2. tech-talk
  3. 193061-198816

Questions about tubes and their subsitites

Hi all.

I use a Cary PH301 phono stage in my system. I have enjoyed this phono pre for many years. Been tube rolling lately as well as swapping various preamps and also some cartridge swapping, trying to find the best combination with what I have. The Cary PH301 uses 5 tubes, 12AU7 buffer, 2 12AX7 for MM and adds 2 12AU7's for MC. I use Sylvania Gold Pin 5751's in the AX7 spot, I have a Sylvania 5814 in the buffer spot (Cary suggests this replacement in the manual). Question one is why is a 5814 considered a replacement for 12AU7 when their values are so far apart? AU7's have gain of less than 20, 5814's are the same gain as 5751, at 70. Why are the 5814's considered to replace 12AU7? 5751 also is 70 but is considered to replace 12AX7, which is at 100. I don't quite understand the hows and whys of this. Any thoughts? Thanks,

Bill

billpete
yogiboy's avatar
yogiboy
5,758 posts
 

I have used Sylvania /Baldwin green label tubes and they are outstanding. I am now using GE 12 type and 5751 tubes in all my gear and I won’t be replacing them. I like them a lot!

billpete OP
7 posts
 

I just got a batch of 5 Sylvania 3 mica 5814's to see what I think of them. I have not tested them yet to make up pairs. After I do, I'll see how they compare to the Gold Pins. I've never really been disappointed by any Sylvania tubes. I have a pretty good collection of Sylvania, RCA, Amperex and others. I do have a fair amount of GE's. I'll have to check to see if I have any of their 5751's but I don't think I do, probably just have AX and AU7's. They were fine when I used them, I just found the Sylvanias more to my liking. I'm sure this stuff varies a great deal from one component to another. I don't think there is any way to make cheap Chinese tubes sound good but I'm sure really good tubes will vary from one component to another. 

Also, wrote to Cary to see what they have to say about my experiment. I've noticed that for a serious listen (which is pretty loud), I've gone from 12 or 1 o'clock to 11 o'clock on the preamp volume. I may remove the SUT just for kicks to see if it gets better or worse. At 11, with no record spinning, I hear a slight tube hiss so I may be close to where I need to be even with the SUT. Only way to figure it out is to try both ways. 

billpete OP
7 posts
 

Yogi

I looked through some of my tubes and found that I have quite a few GE 5751's. I'lll give them a try at some point to see how they compare with the Sylvania GP's. Never heard a word from Cary on my experiment. I have not had the greatest luck with answers from them or others either. VPI was another to ignore me. I have a bearing problem in my HW 19, parked it for now. I did switch it back to the original bearing but have been playing around with some older TT's...........yes, even older than VPI HW 19. An old Lenco and a Micro Seiki. I have others as well....all are old. Still enjoyable. 

More to discover