has anyone used a chip for an input driver to a 2A3 or the like??

djn · 30th September 2010, 03:09 PM

I am building an amp that only has room for one tube each side. Can I use a chip as the driver for a 2A3, 45, 300B or the like???

azazello · 30th September 2010, 04:22 PM

Chip for driving 2A3, 300B....???? Serious.....????

kevinkr · 30th September 2010, 04:45 PM

What's the point? The large swings required mandate high voltage semiconductors (Power mosfets?) or transformers - probably will not sound like a tube amplifier either. Can you fit a pair of 5842/D3A or similar? They're really quite small. Alternately investigate 6112, 6021, 5903, 5744, etc. submini tubes which take up even less space, and could be under chassis mounted if need be..

epitaxial · 05:33 PM

www.electra-print.com

There are designs with power op amps that are getting twice the power from triodes, such as a 25w 300B SE and a 50w 300B PP. It should allow a chip to perform without getting hot, and both the chip and tube have quite good sound. I wouldn't know if it makes sense, but it is best to drive the ouput triodes with as strong a drive as possible, and this may do it.

leadbelly · 30th September 2010, 05:21 PM

It's been discussed more than once. Search on "LM4702" in the tube forum.

quinnling · 30th September 2010, 05:43 PM

DJN,

Have you seen this ?
Electra-Print.com Single Ended A2 6A3/300B

djn · 30th September 2010, 08:51 PM

It was just a thought. The chassis is at the paint show and I don't want to drill more holes if I decide to use another tube. The tube I am using right now is the 6LR8 with a pentode and triode in the same bottle. I am running 350v B+ SE.

I see that the Electra-print is running 500v B+ so that would mean changing PTX as well. Maybe best to leave it be as is.

CLS · 1st October 2010, 02:11 AM

Or, make the gain of your pre amp larger, it can be the driver. Like I did on my recent 2A3 spud preject

There must be around 100Vp-p swing on the output of the pre (now driver), at least.

djn · 1st October 2010, 02:48 AM

hey CLS, it was your build that got me thinking on it. I was just going to build a junk amp with a consol amp type chassis and the chassis has turning into a work of art and I think more fitting of a nicer tube. But at this point, I think I will build it with the 6LR8 and enjoy it.

CLS · 2nd October 2010, 12:02 AM

It's good to hear that

6LR8 seems an interesting tube. I'm thinking of 6EM7 for quite a while, too. Should be fun.

30th September 2010, 03:09 PM	#1
djn diyAudio Member Join Date: Oct 2004	has anyone used a chip for an input driver to a 2A3 or the like?? I am building an amp that only has room for one tube each side. Can I use a chip as the driver for a 2A3, 45, 300B or the like???

30th September 2010, 04:45 PM	#3
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	What's the point? The large swings required mandate high voltage semiconductors (Power mosfets?) or transformers - probably will not sound like a tube amplifier either. Can you fit a pair of 5842/D3A or similar? They're really quite small. Alternately investigate 6112, 6021, 5903, 5744, etc. submini tubes which take up even less space, and could be under chassis mounted if need be.. __________________ www.kta-hifi.net

30th September 2010, 05:16 PM	#4
epitaxial diyAudio Member Join Date: Sep 2010 Location: Middle Canada	www.electra-print.com There are designs with power op amps that are getting twice the power from triodes, such as a 25w 300B SE and a 50w 300B PP. It should allow a chip to perform without getting hot, and both the chip and tube have quite good sound. I wouldn't know if it makes sense, but it is best to drive the ouput triodes with as strong a drive as possible, and this may do it. Last edited by epitaxial; 30th September 2010 at 05:33 PM.

30th September 2010, 05:21 PM	#5
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	It's been discussed more than once. Search on "LM4702" in the tube forum. __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

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30th September 2010, 04:22 PM	#2
azazello diyAudio Member Join Date: Aug 2008 Location: Bulgaria	Chip for driving 2A3, 300B....???? Serious.....????

30th September 2010, 05:43 PM	#6
quinnling diyAudio Member Join Date: Nov 2004 Location: Charlotte	DJN, Have you seen this ? Electra-Print.com Single Ended A2 6A3/300B

30th September 2010, 08:51 PM	#7
djn diyAudio Member Join Date: Oct 2004	It was just a thought. The chassis is at the paint show and I don't want to drill more holes if I decide to use another tube. The tube I am using right now is the 6LR8 with a pentode and triode in the same bottle. I am running 350v B+ SE. I see that the Electra-print is running 500v B+ so that would mean changing PTX as well. Maybe best to leave it be as is.

1st October 2010, 02:11 AM	#8
CLS diyAudio Member Join Date: Jun 2005 Location: Taiwan	Or, make the gain of your pre amp larger, it can be the driver. Like I did on my recent 2A3 spud preject There must be around 100Vp-p swing on the output of the pre (now driver), at least.

1st October 2010, 02:48 AM	#9
djn diyAudio Member Join Date: Oct 2004	hey CLS, it was your build that got me thinking on it. I was just going to build a junk amp with a consol amp type chassis and the chassis has turning into a work of art and I think more fitting of a nicer tube. But at this point, I think I will build it with the 6LR8 and enjoy it.

2nd October 2010, 12:02 AM	#10
CLS diyAudio Member Join Date: Jun 2005 Location: Taiwan	It's good to hear that 6LR8 seems an interesting tube. I'm thinking of 6EM7 for quite a while, too. Should be fun.

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