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Old 28th December 2010, 02:26 PM   #21
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Originally Posted by 20to20 View Post
By your experience you think these tubes are not linear?
no measurements, just listening... so don't know about linearity... but they all sound very good, with a slight edge in each area mentioned.
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Old 4th April 2011, 04:07 PM   #22
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Originally Posted by Trebla View Post
As ever, some varied replies. Thanks.

The amp is a homebrew DIY Paradise Simple EL84. B+ is 290v and sounding superb.

I currently have 4 very nice 6P14p-ev tubes doing push pull duty. But the 2 driver EL84s are unknown Chinese things, which although better than expected, are not as good as the Russian tubes in the bass department.
It's these i'm mainly concerned about.
If i can get away with just replacing these two then great.
Need some deep good quality bass.
Friend's grand father worked in the Nan-jing Tube factories until retirement in the early 90s, he told me a few stories. The factory was established after WWII, and had UK/US tooling, with imported materials; after the commie take-over, production continued, and after they used up the materials, they imported from Eastern Europe. Had a 80 tube from 1951, sounds great. 6V6 (6p6p), 6L6 (6p3p), 2E22 (FD-422) , 6SN7, 6J5 (6c5p), 6SL7 (6n7p), 5U4G (5z3p, 5z3PAT), 5Y3 (5z2p), 805 (Fu-5) and countless other were made in that factory.

There were also tubes factories around CN, like the one in Beijiang (Fullmusic's Mr Liu used to work there, they did some 12AX7(6n4), 12AU7(6n10), 6DJ8(6n11) and the 4p1s (DHT pentode find in Little Dot amp)).

The tube factory in Wunan (nowadays SG), made all the tubes made in the Nanjing Factory plus 6X5, 5842 (6C16, made in the 70s), 6AS7 and military tubes like 832(Fu-32), 829 (Fu-29), 833? (Fu-33), the factory had actually purchased machinery and tooling from Nan-jing's tube factory when the stop the civilian tubes's production. New and Old they sounded worst, had the worst quality in materials and construction; noted that since the 90s, tubes sold retail in CN are left overs from export orders, many of them are not to specifications, a general waste of time in my opinion. (scum bags!!) OEM purchases, such as those box of 50 seems to be better.

The are another tube facotry in Shanghai (6p1/6AK5 and radio tubes I think, big civil/military radio production around that area then), and one in GuangXi (went belly up in the 90s, the factory that made the 4300B, and civilian radio tubes in the old days, toolings sold to Guangdong and became Guiguang NGG tubes, quality still unstable, i had a 300B died on me, the tube were from their second year's production)

Mid 60s~70s tubes from Beijing & Nanjing seems to have a good reputation with local DIYers. I had a pair 6V6 (6P6P) from military packaging, those were OK.

early 1990s CN tubes are the worst, massive problems in quality and materials when the industry was trying to privatised, don't waste you time on those.

Last edited by Willleung; 4th April 2011 at 04:10 PM.
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Old 7th April 2011, 09:45 PM   #23
Ian444 is offline Ian444  Australia
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Join Date: Nov 2008
Location: Brisbane QLD
Quote:
Originally Posted by Trebla View Post
I currently have 4 very nice 6P14p-ev tubes doing push pull duty. But the 2 driver EL84s are unknown Chinese things, which although better than expected, are not as good as the Russian tubes in the bass department.
It's these i'm mainly concerned about.
If i can get away with just replacing these two then great.
Need some deep good quality bass.
Something maybe worth considering is using 6N1P-EV as driver.
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