[mordy]

Hi hypnos 1,
 
I have three Tung Sol 5687 tubes, one with bronze plates from 1966, one black plate 1964, and another black plate unknown year (markings rubbed off). The two black plates look similar. There is a school of thought that the older the tube is, the better it sounds. It may very well be that the workmanship and quality control were better in the early tubes. On the other hand, Audiofanboy (remember him? - wonder what happened to him) advocated that later tubes may have benefited from continuous research and development. In general, I try to approach tubes without any preconceived ideas and let my ears judge.
 
The black plate TS from '64 together with the two Sylvania 6080WB tubes sounds excellent at this time after burn in. This combination is just as good as the two Chatham 6AS7G with the Sylvania 5687 or Sylvania subminiature 7963. At first I thought that the Sylvania 6080's were used because they looked a little grimy and dirty. However, it could be that they just got dirty from lying around without boxes for several decades and they may be new.
 
(Here is another purple water lily from two years ago - no connection to tubes other than beauty)

 
The beautiful sound I am listening to cost me me $13 for the three tubes.

 

[hypnos1]

  Hi hypnos 1,
 
I have three Tung Sol 5687 tubes, one with bronze plates from 1966, one black plate 1964, and another black plate unknown year (markings rubbed off). The two black plates look similar. There is a school of thought that the older the tube is, the better it sounds. It may very well be that the workmanship and quality control were better in the early tubes. On the other hand, Audiofanboy (remember him? - wonder what happened to him) advocated that later tubes may have benefited from continuous research and development. In general, I try to approach tubes without any preconceived ideas and let my ears judge.
 
The black plate TS from '64 together with the two Sylvania 6080WB tubes sounds excellent at this time after burn in. This combination is just as good as the two Chatham 6AS7G with the Sylvania 5687 or Sylvania subminiature 7963. At first I thought that the Sylvania 6080's were used because they looked a little grimy and dirty. However, it could be that they just got dirty from lying around without boxes for several decades and they may be new.
 
(Here is another purple water lily from two years ago - no connection to tubes other than beauty)

 
The beautiful sound I am listening to cost me me $13 for the three tubes.

 
Hey, m...first you taunt me with wonderful memories of times in the Caribbean - viz the lilac-coloured lily, then with your uncanny ability to get good tubes for PEANUTS...have you no pity, lol?!

.
 
ps. You MUST share your guidance on how to get the deals over on the Feliks-Audio thread...PLEASE - it may well be needed to help any interested parties, especially to find some good "cheep cheep" 6SN7s!
 
Cheers...

 

[gibosi]

  I have three Tung Sol 5687 tubes, one with bronze plates from 1966, one black plate 1964, and another black plate unknown year (markings rubbed off). The two black plates look similar. There is a school of thought that the older the tube is, the better it sounds. It may very well be that the workmanship and quality control were better in the early tubes. On the other hand, Audiofanboy (remember him? - wonder what happened to him) advocated that later tubes may have benefited from continuous research and development. In general, I try to approach tubes without any preconceived ideas and let my ears judge.

 
I think there is no doubt that tubes benefited from continuous R&D. However, after a few iterations, most tubes likely reached a level where no further improvements were deemed necessary. Changes after that typically added features, such as higher peak voltage and power ratings for the 6SN7GTA and controlled heater warm-up in the 6SN7GTB (which didn't necessarily make them "better") or reduced the cost of production. Reducing the cost of production was especially important going into the 1960's and later. Solid state was the new state-of-the-art, and by that time many tubes had become mass-produced commodity items manufactured primarily to keep old tube equipment running. If you will, in the early tubes, changes were implemented to make them better. In the later tubes, changes were implemented to make them cheaper.
 
So it is not at all clear to me that the very first version of a tube is the best. But it does make sense that the second, third and fourth versions may well be the best. Fortunately, I cannot afford first versions, but in my experience, tubes manufactured in the 1940's and through the '50's and very early '60's, when tubes were still state-of-the-art, often sound better than later tubes.
 
All that said, Mordy's approach has considerable merit. The vast majority of these tubes were designed for use in IF, HF and VHf applications, and therefore, one cannot assume that the best VHF amplifier is going to be the best audio amplifier. Keeping an open mind can result in considerable savings and serendipitous treasures.

 

[hypnos1]

   
I think there is no doubt that tubes benefited from continuous R&D. However, after a few iterations, most tubes likely reached a level where no further improvements were deemed necessary. Changes after that typically added features, such as higher peak voltage and power ratings for the 6SN7GTA and controlled heater warm-up in the 6SN7GTB (which didn't necessarily make them "better") or reduced the cost of production. Reducing the cost of production was especially important going into the 1960's and later. Solid state was the new state-of-the-art, and by that time many tubes had become mass-produced commodity items manufactured primarily to keep old tube equipment running. If you will, in the early tubes, changes were implemented to make them better. In the later tubes, changes were implemented to make them cheaper.
 
So it is not at all clear to me that the very first version of a tube is the best. But it does make sense that the second, third and fourth versions may well be the best. Fortunately, I cannot afford first versions, but in my experience, tubes manufactured in the 1940's and through the '50's and very early '60's, when tubes were still state-of-the-art, often sound better than later tubes.
 
All that said, Mordy's approach has considerable merit. The vast majority of these tubes were designed for use in IF, HF and VHf applications, and therefore, one cannot assume that the best VHF amplifier is going to be the best audio amplifier. Keeping an open mind can result in considerable savings and serendipitous treasures.

