12B4 versus 6S4 for linestage

rcavictim · 1st December 2005, 03:19 PM

I have been reading the praises given the sonics of the 12B4 miniature triode. I do not possess any of those in my tube inventory but do have a small quantity of serviceable vintage 6S4's which kinda sorta look the same on the outside as far as 9 pin miniature bottle. Has anyone here experimented using the 6S4 as a linestage preamp and if so what were your results/conclusions? Thanx.

andyjevans · 1st December 2005, 10:44 PM

I've used both 12b4 and 6S4A as output tubes in a low power amp, and they both sound good. As you say, the base is similar but not identical, so you can build it with the 6S4As and then try 12b4 at a later date with just changing a couple of wires over.

Mark A. Gulbrandsen · 4th December 2005, 12:10 AM

Well, for starters the Rp is 3600 ohms which is alot higher than the 12B4. So I wouldn't get overly excited about driving a low impedance input with it but a highish impedance would probably be fine. It is capable of disipating 8.5 watts vs the 12B4's 5.5 (absolute max on both!). Be sure to let us know how it sounds....

Mark

rcavictim · 4th December 2005, 12:23 AM

Well as 12B4's aren't expensive and there are rave accolades about it's magic tone whereas there ain't nuttin being touted in a similar vein about the 6S4, if I go to the trouble I might just buy some 12B4's.

Tubes I have no shortage of, so I'm sure I have options without spending money. I was just wondering if someone else had used the 6S4 as a linestage preamp and what they thought of the sound.

Thanx for the replies so far.

andyjevans · 4th December 2005, 08:22 AM

Well as 12B4's aren't expensive and there are rave accolades about it's magic tone whereas there ain't nuttin being touted in a similar vein about the 6S4>

The 6S4 has its fans, though not so obviously. I wouldn't say the 12b4 is magic - it's actually a rather neutral clean sound. The 6AH4 is nice to my ears, and probably the 1626 which I haven't tried yet - they're 1.78k and 2.5k Rp. What is magic is the 2C22/7193, but that's 6.6k Rp and two top caps. Mind, that's where the magic is if that's what you want and you have a high input impedence on your amp. I thank my lucky stars i came across that tube.

1st December 2005, 03:19 PM	#1
rcavictim diyAudio Member Join Date: Jun 2004 Location: Cool end of a soldering iron NW of Toronto	12B4 versus 6S4 for linestage I have been reading the praises given the sonics of the 12B4 miniature triode. I do not possess any of those in my tube inventory but do have a small quantity of serviceable vintage 6S4's which kinda sorta look the same on the outside as far as 9 pin miniature bottle. Has anyone here experimented using the 6S4 as a linestage preamp and if so what were your results/conclusions? Thanx.

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1st December 2005, 10:44 PM	#2
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	I've used both 12b4 and 6S4A as output tubes in a low power amp, and they both sound good. As you say, the base is similar but not identical, so you can build it with the 6S4As and then try 12b4 at a later date with just changing a couple of wires over.

4th December 2005, 12:10 AM	#3
Mark A. Gulbrandsen diyAudio Member Join Date: Sep 2001 Location: Salt Lake City	Well, for starters the Rp is 3600 ohms which is alot higher than the 12B4. So I wouldn't get overly excited about driving a low impedance input with it but a highish impedance would probably be fine. It is capable of disipating 8.5 watts vs the 12B4's 5.5 (absolute max on both!). Be sure to let us know how it sounds.... Mark

4th December 2005, 12:23 AM	#4
rcavictim diyAudio Member Join Date: Jun 2004 Location: Cool end of a soldering iron NW of Toronto	Well as 12B4's aren't expensive and there are rave accolades about it's magic tone whereas there ain't nuttin being touted in a similar vein about the 6S4, if I go to the trouble I might just buy some 12B4's. Tubes I have no shortage of, so I'm sure I have options without spending money. I was just wondering if someone else had used the 6S4 as a linestage preamp and what they thought of the sound. Thanx for the replies so far.

4th December 2005, 08:22 AM	#5
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	Well as 12B4's aren't expensive and there are rave accolades about it's magic tone whereas there ain't nuttin being touted in a similar vein about the 6S4> The 6S4 has its fans, though not so obviously. I wouldn't say the 12b4 is magic - it's actually a rather neutral clean sound. The 6AH4 is nice to my ears, and probably the 1626 which I haven't tried yet - they're 1.78k and 2.5k Rp. What is magic is the 2C22/7193, but that's 6.6k Rp and two top caps. Mind, that's where the magic is if that's what you want and you have a high input impedence on your amp. I thank my lucky stars i came across that tube.

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