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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: 6u8a vs 6678 posted by Tweaker456 on January 27, 2014 at 13:59:36:
Tweaker456,
The ubiquitous 6U8 is a member of a family of related tubes >
6GH8, 6U8, 6BL8, 6EA8
tube....pentode Trans.....power.....triode Trans....power
6GH8......8500 umhos......2.5W......7500 umhos....2.5W
6U8.......7500 umhos......2.5W......5000 umhos....3W
6BL8......5000 umhos......1.5W......6200 umhos....1.7W
6EA8......6400 umhos..... 3.1W..... 8500 umhos... 2.5W
There are a lot of interesting 6U8 family variants >
6U8/ ECF82
RCA- US- NOS
Tung Sol- NOS
Siemens - NOS
Telefunken ECF82- USED
RCA - blk pl, stirrup gtr- 1960- NOS
RCA- 6678- NOS
Sylvania 6678- “Communications Quality”-gr pl- NOS
Sylvania “GB-1252" Gold Brand- gold pin- NOS
Notice the premium “Communications Quality” 6678 and the Gold Brand, gold-pinned “GB-1252"
6GH8A [6U8]
Amperex - France - NOS
Tungsram -Hungary - NOS
Midland- Japan- NOS
RCA- black plate- US- NOS
GE- US- NOS
Zenith- USED
RCA - 1- Motorola, 1- Zenith
It seems the 6GH8A became an inexpensive TV tube and there are warnings not to use the lower quality 6GH8 that are branded by TV makers.
Apparently there is quite a latitude in substitution and Modiaferri, who designed McIntosh tube tuners recommends using the higher output 6GH8A in place of the 6U8 on his designs. I use an Amperex, France 6GH8A in an MR67- very nice.
I don't hear a lot of differences in 6U8 variants, but higher output and stability are probably desirable. Overall, I would suggest Amperex or Tungsram 6GH8A or Sylvania 6678 Communications Quality. I've never tried the Sylvania Gold Brand gold pin GB-1252, but they might be worth looking into only because of rarity- I've only ever seen them offered for sale once!
Happy Åléþtinzį Everybody!
Bambi B
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Follow Ups
- 6U8A , 6678 and Beyond - Bambi B 01/30/1405:22:54 01/30/14 (1)
- RE: 6U8A , 6678 and Beyond - Tweaker456 16:24:15 03/8/14 (0)
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