 
Nice one, gibosi

 

[gibosi]

A Telefunken PCC85 arrived today. As you might remember, this is a 9 volt VHF double triode, 9AQ8 in the US, used in television tuners as RF amplifiers and oscillators. The structure seems quite simple, with box plates and an electrostatic shield. This one was manufactured in Berlin, 1970, probably. The fourth digit is the year, "0", and this coding system was implemented by Telefunken in the late 1960's.
 

 
Rummaging around among a lot of PCC88's I bought quite some time ago, I discovered that one of them was actually a PCC85! lol This one is a Valvo, manufactured in the Hamburg factory, in 1954, similar plates and shield, with a foil disc getter. I vaguely remember not being all that impressed with this tube, but then, I thought it was a PCC88 and was running it on 6.3V!
 

 
The Telefunken is burning in and I expect to spend some time with these tubes over the next several days.

 

[MIKELAP]

 Listening to some 6AV6 tubes sounded good back then still sound good now and as gibosi mentionned back then heres what to look for :                                                                                                                                                                                                                                                                                                       Of all the 6AV6 I have heard, the GE, Toshiba, FIVRE and Tung-Sol 6AV6 (and sisters, 6AT6 / 6AQ6) with box getters have the best sound stage, treble and detail. And further, after reading Mordy's observations, I think I can safely say that any 6AV6 with box-getters should be excellent.                                                                                                                                                                                                                                                                                                       And by the way those tubes are not plug &play first you need to be on EF91- 92 setting then you need to cut off pins 5 and 6 and cover the 2 pins youve just cut off  with electrical tape  and voilà your ready to rock& roll .                                                                                                                                        
 
                                                                                                                                   
 

 

[TrollDragon]

   Listening to some 6AV6 tubes sounded good back then still sound good now...

Nice one, I might just do the same for a while.

 

[mordy]

If you don't want to move the jumpers underneath you can always do the 6-7 wire strap and leave the jumpers in the EF95 setting.
 
EF91/92 = EF95 + 6/7-wire mod. See figure below.
 

 

 

I still remember how I felt when I first stumbled across the box getter 6AV6 variants:
 

 
 
Have not thought of making a comparison with the 5687 tube using 6080 power tubes, but now you piqued my interest. Wonder how they sound with heavy duty industrial grade 6080 backing?

 

[MIKELAP]

  If you don't want to move the jumpers underneath you can always do the 5-7 wire strap and leave the jumpers in the EF95 setting.
 
EF91/92 = EF95 + 6/7-wire mod. See figure below.
 

 

 

I still remember how I felt when I first stumbled across the box getter 6AV6 variants:
 

 
 
Have not thought of making a comparison with the 5687 tube using 6080 power tubes, but now you piqued my interest. Wonder how they sound with heavy duty industrial grade 6080 backing?

Thanks mordy for pointing that out i forgot about that, also if you dont want to freak out everytime you move jumpers get the long jumpers , man its really a night  and day difference lol.                                                                                                                                                                                                                                                            

 

[mordy]

I am sweating profusely. I always do when I change the jumpers underneath. Those little thingamajigs are torture for fumbly old hands and fingers with the added cold sweat feature of worrying about dropping one of them inside the amp. One came off easily, but the second didn't want to budge, but I finally got it out and placed both on the appropriate pins.
I couldn't use the 6-7 wire strap since on this tube pin #6 is cut off.
 
Thanks to my advanced storage system I was able to find the 6AV6 boxtop getter tubes within a few seconds. I have three pairs: Sylvania, Tung Sol and RCA + one Sylvania side getter. The RCA has an unusual "lollipop" style getter. Placing both tubes together makes them look like they have sunglasses on. My notes stated that they sounded the best, so I tried them.
 


The right tube in the box looks like this:
 

 

The box is in the shape of a silver box on top of the top mica. The side getter and brownish getter flash is also seen. This tube is marked C27. I think it is a Sylvania from March, 1962.
 
 
How do the 6AV6 RCAs sound? "Sounded good back then, still sound good now." Concur; however, even though the sound stage may be a little wider than the TS 5687, the bass, although very musical and detailed, doesn't have the slam and punch and doesn't go as deep as the 5687. Will give it time for a final conclusion.
 

 
I'll pop in the other two pairs later to see how it sounds with the 6080s.

 

[MIKELAP]

Got a question for 6hm5 owners do they all sound similar i have  a pair of G.E.'s, are the yugo's better sounding , no car pictures please lol 

 

[kvtaco17]

  Got a question for 6hm5 owners do they all sound similar i have  a pair of G.E.'s, are the yugo's better sounding , no car pictures please lol 

I disliked the GE's... the Yugo's were slightly tilted to the warm side and the Sylvania's were more neutral... the GE's sounded kinda thin... This is from memory...

 

[TrollDragon]

If you grab a pair of the Yugo 6HM5's MIKELAP, let me know how you like them and I'll grab a pair for myself.

 

[Rossliew]

I was just listening to my Mk3 st night with stock output tubes matched with the 6hm5 tubes driving hd600. My oh my, what glorious sound it makes! Palpable mids with punchy bass and smooth top end.

TD, you should get a pair to try out. They are inexpensive.

 

[TrollDragon]

Thanks Rossliew that sounds good, I think I will!