What tube for QUIET phono pre??

[Freecrowder]

Was just posing the question about what tube type for phono front end would be the quietest ? I have just begun testing a Tetra with 12AX7 frontend. I hear some hum at full volume. May just need to play around with grounding /shielding some more. Comparing to my Bottlehead Seduction with 6DJ8 it is qiueter. The 6DJ8 is supposed to be a low noise design from what I have read.
Opinions???

[azazello]

CV4004 - Mullard /100$ aprox/.

[piano3]

6DJ8 and its equivalents are a good choice for low noise if you give it enough current. More ambitious would be 5842 single triode and its family,also Russian 6S3P or 6S4P. Very exotic choice might be Russian 6S45K. However low noise means low white noise,not hum.

[kevinkr]

D3A triode connected has an equivalent noise resistance of around 60 ohms and as SY can also attest is vanishingly quiet in a phono stage. In fact take a look at his article "His Master's Noise" for an excellent discussion surrounding the design criteria for a "blameless" phono stage. (I designed and built a D3A/5842 based phono stage 3 yrs ago, and without a doubt it is the quietest I have ever used)

[Merlinb]

Tubes don't produce hum on their own. Sounds like you need better ground wiring, a cleaner heater supply or B+ supply; different tubes won't fix that. Or maybe there is a transformer of some noisy piece of electrical equipment nearby?

[JMauck27]

These are THE BEST tubes for high-end audio equipment, much different than a guitar tube, these are made to be completely quiet and clean and bring out all the subtle nuances of your recordings. Fantastic tubes, kinda tough to find though, I found some at guitarpartsdepot.com

Hope this helps!

[Wavebourn]

Try VT-120

[ChrisA]

Originally Posted by Freecrowder

Was just posing the question about what tube type for phono front end would be the quietest ? I have just begun testing a Tetra with 12AX7 frontend. I hear some hum at full volume. May just need to play around with grounding /shielding some more. Comparing to my Bottlehead Seduction with 6DJ8 it is qiueter. The 6DJ8 is supposed to be a low noise design from what I have read.
Opinions???

"Hum" is not caused by a noisy tube. When we talk about a "quiet" tube we are talking about random thermal noise or "white noise" or "hiss". If you have hum this is something else.

Hum is caused by the AC power supply leaking into the signal. There are many paths by which it can leak:
1) ripple in the DC power supply
2) AC from the heater supply
3) magnetic leakage from the power transformer
Lots of other ways but fix the above first

[mogliaa]

Blackened Brimar 6SN7GT/CV1988 as recommended by Jones. Expensive but worth the investment for a RIAA pre-amplifier with 6SL7 as well