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Help I.D. a tube

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S Clark

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Help I.D. a tube
« on: 20 Jan 2021, 10:58 pm »
Yellow Sylvania, mixed in with a bunch of 12AX7s. 
Just to the right of the large yellow block "Sylvania" is a smaller distinct "1h".  Below the 1h is a smaller acz
Near the top is a vertical USA. The horizontal number just to the left of the USA most likely ends in 8 (possibly 5). Not built like a 6dj8 type. Any suggestions beside throw it away?
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FullRangeMan

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Re: Help I.D. a tube
« Reply #1 on: 20 Jan 2021, 11:23 pm »
Its said ACZ are GE made in usa.
Silvania 19 70s years have few praises.
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charmerci

Re: Help I.D. a tube
« Reply #2 on: 20 Jan 2021, 11:39 pm »
There's some Sylvania 5931 Triple Mica H1-1 tubes on ebay now. They them?
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S Clark

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Re: Help I.D. a tube
« Reply #3 on: 20 Jan 2021, 11:51 pm »
No, they look like a 12au7, but the !h and acz don't match any 12au7 I can find. 
Gustavo, do you know where I can verify the "acz" lettering as meaning GE?

Looks like the left tube with the small letters at the end of the Sylvania


.
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FullRangeMan

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Re: Help I.D. a tube
« Reply #4 on: 21 Jan 2021, 12:23 am »
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S Clark

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Re: Help I.D. a tube
« Reply #5 on: 21 Jan 2021, 03:30 am »
I've found a reference that the "acz" may mean higher output.  Still don't know what it is.
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FullRangeMan

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Re: Help I.D. a tube
« Reply #6 on: 21 Jan 2021, 08:04 am »
Transcendental marketing goo tô guitar amps.
  HG = high grade (low noise & microphonics) for use in all stages of mid and low gain amps and all but the first stage in high gain amps.

HG+ = high grade plus (extremely low noise & microphonics) for use in the first stage in high gain amps.

12AX7AC5: 5th generation Chinese. The "standard" Chinese 12AX7 that almost every tube supplier sells. Short plates with a division shield between them. Tone: strong highs and mids with a slightly subdued bass character that can make some amps feel tighter...it depends on the amp and the player's touch. A great tube for a high gain amp or a lower gain amp that needs a little more bite.

12AX7AC7: 7th generation Chinese. An attempt to make a more NOS style tube. Longer plates than the AC5 but not nearly as long as a Sovtek LPS. No division shield between the plates. Tone: strong highs and fuller mids than an AC5 with a full, round bass character...a bit fuller than a TungSol reissue. Not so great in the first stage of a high gain amp but it does work well in later stages for a little more warmth. Sounds great in old Fenders but terrible in Rivera era Fenders.
« Last Edit: 21 Jan 2021, 09:50 am by FullRangeMan »
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