[TK16]

Amplification factor for a 2C51 is 35, 6922 is 33, maybe that's the reason it is more susceptible to noise in the 2C51/5670 variants.

Looks like 6N3P is 33 I think. 30.3 for 6N23P. If my source was correct.
http://www.trioda.com/tools/triode.html

 

[Zachik]

Would an attenuator between source and LP help?
I mean we all know by now that the gain on the LP is pretty high, and there is no low/high gain switch, unfortunately...

Have ANY of you guys try an attenuator? If so - which? and would you recommend it or did it cause degradation in sound quality?

 

[Zachik]

I was discussing the LP with a buddy (who does not own one), and he mentioned 6CG7 tubes... according to him:
"It's a 9-pin version of the 6SN7, and is pin-compatible with a 6922 (no adapter needed). Amplification factor of 20. Only thing is that it pulls 600 milliamps of heater current versus 300 for the 6922 (the 396A pulls 500). Can the amp handle the higher heater current? Sounds like it handles the 500 milliamps for the 396A..."

I know @runeight is going to protest... but did anyone try or think about 6CG7 tubes? (no mention in this thread so far...)

 

[TK16]

600ma is way too high for the amp.

 

[Zachik]

600ma is way too high for the amp.

So where do you draw the line? I mean 396A is already at 500ma... and people use it...

 

[Phantaminum]

So where do you draw the line? I mean 396A is already at 500ma... and people use it...

Tube information:
https://www.radiomuseum.org/tubes/tube_396a.html

It pulls 350ma.

 

[TK16]

So where do you draw the line? I mean 396A is already at 500ma... and people use it...

You can run tubes around 350ma and under. 6922 variants, 2C51 variants, ECC82/12AU7, 6N3P. May of missed some but these are major players. You can't use E180CC (400ma draw) or the ECC81/ECC83/6N2P/6CC41 family due to the high multiplication factor.

 

[Zachik]

You can run tubes around 350ma and under. 6922 variants, 2C51 variants, ECC82/12AU7, 6N3P. May of missed some but these are major players. You can't use E180CC (400ma draw) or the ECC81/ECC83/6N2P/6CC41 family due to the high multiplication factor.

So, after buying several different 12AU7 pairs, what are your (and others') conclusions?
1. How do 12AU7 tubes compare (specifically in LP) to 6922 tubes, sound wise?
2. Are they likely to be noisy like 396A, or quiet like 6922 tubes?
3. Which are you recommending? @TK16 - early on in this thread Tele were your favorites IIRC. Since you bought others. How would you rate them?

 

[TK16]

With a few exceptions, I have found the best tubes imo require an adapter. Some exceptions Siemens, Telefunken, PW and D getter Heerlen 6922, some UK tubes. The Telefunken ECC82 are fantastic, but my favorite ECC82 is Blackburn Mullard square getter ECC82. Got some fantastic tubes in the ECC81 are truly top 4 or 5 pairs I ever heard. Talking about the Valvo Hamburg 6201 50's PW and early 50's Copenhagen ECC81. Amplification factor on ECC82 is 17 so you have a very good chance in no noise tubes.

 

[runeight]

So where do you draw the line? I mean 396A is already at 500ma... and people use it...

DO NOT use anything that takes more than 350mA heater current. If you do you might see longer term problems. The DC/DC converter that supplies the heater current has a MAX of 400mA. If you draw close to this or any more than this that converter is at risk. 350mA MAX protects the other parts of the heater circuit.

Be careful with what you are doing.

 

[TK16]

Anybody looking for a good priced Telefunken E188CC pair? My bro here has a pair.
https://www.head-fi.org/threads/tubes-price-drop.898467/

 

[Zachik]

DO NOT use anything that takes more than 350mA heater current. If you do you might see longer term problems. The DC/DC converter that supplies the heater current has a MAX of 400mA. If you draw close to this or any more than this that converter is at risk. 350mA MAX protects the other parts of the heater circuit.

Be careful with what you are doing.

Got it. Thanks Alex!

 

[MikeW]

What's the best tube pair you can find for ~200$. Adapters are ok.

How are the amperex a-frames? pretty cheap on ebay

 

[Wes S]

What's the best tube pair you can find for ~200$. Adapters are ok.

How are the amperex a-frames? pretty cheap on ebay

Depends on your system, and what you are wanting, to tweak. To many variables to have one best tube, for all.

 

[MikeW]

I prefer mid bass bump with slightly rolled off high end and a forwardish staging, not schiit forward but not huge, I find the stock tubes to be a little too wide for my pref.