12b4a phase splitter! The best?

el156 · 15th April 2010, 10:37 AM

Hello everibody
I am working in my latest amp and testing phase splitters to find up the best sounding one!
The output is EL34 ultralinear PP and tested 12At7,12Au7,12aX7 as phase splitters, but i found in my old box 2 12B4A tubes, and connected them with 9K resistor cathod to ground,9K plate to B 300V and grid to previous tube plate (12At7) with 100V plate voltage! And i found i have the best sound i ever had!
Does someone tested this tube (12B4A) as phase splitter?
If not TEST IT because it sounds raelly NICE!
Best Regards!

andyjevans · 15th April 2010, 01:20 PM

This is a concertina you are talking about?

Bandersnatch · 15th April 2010, 01:53 PM

hey-Hey!!!,
Running a pair as LTP in a linestage. B+ near 500, 20k plate loads, CCS tail and plate voltage ~125. Very nice performance and balanced output to drive a Rane crossover. tried also triode-strapped EL86 with similar results, slight edge to the 12B4. Quite sensitive to vibration picked up from the top plate from the power supply Iron. Going to fix it with a separate plate for the amplifier section and some damper rings like herbies tube dampers.
cheers,
Douglas

el156 · 15th April 2010, 03:21 PM

Quote:

Originally Posted by andyjevans

This is a concertina you are talking about?

Yes, concertina or i thik is also called cathodyne ! I only have 3 12B4A and would like to buy some more ! If someone has some to sell ,i am interested in some!
THANKS (Obrigado)

Palustris · 15th April 2010, 03:47 PM

That makes sense as with a concertina (split load) you want a tube with low mu (there is no gain with this stage anyway) and high transconductance. The 12AT7 and 12AX7 would be eliminated right away as unsuitable given the requirements. If you like the 12B4 then try the 6S4. Even better try the 6EM7 with the high mu as the voltage amp and the low mu as the phase splitter.

radiostar · 15th April 2010, 09:03 PM

ECC40 is also interesting, simply adore that tube specially like phase splitter!

15th April 2010, 10:37 AM	#1
el156 diyAudio Member Join Date: Apr 2010 Location: ALBUFEIRA ;PORTUGAL	12b4a phase splitter! The best? Hello everibody I am working in my latest amp and testing phase splitters to find up the best sounding one! The output is EL34 ultralinear PP and tested 12At7,12Au7,12aX7 as phase splitters, but i found in my old box 2 12B4A tubes, and connected them with 9K resistor cathod to ground,9K plate to B 300V and grid to previous tube plate (12At7) with 100V plate voltage! And i found i have the best sound i ever had! Does someone tested this tube (12B4A) as phase splitter? If not TEST IT because it sounds raelly NICE! Best Regards!

15th April 2010, 01:53 PM	#3
Bandersnatch diyAudio Member Join Date: Jul 2003 Location: Ann Arbor, MI	hey-Hey!!!, Running a pair as LTP in a linestage. B+ near 500, 20k plate loads, CCS tail and plate voltage ~125. Very nice performance and balanced output to drive a Rane crossover. tried also triode-strapped EL86 with similar results, slight edge to the 12B4. Quite sensitive to vibration picked up from the top plate from the power supply Iron. Going to fix it with a separate plate for the amplifier section and some damper rings like herbies tube dampers. cheers, Douglas __________________ the Tnuctipun will return

15th April 2010, 09:03 PM	#6
radiostar diyAudio Member Join Date: Apr 2009	ECC40 is also interesting, simply adore that tube specially like phase splitter! __________________ tubes.rs facebook.com/tubes.rs

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15th April 2010, 01:20 PM	#2
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	This is a concertina you are talking about?

15th April 2010, 03:47 PM	#5
Palustris diyAudio Member Join Date: Aug 2006 Location: Cape Cod	That makes sense as with a concertina (split load) you want a tube with low mu (there is no gain with this stage anyway) and high transconductance. The 12AT7 and 12AX7 would be eliminated right away as unsuitable given the requirements. If you like the 12B4 then try the 6S4. Even better try the 6EM7 with the high mu as the voltage amp and the low mu as the phase splitter.

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