith by the GEC / MO Valve Company. The label applied after the manufacturing process - GEC or Osram or Marconi - was more a function of marketing than anything else. That said, the Marconi label is often found on older tubes, and it may well be that older U52 sound different than newer ones. However, I do not know this to be true....

 

[auricgoldfinger]

  To the best of my knowledge, all U52 were manufactured in Hammersmith by the GEC / MO Valve Company. The label applied after the manufacturing process - GEC or Osram or Marconi - was more a function of marketing than anything else. That said, the Marconi label is often found on older tubes, and it may well be that older U52 sound different than newer ones. However, I do not know this to be true....

 
GEC and Marconi were separate companies that were later merged.  The brands were made in different plants in different countries, and they have distinct sound qualities.  Their tubes were originally made for different end user markets.
 
That is all factual information, not conjecture.

 

[gibosi]

From the Wikipedia article on Marconi-Osram Valve:
 
"The company was founded in 1919, when the valve making interests of GEC (Osram) and the Marconi Company were combined."
 
This was a good 20 years before the U52 was developed and manufactured at Hammersmith.

 

[auricgoldfinger]

  From the Wikipedia article on Marconi-Osram Valve:
 
"The company was founded in 1919, when the valve making interests of GEC (Osram) and the Marconi Company were combined."
 
This was a good 20 years before the U52 was developed and manufactured at Hammersmith.

 
The tubes were made in different plants in different countries.  They have different sound signatures.  Talk to dealers, or listen to them yourself.  If your system is good enough, you will hear differences.

 

[Oskari]

The tubes were made in different plants in different countries.  They have different sound signatures.  Talk to dealers, or listen to them yourself.  If your system is good enough, you will hear differences.

If your U52s are true UK U52s, then they clearly were not made "in different plants in different countries". On the other hand, if your Marconi is a, say, Canadian-made tube, perhaps you should make this known.

 

[gibosi]

  The tubes were made in different plants in different countries.  They have different sound signatures.  Talk to dealers, or listen to them yourself.  If your system is good enough, you will hear differences.

 
How about some pictures?

 

[auricgoldfinger]

I stand corrected regarding the country of manufacture.  I got the Marconi out of storage and it is clearly marked as made in England.  My apologies to all.
 
That said, the tube have different sound signatures.  You can ascribe it to whatever reason you choose...I really don't care.  If your system is good enough, you will hear the difference.  If your system is not sufficiently transparent, the tubes may sound indistinguishable to you.
 

 

[gibosi]

  I stand corrected regarding the country of manufacture.  I got the Marconi out of storage and it is clearly marked as made in England.  My apologies to all.
 
That said, the tube have different sound signatures.  You can ascribe it to whatever reason you choose...I really don't care.  If your system is good enough, you will hear the difference.  If your system is not sufficiently transparent, the tubes may sound indistinguishable to you.
 

 
Again, how about some pictures?
 
It is certainly possible that this tube was manufactured by another British company and relabeled as a Marconi U52. This was common practice back in the day. With good pictures, the construction will reveal which company manufactured the tube and the approximate date of manufacture.

 

[Seamaster]

I think there are brown base and black base U52, i have one of each. they have different gaters

 

[gibosi]

I think there are brown base and black base U52, i have one of each. they have different gaters

 
Usually, black bases are older than brown bases. Do the two that you own sound different?