Tung Sol Reissue 12AX7 not for CF stage !!!

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weasel
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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by weasel » Sat Oct 11, 2008 8:48 am

What is your cathode voltage? I'm thinking possibly they're failing from high cathode heater voltage rather than too much current - you'll find 12ax7 datasheets actually state max 200V heater to cathode. A good idea is to reference the centre tap of the filament supply to above ground - just voltage divide tap off B+.

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Guitarjb » Mon Dec 15, 2008 12:50 am

I agree that the Tung Sol 12ax7 reissue tubes sound great. But...I have had two which had a "hum" issue and I found out that this problem has not been uncommon with them.

Joe

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by LivewireBlanco » Tue Dec 23, 2008 6:39 pm

Been running the Tung Sol RI in my V2 on my JTM45 and Marshall Vintage Modern for almost a year now and they still sound excellent. Did I just get a good batch or what???
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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by HTH » Tue Dec 23, 2008 7:25 pm

weasel wrote:What is your cathode voltage? I'm thinking possibly they're failing from high cathode heater voltage rather than too much current - you'll find 12ax7 datasheets actually state max 200V heater to cathode. A good idea is to reference the centre tap of the filament supply to above ground - just voltage divide tap off B+.
^ +1

exactly what I was thinking when reading this thread too. referencing the heaters at around 50v will take the stress off the CF stage and makes the amp hum less too in my experience.
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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Ricky Lee » Mon Jan 05, 2009 2:18 pm

I have Tung Sol 12AX7 in all sockets of my 68 12xxx which has an extra tube for the effects loop and they sound great. However, I did have one go bad very quickly in v2 which I replaced with another Tung Sol 12AX7 that has lasted for months now with no issues. Maybe this is limited to just a bad batch of tubes.
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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Beserkr » Sat Jan 10, 2009 2:00 pm

How do the US made Tung-Sol compare to the re-issues?

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by novosibir » Sat Jan 10, 2009 2:47 pm

Beserkr wrote:How do the US made Tung-Sol compare to the re-issues?
Like a Boéf Stroganoff to a Hot Dog.

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Beserkr » Sun Jan 11, 2009 12:44 am

novosibir wrote:
Beserkr wrote:How do the US made Tung-Sol compare to the re-issues?
Like a Boéf Stroganoff to a Hot Dog.

Larry
Would they work well as a PI driver?

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by novosibir » Sun Jan 11, 2009 3:12 pm

What? The Hot Dog or the Boéf Stroganoff?

You aren't a friend of too many words, aren't you?

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Beserkr » Sun Jan 11, 2009 4:28 pm

novosibir wrote:What? The Hot Dog or the Boéf Stroganoff?

You aren't a friend of too many words, aren't you?

Larry
:D LOL

Ok, you got me.. I would be wondering about the Boéf Stroganoff aka NOS Tung-Sol..

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Rickey_Dee » Wed Feb 25, 2009 5:44 am

had tung sol 12ax7's too, after about 1 year the tube in the cf stage died... so i'd recommend replacing them and saving them as a spare tube for V1 or whatever, as they could fail at any time, even after 1 year. anyway, i'm using nos miniwatts and telefunken in this amp now, but i only gig with the tung sol's and a gt 12ax7m in v2 that i had left, cause no one in the crowd will mention if there is nos glass in your amp.
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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by baron55 » Fri Jul 03, 2009 9:54 am

Most of the 12AX7 types out of Sarotov (Sovtek, Electro Harmonix, Tung Sol, New Sensor) cannot handle the high cathode voltages.

Some of the design spec sheets I have seen on these tubes says the heater to cathode limit is 100volts, which is well below the 12AX7/ECC83 design spec of 180 to 200v.

Supposedly the Sovtek 12AX7WC can, but I have no experience or data on this tube.

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Roe » Fri Jul 03, 2009 11:29 am

this topic has not received the attention it deserves as people put the TS "RI" in the cathode follower all the time. even amp manufactures does this, selling something that will only last for a few days.

my 45/100 has 360v on v2 BTW :twisted:
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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by darkbluemurder » Mon Jul 06, 2009 6:11 am

The first two samples of the Tungsol RI sounded great. I then bought more, only to find out that they don't hold up in the phase inverter spot. I also found out that when used in amps where the first gain stage has a low value Rk the tube will cause the scratchy volume pot effect. By the average they are more microphonic than JJs or Chinese. Conclusion: I won't touch 'em again.

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Re: Tung Sol Reissue 12AX7 not for CF stage !!!

Post by Big Mike » Mon Jul 06, 2009 11:29 pm

I mostly use them in V1 of my cathode bias amps.
No issue (tung sol).
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